The Importance of Quality Control in Mold Manufacturing

 By Joy Zhao

Mold manufacturing is usually small batch or single production, and the production process is complex with long lead time. Mold quality of high or low, to a great extent, decides the quality of products. It benefits and new product development ability. Therefore it has become an important symbol of measuring a company product manufacturing level. The quality of the mold is the most direct embodiment of a mold manufacturer’s strength. As an enterprise of mold industry, to improve their production levels, the first step is to guarantee the mold quality, and the life of the mold is the most important effect of the quality of the mold.

mold manufacture factory

The mold manufacturing process is a complex process, from the design, processing, assembly, debugging and other steps, and finally can be really put into use, in the whole life cycle, the factors affecting the quality of the mold are mainly the following ten aspects:

1. Mold steel is the decisive factor of mold quality

The selection of reasonable steel is the most important. The criteria for selecting steel are:

  • Requirements for injection molding materials – different plastics should use different steels, such as high polishing requirements, corrosion resistance requirements, and so on;
  • Price – steel performance is good, not the more expensive the better; Taking into account the cost of the mold, the mold steel should be selected complied with corresponding material with competent mold life to avoid unnecessary waste;
  • Heat treatment. The surface treatment of the mold is also very important. Nitriding – can enhance the surface hardness of steel, effectively extend the life of the mold; Electroplating – can effectively modify the mold steel, for some need high brightness and corrosion resistant plastic parts can use electroplating to enhance and improve the performance of steel.

2. Structural design Pipe structure design

Mature mold structure not only takes into account the product material properties – shrinkage rate, forming temperature, elastic tensile deformation coefficient, etc., but also takes into account the cooling water, opening and closing mold speed. Reasonable mold structure can effectively extend the life of the mold and ensure the smooth production of the mold and to improve efficiency and reduce costs.

3. Mold processing workers want to do well, they must first improve their tools

Mold process arrangement is particularly important. Reasonable process arrangement can speed up the production cycle, shorten the processing time, and effectively save costs. And more importantly, accurate and reasonable processing can ensure the stability and prolong the life of the mold in the production process. Some processing errors will lead to mold welding, no matter how good the welding is, it is a loss to the mold; In addition, poor processing may affect the action of the mold, reduce the life of the mold, and lead to the mold cracking or even breaking during the production process.

workers in the mold factory

4. Standard parts although does not directly participate in the molding, it controls the operation of the entire mold

Good standard parts should be well wear – resisting, hard enough, high precision without easily deformed. The difference between the standard parts of different brands is very large.

5. The touch (flying die) relies on the experience of the mold fitter, seemingly simple work is the most technical content of the work

The plate mold is the simplest, and the fractal surface is basically qualified as long as there is no flash break, unlike the auto parts mold, which is very troublesome, not only the fractal surface is more irregular, but also often includes multiple sliders and top blocks. At the same time, other problems of the mold can be improved and perfected through the touch. So it’s a comprehensive work.

6. Polishing is the last step in the manufacture of the mold

Polishing directly reflects on the plastic parts, so this is the most face-saving job. Polishing can also play a role in helping and supplementing the mold action, especially for demoulding.

7. Mold assembly is like the assembly of the machine.

Each part and screw cannot be wrong, otherwise the consequences will be quite serious. Too light will lead to product defects, affect production, and too heavy will completely damage the mold, resulting in scrap. So the assembly work must be very detailed. In the assembly process, pay attention to the cleaning of the mold, especially the water and screw holes, be sure to blow the iron filings inside.

8. Hot runner or cold runner actually has the least impact on the quality of the mold

The customer can design the hot runner, especially some large customers. Internationally well-known brands do very well both in quality and after-sales service, so there is generally no problem in quality. The main problem of the cold runner is how to ensure the balance of injection molding, the size of the gate, the injection pressure and so on.

9. Cooling is quite important to a mold

The mold may be too hot to form, and even lead to mold deformation and failure. Therefore, excellent waterway design is particularly important, including the layout density, diameter, links between each other and so on.

10. Mold maintenance is mainly the maintenance in the production process

The mold is like a car, if not used for a long time without maintenance, it may lead to the mold scrap. Therefore, every time the mold is used, it is necessary to carry out comprehensive maintenance, especially the rust prevention of the forming part and the rust prevention of the main moving parts. Because the mold is connected to water during the production process, it may sleep on the mold during the installation or disassembly process, so it is necessary to ensure the drying of the mold, and then brush a layer of oil protection.

Parts of Home Appliances
Parts of Car made by Mold


1. How to do mold materials factory inspection?

2. Methods to control mold processing precision?

3. How to make mold production under well control?

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