This scientific research was carried out at the INPUD company “1ro de Mayo” at the Kupres plant in the foundry workshop, where the coffee machine parts are manufactured.
With this work, the smelting process was characterized, the operations carried out in it are described, the relationship of the process with the environment is determined, and the process and handling of production and transport and stays are described. that the pieces pass. In it, the possibilities of improvements in the process, the ways to carry them out and the repercussion of the same on the production process and on the job that limits the production process (bottleneck) are exposed.
The current economic situation in our country is related to the changes experienced in ownership, as well as the relationships between plan and market. Business improvement has also played an important role, being one of the factors that will most lead to the future development of the country. The technological advances produced in the last years have motivated the increase of the importance that is given to the study of the manufacturing process of the products, and as an indispensable element for the assurance of the quantity and quality of the production, where they should be used. Coordinated men, equipment, materials, energy and information in conjunction with the environment.
Due to the increasing competition in the world market, Cuban companies are forced to increase the quality and carry out an extensive study in the preparation, execution and sale of production, with the aim of optimizing and making the most of each process, developing products that be able to compete at the highest level in an increasingly globalized market.
This work was carried out within the INPUD company “1 de MAYO” in the coffee production plant (KUPRES) and in the foundry workshop of this plant, this company began the production of coffee machines in 1975, from this date up to the end of 1999, 2 843 118 units of different types have been manufactured. With the upsurge of the Special Period, this production was strongly affected from 1991 to 1993, and it is in 1994 when its production resumes.
Since 1997, the demand for it has increased, on the part of the Currency Collection Store Chains, which are its main clients, as well as exports to the Dominican Republic, Mexico and Panama.
Currently, four types of coffee machines are manufactured: 1, 3, 6, and 9 cups, with the 6 cups being the most popular.
This work aims to: show the relationships between the production execution process with the rest of the processes carried out in the organization, describing the process based on its characterization, determining opportunities for improvement to make it more effective and competitive, as well as evaluating the impact of said improvements.
The following methods and techniques were used for this study:
- System focus Gantt chart Schemas Interviews Indicator calculation Cause - effect diagram OTITY Paretto diagram
1. Development
1.1. Characteristics of the casting process at the Kupres plant
In the KUPRES plant, the production of 1, 3, 6 and 9-cup coffee machines is carried out, which has four production processes:
- Casting of the lower, upper and lid glass parts Machining Polishing - scrubbing Assembled
In this work the study of the casting process was carried out, which is the primary process and from it the other processes are developed, it is classified as basic and technological and is carried out in the casting workshop, casting the bars of aluminum to be converted into the pieces that make up the coffee machines as a finished product (lower, upper and lid glasses).
1.2. Productive process
The smelting process encompasses a series of operations throughout its development which are: Firstly, the smelting of the aluminum bars in the tipping furnaces occurs, which works through a system of oil injection burning, melting the aluminum over 900 ºC, the molten aluminum passes through a traveling crane to the maintenance furnaces in charge of maintaining the aluminum at a temperature of 760 ºC to 800 ºC. Then the pieces are melted in the cup holder machines, later the lower and upper glasses are transferred to the cut-off station of the sink, while the lids are taken to the flah elimination station. The lower glasses and lids are then passed to the deburring machines and the upper glasses are transferred to the flash removal station.
Organization, planning and production preparation
The productive technical subdirectorate, the sales department and the plant management meet monthly to prepare the production plan taking into account the demand for the product per assortment, from there a strategic plan is prepared in view of the fulfillment of the production plan as shown in Annex 1. After the plan is approved, in the plant the technical - material supply is guaranteed, in the specific smelting process of the raw material (aluminum), there is a cooperation plan between the Kupres and Proher plants (tooling plan) for maintenance of moles and dies .
Production flow
The raw material is stored in a main warehouse and is transported by forklift to the plant, then it is temporarily stored until it passes to the weighing and from there it is transported to the tilting furnaces, the traveling crane transports the molten aluminum to the furnaces of maintenance to melt the pieces in the chuck machines, by means of wheelbarrows the lids go to the elimination of the flash and the lower and upper glass to the cut of gutters, then the lids the lower glasses go to the deburring machines and the upper ones are taken to the elimination of flash. Later these pass to the deburring machines as well. The production flow of the process is shown in Annex 2. Production is massive and was determined as follows:
As the value of ¨ k¨ is greater than 0.85, this is justified.
