Production Management And Material Control in Investment Casting Factory

Abstract:

This paper describes the key points of production planning in investment casting plants, the purpose, methods and steps of on-site production management, and reasonable material control methods.

The production management of lost wax casting plants mainly revolves around the production of qualified castings and accurate delivery dates. Material control is to ensure the timely supply of production materials and reasonable inventory, and to occupy as little working capital as possible.

The entire production management should firmly grasp the four major factors of quality, cost, delivery date and safety, that is, to achieve the survival and development of the enterprise with high quality, and to reduce costs for the enterprise to obtain more profits. Accurate delivery dates are used to gain credibility. Safety production is the basis of all work. Daily management should pay attention to the initiative and enthusiasm of employees, the quality awareness, problem awareness and improvement awareness of each manager, and eliminate the safety hazards found in daily life. You must know that there are 1,000 safety hazards behind every safety accident.

1. Production Plan Making:

The production plan is the core of the entire production management and process control. In order to make the

 production plan practical, feasible and effective. You should be familiar with the mold situation in the factory. The maximum shift output of wax molds of various products, the process output rate, the problems that are prone to occur in the process, etc.

① After receiving each production task order, first verify the mold condition, wax mold shift output and re-check the mold to ensure that there are no problems with the mold.

② Combined with the problems found in the sample production or the experience of the original production, the damage rate and production cycle in the process are verified. Generally, it can be invested at 103-110% of the planned number, and complex parts can be arranged at more than 110%. In short, this number should be flexibly determined taking into account the process reliability and the proficiency of subsequent operators. If the damage rate or scrap rate is high in the middle, it should be supplemented in time to avoid delaying the delivery date.

③ Determine the delivery date: According to the planned quantity, the wax shift production is used to determine the final time for the wax mold to be completed. Shell making generally takes about 7 days, melting and pouring takes 1-2 days, and post-processing takes 2-7 days for grinding, welding, and shaping, plus about 2 days of flexible time, that is, under normal circumstances, after the wax mold is completed, add about 15 days for the final delivery date. The delivery date for complex castings is calculated according to special circumstances. When the production volume is large, it can be delivered in batches.

Based on the above situation, a production plan and execution table can be made, as shown in Table 1.

Table 1 Production Plan and Execution Table

2. Control of the Operation Process

Each production team should be controlled according to the production plan and execution table shown in Table 1. The production progress and quantity of wax molds, shell making, smelting and post-processing should be reported to the production plan in the form of a daily report (this table can also be used as the basis for piecework wages). The daily report of each team must be signed by the team leader of the next process. The wax mold and post-processing daily report must also be signed by the quality inspection of the shift. The production planner should understand and supervise the production progress of each team at any time and adjust the production plan in time. The following control should be carried out on each production team.

Wax mold team: 

based on the tree after quality inspection, the variety, time, and quantity after the tree are received, and reported to the production plan before each shift. This report must be signed by the quality inspection and shell making team leader. In addition, when assembling the tree, the steel grade mark should be made on the die head as required.

Shell making team: 

With dewaxing as the dividing line, the shell moulds after dewaxing on the day shall be reported according to the variety and quantity, together with the shell damage and dropped parts of the shell making on the day, to the production plan. This report shall be signed by the smelting team leader. For those with more shell damage or insufficient number, timely plan to make up the number and instruct the team to find out the cause to avoid the same mistake next time.

Melting team: 

Based on the original records of smelting operations, the types, quantity, and number of broken and leaked shells of castings poured on the day shall be reported to the production plan. For those with unsafe casting quality, the shell mold should be opened in time. If there is a problem, it should be noted in this report. The production plan needs to make up the number in time according to the situation.

Post-processing team: 

The number of types of castings put into storage on the same day and the number of types of castings after the initial inspection on the same day shall be reported to the production plan. This form must be signed by the quality inspection, and the production plan pays special attention to the number after the initial inspection. It is best to go to the post-processing site to check in person. Finally, re-verify whether the delivery can be made as planned. Otherwise, contact the business department for the specific number of deliveries that can be made as planned or re-determine the delivery time.

The production of make-up castings is also very important for the completion of the production plan. Such castings should be operated by the foreman of each team or the foreman's designated technically skilled employees to ensure production progress and quality.

3. Control of Other Links That Affect Production Progress

3.1 The integrity and reliability of the mold should be checked and repaired at any time.

3.2 Wax treatment has a long cycle, so process discipline must be strictly enforced and no problems should occur. And the progress of wax treatment should be adjusted in time according to the production volume, and production should not be affected by wax problems or untimely supply.

3.3 The medium frequency machine should be well maintained because of the great difficulty in maintenance technology and generally there is only one medium frequency machine in the precision casting plant, so it should be absolutely guaranteed to operate reliably. This is very important, and all wearing parts of the equipment should be in stock.

3.4 Due to the particularity of the precision casting process, each process must be implemented on a piece-rate basis, and the piece-rate should be counted individually or collectively and then distributed again. For the waste products in each process, the person in charge must be identified and improvement methods must be proposed, so as to improve the sense of responsibility and efficiency of employees. But at the same time, the role of quality inspection in each process must be strengthened.

4. Control of Material Consumption

Based on the materials and quantity of the orders received, the yield rate of the combined process, and the die recycling cycle, the material consumption quota is used, and the number of various materials required is budgeted and compared with the warehouse inventory. If it is lower than the minimum inventory standard, a purchase must be made in time. Calculate monthly and compare the actual material consumption with the quota. If the quota is exceeded, the reasons need to be investigated and measures should be taken to prevent similar situations from happening in the future or revise the quota.

5. Summary

5.1 The production plan maker has a comprehensive and practical understanding and grasp of the entire factory's production capacity, and can make as practical a production plan as possible.

5.2 The production of each production team should be under the effective command of the production supervisor (director), organize production with the production plan as the core, keep abreast of the dynamics of the production site at any time, and take measures to ensure the smooth completion of the production plan.

5.3 Material control has a great impact on production costs, especially some main raw materials should be strictly controlled in order to reduce production costs as much as possible.