A reliable plastic mold design is mainly reflected in the quality of the plastic products formed (appearance quality and dimensional stability), convenient, rapid, and concise processing and manufacturing, saving funds and manpower, leaving room for correction and improvement, safe and stable use, easy maintenance, short molding cycle and long service life during injection molding, and reasonable mold manufacturing process.
01
Main Process of Factory Mold Design
The customer provides product drawings → analyzes the product → confirms the plastic variety → confirms the mold material → converts to engineering drawings → uses shrinkage to create mirror images → improves assembly drawings → sets mold blanks → sets mold kernels → draws → 3D divides → determines the runner/gate method → conducts structural design according to the arrangement diagram → disassembles inserts → corrects 3D → produces engineering drawings (mold kernels/inserts/mold blanks/loose parts) → creates BOM tables → proofreads and reviews.
02
Several aspects that should be noted in design
1) When starting mold design, we should pay more attention to considering several options, weigh the advantages and disadvantages of each option, and choose one from them. For T-molds, we should also take them seriously. Due to time constraints, it was believed that a reasonable design, through practical production and use, would definitely have room for improvement.
2) After submitting the design plan, it is necessary to communicate more with the factory to understand the processing process and manufacturing usage. Each set of molds should have a fixed analysis experience, summarizing the process of gains and losses, in order to continuously improve the level of mold design.
3) When designing, refer to similar drawings designed in the past and learn from their experiences and lessons.
4) The mold design department should be a whole, and each design member should not act independently, especially in terms of summarizing the conclusions of mold design, which must have a unique style.
03
Mold Design Basis
The main basis is the product drawings and samples provided by the customer to us. Designers must carefully and thoroughly analyze and digest the products and templates, and at the same time, they must verify all projects one by one during the design process.
1. Accuracy of dimensions related to dimensional accuracy
1) Plastic products with high appearance requirements and low dimensional accuracy requirements, such as toys, can have specific dimensions that match well except for accessories.
2) Products with strict requirements for appearance and size
Is the demolding slope reasonable.
The wall thickness and uniformity of the product.
Plastic type. (Selection and determination of shrinkage rate of mold steel)
Surface requirements.
Product color.
In general, color has no direct impact on mold design. When the wall thickness and appearance of the product are large, it is easy to produce uneven color; And the darker the color, the more obvious the product defects are exposed.
2. Is there any post-processing after the product is formed
If there are surface plated products and the first mock examination has multiple cavities, it must be considered to set up auxiliary flow channels to connect the products together and separate them after the plating process is completed.
3. Batch production of products
The batch size of products is an important basis for mold design, and customers must provide a range to determine the number, size, material selection, and lifespan of mold cavities.
4. Injection molding machine specifications
5. Other customer requirements
Designers must carefully consider and verify to meet the requirements of acceptability.
04
General process of mold design
1) Analyze and digest the products and samples.
2) We should understand whether the customer has any requirements for the specifications of the injection machine to determine the range of mold size.
3) Determine the number and arrangement of cavities.
4) Determine the parting surface.
5) If there are rows or diagonal structures, they should be understood first.
6) Pouring system design
7) Determination of inlay structure.
8) Ejection and reset system design.
9) Design of cooling and heating systems.
10) Guiding and positioning devices.
11) Determine the mold and select standard parts.
12) Selection of mold steel.
13) Complete the structural diagram, mold drawing, and material cutting.
14) Finally, print out the drawing, verify it, and submit it to the mold design team leader and supervisor.
05
Trial mold and repair mold
Although mold design is carried out under predetermined process conditions when selecting molding materials and equipment, people's understanding is often incomplete. Therefore, it is necessary to conduct trial mold tests after the mold processing is completed to see the quality of the formed parts. After discovering, carry out mold repair to eliminate errors.
There are many types of defects in plastic parts, and the reasons are also complex, including mold and process conditions. The two are often intertwined. Before repairing the mold, a detailed analysis and research should be conducted based on the actual situation of the defective phenomena in the plastic part, to identify the reasons for the defects in the plastic part, and propose remedial methods. Because the forming conditions are easy to change, the general practice is to first change the forming conditions. When changing the forming conditions cannot solve the problem, repair of the mold is only considered.
Repairing molds should be more cautious, and if you are not very sure, you should not act recklessly. The reason is that once the mold conditions are changed, major modifications and restoration to the original state cannot be made.
06
Organize data for archiving
After testing, if the mold is not in use temporarily, it should be completely cleaned of demolding slag, dust, oil stains, etc., coated with butter or other anti rust oil or anti rust agent, and sent to a storage location for safekeeping.
From the beginning of mold design to the successful processing and inspection of the mold, the technical data generated during this period, such as task books, part drawings, technical instructions, mold assembly drawings, mold part drawings, base drawings, mold design instructions, inspection record forms, trial mold repair records, etc., shall be systematically organized, bound, numbered, and archived according to regulations. This may seem troublesome, but it is very useful for repairing molds and designing new ones in the future.
