Plastic mold production process_Plastic mold production process


Author: MULAN –Plastic Molding Manufacturer

​Plastic mold production process_Plastic mold production process With the rapid development of the plastics industry and the continuous improvement of general and engineering plastics in terms of strength and precision, the application range of plastic products is also expanding, such as: household appliances, instruments In instrumentation, construction equipment, automobile industry, daily hardware and many other fields, the proportion of plastic products is increasing rapidly. It brings different requirements to the plastic mold processing technology. A good process preparation document can affect the production cost and product quality. The following suggestions are made on the compilation of plastic mold processing technology: the basic principles of plastic mold processing technology.

Based on our own manpower and material resources and the data or drawing requirements provided by customers, we will compile feasible process documents as soon as possible to produce high-quality products with usability. In the framework of this basic principle, fast, good, and economical are the core contents, which run through the whole process. "Fast": It requires the compilation of the shortest time-consuming process documents in the shortest time. The following four points should be paid attention to in the work: 1. The craftsman should be able to be familiar with the machine tool equipment and technical level of the unit, and it is best to operate Through each machine tool, we have a good understanding of processing to meet the requirements of the complexity and particularity of mold parts, so that we can quickly determine the best processing process and increase the speed when we get a drawing.

2. Determine the reasonable minimum machining allowance. Between the upper and lower processes and the rough and fine processes, a necessary machining allowance is reserved to reduce the processing time of each process. 3. Since most of the mold parts are single pieces and small batches, the process cards cannot be as detailed and detailed as batch products, but we must strive to understand at a glance without any omissions. The key processes must be explained clearly. Reduce operator adaptation time and reduce processing errors.

4. The jigs, measuring tools and auxiliary tools needed in the processing process should be designed in advance and prepared in advance. "Good": It requires craftsmen to be able to write the most reasonable and best process documents to prevent and deal with problems in the process of processing. It is also one of the criteria to measure whether a craftsman is excellent. The following points should be paid attention to: 1. Arrange the heat treatment process reasonably.

One of the characteristics of mold products is the mechanical properties of the material. The heat treatment requirements are very strict. Key parts such as punch and die, fixed plate, etc. should be annealed at the beginning to improve the processing performance. After quenching, aging should be carried out to eliminate stress deformation. 2. Strictly distinguish between rough and fine processing. -Generally, the division of rough and fine processes is determined by the heat treatment process, and the processing after the final heat treatment is mostly finishing.

The margin should be arranged in the rough machining stage as far as possible to reduce the loss of tools and the loss of electrodes and electrode wires used in electric machining. 3. Pretreatment process measures should be used. For some parts such as dies and punch fixing plates with a lot of material removed in the middle, a single side allowance of about 0.5 mm should be used before finishing, and a rough cavity should be processed first, then quenched and aged, and then finished. , in order to eliminate the processing internal stress deformation.

For some thin-walled parts, such as the discharge sleeve, a reinforced process table should be pre-processed to prevent deformation of the processing clamp. 4. Properly set aside processing benchmarks. In production, we often encounter the problem that the processing benchmark cannot coincide with the design benchmark. At this time, it is necessary to pre-process a process benchmark to facilitate the processing of each process.

For high-precision products such as progressive dies, dimensional accuracy conversion is required. 5. Professional terminology is also required. In the process documents, it is necessary to make full use of well-known professional terms and processing expression methods to clearly convey the processing intention, and to avoid color and vague language such as "processing to drawings" and "shaping and dimension tolerances to requirements". It is organically combined with the drawings to make the parties understand what to do and how to do it, which is also convenient for the inspectors to "save": it is to fully save manpower, material resources, financial resources, and improve unit production efficiency.

The following points should be paid attention to: 1. Using the viewpoint of mechanical processing technology and overall planning, for single-piece and small-batch products such as molds, the principle of centralized process processing should be adopted, and the processing should be arranged on one machine tool as much as possible to shorten the processing time. Process flow, which can reduce repetitive labor time such as clamping, drawing recognition, calculation, etc., reduce the time for sequence transfer and inspection, and improve production efficiency. 2. Fully estimate the man-hour quota for each machine tool, try not to use the slow one if it can be fast, and never use the finishing machine tool if it can be solved by rough machining, which is also conducive to protecting the accuracy and service life of the machine tool and saving cost. 2. Processing of plate, shaft, and special-shaped parts In the mold parts, there are many plate parts, mainly including fixed plates, upper and lower templates, unloading plates, backing plates, etc. The processing of such parts has some common features , taking the fixed plate of the progressive die as an example, its technological process can be summarized as follows: blanking 7 forging 7 annealing (normalizing) 7 blunderbuss cutting 7 rough grinding 7 machining center 7 quenching 7 semi-fine grinding 7 aging (stress relief annealing) 7 fine grinding 7 wire cutting, EDM.

Shaft mold parts are mostly convex and concave molds. The processing process is generally as follows: blanking 7 annealing 7 car 7 quenching (or tempering) 7 grinding tip hole 7 rough grinding 7 aging 7 fine grinding 7 fitter. After fine grinding, surface treatments such as bluing and nitriding can also be carried out as required. According to the different requirements of special-shaped parts, we can treat them differently when preparing the process, and strive to optimize the processing process.

3. The processing of assembled processing parts For - - the whole mold, some parts need to be assembled and processed due to the performance requirements. As a craftsman, it is extremely important to understand the assembly relationship between parts and the role of parts in the entire mold, so as to arrange the combination or matching process reasonably. For progressive molds, the size of the parts is mostly determined by the design, and there are few parts that need to be processed. Here are some parts and parts that need to be processed as follows: 1. The guide pillars of the upper and lower mold bases, Guide bushing hole.

