Release time：2021-10-29
Plastic mold is the abbreviation of combined plastic mold, which is used for compression molding, extrusion molding, injection molding, blow molding and low foaming molding.
classification
A. Injection molding mold - TV shell, keyboard keys, electronic products, plastic products around computers, toys, household supplies (most commonly used).
B. Blow mold - beverage bottle.
C. Compression molding molds - bakelite switches, scientific porcelain bowls and dishes.
D. Transfer molding mold - integrated circuit products.
E. Extrusion mold - glue pipe, plastic bag.
F. Thermoforming mold - transparent molding packaging shell.
G. Rotary molding mold - soft rubber doll toy.
The following issues need to be paid attention to in plastic mold design:
1. The thicker part of the product should be set at the rubber inlet to ensure smooth and complete mold filling;
2. It should be opened at the place that does not affect the appearance and function of the product, but at the edge or bottom;
3. In the cold material hole near the gate, the pull rod is often set at the end to facilitate the demoulding of the runner;
4. For large or flat products, multi-point pouring is recommended to prevent product warpage and material shortage;
5. Its position should be the shortest in the process of plastic filling, so as to reduce pressure loss and facilitate mold exhaust;
6. Avoid setting gates near the slender core to prevent the material flow from directly impacting the core, causing deformation, dislocation or bending;
7. The gate size is determined by the product size, geometry, structure and plastic type, and can be modified according to the mold test conditions;
8. Through mold flow analysis or experience, we can judge whether the seam line caused by the gate position affects the appearance and function of the product, and we can add cold material holes to solve it;
9. When a mold has multiple cavities, the same product is poured symmetrically. When different products are formed in the same mold, the largest product should first be placed near the sprue.
Key points
1、 Don't just focus on product design and ignore plastic mold manufacturing.
When developing products or trial producing new products, some users often only pay attention to the initial research and development of products, and ignore the communication with plastic mold manufacturers. After the preliminary determination of the product design scheme, contacting the mold manufacturer in advance has two advantages:
1. It can ensure that the designed product has a good forming process and will not modify the finalized design because the parts are difficult to process.
2. Mold manufacturers can make design preparations in advance to avoid careless consideration in a hurry, which will affect the construction period.
3. In order to manufacture high-quality plastic molds, only the supplier and the demander cooperate closely can the cost be reduced and the cycle be shortened.
2、 Don't just look at the price, but consider the quality, cycle and service in an all-round way.
1. There are many kinds of molds, which can be roughly divided into ten categories. According to the different requirements of part materials, physical and chemical properties, mechanical strength, dimensional accuracy, surface finish, service life, economy and so on, different types of molds are selected for molding.
2. High precision molds need to be processed on high-precision CNC machine tools, and there are strict requirements for mold materials and molding processes. Cad/cae/cam mold technology should be used in design and analysis.
3. Because some parts have special requirements in forming, the mold should adopt advanced technologies such as hot runner, gas assisted forming, nitrogen cylinder, etc.
4. The manufacturer shall have CNC, EDM, wire cutting machine tools and CNC profiling milling equipment, high-precision grinding machines, high-precision CMM, computer design and related software.
5. For general large stamping dies (such as auto panel dies), it is necessary to consider whether the machine tool has a blank holder mechanism, even edge lubricant, multi station progressive, etc. In addition to stamping tonnage, stamping times, feeding devices, machine tools and die protection devices should also be considered.
6. The manufacturing methods and processes of the above molds are not possessed and mastered by every enterprise. When choosing a partner, we must understand its processing capacity, not only the hardware equipment, but also the management level, processing experience and technical strength.
7. For the same set of molds, sometimes the quotations of different manufacturers sometimes differ greatly. You should not pay more than the value of the mold, nor less than the cost of the mold. Like you, mold manufacturers should make reasonable profits in their business. Ordering moulds with much lower prices will be the beginning of trouble. Users must start from their own needs and comprehensively measure.
3、 Avoid multi head cooperation and try to integrate plastic mold production and product processing.
1. Using qualified molds (qualified samples) does not always produce qualified products in batch. This is mainly related to the selection of machine tools, forming process (forming temperature, forming time, etc.) and the technical quality of operators.
2. If there is a good mold, there should also be a good molding process. It is best to cooperate through one-stop cooperation and try to avoid multi head cooperation. If the conditions are not met, one party shall be selected to bear all the responsibilities, and it shall be clearly stated when signing the contract.
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