Through the years, humanity has been able to show how processes have been subject to constant changes and improvements.
Thanks to industrial engineering or professions to order, man has been able to establish study methods of these processes, to refine them in subsets of tasks or smaller jobs, and in this way study a complete job.
increase-productivity-improvement-primary-supplyR. Aguilar (2010) mentions that among the most common problems that arise in production lines is an imbalance in workloads, so it is easy to observe that while operators in some areas are idle, others are overloaded. In this way, it is convenient to prepare a time study in one of the production lines, with which a workload balance can be performed and the workforce better distributed, thereby creating more efficient production lines.
Workload balancing is carried out under the principle of “tack time”, which considers the time available per day and the demand that is intended to be covered with that time. For this, it is necessary to standardize the cycle times in the different work areas and verify that they do not exceed said activities, they will modify the activities assigned to each operator, so that they work the same amount (Muñoz, 2009).
THEORETICAL FRAMEWORK
In every company, the design of lines for production systems is of utmost importance because the economic situation of the same depends on the manufacturing performance. As all manufacturing is a function with added value, the efficiency of the activities will contribute significantly to the economic profitability of the company in the short and long term (Muñoz, 2009).
Therefore, this author mentions that the current environment demands that companies respond quickly to the multiple requirements of customers. Based on this, manufacturing strategies have emerged, including lean manufacturing, which is seen as a viable and effective method of achieving efficiency.
Lean manufacturing or "lean manufacturing" is a generic term given to the applications of the Toyota production system. This system refers to both flexible, manageable, synchronous manufacturing, and manufacturing according to the flow of demand. The ultimate goal of such a system is to reduce the seven main wastes as presented by Taiichi Ohno. Among these wastes are: processing, unnecessary movements, waiting, stock levels, overproduction, transportation and correction of defects (Lareau and Kaufman, 2003).
Thus, "The value of lean manufacturing is to eliminate all waste or dump, including operations that do not add value to the product, service or processes" (Belohlavek, 2006). In this sense, muda is a very simple and useful Japanese word that means any activity, process or operation that does not add value to the product or service for the consumer or customer (William, 2003).
Thus, in the company under study, a new product called “BT Ibox” has been introduced, in which its production line does not have the necessary adjustments for its correct operation since it mainly presents leisure time and “scrap” (waste), so you want to eliminate this waste. The authors Kosky, Balmer, Keat and Wise (2009), assure that lean manufacturing is the optimal way to produce goods through the elimination of waste and the implementation of flow. According to the same authors, lean manufacturing is a process management philosophy that focuses on reducing the 7 wastes identified by Toyota. Lareau and Kaufman (2003) say that the 7 wastes classified by Taiichi Ohno, father of the Toyota production system are the following:
- Overproduction Inventories Defects, rework and repairs Process movement Waits (queues) Transport
For his part, the author William (2003) mentions that these are some examples of waste or shedding that occur in the areas or production lines:
- Over-staffed work areas Unbalanced production lines. An operation, person, or team works at a faster or slower rate than others on the line. • Lack of work assignment. Operators lacking adequate training. Waiting for mold changes or adjustments. Poor work area setup. Errors in planning or scheduling and work sequences. Excessive travel distance of products during the production process.
Balancing workloads
The authors Suñé, Arcusa and Gil (2004), point out that the most interesting aspect in the design of a production or assembly line consists in distributing the tasks so that the productive resources are used in the most adjusted way possible, throughout of the whole process. The problem of balancing production lines consists of subdividing the entire process into production stations or workstations where a set of tasks will be carried out, so that the workload of each position is as adjusted and balanced as possible to a cycle time. A chain will be said to be well balanced when there are no waiting times between one station and another.
The steps to start the study of balancing or balancing lines is the same as in any other type of production process that consists of:
- Define and identify the tasks that make up the production process. Time necessary to develop each task. The necessary resources. The logical order of execution.
Likewise, the author Meyers (2000), points out that the purposes of the assembly line balancing technique are the following:
- Equalize workload between assemblers Identify bottleneck operation Determine number of workstations Reduce cost of production Establish standard time
The balancing of lines is done so that in each work station there is the same cycle time, that is, the product flows from one station to another each time the cycle time is met, so it does not accumulate. All stations must pass the work done to the next workstation each time the cycle time is met, therefore there are no bottlenecks because all stations take the same time.