The height of the limit column when the die is stamped. The gap between the upper and lower knives when cutting and opening strips. The preparation of mold processing technology has strong plasticity, but as long as you are willing to work hard, use your brain, and go through continuous summary and continuous improvement, you can process high-quality and low-cost products.

The process flow of mold making is as follows: drawing review-material preparation-processing-mold base processing-mold core processing-electrode processing-mold parts processing-inspection--assembly-flying mold-testing mode-production A: mold base processing: 1 dozen numbers , 2 A/B plate processing, 3 panel processing, 4 thimble fixed plate processing, 5 bottom plate processing B: mold core processing: 1 flashing, 2 rough grinding, 3 gun bed processing, 4 fitter processing, 5CNC rough processing, 6 heat treatment , 7 fine grinding, 8 CNC finishing, 9 electric discharge machining, 10 mold saving C: mold parts processing: 1 slider processing, 2 pressing block processing, 3, split cone sprue sleeve processing, 4 insert processing mold base processing The details should be numbered uniformly, and the mold core should also be numbered. It should be consistent with the number on the mold base and in the same direction. It is easy to make mistakes during assembly. A/B board processing (that is, the processing of movable and fixed mold frames), a: A/B board processing should ensure that the parallelism and verticality of the mold frame are 0.02mm, b: gun bed processing: screw holes, water delivery holes, thimbles Holes, machine nozzle holes, chamfering C: fitter processing: tapping, trimming. Panel processing: the gun bed processes the nozzle hole of the boring machine or the nozzle hole of the processing material.

Thimble fixed plate processing: blunderbuss processing: The ejector plate and B plate are connected with back pins, and the B plate faces upward, and the ejector pin hole is drilled from top to bottom. Rough machining, and then finish machining in place with a gunknife, chamfering. 5. Bottom plate processing: gun machine processing: scribing, correction, boring, chamfering. (Note: Some molds need to be strengthened, such as drilling screw holes on the thimble plate) Details of mold core processing (1) Rough machining of flying six sides: processing on the gun bed to ensure vertical degree and parallelism, leaving a grinding allowance of 1.2mm (2) Coarse grinding: large water grinding processing, grinding the large surface first, and clamping the small surface with a batch to ensure that the verticality and parallelism are at 0.05mm and leaving a allowance of 0.6- 0.8mm (3) Machine tool processing: first correct the head of the machine tool to ensure that it is within 0.02mm, correct and press the workpiece, first process screw holes, ejector pin holes, threading holes, countersunk heads for inserting needles, and machine Tsui or material nozzle hole, taper hole chamfering and then make water delivery hole, blunderbuss R angle.

Fitter processing: tapping, typing code 5) CNC rough machining and external heat treatment (HRC48-527) fine grinding; large water milling to minus 0.04mm than the mold frame, ensuring parallelism and perpendicularity within 0.02mm 8) CNC finishing 9) EDM 10) Save mold, ensure smoothness, and control cavity size. 11) Process inlet gate, exhaust, zinc alloy - generally the gate opening is 0.3-0.5mm, the exhaust opening is 0.06-0.1mm, the aluminum alloy gate opening is 0.5-1.2mm, and the exhaust opening is 0.1-0.2mm, plastic Open the exhaust to 0.01-0.02 as wide as possible and thinner. The plastic mold manufacturing process can be roughly divided into the following steps: Process analysis of plastic products.

Before designing the mold, the designer should fully analyze and study whether the plastic product conforms to the principle of injection molding processing, and needs to negotiate carefully with the product designer, and a consensus has been reached. This includes conducting necessary discussions on the geometric shape, dimensional accuracy and appearance requirements of the product, and avoiding unnecessary complexity in mold manufacturing as much as possible. Mold structure design.

- A set of high-quality molds requires not only good processing equipment and skilled mold manufacturing workers, but also a very important factor is to have good mold design, especially for complex molds, the quality of mold design accounts for 80% of mold quality %above. An excellent mold design is: under the premise of meeting the requirements of customers, the processing cost is low, the processing difficulty is small, and the processing time is short. To achieve this, not only must fully digest the requirements of customers, but also the injection molding machine, Understand the mold structure, processing technology and the mold factory's own processing capabilities. Therefore, to improve the mold design level, the following points should be done: 1. Understand every detail in each set of mold design, and understand each mold in the mold. The purpose of each part. 2. Refer to the previous similar design when designing, and understand the situation in its mold processing and product production, and learn from the experience and lessons. 3. Learn more about the working process of the injection molding machine to deepen the mold Relationship with injection molding machine. 4. Go to the factory to understand the process of processed products, understand the characteristics and limitations of each processing. Adopt the mold structure that has been relatively successful before. 7. Learn more about the impact of water entering the mold on the product. 8. Study some special mold structures and understand the latest mold technology. Determine mold materials and select standard parts. When selecting mold materials In addition to considering the accuracy and quality of the product, it is also necessary to make the right choice in combination with the actual processing and heat treatment capabilities of the mold factory. In addition, in order to shorten the manufacturing cycle, the existing standard parts should be used as much as possible. Fourth, parts processing and Mold assembly. In addition to the best structure and reasonable tolerance fit in the design of the mold, part processing and mold assembly are crucial. Therefore, the selection of machining accuracy and processing methods is absolutely dominant in mold manufacturing Status. The dimensional error of molded products is mainly composed of the following parts: 1. The manufacturing error of the mold is about 1/32. The error caused by mold wear is about 1/63. The error caused by uneven shrinkage of the molded parts is about 1 /34. The error caused by the inconsistency between the scheduled contraction and the actual contraction is about /6 total error = (1) + (2) + (3) + (4).

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