How to Improve the Life of Injection Mold?

Mold life has always been an important factor affecting the profitability of injection molding projects. If the life of the mold can be increased beyond the design requirements through a reasonable method, the profitability of the enterprise will be significantly improved. In this article, we will explore the paths to improve the life of injection molds together.

1. Reasonably set the clamping force

Correctly setting the clamping force of the injection molding machine is very critical and important to improve the life of the mold. If the clamping force is set too high or too low, it will have an adverse effect on the life of the mold.

  • If the clamping force is set too low, the injection pressure may exceed the clamping force, and the mold will expand or even be damaged during the injection molding process.
  • If the clamping force is set too high, the injection molding machine will exert excessive pressure on the parting line, vent area and mold parts of the mold, thus damaging the mold.

In order to avoid these situations, we can use mold flow analysis or use the following formula to calculate the ideal clamping force for each mold:

Clamping force = projected area x material clamping force factor x safety factor

  • Among them, the projected area includes the product and the runner.
  • The clamping force factor of the material can be obtained from the material physical property table or the material supplier.
  • The safety factor is selected according to the actual situation, which is related to the stability of the injection molding machine, the structure of the mold, etc., generally 1.5~2.

2. Low pressure clamping setting

Set low-pressure clamping on the injection molding machine to protect the mold. Set the high pressure lockout position no more than 0.05 inch of the actual die contact position. Gradually reduce the low pressure clamping pressure until the mold does not lock.

At this time, the mold clamping pressure will rise slowly, so that the mold will gradually transition from low pressure mold clamping to high pressure mold clamping.

Also, set the mold close timer to 0.5 seconds more than the actual mold close time requirement. For example, if the actual mold closing time is 0.6 seconds, set the mold closing timer to 1.5 seconds.

Improve the Life of Injection Mold

3. Reasonable mold opening and closing settings

The mold closing speed affects the cycle time. However, the mold closing speed is not as fast as possible. Because too fast clamping speed will cause excessive wear or damage of mold parts.

It should be ensured that the transition from fast-close to slow-close is smooth and that slow-close occurs before the pins and parts are mated. Make sure the transition between fast and slow molds is also smooth, and that fast molds occur after all products and parts come out of the mold.

4. Reasonable ejection setting

Improper ejection mechanism settings may affect the life of mold due to excessive ejection or due to improper product ejection, resulting in compression molding problems and damage to the mold.

The part needs to be ejected correctly from the mold based on the amount of separation required for the actual product. Excessive ejection can cause excessive pressure on the ejector pin. In addition to the amount of ejection, the setting of the ejection pressure should not be too large, which needs to be based on actual product needs.

5. Reasonable hot runner setting

The startup and shutdown method of the hot runner can affect the life of the mold. Improper start-up can lead to mold swelling, requiring formwork removal and repairs. Before production, the valve gates need to be manually operated to verify that the settings are correct and that they are in good working order.

Lead out the material in the hot runner through the guide plate and measure its temperature to verify whether the material temperature meets the requirements. During hot runner shutdown, the hot runner temperature should be reduced immediately to reduce the risk of material degradation.

6. Reasonable mold cooling setting

Excessive mold temperature will have an adverse effect on mold life. Therefore, limiting the mold temperature to the minimum requirement for acceptable part appearance is an effective way to improve mold life.

In addition, it should be ensured that the temperature difference between the movable side and the fixed side of the mold does not exceed 6℃. A temperature difference higher than this range will lead to a large difference in the thermal deformation of the molds on both sides. And that will further causing the problem of poor opening and closing of the mold, resulting in wear or damage to the mold.

7. Mold cleaning and maintenance

Mold in a production environment should be inspected, cleaned and lubricated at least once per shift. During the process, attention should be paid to signs of mold wear, such as galling, parting line wear, burrs, and metal shavings.

The following actions will help reduce unplanned maintenance events:

  • Developing a regular preventive maintenance schedule
  • Keeping mold repair records
  • Reviewing recurring maintenance events to establish preventive maintenance frequency

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