Standardized work
In every manufacturing company we can find production lines, and they are responsible from design to production. Therefore, what would the result be like if each person in each area worked differently? For example, if the operation method was different between each of the shifts. Possibly the following problems would arise:
- Different defects are produced by each of the members It is difficult to know the cause of the operation failures Improving the operation becomes problematic since everyone performs the operation according to their way of thinking • Unsafe acts are performed by each of the members Training and training of personnel is difficult Delays between operations are generated that are reflected in non-compliance with deliveries from production to the next process Costs due to product damage due to poor practices in the operation are increased.
Productivity
Therefore, the standard operation must include all the important requirements within the organization and include them so that these are carried out in a systematic way (González, 2007). Productivity Productivity is a measure of process performance, and can be expressed as the output / input ratio. The resources or productive factors considered as inputs may have both a material and human character. The resulting products considered as output, can refer to fixed assets or services provided (De la Fuente, 2006).
Time study with stopwatch
It's the method most manufacturing employees think of when talking about time standards. Frederick W. Taylor began around 1880 to use the stopwatch to study work. Due to its long history, this technique is included in many manufacturing companies. Time studies are defined as the process of determining the time required by a skilled and well-trained operator at a normal pace to do a specific task (Meyers, 2000). There are two basic methods of time study with the use of the stopwatch, the continuous and the return to zero.
Continuous method. The continuous method is used for tasks that are very specific, that are difficult to divide into subtasks; then it consists of letting the stopwatch run from the beginning of the task until it is finished, recording the total time (Sancho, 2008).
Return to Zero Method. In the zero-return method, the timer is read at the completion of each subtask, and then immediately reset. When the next item starts, the stopwatch starts from zero. The final time will be the sum of the times of each subtask into which the task has been divided (Sancho, 2008).
"Takt Time"
The "takt time" is the time in which a unit of product must be obtained. It is a well-known term in manufacturing which is used to establish the time it must take to complete a unit to meet demand. Tolerances or supplements It is the supplement that is added to the basic time to give the worker the possibility of recovering from the physiological and psychological effects caused by the execution of certain work under certain conditions and so that they can attend to their personal needs (Sempere, Miralles, Romano and Vicens 2003).
METHODOLOGY
Figure No. 1 shows the methodology implemented for the development of the project
"Increase in productivity through the improvement of primary supply":
Figure No. 1 Methodology developed. (See PDF)
ANALYSIS OF RESULTS
Routes 3A & 3B (Convoy)
After taking times with a stopwatch, it was detected that in routes 3A & 3B there was an opportunity area, that is, that currently the plant had a “HC” (“Headcount”) for each route, however it was possible to unify both routes resulting in the benefit of a "HC".
The timed times were as follows:
As can be seen in the previous figure, the cycle time of route 3A is 32.19 minutes while the cycle time of route 3B is 40.29 minutes, if the purchase orders for the supply of material arrive every 60 minutes, this means than:
- The “HC” of route 3A is only working 53.65% of the available time (60 minutes), which means that it has 46.35% of dead time. The “HC” of route 3B is only working 67.15 % of available time (60 minutes) which means that it has 32.85% of dead time.
Routes 1G & 1F (Forklifts)
The study of the work applied to routes 1G & 1F is compared since if possible these routes could be unified since both take the material from the M1 warehouse and supply it to the “B&K” (“Block and kit”) and to the areas of “pre-pickings” & “subassy” located in the “trim” area. After taking times using a stopwatch and analyzing the numbers, the following graph was obtained as a result:
As can be seen in figure 3, the cycle times of both routes are high and very close to the available time (red line), so it can be said that the dead time of both "HC" is reduced and necessary as a safety time if is that an anomaly occurs.
Once the times had been analyzed, the question was answered: Do the current conditions of the routes favor their unification? The answer to the question is NO since both bars are well above the ideal time for the unification of the routes (green line), if the routes were to be unified, a single "HC" could not supply all the material requested by the material collection system, for which it can be stated that it would cause delays in the modulation operations of the trim area, thus generating line stoppages in production.
Due to the results obtained, it is recommended that both routes continue to work independently and despite the fact that there are improvements in the process, these are not sufficiently impactful for reducing cycle times.
Routes 2C & 2D (Forklifts)
The study of the work applied to the 2C & 2D routes is compared, since if possible these routes could be unified since both take the material from the M2 warehouse and supply it to the “B&K” and the “pre-picking” areas & "Subassy" located in the "chassis" area. After taking times using a stopwatch and analyzing the numbers, the following graph was obtained as a result:
As can be seen in figure 4, the cycle times of both routes are high and very close to the time available (red line), so it can be said that the dead time of both "HC" is reduced and necessary as a safety time if is that an anomaly occurs.