Process cycle length
In the plant the type of movement of the work object is combined, guaranteeing the continuity of the work; It is impossible to calculate the exact batch, so we took a sample of 6 pieces of the lower glass type and analyzed its course in the casting, gutter cutting and deburring process by calculating the duration cycle of the process and drawing up a Gantt chart. Combined displacement
- Ti-1 <ti> ti + 1 Time not significant. Ti-1> ti> ti + 1 Time not significant. Ti-1> ti <ti + 1 Short time (TC). Ti-1 <ti> ti + 1 Long time (TL).
0 <9 <12 not significant.
9> 8> 0 not significant.
There is no short time (TC).
9 <12> 8 there is long time (TL).
q = 6
Operation (1) foundry t = 9 (sec / pcs).
Operation (2) Cutting of gutters t = 12 (sec / pcs).
Operation (3) Rebabe t = 8 (sec / Pzas).
Gantt diagram
OP You (sec. By pieces)
Storage
When the raw material enters the workshop, it is deposited in a temporary storage area, placing the aluminum bars on top of the aisles. After the pieces are cast, there is temporary storage of the parts throughout the process. These storages are carried out in groups of trays.
1.3. Handling and transportation
The aluminum bars are transported in trolleys to the tilting furnaces, then when the aluminum is ready for smelting (900 ºC) it is transported by the traveling crane to the maintenance furnaces. Once the raw material is there, the operator of the cup holder machine uses a ladle to pour the aluminum in a liquid state into the mold of the machine, after melting the part, it uses the tongs to place them on the tray where they are transported by means of wheelbarrows. With four wheels that are the most flexible to the flash elimination station, where the operator, using a wooden bar, removes the largest burrs, culminating this operation, the pieces are transported in trays to the rabbet stations.
1.4. Fundamental elements of quality control, environmental management and technological management
In the casting operation There is a quality control technician who controls the cleaning of the molds as well as the temperature of the aluminum in the maintenance furnaces from the beginning of the operation. After the pieces are fused, the technician controls the quality of these by observation, determining the absence of pores or cracks, and samples each batch, controlling the depth of the flanges, the distance between them and the diameter of the hole for the screw. Measurements are made with the vernier caliper. The pieces continue through the production line in the flash deburring and elimination area where quality is controlled at the end of this process by observing 100% of the pieces, it is inspected for burrs or pores, this control is carried out by another quality technician.These quality technicians report to the brigade leader. Two types of molds are used in the process, the Italian and the Cuban, presenting the latter with quality problems, causing unnecessary costs of raw material when melting the bottom of the coffee maker. The workshop has procedures stipulated by ISO 9002 in which the different possible techniques to be used by the plant management appear, and the use or not of these depends on each leader.The workshop has procedures stipulated by ISO 9002 in which the different possible techniques to be used by the plant's management appear and the use or not of these depends on each leader.The workshop has procedures stipulated by ISO 9002 in which the different possible techniques to be used by the plant's management appear and the use or not of these depends on each leader.
The Annex 3 shows the most common defects presented by different parts along the entire production process. In order to know which of these defects are the most frequent, a Paretto diagram was made with the defects that affect the casting process, pores, cracks, gaps, sucking and blows, and it was demonstrated that by eliminating the defects of pores and cracks, 80% of the quality problems will be solved. These results are reflected in Annex 4. The Annex 5 shows a diagram cause and effect of one of the major causes affecting the quality of coffee 6 cups: the cracks.
The process under study is one of the most backward in the plant and the tine-holder machines are overused so they break frequently, for these reasons the tine-holder machines are currently being replaced by Italian-technology, manual ones, which are faster and more efficient since they reduce the consumption of materials, and being manual they avoid the purchase of the ball boxes that the spindle machines need and that makes their acquisition in the market difficult. The Kupres plant already has national competitors in Guanabacoa, Havana, where the CubaLux coffee machine factory was recently created, for this reason the plant is working on a new coffee machine project that is a copy of an Italian model (Italy is the leader in the production of coffee machines in the world), also working on a new type of octagonal coffee machines,the 12-cup coffee maker, mainly for the demand of cafes and hotels.
