Do you know the 10 factors that affect the quality of injection molds?

Do you know the 10 factors that affect the quality of injection molds?

Mold manufacturing is a complex process, spanning design, processing, assembly, commissioning, and ultimately, actual use. Throughout its lifecycle, the following 10 factors significantly impact mold quality.

1. Mold Steel
Steel is a crucial factor in mold quality, and choosing the right steel is paramount. The criteria for selecting steel are:
① Different plastics require different steel grades, such as those requiring high polish and corrosion resistance.
② Price: Steel should be functional, not expensive. Considering mold cost, mold steel should be selected to ensure the mold's lifespan, avoiding unnecessary waste. Generally, P20 material has a lifespan of around 300,000 kilowatts; 2738 material is generally rated at 500,000 kilowatts; and H13/2344 material typically lasts from 800,000 to 1,000,000 kilowatts. The choice depends on the specific application.
③ Surface Treatment: Surface treatment of molds is also crucial. Nitriding can enhance the surface hardness of steel, effectively extending mold life. Electroplating can effectively modify mold steel, and can be used to enhance and improve the properties of plastic parts requiring high brightness and corrosion resistance.

2. Structural Design
A sophisticated mold structure not only considers product material properties, shrinkage, molding temperature, and elastic tensile deformation coefficient, but also takes into account factors such as cooling water lines and mold opening and closing speeds. A reasonable mold structure can effectively extend mold life, ensure smooth production, improve efficiency, and reduce costs.

3. Mold Processing
Mold process planning is particularly important. A reasonable process plan can accelerate production cycles, shorten processing time, and effectively save costs. More importantly, precise and reasonable processing ensures mold stability during production and extends its lifespan.
Processing errors can sometimes lead to mold welding, which, no matter how well the weld is done, is detrimental to the mold. Furthermore, poor processing can affect mold movement, shorten mold life, and cause cracking or even breakage during production.

4. Standard Parts
Although standard parts don't directly participate in the molding process, they control the entire mold's operation. Good standard parts should be wear-resistant, rigid, precise, and free of deformation.

5. Mold Flipping
Mold flipping relies on the mold fitter's experience. While seemingly simple, it's the most technically demanding task. Complex molds rely heavily on this skill. Flat molds are the simplest; as long as the fractal surfaces are free of flash and discontinuity, they're generally acceptable.
Automotive parts molds, for example, are much more complex. Not only are the fractal surfaces irregular, but they often include multiple sliders and ejector blocks. Mold flipping can also be used to improve and refine other mold issues, making it a comprehensive process.

6. Polishing/Skin Graining
Mold polishing is the final step in mold manufacturing. Polishing directly affects the plastic part, making it a highly visible task. Polishing also aids and supplements mold movement, making it particularly valuable for mold release. Often, mold production failures stem from inadequate polishing, excessive resistance, difficulty in demolding, and even whitening and cracking.

7. Mold Assembly
Mold assembly is like assembling a machine; every component and every screw must be flawless. Failure to do so can have serious consequences, ranging from product defects and production disruptions to complete mold damage and scrapping. Therefore, assembly must be performed with extreme care. During assembly, special attention must be paid to mold cleaning, especially around the waterways and screw holes. Iron filings must be blown out.

8. Hot Runner or Cold Runner
This has the least impact on mold quality, as hot runners are typically custom-designed by the customer, especially large clients. Well-known international brands offer exceptional quality and after-sales service, so quality is generally not a concern.
However, the quality of some domestic hot runners varies greatly. Some small businesses, seeking cost savings and price advantages, use unreliable heating and conduction components, which can easily lead to problems. The main challenge with cold runners is ensuring injection balance, gate size, injection pressure, and other factors.

9. Cooling Water Circuits
Anyone with mold experience knows how crucial cooling is to a mold. Due to rising prices and labor costs, even a single second saved in injection molding cycle time is unimaginable when producing large quantities of products.

However, speeding up the production cycle also increases mold temperature. If not effectively controlled, molds can become too hot to form parts, or even deform and become scrapped. Therefore, excellent waterway design is crucial, including the layout density, diameter, and interconnections of the waterways.

10. Mold Maintenance

Mold maintenance primarily involves maintenance and upkeep during the production process. Molds are like cars; if left unused and unmaintained for extended periods, they can become scrapped. Therefore, comprehensive maintenance is essential after each use, especially for rust prevention of the molding area and key moving parts.

Because molds are exposed to water during production, there's a risk of spillage during installation or removal. Therefore, it's crucial to ensure they're dry and then apply a coat of oil for protection.