Kanban is a tool governed by rules, which serves to organize the flow of production based on the operation of a supermarket or the process of pulling what is required, using visual instruction labels that serve as work orders for:
kanban-explanation-cards-instruction-variants- Production, indicating at least what has to be produced and in what quantity, as well as indications of stoppage and incorporation of changes to production allowing immediate action in its programming; Transport, what to mobilize, how to do it and by what means.
It is an expedited scheduling of customer demand based on current consumption that will exclusively replace what is consumed, producing only what is indicated on the instruction cards instead of using forecasts. It is a "paperless production control system, where the authorization to pull or produce comes from the subsequent process" and not from forecasts or assumptions. It is a fundamental part of the Lean Manufacturing developed by Toyota, which focuses on controlling the work in progress of the process. Communicate visually what to produce; seeking to make a small batch operation as fluid as possible to achieve a process as continuous as possible, guaranteeing the continuity of consumption. The objective sought is to minimize work in progress and consequently minimize inventories,based on continuous supplies so that you have the amount you need, where you need it when you need it.
A Kanban card is an authorization to produce and / or move inventory. The Kanban card system is a method that controls stocks and uncovers problems and opportunities for change. Cards can be replaced with an electronic system. The typical analogy is that of a boat navigating a river, in which the level of the river represents the stock in the inventory, which being very high causes all waste and waste to be hidden; but it also causes cash flow problems, lost opportunities in other more profitable investments. When the company tries to lower the inventory level (water level), problems appear (rocks).High levels of inventory compensate indefinitely (until shareholders realize the unproductivity) deficiencies, waste and waste. If something is not known to be hidden, its severity cannot be measured and therefore no correction is sought.
The sum of all the Kanban of a company represents the current level of inventory and therefore it can be said that reducing them will achieve improvements in the global operation of the company. The Kanban System fulfills two main functions:
• Production Control (Integration of processes and the development of Just-in-Time JIT).
• The Improvement of the Processes (Elimination of waste / waste, Organization of the work area, MTP preventive and productive maintenance, etc.).
The use of the Kanban System immediately reveals unproductiveness and hidden problems, forcing to correct the root problem (Ishikagua, 5W-1H), carrying out a creative and productive analysis that leads to proposals for solving problems and implementing continuous improvement..
Actions prior to the implementation of the Kanban System
This system cannot be implemented overnight in a company, before starting the use of the Kanban System it is necessary to develop a process of smoothing the production of the current flow of material, if there are very large fluctuations in the integration of the Kanban processes will present problems and create clutter. LABELED / MIXED PRODUCTION SCHEDULE.- It serves to determine a production scheduling system for final assemblies, developing a mixed and labeled production schedule. The staff must be trained in the use of this tool, know and practice the time reduction systems for model changes: SMED, Small batch production, Jidoka: automation with quality self-control, visual control of problem alert: Andon, Devices fail-safe: Poka Yoke,Total Productive Maintenance (MTP), etc. all of this is a prerequisite for introducing Kanban and avoiding setbacks on the production line. SMED is a technique used to minimize machine downtime in process change or maintenance preparations, etc. It establishes a way to analyze the preparations, differentiating between internal operations (they must be carried out with the machine stopped) and external (they can be carried out before and after stopping).It establishes a way to analyze the preparations, differentiating between internal operations (they must be carried out with the machine stopped) and external (they can be carried out before and after stopping).It establishes a way to analyze the preparations, differentiating between internal operations (they must be carried out with the machine stopped) and external (they can be carried out before and after stopping).
Poka Yoke comes from the Japanese words "Poka" (inadvertent mistake) and "Yoke" (to prevent). A Poka Yoke device is any mechanism that helps prevent errors before they happen, or makes them too obvious for the worker to notice and correct them in time before they arise. The purpose of Poka Yoke is to eliminate defects in a product by preventing or correcting errors that arise as soon as possible.
Andon. Japanese term for alarm, visual indicator or signal, used to show production status, uses audio and visual cues. It is a display of lights or luminous signals on a board that indicates the working conditions on the production floor within the work area, the color indicates the type of problem or working conditions. Andon means HELP!
MTP is essential to be able to apply Kanban, which is why operational staff must be familiar with and practice focused improvements, continuous training and self-training, Autonomous Maintenance and have specialized support for Progressive or Planned Maintenance and Quality Maintenance. Without these tools the Kanban will not be impossible but it will be very complex and difficult; like: Rowing against the mighty current. The MTP reduces and tends to eliminate: 1. Losses due to failures, 2. Losses due to model change and fit, 3. Losses due to minor stops, 4. Losses in speed, 5. Losses due to quality defects and rework, 6 Performance losses. All of which will reduce and tend to avoid EMERGENCIES in the operation.
Principles on which the Kanban System is based:
* The required quality must always be supplied first time, NEVER supply something that does not meet what is required or that may cause problems in any of the subsequent stages. When detected, it will be notified immediately to correct in the own workstation.
* Eliminate or at least minimize all waste / waste. Do only what is necessary in the order on the instruction cards.
* Indispensable teamwork seeking continuous improvement.
* Seek the flexibility of the system to be able to execute the necessary actions if an anomalous situation arises that causes a change in the prioritization of production.
* Establishment of excellent long-term relationships and loyalty with both Suppliers and Customers.
Considerations before implementing Kanban and continuous monitoring. Verify that all staff (new incomes at all levels) always unify criteria, language used within the company and are familiar with:
1. Assembly production scheduling system and the development of the mixed production and labeling system.
2. Established Kanban path that reflects the flow of materials, involving the designation of places so that there is no confusion in the handling of materials, making it obvious when the material is out of place or not in stock.
3. The use of Kanban is linked to small batch production systems, all personnel must practice and be aware of this way of producing.
4. Items of special value should be treated differently.
5. Maintain good communication linked from the sales department to production without skipping any stage of the process, avoiding distorted information, especially for those seasonal cyclical items that require high production in a short time. Good communication and collaboration between the Company and Suppliers is essential.
6. Keep the Kanban system updated and continually improve it to reduce WIP (Work in Progress).
Rules of the Kanban System. Like all tools, Kanban has rules for its correct operation and they must be respected. A simile is the use of a knife or a guillotine, which have handling rules, such as that it should be taken from the handle and not from the sharp blade. If we do not follow this simple rule that is obvious, we could have serious problems. Likewise, if the Kanban rules are not respected, serious problems can arise in the process. In the case of the knife we do not see it as a rule due to the familiarity that exists with its use. The same will happen with the Kanban after it is a habit to use it by using it several times daily.
Rule 1. Defective product must not be sent to the next stage or subsequent process. The stage of the process that produces a defective product can and should be discovered immediately. The problem discovered must be disclosed to all the personnel involved, a solution must be found that eliminates the root cause in the safest and most economical way. The possibility of using Poka Yoke should be analyzed. Recurrence should not be allowed.
The subsequent process or stage is also called "Customer" and can be Internal or external and the preceding one is also called "Supplier" being internal or external. ISO 9000 eliminates the need to repeat (internal or external) and takes it as understood as the case may be.
