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factors affecting the quality of injection molds

Mold manufacturing is a complicated process. From the steps of design, processing, assembly, debugging, etc., to the final use, there are mainly 10 factors that affect the quality of mold.

1.Mold steel

Steel is the decisive factor in the quality of the mold, and choosing the right steel is the top priority. The criteria for choosing steel are as below:

  • requirements for injection molding materials

Different plastics material should use different steels for the mold, such as requirements for high polishing, corrosion resistance, etc.

  • price

it is wrong that the most expensive steel is the best. Considering the cost of the mold, the mold steel should use the material corresponding to the lifetime of the mold in order to avoid unnecessary waste.For example, the life of the general P20 material is about 300,000 shoots;2738 steel can be 500000 shoots;H13/2344 can be 800,000-1,000,000 shoots.

  • surface treatment

The surface treatment of the mold is also very important. Nitriding can enhance the surface hardness of steel and effectively extend the mold lifetime. Electroplating can effectively modify the mold steel. For some high-brightness and corrosion-resistant plastic parts, electroplating can be used to enhance and improve the performance of the steel.

2. Structure design

The good mold structure not only considers the product material properties, shrinkage rate, molding temperature, elastic tensile deformation coefficient, etc., but also considers the cooling water passage, the speed of opening and closing the mold. Reasonable mold structure can effectively extend the lifetime of the mold and ensure the smooth production of the mold, improve efficiency and reduce costs.

3. Mold process

If a worker wants to do something good, he must first sharpen his tools. The arrangement of the mold process is particularly important.the reasonable mold 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 the mold lifetime during the production process.

Some machining 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 mold movement, reduce the mold life, and cause the mold to crack during the production process,even broken.

4.Standard Parts

Although the standard parts are not directly involved in molding, they control the operation of the entire mold. Good standard parts should be wear-resistant, hard enough, high precision, and not suitable for deformation. The standard parts of different brands have different price. Somtimes,it is not good to buy the cheapest standard parts for saving the cost.

5.Mold collision

Mold collision looks very simple,but it has a big influence on the mold quality.Rich expensive of the mold collision is very important of the mold fitters,especially for complicate mold.For example, the auto parts mold,the parting surface is irregularity, and also with sliders,ejecting block,etc.The mold maker has to take care of the other parts matching while doing the mold collision.

6.Mold polish and grained Leather

The mold polish is the last step in the mold manufacture. Polishing directly reflected on the final product, so this is the most face-to-face job. Mold Polish also helps and complements the mold movement, especially for mold demolding. Generally,some mold production is not smooth because the bad polishing, the resistance is too big, which cause the difficult demoulding, and even the eject the product white,crack and so on.

7.Mold Assembly

Mold assembly is like assembling a machine. Every component and every screw can’t go wrong. Otherwise, the consequences will be quite serious. If it is small problem, it will lead to product defects, affecting production.if it is a big problem,it may completely damage the mold and cause scrapping. Therefore, the mold assembly work must be very detailed. In the assembly process, need to pay attention to the cleaning of the mold, especially the water circuit and screw holes. Be sure to blow off the iron filings inside.

8.Hot runner or cold runner

If the mold is designed with the cold runner, pay attention on the injection balance,sprue size,injection pressure needed,etc. If the mold is designed with hot runner,it is better to choose famous brand hot runner,such as YUDO,HUSKY,HASCO,MOLD-MASTERS,etc. Although they are expensive,but quality can be ensured.Of course,if the budget is limited,Chinese brand hot runner can also be choosed.But since there are too many companies for making the hot runner,some are good quality,some are bad quality.Whatever, we Mingyu Mold has cooperated with several hot runner companies whose hot runner system is stable and reasonable price.

9.Cooling channel

Cooling is very important to the mold.Due to the increase of the cost and labor wages,more and more plastic factories want to reduce the mold cycle time when mass-production.However,when the cycle time is reduced,the mold temperature will rise.If it is not effectively controlled,the mold will be too hot to form, and even the mold deformation and be scrapped. Good cooling channel will help cool down the mold and control the mold temperature.

10.Mold maintenance

Mold maintenance is very important to the mold lifetime.The mold is like a car. If it is not used for a long time without maintenance, it may cause the mold to be scrapped. Therefore, every time the mold is used, it must be fully maintained, especially the rust prevention of the molded part and the rust prevention of the main moving parts. Because the mold has to be connected to the cooling water line during the production , if water may be drop to the mold during the installation or disassembly process, it is necessary to ensure that the mold is dry and then brush a layer of oil for protection (or spray anti-rust sparyer).

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