A reliable plastic mold design is mainly reflected in the quality of the molded plastic products (appearance quality and dimensional stability). It is convenient and fast during processing and manufacturing, which not only saves money and manpower, but also leaves room for correction and improvement. It is safe, stable and easy to maintain during use. It has a shorter molding cycle and longer service life during injection molding, as well as reasonable mold manufacturing process.
1. The main process of factory mold design
The customer provides product drawings → analyze the product → confirm the plastic variety → confirm the mold material → transfer the engineering drawing → multiply the shrinkage to make a mirror image → improve the assembly drawing → order the mold base → order the mold core material → demold → 3D mold splitting → determine the runner/gate method → refer to the ranking diagram for structural design → remove the inserts → correct 3D → engineering drawings (mold core/inserts/mold base/loose parts) → make a BOM table → proofread and review.
2. Several aspects that should be paid attention to in design
1) When starting mold design, you should pay more attention to considering several options, weigh the advantages and disadvantages of each option, and select one from them. After production and use practice, there may be room for improvement.
2) After handing over the design plan, you should communicate more with the factory to understand the processing process and the situation in manufacturing and use. Each set of molds should have a fixed analysis experience, and the process of summarizing gains and losses can continuously improve the level of mold design.
3) When designing, refer to similar drawings designed in the past and learn from their experience and lessons.
4) The mold design department should be a whole, and each design member cannot act independently. Especially in mold design, there must be a unique style.
3. Basis of mold design
The main basis is the product drawings and samples provided to us by customers. Designers must carefully and in detail analyze and digest the products and samples, and at the same time, all items must be checked one by one during the design process.
1. Correctness of dimensions related to dimensional accuracy
1) For plastic products with high appearance requirements and low dimensional accuracy requirements, such as toys, the specific dimensions can be matched except for transfer. 2) Products with strict appearance and dimensional requirements
Whether the demoulding slope is reasonable. Product wall thickness and uniformity. Plastic type. (Selection of mold steel and determination of shrinkage rate) Surface requirements. Product color.
Generally, color has no direct impact on mold design. When the wall of the product is thick and the appearance is large, it is easy to produce uneven color; and the darker the color, the more obvious the defects of the product are exposed.
2. Is there any post-processing after the product is molded?
If there are products with surface electroplating and one mold has multiple cavities, it is necessary to consider setting up auxiliary flow channels to connect the products together and separate them after the electroplating process is completed.
3. Product batch
The batch of products is an important basis for mold design. Customers must provide a range to determine the number of mold cavities, size, mold material selection and life.
4. Injection molding machine specifications
5. Other customer requirements
Designers must carefully consider and check to meet customer requirements.
IV. General process of mold design
1) Analyze and digest the product and sample. 2) It should be understood whether the customer has requirements for the injection molding machine specifications to determine the mold size range. 3) Determine the number of cavities and rank them. 4) Determine the parting surface. 5) If there are row positions and oblique structures, they should be understood first. 6) Design of the pouring system. 7) Determination of the inlay structure. 8) Design of ejection and reset system. 9) Design of cooling and heating system. 10) Guiding and positioning device. 11) Determine mold base and select standard parts. 12) Select mold steel. 13) Complete structural drawing, mold base drawing, and cut materials. 14) Finally print out the drawing, check, and submit to the mold design team leader and supervisor.
V. Mold trial and mold repair
Although the mold design is carried out under the expected process conditions when the molding materials and molding equipment are selected, people's understanding is often imperfect. Therefore, it is necessary to conduct mold trial after the mold processing is completed to see the quality of the molded parts. Find problems and repair the mold to eliminate errors.
There are many types of bad phenomena in plastic parts, and the reasons are also very complicated. There are reasons related to the mold and the process conditions, and the two are often intertwined. Before repairing the mold, a detailed analysis and study should be carried out according to the bad conditions of the plastic parts to find out the causes of the defects of the plastic parts and propose remedial methods. Because the molding conditions are easy to change, the general practice is to change the molding conditions first. When changing the molding conditions cannot solve the problem, consider repairing the mold.
Repairing molds should be more cautious, and you should not act rashly without full confidence. The reason is that once the mold conditions are changed, no major modifications or restoration can be made.
6. Organize the data for archiving
After the mold is tested, if it is not used temporarily, the demoulding residue, dust and oil should be completely wiped off, butter or other anti-rust oil or anti-rust agent should be applied, and it should be sent to a storage place for safekeeping.
From the design of the mold to the successful processing of the mold, and then to the qualified inspection, the technical data generated during this period, such as the task book, part drawing, technical manual, mold assembly drawing, mold parts drawing, base map, mold design manual, inspection record sheet, trial mold repair record, etc., should be systematically organized, bound, numbered and archived according to regulations. This seems troublesome, but it is very useful for repairing molds and designing new molds in the future.