Once the times had been analyzed, the question was answered: Do the current conditions of the routes favor their unification? The answer to the question is NO since both bars are well above the ideal time for the unification of the routes (green line), if the routes were to be unified, a single "HC" could not supply all the material requested by the material collection system, for which it can be said that it would cause delays in the modulation operations of the chassis area, thus generating line stoppages in production.
Due to the results obtained, it is recommended that both routes continue to work independently and despite the fact that there are improvements in the process, these are not sufficiently impactful for reducing cycle times.
Routes 2E & 2F (Forklifts)
The study of the work applied to routes 2E & 2F is compared, as if possible these routes could be unified since both supply material in the chassis area. After taking times using a stopwatch and analyzing the numbers, the following graph was obtained as a result:
As can be seen in figure 5, the cycle times of both routes are high and very close to the available time (red line), so it can be said that the dead time of both "HC" is reduced and necessary as a safety time if is that an anomaly occurs.
Once the times had been analyzed, the question was answered: Do the current conditions of the routes favor their unification? The answer to the question is NO since both bars are well above the ideal time for the unification of the routes (green line), if the routes were to be unified, a single "HC" could not supply all the material requested by the material collection system, for which it can be said that it would cause delays in the modulation operations of the chassis area, thus generating line stoppages in production.
Due to the results obtained, it is recommended that both routes continue to work independently and despite the fact that there are improvements in the process, these are not sufficiently impactful for reducing cycle times.
Plastic & Covetable Routes (Forklifts)
The study of the work applied to the plastic & desirable routes is compared since at present both routes are unified and the study was carried out with the aim of verifying if both routes can continue to work together or it is necessary to separate them, the results obtained were:
As can be seen in figure 6, the cycle times of both routes are short, therefore the two routes can continue to be worked by a single “HC” since the operating time does not exceed the available time, which is why the material correctly.
Operations carried out in the “chassis” area
After taking the times of the "pre-picking" and "subassy" operations carried out in the "chassis" area, a graph with the workloads of each "HC" was drawn up, obtaining the following results:
As can be seen in figure 7, all “HCs” have a considerable percentage of dead time (space between the red line and each bar) since the time available to carry out the operation of one piece or pieces per vehicle is 1.56 minutes which represents the touch time of the plant assemblies with a “JPH” (“Jobs Per Hour”) of 32 units and all the workloads of the “HC” are below 1.14 minutes, that is, on average the “ HC ”from the“ chassis ”area are found for 27.30% of the time available without performing any activity. This condition is an area of opportunity for a re-distribution of workloads, obtaining 1 “HC” as a benefit.
Operations carried out in the trim area
After taking the times of the "pre-picking" and "subassy" operations carried out in the "trim" area, a graph with the workloads of each "HC" was drawn up, obtaining the following results:
As can be seen in figure 8, all the “HCs” have a slight percentage of dead time, which is why it is not possible to remove 1 “HC” from the operation since when performing a re-distribution of the workloads with only 7 “HC” operating times would exceed the tact time which could cause line stoppages due to non-compliance of parts in the production area according to demand. Although the times did not favor the fulfillment of the project objective, two operations were detected that could be delegated to people from “B&K”:
- “Cover antenna.” “Steering Wheel”.
CONCLUSION
As its name indicates, the benefit for the company was the increase in productivity through the improvement of primary supply. At the end of my stay there, the department stayed with the current cycle times of most of its operations and also came up with two proposals that, if established, would bring the following benefits:
As the previous figure shows, the project is planned to have a positive impact on 4 internal indicators:
- C: Costs. G: People.T: Time.Q: Quality of supply.
In a few words, when applying the proposals presented, the NISSAN Mexicana A2 material handling department will be working with lower cost, the same quality and with greater productivity.
GLOSSARY
Anomaly: A change or deviation from what is normal, regular, natural, or predictable.
"B&K": For its acronym in English "Block and kit", are the final areas of the materials handling department in which all the vehicle parts are concentrated and are modulated (taken) according to the sequence of the unit since the sequence will show the type of pieces with which it was required.
"Chassis": It is a production area where the entire chassis of the unit and exterior components of the body are assembled.