Rule 2. Subsequent processes or stages will require only what is necessary.
In other words, the subsequent process "Customer" will exclusively order the material it needs from the previous process "supplier", only in the necessary quantity and at the right time. Waste is created if the previous process "Supplier" supplies parts or materials to the subsequent process "Customer" at the time that it does NOT need them or in a greater quantity than it needs, resulting in wastes that can be very varied, including waste due to the excess of overtime used, waste in excess inventory that they keep unnecessarily, and the loss of capital investment for new processes without knowing that the existing one has enough capacity for what is really required.The worst waste occurs when your limited resources are spent on something that is not required or does not work. The second rule eliminates this type of waste and waste. The only thing that will be sent to the next stage is exclusively what is required in the instruction established by the immediate subsequent process or "Client" complying with the quality, quantity, in the place and time required. By complying with this Rule 2, inventory build-up of indirect materials, work in progress, finished products, and rework will be minimized. This mechanism should be used from the last process to the initial one. The conditionals that ensure that subsequent processes will not arbitrarily pull or require unnecessary materials from the previous process are:The second rule eliminates this type of waste and waste. The only thing that will be sent to the next stage is exclusively what is required in the instruction established by the immediate subsequent process or "Client" complying with the quality, quantity, in the place and time required. By complying with this Rule 2, inventory build-up of indirect materials, work in progress, finished products, and rework will be minimized. This mechanism should be used from the last process to the initial one. The conditionals that ensure that subsequent processes will not arbitrarily pull or require unnecessary materials from the previous process are:The second rule eliminates this type of waste and waste. The only thing that will be sent to the next stage is exclusively what is required in the instruction established by the immediate subsequent process or "Client" complying with the quality, quantity, in the place and time required. By complying with this Rule 2, inventory build-up of indirect materials, work in progress, finished products, and rework will be minimized. This mechanism should be used from the last process to the initial one. The conditionals that ensure that subsequent processes will not arbitrarily pull or require unnecessary materials from the previous process are:The only thing that will be sent to the next stage is exclusively what is required in the instruction established by the immediate subsequent process or "Client" complying with the quality, quantity, in the place and time required. By complying with this Rule 2, inventory build-up of indirect materials, work in progress, finished products, and rework will be minimized. This mechanism should be used from the last process to the initial one. The conditionals that ensure that subsequent processes will not arbitrarily pull or require unnecessary materials from the previous process are:The only thing that will be sent to the next stage is exclusively what is required in the instruction established by the immediate subsequent process or "Client" complying with the quality, quantity, in the place and time required. By complying with this Rule 2, inventory build-up of indirect materials, work in progress, finished products and rework will be minimized. This mechanism should be used from the last process to the initial one. The conditionals that ensure that subsequent processes will not arbitrarily pull or require unnecessary materials from the previous process are:This mechanism should be used from the last process to the initial one. The conditionals that ensure that subsequent processes will not arbitrarily pull or require unnecessary materials from the previous process are:This mechanism should be used from the last process to the initial one. The conditionals that ensure that subsequent processes will not arbitrarily pull or require unnecessary materials from the previous process are:
* Material should not be required without a KANBAN card. * The articles that are required must not exceed the number of KANBANs admitted. * A KANBAN label must always accompany each item.
See CASE “A” drawing that is shown below, it is issuing a production Kanban to the previous process or “supplier” without having consumed all of the material because in turn the emitting process has already received a production Kanban from the subsequent process or Client ”.
Rule 3. Produce exclusively the exact quantity required by the subsequent process or "Customer". The same process must limit its inventory to the minimum sine qua non, for which it commits to:
* Do not produce more than the Kanban number. * Slowly reduce the amount of Kanban circulating to reduce work in process by unveiling and solving problems that will arise from reducing inventory.
Rule 4. Balance and smooth production. If we produce only the necessary quantity required by subsequent processes, it is essential for all processes to be able to maintain the team and workers in such a way that they can produce materials at the necessary time and in the necessary quantity. In this case, if the subsequent process "Customer" requests material in an irregular and discontinuous way with respect to time and quantity, the previous process "supplier" will require personnel and machines in excess to be able to satisfy that need. The fourth rule is essential in these cases, production must be balanced or smooth to avoid waste and waste. To achieve balance and leveling or smoothing of production it is essential to maintain: Balance and synchronization of the flow;Consistent satisfactory quality and full participation of workers and employees, recommended to use Heijunka technique.
Heijunka or Level Production is a technique that adapts production to fluctuating customer demand. The Japanese word Heijunka, literally means "to make flat and level." Customer demand must be met by customer's required delivery, but customer demand is fluctuating, while factories prefer it to be "level" or stable. A manufacturer needs to match these production demands. The main tool for smoothing production is the frequent change of the exemplary mixture to be run on a given line. Instead of running large batches of one model after another, small batches of many models should be produced in short periods of time. This requires faster changeover times (SMED), with small batches of good parts delivered more frequently.
Rule 5. Kanban is a suitable means of avoiding assumptions that lead to waste and waste or shortages. It allows the adaptation of small fluctuations in demand or production demands. Kanban should be the source of information for production and transportation. Since workers will depend on Kanban to carry out their work, the balance of the production system takes on a very high importance.
It is not allowed to assume whether the subsequent process "Customer" will need more material the next time it requests, nor is it valid for the subsequent process "Customer" to ask the previous process "Supplier" if it can start the next batch a little earlier. Upon receiving the Kanban, the only information that will be given is only that contained in the Kanban cards to avoid information distortions. The Kanban System allows you to adapt to sudden changes in demand levels or production demands.
Rule 6. Stabilize and standardize the process to minimize the Number of Kanban. The way forward to avoid defects in what is produced is to carry out the work within a stable, standardized and streamlined process. By using statistical techniques, such as Six Sigma. The job must be done right the first time, from the beginning and through each work station to ensure a high level of quality, eliminating the probability of having to require unnecessary rework, making use of Poka Yoke systems that anticipate and eliminate possible errors. The Kanban number expresses the maximum amount of stock of material and product, and should be kept as low as possible. If a process is stable and has been streamlined, it is possible to reduce the Number of Kanban required (Rule 3).
Standardized work is a management system for manufacturing cells. It is the key to the productivity of the value chain. There are three key elements in standardized work: • Takt-time: “Rate” at which work cells must operate to satisfy the customer. • Work sequence: Who does what? (One sequence for each person). • Standard WIP (Work In Process): What is the minimum WIP required and where is it?
Standardized work has a standardized documentation system. It has to be simple, it has to be updated as improvements are made, and it has to be compliant to eliminate variability.