In this process there is environmental contamination due to the fact that the extractors of the vasculating furnaces do not work at their maximum capacity, in addition to being located in a position where air brings the gases back to the plant, to counteract this, it is added to the furnaces. An environmental gasifier, the maintenance furnaces do not have local extractors, which causes a temperature in the plant east between 35ºC and 38ºC and that all the gases from these furnaces remain in the workshop. Each grinding and deburring machine also has a filler extractor but these need a repair which causes contamination in the medium.
1.5. Economic valuation in the casting process
In the Kupres plant, expenses are not carried out per process but at the plant level, making it impossible to know how much expenses are incurred in the smelting process. There are direct expenses such as material expenses, wages and social security, fixed expenses such as amortization and variable expenses such as monetary expenses. In the plant, no general balances are made, these are taken to the company level, so it was impossible for us to also calculate the liquidity, solvency and performance ratios, only the Income Statement shown in the Annex 6 shows an increase in expenses and costs for the month of May with respect to the monthly average. However, sales revenues are higher this month, which allows an increase in profit in the period.
2. Opportunities for improvement
2.1. Improvement proposals
- Stabilization of injection smelting processes: the design and construction of a water circulation system must be carried out, in addition to training the personnel of the same.Reduce rejection rates in the process: carry out studies aimed at reducing thickness of the upper and lower vessels. Elimination of the contamination in cast iron: repair the smoke and gas extractors in the vasculating furnaces, placing natural extractors and use of non-toxic substances as degacifiers. Improve the quality of the molds: replace the Cuban molds with Italian molds. Eliminate setbacks of the pieces, although it is not possible to distribute them again in the plant because it is expensive, then install new machines. Greater use of injection machines and mold holders:need for national and foreign technical collaboration, including the request for offers of machines, molds, molds as well as managing and studying updated literature on the subject. Improve technological management in the company.
2.2. Impact of improvements
- Decrease in production and raw material costs. Introduction of advanced technology. Increase in production with better quality and efficiency. Greater motivation and safety of workers in the workshop. Reduction of technological instability in the production process. Greater competitiveness in an increasingly demanding market Better understanding of the new quality standards stipulated by ISO 9002
2.3. Queuing theory application to analyze the workload in the flash elimination station.
In order to analyze the workload of the flash elimination station, it was decided to use the queue theory or waiting phenomena. For this, observations were taken of the time between arrivals of the upper glass pieces of the coffee machines, obtaining, when applying goodness-of-fit tests using the Best fit software, that it follows an exponential distribution with an average of 7.53 min./piece.
Observations of the processing time of each piece were also made with the job, obtained by applying the goodness-of-fit tests of the Best Fit software, which follows a weibull distribution with the parameters of 0.186 and 0.756.
With these data, a Win QSB software run was run with its Queuing Analysis option obtaining the results.
From an analysis of these results, it can be inferred that the use and utilization of the operator of the job is very low, so it can be concluded that this operation does not constitute a bottleneck in the production process.
Measures to take:
Carry out a study of the operator's work content, including among its functions that of self-control of the quality of its production or that perform other tasks within the workshop, since it has been shown that its high workload is concentrated in the first hours of the working day.
Conclusions
- The process is affected by the environmental conditions present in the workshop; These are due to the poor functioning of the gas extractors in the vasculating furnaces as well as their wear due to 30 years of operation that causes gases to escape and circulate throughout the workshop. expenditure of materials and the increase in the cost of production, although studies have been carried out and the implantation of manual casting machines with Italian technology has already been approved, but this is not being carried out with the necessary speed. technological management level, but the plant is not among the leaders in this regard, which makes its level of efficiency lower than others.Low level of management of parts supplies for maintenance. Quality control during the process is good, it is demanded for the quality of each component part and the workers are aware of the quality of the product. There is a lack of protection means in the areas required and little demand from the bosses for the use of those that exist… The two most common defects in the casting process according to studies carried out applying the Paretto diagram are, pores and cracks.The two most common defects in the casting process, according to studies carried out applying Paretto diagrams, are pores and cracks.The two most common defects in the casting process, according to studies carried out applying Paretto diagrams, are pores and cracks.
recommendations
- Work on the stabilization of the smelting process. Repair the gas and dust extractors and use non-toxic substances such as degacifiers. Provide the worker with the necessary protection means in the areas that require it, as well as demand their use. Increase the training of workers in the implementation of ISO 9002.Improve the quality in the construction of molds to die-cast by Proher.Reduce the rejection rates in the process.Increase the management in the search for suppliers of spare parts.Exceed the process for the implementation of Italian technology manual casting machines.
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