Bottleneck: Different activities that slow down the processes, increase waiting times and reduce productivity, resulting in increased costs as a final consequence. Bottlenecks produce a considerable drop in efficiency in a given area of the system, and occur both in personnel and machinery, due to different factors such as lack of preparation, training or training in the case of personnel, or lack of proper maintenance in the case of machines and equipment.
“HC”: For its acronym in English “Headcount”, it is the way of appointing a person of the operative group within NISSAN.
"JPH": For its acronym in English "Job Per Hour", is a term used within NISSAN that refers to the number of final units that the plant assembles per hour.
Lean Manufacturing: There are several tools that will help eliminate all operations that do not add value to the product, service and processes, increasing the value of each activity carried out and eliminating what is not required. Reduce waste and improve operations, always based on respect for the worker.
Methodology: Refers to the path or set of rational procedures used to achieve the objective or objectives.
Modulation: Action of taking stored material and placing it in the requested place.
“Pre-picking”: It is an activity within the materials handling area which consists of placing sequenced parts or kits inside the “B&K” with the purpose of reducing the workloads of the “HC” of “B&K” and to reduce the trajectory distance of the “AGV” and therefore the modulation time. It is an activity that does not add value to the product.
Productivity: It is a measure of the performance of the process, which can be expressed as the output / input ratio. The resources or productive factors considered as inputs may have both a material and human character. The resulting products considered as output, may refer to fixed assets or services provided.
Scrap: Refers to all waste, defects and / or residues derived from the industrial process.
"Subassy": Word that in Spanish means subassembly is an activity within the area of material handling which consists of making an assembly with the purpose of reducing workloads in the production area, since the piece arrives ready for its final assembly to the unit. It is an activity that does add value to the product since it is transformed.
Cycle time: It is a parameter that is defined for each process. It will be the time in which a process runs. Either a machine process or a manual process. This time is defined according to a series of parameters and different aspects related to productivity and production management will depend on it.
Standard time: It is the pattern that measures the time required to complete a unit of work, using standard method and equipment, by a worker who possesses the required skill, developing a normal speed that can be maintained day after day
Dead time: Time during which a machine or person is unproductive.
Touch time: It is the time in which a unit of product must be obtained. It is a well-known term in manufacturing which is used to establish the time it must take to complete a unit to meet demand, in short it is the speed of the production line.
Standard work: It is the best established method, to carry out the operation, so far.
"Trim": It is a production area where internal parts of the unit's body are assembled.
BIBLIOGRAPHIC REFERENCE
- Aguilar R. (2010). “Balance workloads based on the principle of“ takt time ”, in a line of industrial refrigerators.” Belohlavek, P. (2006). "OEE: Overall Equipment Effectiveness". Editorial Blue Eagle Group. De la Fuente, D. (2006). "Organization of production in engineering". Editorial Ediuno.González, (2007). Administrative Panorama Magazine. “Lean manufacturing. Main tools ”. Beachmold Mexico S. de RL de CV Kosky, P., Balmer, R., Keat, W., & Wise, G. (2009). "Exploring engineering: an introduction to engineering and design." Editorial "Academic Press". Lareau, W., & Kaufman R. (2003). "Office Kaizen: How to Control and Reduce Management Costs in the Company". Editorial FC.Muñoz Negrón, D. (2009). "Operations Management: Business Process Management Approach".Editorial "Cengage Learning". Meyers, F. (2000). "Studies of times and movements". Editorial Pearson Sancho Frías, J. (2008). "Implementation of products and services". Editorial Vértice.Sempere Ripoll, F., Miralles Insa, C., Romano, C., & Vicens Salort, E. (2003). ”Applications to improve work methods and time measurement”. Editorial Polytechnic University of Valencia, Suñé Torrents A., Arcusa Postils I., & Gil Vilda F. (2004). "Practical manual for the design of productive systems". Editorial Díaz de Santos. William, B. (2003). “The Hidden Power of Productivity” '. Editorial Norma."Applications to improve working methods and time measurement". Editorial Polytechnic University of Valencia, Suñé Torrents A., Arcusa Postils I., & Gil Vilda F. (2004). "Practical manual for the design of productive systems". Editorial Díaz de Santos. William, B. (2003). “The Hidden Power of Productivity” '. Editorial Norma."Applications to improve working methods and time measurement". Editorial Polytechnic University of Valencia, Suñé Torrents A., Arcusa Postils I., & Gil Vilda F. (2004). "Practical manual for the design of production systems". Editorial Díaz de Santos. William, B. (2003). "The Hidden Power of Productivity" '. Editorial Norma.