Rule 7: The Kanban must be processed in all work centers in a strict manner to what is established on the board for the order in which it reaches them in stabilized processes. {The order of priority modifies the arrival and will be used only with Emergency Kanban equivalent to a Card in the Red Zone of the Board or Red Kanban} When a work center has various Kanban entries from different processes in its input Board, service must be provided to the Kanban according to what is established on the Board for the order in which they have been arriving within a stabilized process. Any failure in this rule will cause a gap in the production rate of one or more of the subsequent processes. See K. Urgent, K. Emergency and Red Card or Red Zone,which should be reduced and seeking their elimination with efficient Total Productive Maintenance (MTP), Poka Yoke, SMED and efficient Certified Suppliers.
TYPES OF KANBAN
The use of Kanban is very common in daily life, it is carried out in a batch production, we are just not used to knowing them or giving them such a name.
The photo is exemplified by an activity as simple as requesting a new checkbook from the Bank. It is shown that before finishing using all the checks, with five unused checks still remaining, - it is authorized or requested - through the Production Kanban for the Bank to start the "production or replacement" of a new checkbook for the subsequent process or person who issues the Production Kanban. The five remaining checks are the operating or security margin of the account holder in order to have continuity in its operation. At the same time, for the Bank they represent the time required to prepare and issue a new checkbook that satisfies the Bank's internal security and control requirements, such as printing the name,the account number and the serialization of the account holder's checks to be delivered.
Something similar happens in an industrial operation, as can be seen in the example in the drawing, when starting to work with the third frame, the previous process is authorized to replace the frames used by the subsequent process. Call them racks, checks, bodies, engines, etc. depending on the process in question.
The best operation of a Kanban System is to make the operation and control as visual as possible and to try to handle it directly by the operators, the one who requires the service and the one who provides it; avoiding waste of unnecessary supervision or overproduction, etc. Returnable packaging such as Kanban is often used in industry and commerce - (a pallet or container that is returned once stocks have been consumed). The empty container is the authorization for the replacement of the new stock (CASE “B” of the drawing).
See comment on Rule 2 One or the other is used- CASE “A” or CASE “B”.
When the number of variables that are handled in the restocked products are many and the differentiation is very small between the different products, in addition to the instructions that are usually indicated in the standard Kanban according to the product itself, to speed up the operation of the supplier, sometimes it is customary to include a barcode to speed up the detailed display of all requirements and automate the system. If the supplier is at a considerable distance, electronic Kanban is usually used, although visual control is preferable to ensure an immediate response as established by the JIT. When handling product families it is feasible to use Generic Kanban,that authorize the start of production without supplying the specific information on which specific family member the next supply should be prepared.
As will continue to be seen later, there are variants that present different very particular characteristics, in some implementations of the Kanban system three cards are used, in other two types of cards, while in others they only use one and in some cases only containers are used. of materials and no cards are used. On the other hand, there are variants of the Kanban system in which colored cards are handled, some only use three colors (green, yellow and red) and in other variations of the Kanban system more than six different card colors are used to contemplate special conditions. Another variant is the three areas of green, yellow and red that can be seen on some card boards.
Additionally, some other Kanban systems present peculiarities in relation to the way in which information flows through the production process between the work centers to be coordinated and controlled. Additionally, the Kanban system operation can be carried out manually and in other cases it is essential to use systems assisted by software and hardware, depending on a series of factors such as the large number of parts to be used in a sub-assembly and the integration of those numerous subassemblies in a final assembly line (see optimizations made by Georg Krieg). In conclusion, there is NO single, generally accepted classification criterion,The important thing is to first understand the problem and hence the rules on which the Kanban system is based in order to apply it correctly and seek its optimization by reducing the WIP.
CONTENT, TYPES, FORMS, QUANTITY AND METHOD OF USE OF KANBAN CARDS.
The specific content and forms of each card are different from company to company, they must provide the necessary information so that any operator within each company can take the necessary actions without a doubt, through prior training. The same is true for external providers. In some companies "balls" are used and not cards.
Signal or Supplier Kanban: The systems that use this card specifically under this name, use it as the first Kanban and it serves as authorization to the last workstation (generally the final assembly) to order the work centers or previous suppliers to start processing the materials. Not all Kanban systems handle this card under this specific name. Since some other Kanban systems employ the name Signal Kanban for cases where a production card cannot be placed close to the material (e.g. if the material is being heat treated), and has to be hung close to the since this material is processed to "signal" it and hence the "Signal" operators call it. Others use a card they call “Signal Kanban,Flag or Material ”to specify the manufacturing batch to control maximums and minimums. For the same reason, it is not widely used as such and may initially create confusion for personnel from different production facilities. It needs to be clarified to avoid confusion.
Production or Process Kanban (P-Kanban): Indicates at least the Type and Quantity to be produced by the previous process, taking into account its Characteristics, as well as sometimes depending on each company, the Number of pieces per container, Point output storage, identification and collection point of the necessary components. This type of card is widely used. Some companies use different "forms" of production cards, the usual ones are:
See: Toyota production system: an integrated approach to just-in-time. Jasuhiro Monden. These three forms of card are not in widespread use and their meaning varies from business to business. See: Implementation of a Multi-triangular Kanban system. http://www.iienet.org/uploadedFiles/IIE/Community/Technical_Societies_and_Divisions/Lean/Lean_details_pages/Fei%20Gao%20-%20Implementation%20of%20a%20multi-triangular%20Kanban%20system%20in%20an%20electronic.pdf
www.lean.org/Common/LexiconTerm.aspx?termid=242&height=550&width=700
Transport or Material Withdrawal Kanban (T-Kanban): They transmit from a station to the predecessor (supplier) the needs of material from the successor station (client). It is attached to the container. The minimum information they contain is the following: Item transported, Number of pieces per container, Order number of the card, Origin and Destination. This type of card is in widespread use, but the amount of information content varies from business to business.
KANBAN Three Card System Let us consider a factory where the workstations are placed one after the other and the production flow (material flow) circulates from left to right, according to the following representation:
Supplier to Position 1 to Position 2 to… to Position n to Customer
In the Kanban System, the request for a product is what starts production (pull production of inventory minimization) In the drawing it is observed:
The Customer (external) places an order Position n receives a Signal KANBAN Then, Station n needs the products to fulfill the Signal Kanban The operator of Station n takes the types (in terms of type and batch of material) of (empty) containers according to what you need and sends them to Post n-1, each accompanied by: * «n-1» Transport Kanban (without any information and inside the containers) that go inside containers and will be used by the n-1 remaining workstations. * A Production Kanban (with all the necessary information) attached to the container and is an order for Station n-1.
The operator of Station n-1 takes a Transport Kanban (empty), removes the Production Kanban from the containers, and places both types of KANBAN in a place close to his position, if necessary takes more containers (empty) according to to what he needs and takes them to Post n-2, accompanied, each of the containers he took, of: * «n-2 ″ Transport Kanban (without any information and inside the containers) that go inside the containers and will be used by the n-2 remaining jobs.
* A Production Kanban (with all the necessary information) attached to the container and is an order for Station n-2.
THIS PROCESS IS REPEATED UNTIL POST 1 IS REACHED
THE INFORMATION FLOW ENDS HERE Station 1 removes the Production Kanban from the containers, takes the (2-1 = 1) Transport Kanban that were sent to them by Station 2 and that is when the materials processing begins.
HERE BEGINS THE MATERIAL FLOW When Station 1 finishes this processing (first processing), it places the types of materials already processed in their respective containers, fills in the corresponding information in the Transport Kanban and attaches them to the outside of the container.
The container is then sent to Station 2.
Station 2 receives the containers with the materials already processed at Station 1, verifies according to the Transport Kanban (which already contains information) and begins to work according to the Production Kanban (which was posted near his work station and which It was previously sent by Station 3)
When Station 2 finishes this processing (second processing), it places the types of materials already processed in their respective containers, fills in the corresponding information in the Transport Kanban and attaches them to the outside of the container.
THIS PROCESS IS REPEATED UNTIL YOU REACH THE POSITION n This operating system is the most common in small and medium-sized companies since it can be generalized to different types of simple products without large numbers of parts and sub-assemblies, factories and / or external suppliers and is usually manual use. Workstation1 issues supply orders to external suppliers via Supplier Kanban.
With the Kanban System Technique, the order management process and its follow-up are simplified, since it is the end end of the production chain who starts the whole process according to its own needs, contrary to what happens in other systems. It is a fast, simple, accurate and reliable information system.
Two-Card KANBAN System When using the two Kanban, you have a dual card system. Sometimes the production order and transport functions are combined on a single card.
Continuous flow processes This system is not for all companies. It is widely used by medium and large companies, especially the latter aided and complemented by electronic systems with specialized hardware and software. It can work when the flow is uniform and the product mix is very stable. An implicit assumption is that in this system the setup operations are short on all workstations. This is required so that each work center can change part production as often as necessary to meet the demand specified by the P-Kanban. If the output is slow, the whole process is done slowly and if it is sped up, the process is done faster. Variability tends to disrupt the Kanban system.Then additional cards (or containers) must be inserted to avoid missing.
Descriptive study of a continuous flow process with a dual card system.
The system has two control cycles, a P cycle to control work cell operation and a T cycle to control material transfer between work centers. The parts are stored in containers. Each container carries a fixed quantity of product, whose production authorizes a P-Kanban and whose movement authorizes a T-Kanban. Each container at the warehouse entrance (a) has a T-Kanban. Similarly, each container at the warehouse exit (b) has a P-Kanban. To understand how the system operates, each cycle is analyzed separately.
Cycle P. When a predetermined number (batch) of P-Kanban accumulates in the P-Kanban mailbox (c) of work center i, it indicates that work center i should produce a batch. The P-Kanban are removed from the mailbox and taken to the card exchange point (1) at the warehouse entrance (a). There, the T-Kanban is removed from each container and replaced with a P-Kanban. The T-Kanban are placed in the T-Kanban mailbox (d). The number of containers in this exchange is equal to the number of P-Kanban in the mailbox. Production begins and each container has a P-Kanban. When finished, the finished batch is placed on the warehouse release (b), its P-Kanban is removed and placed back in the P-Kanban mailbox (c). The P-Kanban mailbox makes the cards visible and shows the work queue to be done in the work cell.
Cycle T. When a predetermined number of T-Kanban is accumulated, they are removed from the T-Kanban mailbox (d) at work center i and taken to the card exchange point (2) at work center (i - 1). The P-Kanban are removed from each box and replaced by the T-Kanban. The P-Kanban are placed in the P-Kanban mailbox of work center (i -1) and the containers with T-Kanban are transported to the warehouse entrance (a) of work center i. The amount released for the T-Kanban to move is sometimes replaced by the control in which the T-Kanban move is performed at fixed intervals.
The analysis of the P cycle and the T cycle demonstrates how the reciprocal interdependence of a pull system works.
In Kanban systems, there is no material container without a Kanban card, only one P-Kanban authorizes production and only one T-Kanban authorizes transportation. These guides require that all work centers are synchronized.
Single Kanban or Tunnel Kanban card system. The system is simpler at the cost of losing control. The transport of materials is controlled with the T-Kanban, there is no P-Kanban. The parts are produced according to a daily schedule and are moved forward with the T-Kanban. The Kanban of a card rigidly controls deliveries, the user work center never has more than one or two parts containers and the supply point that serves it is eliminated. Alleviating clutter and confusion around points of use is a bonus. Produced parts are allowed to accumulate in excess at the point of supply that serves the producing work center;But backlog need not be severe in companies where it is relatively easy to associate the required quantity and timing with the end product schedule. There are companies that produce: motorcycles, motors, pumps and generators; consumer gadgets, toys that use this single card Kanban system.
In general, the “buffer controlled inventory” is higher in this system than in the previous ones since the production is controlled by the program. Single card systems work well when production time is short and a detailed production schedule can be created.
Kawasaki, with the one card system, improves productivity by withdrawing workers from the final assembly operation until the Andon's yellow lights come on indicating problems that need to be corrected. Nihon Radiator Co., also uses the single card, has a vigorous total quality control system, characterized by a continuous series of continuous improvement projects.
Some North American companies have commented when referring to the Kanban system of a card that: "It looks like the old 2-tray system." The 2-tray system is a visual replenishment point technique: When one sees that the stock of a part number has decreased to the point where the last box is to be opened (or taken from the second tray), place an order. In the Kanban of a card: 1. Standard containers are used. 2. The quantity in each container is exact, so inventory is easy to count and control. 3. The number of full containers at the point of use is only one or two. 4. The amount in the container is small, so that at least one container (usually several) is consumed daily. 5. In the production section,Containers are filled with small batches, which requires that prep times have been reduced previously in order to keep small batches economical.
It is convenient to visualize that in all cases of the Kanban System, the possible use of “small controlled inventories” (depending on variability and production volume) is foreseen, used as buffers and aids for balancing and leveling the operation of the process and protection. against variations. These must be reduced until the optimum is achieved or at least reduced to a value that is close to the optimum point, since one of the wastes that affect the daily operation and the cash flow of companies is having excessive inventories without control. that hide waste and correctable flaws. A variant of the Kanban System is the Water Spider Method (Mizusumashi) or Water Strider Method (Total Flow Management. Euclides A. Coimbra. Kaizen institute. 2009).
The Water Spider (WS) method is based on maintaining a constant supply of parts in front of the operator to reduce the number of stops on the line. Your goal is to get the parts as close to the workstations and the assembly line as possible. The parts that are handled are typically small and repetitive in use. Bulky or oversized parts are grouped and arranged according to the order in which they will be used and delivered on a cart that is placed within easy reach of the operator.
WS is used mainly in Electronic parts and with consumables. Additionally, it is customary to give this name "water spider" to the person who handles the material, responsible for making regular tours around the plant process, collecting and distributing Heijunka and Kanban cards, moving the materials according to the schedule and Kanban. Sometimes chains are used to transport the supply of some pieces.
There is also what is called "Milk Run" to collect from the suppliers the necessary quantities only when they are needed, in this way the transport vehicle passes through several suppliers and collects the quantity that is needed for the production of each day, which is another variant of the Kanban System. A floor Space valuation method for automotive electronics. Gokhan Sarpkaya. Auburn University. 2009 and lean enterprice systems: using IT for continuous improvement. Steve Bell.
www.2dix.com/view/view.php?urllink=http://www.tbmcg.com/acrobat/Waterspider_Oct_98.pdf&searchx=water spider kaizen
catarina.udlap.mx/u_dl_a/tales /documentos/mam/sandre_z_m/capitulo3.pdf
Variants in the use of Color Cards in Kanban Systems.
1. Systems using three colors cards colors mean requirements to increase or decrease the amounts of the buffer (buffer)
www.excellence1.com/Overcome_MRP_and_Kanban_difficiencies_using_Sigmabin.pdf
Kanban Green: The material must be replenished in the normal cycle restocking.No problem within acceptable limits. Above the reorder point.
Yellow Kanban: It should be addressed as soon as possible because it can get out of control, is borderline and requires immediate reordering. Below the reorder point.
Red Kanban: It means the inventory depleted position and the material must be rushed. Urgent Action Required Due to Imminent Shortage. Below the safety margin.
www.sme.org/cgi-bin/get-newsletter.pl?LEAN&20040309&3&.
Calculation of each color of cards.
Once you have the size of the Kanban and the number of units per container per card, the next step is to define the number of cards of each color (Green, Yellow and Red).
Green = Lot Size / Quantity of units per container or card. Example: The number of units per container is 50 and it is decided to replace in batches of 500 units, with which there will be 500/50 = 10 green cards to accumulate 500 units (batch size).
Yellow: Its formula uses a Safety Inventory, the Average Average Demand, taking into account the variations in the supplier's delivery time and its level of Reliability, which will be a percentage of the size of the Kanban divided by the number of units of the container / card.
Red: It is the demand during the delivery time divided by the number of units in the container / card. In other words, it is the demand or consumption while it is replenished. If a card reaches Red, it means that the process will have to stop due to lack of material. Before this case happens, it would be thought to use a Transitory Kanban, and before doing so, verify that the Rules are always followed.
Another way would be to calculate the critical level that would force the use of a Red card. Mathematically it would be: The Customer cycle time / Supplier replacement time.
Customer cycle time / Provider replacement time = number of cards to initiate Red card.
2. Systems that use a range of cards of different colors, see details and features at:
mdcegypt.com/Pages/Management%20Approaches/Lean%20enterprise/Kanban/Kanban.asp.
Transportation Cards: Yellow
Production Card: Green
Kanban for rework authorization: Orange
Kanban for authorizations for special cases and temporary uses: Blue
Kanban for emergency authorizations: Silver
Transitory Kanban Types Mauricio Lefcovich establishes “Other types of Kanban” at:
In the opinion of the author of this document, the first two examples of M. Lefcovich (K. Urgente and K. de Emergencia) are used in the early stages when the implementation of the Kanban System is beginning and the implementation has not yet matured and familiarized. application of Total Productive Maintenance, SMED and Poka Yoke or the Continuous Improvement stage is being deployed). The active participation of each of the members of the work team, monitoring the compliance and application of the Kanban Rules, the use of MTP, SMED, Poka Yoke and a selection and constant Development of Suppliers will minimize the need for these two types of Kanban indicated by M. Lefcovich. The five additional Kanban indicated, from my point of view are variants of the Basic Production and Transport Kanban.I consider it a valuable contribution to broaden the vision of the initiation stages and Continuous Improvement of the System in addition to the other tools. It highlights the obligation for each one to monitor and enforce the Fundamental Rules to be followed and to maintain constant training and development of personnel in the use of the other pillars of Kaizen / Lean Manufacturing. In my opinion, the “other Kanban” could be generically called: Transient Kanban:The “other Kanban” could be generically called: Transient Kanban:The “other Kanban” could be generically called: Transient Kanban:
• Urgent Kanban. It is issued in the event of a shortage of a part or item. In extraordinary situations, the urgent Kanban is issued, which must be collected immediately after use.
• Emergency Kanban. An emergency Kanban will be issued temporarily when materials or elements are required to deal with defective units, machinery breakdowns, extraordinary work or special efforts in weekend operations.
• Kanban work order. Whereas the Kanban mentioned so far apply to a repetitive production line of products, a work order Kanban is arranged for a specific production line and is issued on the occasion of each work order.
• Unique Kanban. When two or more processes are so closely linked to each other that they can be seen as a single process, it is not required to exchange Kanban between such adjacent processes, but rather a common Kanban token is used for the various processes. This kanban is called a single kanban and is similar to the "single ticket" valid for two adjacent railways.
• Common Kanban. A movement (transportation) Kanban can also be used as a production Kanban when the distance between two processes is very short and both have the same supervisor.
• Truck used as Kanban. Kanban is often very effective when used in combination with a wheelchair, container, or truck. The truck usually plays the role of Kanban. In such a way, the personnel in charge of placing components or supplies on the trucks will take the empty cart to the previous process, that is, to the assembly or generation process and will collect such supplies or elements there, changing it for the empty one, another cart filled with the necessary supplies or elements. Although, following the general rule, the parts should have a Kanban attached, in this case the number of trucks has the same meaning as the number of Kanban. In my opinion it is part of the Water Spider.
• Label. A conveyor chain is often used to transport parts to the assembly line, which carries the parts hanging on hangers. To each of these, at regular intervals, a label is attached that specifies which pieces, in what quantity and where they should be suspended from the chain. In this case, the tag is used as a type of Kanban. Be part of the Water Spider again.
Continuous improvement induces us to reduce delivery time, batch size and increase the reliability of the process and further develop the Supplier that feeds the process under study. This may lead to the need for a Transitional Kanban. When they cease to be transitory and Urgent and Emergency Kanban are constantly required, it is an indication that there are areas that need a thorough review, starting with training and greater staff involvement in all the auxiliary tools of Lean Manufacturing / Kaizen.
Kanban calculation
There are numerous variants in the Kanban calculation method, some formulas for this calculation elaborated by different authors, software companies, etc. are shown.
The bases for the calculation of Kanban, obviously must respect the rules on which the Kanban System is based, therefore they must adhere to a system of pulling only what is needed (quantity factor) when it is needed (time factor). Inventories are one of the seven wastes identified by Lean Manufacturing, so Kanban must be a controlled inventory both in the time it waits for its use (time factor), and the indispensable quantity that constitutes the Kanban (quantity factor). The time and quantity factors mentioned above force to consider the daily demand of the Client who uses the product made by the preceding operation, which leads to consider the need to take into account the rhythm of use of the product that the Client consumes or Takt Time to avoid shortages or overproduction.The product requirements are generally not permanent, nor continuous and even less stable, reasons for which it is necessary to take into account the variations to minimize waste, so it is convenient to use a factor that quantifies the Average Mean Deviation (WMD) to smooth fluctuations in demand for the product to be consumed from the previous process, trying to reduce its excess or shortages. All this, aimed at establishing a balanced flow of the total inventory controlled by means of a certain number of instruction cards or Kanban size, establishing in this way that each card or container controls an equal quantity allowing a slight flexibility, with which we can obtain the desired objective.nor continuous and even less stable, reasons for which it is necessary to take into account the variations to minimize waste, so it is convenient to use a factor that quantifies the Average Average Deviation (WMD) to smooth fluctuations in the demand for the product to be consumed. of the previous process, trying to reduce its excess or shortages. All this, aimed at establishing a balanced flow of the total inventory controlled by means of a certain number of instruction cards or Kanban size, establishing in this way that each card or container controls an equal quantity allowing a slight flexibility, with which we can obtain the desired objective.nor continuous and even less stable, reasons for which it is necessary to take into account the variations to minimize waste, so it is convenient to use a factor that quantifies the Average Average Deviation (WMD) to smooth fluctuations in the demand for the product to be consumed. of the previous process, trying to reduce its excess or shortages. All this, aimed at establishing a balanced flow of the total inventory controlled by means of a certain number of instruction cards or Kanban size, establishing in this way that each card or container controls an equal quantity allowing a slight flexibility, with which we can obtain the desired objective.reasons why it is necessary to take into account the variations to minimize waste, so it is convenient to use a factor that quantifies the Average Average Deviation (WMD) to smooth fluctuations in the demand of the product to be consumed from the previous process, trying to reduce its excess or shortage. All this, aimed at establishing a balanced flow of the total inventory controlled by means of a certain number of instruction cards or Kanban size, establishing in this way that each card or container controls an equal quantity allowing a slight flexibility, with which we can obtain the desired objective.reasons why it is necessary to take into account the variations to minimize waste, so it is convenient to use a factor that quantifies the Average Average Deviation (WMD) to smooth fluctuations in the demand of the product to be consumed from the previous process, trying to reduce its excess or shortage. All this, aimed at establishing a balanced flow of the total inventory controlled by means of a certain number of instruction cards or Kanban size, establishing in this way that each card or container controls an equal quantity allowing a slight flexibility, with which we can obtain the desired objective.All this, aimed at establishing a balanced flow of the total inventory controlled by means of a certain number of instruction cards or Kanban size, establishing in this way that each card or container controls an equal quantity allowing a slight flexibility, with which we can obtain the desired objective.All this, aimed at establishing a balanced flow of the total inventory controlled by means of a certain number of instruction cards or Kanban size, establishing in this way that each card or container controls an equal quantity allowing a slight flexibility, with which we can obtain the desired objective.
Kanban Size = KK = DDP * TR * (DMP + 1)
Average Daily Demand = DDP
Replacement Time = TR
Average Average Demand = DMP
Number of Cards = NT NT = DDP * TRC * (IS + 1) / K
Time of Replenishment of a Container = TRC
Safety Inventory = IS
Variants of the Calculation of the N ° of Kanban.
The variations indicated are valid and the formulas shown imply adaptations to the combination of process, market, supply, etc. There will definitely be a larger range of possible formulas, the important thing to know is that there are many acceptable variants:
Option 1.
Kanban # = (DD * LT + SS * SQRT (LT / TB)) / KB + (DD * EPEI) / KB
DD = (units) daily demand. LT = (days) lead time for restocking. SS = Statistically calculated safety inventory. SQRT = square root. TB = (days) duration of the safety inventory container. KB = (units) quantity per Kanban. EPEI = (days) Vendor resupply interval
Option 2.
# KB = (DD * (LT + SS)) / (KBS +1)
#KB = No. of Kanban. DD = daily demand. LT = delivery time. SS = safety inventory. KBS = Kanban size
SS = R * SQRT (W) * MAD It is used when the replenishment time is greater than the forecast period
SS = R * W * MAD It is used when the Replenishment Time <= Forecast period
R = Relationship between forecast accuracy and service level. R refers to the statistic of the normal distribution. The value taken by R is directly related to the area under the curve of said distribution (the normal distribution is in the shape of a Gaussian bell). If you go to a normal table (generally with zero mean and one standard deviation), you must enter with 1- the level of service specified in the system. It is assumed that the consumption history follows a normal distribution. This is a reasonable assumption since the greater the consumption history the better the normal distribution represents it (according to the central limit theorem).
W = Replenishment Time (in days) / Forecast period (in days)
MAD = Absolute Mean Deviation
SQRT = Square Root
Option 3.
Total Inventory Required = (Average Demand Period * Replenishment Time) + 1 or 2 Sigma + Safety Inventory.
Option 4.
Total Required Inventory = (Average Demand Period * Replenishment Time) * 1X X = 20 to 40% Number of Containers = Total Required Inventory / Container Size
Option 5.
# Kanban = ((AD * RT) + (SF * SD)) / SCQ
AD = average demand period.
RT = replenishment time within the same concept as AD.
SF = Z factor, 1.28 is regularly used for 90%, 1.645 for 95% and 2.33 for 98%.
SD = standard deviation of demand.
SCQ = the standard quantity container.
Option 6.
# Kanban = average demand during delivery time + safety inventory) / container quantity.
Option 7.
www.transtutors.com/homework-help/Industrial+Management/Just+in+Time+Production+System/number-of-Kanban-calculation.aspx
N = (dL + S) / C
N = N ° of Kanban d = Average demand per hour L = delivery time in hours S = security C = container quantity
Option 8.
SAP on their website http://help.sap.com/saphelp_46c/helpdata/en/ cb / 7f8c3943b711d189410000e829fbbd / content.htm
K = ((RT * AC) / Cont) * (SF + C)
K = number of Kanban {No. of Kanban}. Cont. = Content by Kanban. RT = lead time of replenishment by Kanban. AC = average consumption per period of time. SF = safety factor. C = 1 {constant, default = 1}.
Cycle Control Calculation: http://help.sap.com/printdocu/core/Print46c/en/data/pdf/PPKAB/PPKAB.pdf
(N ° of Containers - 1) x Container Content = Consumption over time Replenishment of Containers
N ° of Containers = (((Consumption / Time Unit) x Delivery time of container replenishment in unit of time) / Container Content) +1
Option 9. Wayne Marhel http: // elsmar. com / Forums / showthread.php? t = 21902 sets:
(Daily Demand x (Run Frequency + Lead time + Safety Time)) / Container Capacity
Daily Demand = daily demand = customer consumption expressed as No. of units.
Run Frequency = Run Frequency = frequency that is decided to establish and produce the product in question. This is expressed as a unit of time. For a five-day work week, the product run each day must equal (1), every third day must equal (3), etc.}.
Lead Time = Delivery Time = Manufacturing delivery time (processing time + disposition time + waiting time in queue) + delivery time for Kanban recovery expressed as a unit of time}
Safety Time = Safety Time = Adjustment for variations in demand and supply, expressed as a unit of time. It should be kept as low as possible. Container Capacity = Container Capacity = number of units per container (the number of units inside a container is always the same number.
Option 10.
World Class Manufacturing on its website offers a calculator for Kanban: http: // world-class -manufacturing.com/en/Kanban/Kanban.html Using the formula:
Total Required Inventory (TRI) = Weekly Part Usage * Lead time * Number of locations for stock
{Total required inventory (ITR) = weekly partial utilization * delivery time * number of locations for inventory}
# Kanban = TRI / Container Capacity {N ° Kanban = total inventory required / Container capacity}.
Option 11.
Oracle on its web page sets the following formula: http://download.oracle.com/docs/cd/A60725_05/html/comnls/us/mrp/kbovw.htm
(C -1) * S = D * L
C = Number of Kanban cards S = Kanban size D = Average daily demand L = Delivery time (in days) to resupply a Kanban
Option 12.
Kanban No. = (DD * TC * FS) / TL
DD = Daily demand Units TC = Order Time for Cycle FS = Safety Factor TL = Lot Size
A Safety Factor equal to one presupposes that the withdrawal kanban must always be delivered on time whenever the parts are needed without defects, implying a satisfactory continuous process performance. That is, there should be no delays in the system. Initially, for calculation purposes and to avoid that the process stops as a result of the lack of parts, it can be used temporarily, an additional Kanban as a safety factor until the system works properly and the personnel are fully familiarized; In practice, controlled inventory flow buffer or regulator stations are used, which should be reduced until the optimum is achieved and the Takt Time is satisfied, which is one of the objectives of the production scheduling planning.
The Takt Time or Production Rate, is calculated by dividing the available production time (or the available work time per shift) by the total amount required (or the customer's demand per shift). It is calculated in units of time, the seconds being the most used.
Takt Time = Available production time or Work time per shift. Total amount required Customer demand per shift
There are studies carried out by different researchers who have analyzed algorithms to find the optimal Kanban number for both single-product Kanban systems and multi-product Kanban systems produced in an industrial facility. Berna Dengiz & Cigdem Alabas found that the technique called Tabu Search that substantially reduces the experimentation time to achieve the optimum. http://www.informs-sim.org/wsc00papers/106.PDF Georg N. Krieg states that a company can only reap the full benefits of a Kanban control system until after determining the optimal system configuration or at most as close as possible to that goal,which is greatly complicated by the number of key variables that have to be simulated in the computer and evaluated to analyze the behavior of the system within a reasonable time, even for the simplest system of a single product, increasing the complexity when passing to a multi-product Kanban system. http://www.wseas.us/elibrary/conferences/2009/genova/ICOSSSE/ICOSSSE-54.pdf Examples of the simplest models of the GN Krieg Kanban System for optimization, details and analysis can be found in Kanban- Controlled Manufacturing Systems.pdf Examples of the simplest models of the GN Krieg Kanban System for optimization, details and analysis can be found at Kanban-Controlled Manufacturing Systems.pdf Examples of the simplest models of the GN Krieg Kanban System for optimization, details and analysis can be found at Kanban-Controlled Manufacturing Systems.
Kanban Card Board
Priority assignment guidelines within the Kanban board
The card board is the place where it is intended to analyze the possibility that a series of orders converge in a certain sequence as the order of lot size decisions and from the moment an order is sent, to modify said sequence or, on the contrary, to operate following a FIFO Lane behavior.
In a pull system, the subsequent stage has the final authority, so that any adjustments that must be made in a certain workstation on the sequence that must be made according to what is requested by that workstation.
On the other hand, in a push system, the preceding stage is the one that has the authority over this decision; so you can adjust the sequence to improve service or "cut costs." For this, some dispatch rules can be used that optimize some measures of the behavior of the system and that require the use of global information, although it should also be noted that some of the priority rules use information from the subsequent station.
In this regard, it should be noted with regard to prioritization that the Kanban system has an element that, in a way, can be considered part of a push control policy. This can occur in the event that at a certain stage many cards are received authorizing the production of new items. In these circumstances, the cards are usually placed on a control panel that allows total visibility of the orders that have been made to that work center. The three zones that exist in a typical production control panel indicate that the system under consideration is of the pull type, since those that are in the red zone must be produced first. However, within the same area the person in charge of the work center can produce in any order,allowing a decrease in the preparation of the equipment when producing several batches of the same item. This element, which is based on local initiative and local information from that stage, gives the Kanban system a clear advantage over other manufacturing systems as long as there is fluid communication regarding the global benefit of the company and not only of a special area, focusing on the satisfaction of the final external customer, following the priorities pre-established by the company for prioritizing market sectors and types of customer.It gives the Kanban system a clear advantage over other manufacturing systems as long as there is fluid communication seeing the global benefit of the company and not only of a special area, focusing on the satisfaction of the final external customer following the priorities pre-established by the company prioritizing market sectors and types of customer.It gives the Kanban system a clear advantage over other manufacturing systems as long as there is fluid communication seeing the global benefit of the company and not only of a special area, focusing on the satisfaction of the final external customer following the priorities pre-established by the company prioritizing market sectors and types of customer.
KANBAN IMPLEMENTATION IN FOUR PHASES. Phase 1. Train all staff in the principles of Kanban, and the benefits of using Kanban. Phase 2. Implement Kanban in those components with the most problems to facilitate their manufacture and to highlight the hidden problems. Training with staff continues on the production line. Phase 3. Implement Kanban in the rest of the components, this should not be a problem since for this the operators have already seen the advantages of Kanban, all the opinions of the operators must be taken into account since they are the ones who know best the system. It is important to inform them when work will be carried out in their area. Phase 4. This phase consists of the review of the Kanban system, the reorder points and the reorder levels,It is important to take into account the following recommendations for the correct operation of Kanban: 1. No work should be done out of sequence
2. If any problem is found notify the supervisor immediately. 3. It must be verified that new staff are aware of the type of Kanban System that is handled internally (with the variants specifically handled).
Interrelation of the Kanban System with "Supermarkets", "Pacemaker", "FIFO Lane", "CONWIP" and "POLCA".
It seeks to develop continuous flow (produce a part and pass it immediately to the next process without stalling between processes to eliminate intermediate inventories or WIP work in process) where possible.
Supermarkets and Pacemaker.
Supermarkets are used where continuous flow cannot be developed, they are small controlled warehouses with predefined locations for each reference in which there is a maximum inventory limit per reference (stock standard). Since this limit is never exceeded, Supermarkets are used to control the inventory in progress and by derivation the lead time (delivery time).
On the other hand, Supermarkets are replenished based on registered consumption until the maximum limit is covered according to a Pull criterion (“Pull System”). The need to replace a specific reference generates a Pull signal that activates the manufacture or restocking of the Supermarket. In this way, Supermarkets are used to manage the flow of materials and synchronize manufacturing with demand.
Supermarkets establish a maximum quantity per reference, therefore, it is applicable for standard components or products and never for products with a high degree of customization and a multitude of potential references. The process where production is controlled is called Pacemaker Process, this pacemaker sets the pace of all the previous processes. Only this process is scheduled and the previous ones should work at your own pace. It should be set as close as possible to the end or external customer so that it controls as much of the previous processes as possible. Try to distribute the production of different products evenly over time in the pacemaker process. The product mix must be leveled uniformly over a period of time,for which the tool change times (SMED) must be reduced almost completely.
FIFO lanes (FIFO Lane).
FIFO Lanes or FIFO Lanes are areas of accumulation of small controlled inventories that link two processes that cannot be established in continuous flow.
The concept of the FIFO lane (FIFO Lane) is somewhat similar to a gravity roller path between two points:
• First thing in, first thing out.
• There can be no more than a maximum number of boxes on the conveyor.
The FIFO Lane (FIFO Lane) aims to:
• That the first thing in is the first thing out to reduce the dispersion of Lead Time.
• Establishes a maximum capacity for the set of accumulated products. If the quantity is exceeded, it generates a signal to block the entrance and thus limit the maximum current inventory.
Unlike the Supermarket, the FIFO Lane is adapted to personalized products with high reference potential. What controls the FIFO Lane is not the maximum inventory of each reference, it controls the maximum inventory of the set of accumulated references.
CONWIP. Constant Work in Process.
The CONWIP System is also referred to as "Long Pull". It is a variant of the Pull System, you could say that it is a kind of single stage Kanban System and it is also a hybrid reciprocating system. FIFO Lanes (FIFO Lanes) control inventory in progress between two consecutive processes. The CONWIP System controls the ongoing inventory accumulated in an area of the value chain with different processes and routes.
Hopp and Spearman propose the CONWIP System as an alternative to the FIFO Lane. Rother and Shook do not differentiate these two systems, stating that CONWIP already existed without a defined name in the Japanese literature exposed by Hyer. CONWIP system or Inventory in constant progress. In CONWIP, two control points are established within the value chain: one for entry and one for exit. The maximum amount of work in process is limited, trying to translate inventory units into time units, which can accumulate between the two points. The system works when a quantity of material comes out, an authorization is released to enter an equivalent quantity in working time (Production Authorization Cards or Kanban). Therefore, CONWIP serves to control the inventory in progress.Companies that use CONWIP ensure that this system achieves lower levels of WIP (Work in Process) than the Kanban systems themselves.
POLCA (Paired Overlapping Loops of Cards with Authorization) Superposition of pairs of loops {circuits} of Authorization Cards
The POLCA system was introduced by Rajan Suri in 1998, in his book: Quick Response Manufacturing, A Company wide Approach to Reducing Lead Times.
The POLCA system aims to optimize the work flow in discontinuous environments characterized by working with complex and variable Products and Process Paths. Analyze and rationalize the flow of materials and processes, grouping material flows in Cells, when feasible. The Layout of the Plant is defined below, identifying the physical relationship between each Cell, not between the different work centers that are part of the Cells.
Each Cell is then identified with a simple name, such as C1, C2, C3, etc. and common material flows between Cells are identified, for example: C1-C2, C2-C3, C1-C3. In this way, each pair of Cells is associated with a box of Kanban cards (POLCA Cards) that controls the workflow between pairs of Cells. In this way, the POLCA System does not intend to control the flow of materials within each Cell, but rather controls the flow of materials between pairs of Cells.
The number of POLCA Cards that are assigned to each pair of Cells is controlled at all times to minimize the WIP (Work In Process) and is determined based on forecasts.
It must be taken into account that the establishment of forecasts on a single product or mix or variable mix of products in workshops in ETO (Engineering To Order) or MTO (Make To Order) environments can be very complicated.
It is necessary to make the forecasts on a "Higher Level" following a logical strategy such as grouping by product families, in such a way that the workload between each pair of Cells can be estimated.
The HL / MRP (High Level MRP) system calculates total demand based on planning horizons of one or several months, using firm manufacturing orders and product forecasts. In this way, the Planning department is in charge of adding or removing cards depending on the workload that has been anticipated. If demand changes, the value stream can be rebalanced by adding or removing POLCA cards in cell pairs where needed.
Forecasts are used only to plan and periodically add / remove POLCA cards to control plant WIP. Therefore, the works are not carried out in the plant until:
1.- There is a firm order from the client
2.- There is authorization to start the task
3.- There is a POLCA card waiting to be withdrawn to begin work in the relevant Cell.
4.- POLCA cards differ radically from Kanban Cards and the amount is calculated differently.
For POLCA systems consult: Planning and implementing POLCA: a card-based control system for high variety or custom engineered products. 2009. Ananth Krishnamurthya & Rajan Suria
MRP = Material Requirements Planning = Material Requirements Planning.
BIBLIOGRAPHY
- Cuatrecasas Lluís Advanced process and production plant designs Flexible Editorial Profit Barcelona Spain. 2009Cuatrecasas Lluís Competitive Management of Stocks and Production Processes. Barcelona Spain 2003 Krieg Georg. Kanban- Controlled Manufacturing Systems Catholic University of Eichstaett-Ingolstadt 2003.Ingolstadt, Germanyhttp: //www.informs-sim.org/wsc00papers/106.PDF Berna Dengiz Cigdem Alabas.SIMULATION OPTIMIZATION USING TABU SEARCH Gazi University. 2000 Ankara / TURKEYGross John M. & Mcinnis Kenneth R. Kanban Made Simple: demystifying and applying Toyota's legendary Manufacturing Process. AMACOM 2003 NY USA Vatalaro James C, Taylor Robert. & Taylor E. Robert. Implementing a mixed model Kanban System: The lean Replenishment Technique for pull production. Productivity Press 2005 NY. USA Louis S. Raymond. Custom Kanban:Designing the system to meet the needs of your environment. Productivity Press 2006 NY USA. Asay D. & Wisdom L. Kanban for the shopfloor. Productivity Press 2002 NY. USA.Crespo Franco T., Velando Rodríguez ME & García Vázquez JM Alternatives to use a Kanban-type production control system. European Research on Business Management and Economics. University of Vigo. 1998. Ruíz Usano R., Framiñán JM, Crespo A. & Muñoz MA Push-Pull control systems a comparative study. CONWIP University of Seville. Hyer N. & Wemmerlov U. Reorganizing the Factory. Productivity Press. 2002. Portland, Oregon. USES.& García Vázquez JM Alternatives to use a Kanban-type production control system. European Research on Business Management and Economics. University of Vigo. 1998. Ruíz Usano R., Framiñán JM, Crespo A. & Muñoz MA Push-Pull control systems a comparative study. CONWIP University of Seville. Hyer N. & Wemmerlov U. Reorganizing the Factory. Productivity Press. 2002. Portland, Oregon. USES.& García Vázquez JM Alternatives to use a Kanban-type production control system. European Research on Business Management and Economics. University of Vigo. 1998. Ruíz Usano R., Framiñán JM, Crespo A. & Muñoz MA Push-Pull control systems a comparative study. CONWIP University of Seville. Hyer N. & Wemmerlov U. Reorganizing the Factory. Productivity Press. 2002. Portland, Oregon. USES.Portland, Oregon. USES.Portland, Oregon. USES.
