Mold life has always been an important factor affecting the profitability of injection molding projects. If a reasonable method can be used to make the life of the mold to appreciate more than the design requirements, then the profitability of the enterprise will be significantly improved. This paper will explore seven ways to improve the life of injection mold.
● path 1: set mold locking force reasonably ●
It is very important to set the locking force of the injection molding machine correctly for improving the life of the mold. Too high or too low setting of the locking force will have an adverse effect on the life of the mold. If the mold locking force is set too small, the injection pressure may exceed the mold locking force, and the mold will be opened or even damaged during the injection process. If the locking force setting is too large, the injection molding machine will exert too much pressure on the parting line, exhaust area and mold parts of the mold, thus damaging the mold.
In order to avoid these situations, the mold flow analysis or the following formula can be used to calculate the ideal clamping force of each set of mold:
Clamping force = projection area X material clamping force factor X safety factor
Among them, the projected area includes products and flow channels. The locking force factor of the material can be obtained from the material property table or consulting 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.
● path 2: low pressure die closing setting ●
Set low pressure close on the injection molding machine to protect the mold. Set the high-pressure locking position to 0.05inch higher than the actual mold contact position. Gradually reduce the low-pressure die closing pressure until the die is not locked.
At this time, the mold locking pressure will rise slowly, so that the mold will gradually transition from low-pressure mold closing to high-pressure mold closing.
In addition, set the die close timer to 0.5 seconds higher than the actual die close time requirement. For example, if the actual mold closing time is 0.6 seconds, set the mold closing timer to 1.5 seconds.
● path 3: reasonable opening and closing die setting ●
The mold closing speed affects the cycle time, but the faster the mold closing speed is, the better. Because too fast closing speed will lead to excessive wear or damage of mold parts.
It should be ensured that the transition from quick closing to slow closing is smooth and that the slow closing occurs before the pins and components fit together. Make sure that the transition between fast and slow opening is smooth, and that fast opening occurs after all products and components are out of the mold.
● path 4: reasonable ejection setting ●
Incorrect setting of ejection mechanism may endanger die life due to excessive ejection or improper ejection of products, resulting in die pressing problems and die damage.
It is necessary to eject the parts from the mould correctly according to the separation amount required by the actual product. Too much ejection will cause too much pressure on the ejector pin. In addition to the ejection volume, the ejection pressure should not be set too large, which should be based on the actual product needs.
● path 5: reasonable hot runner setting ●
The start-up and shut-down method of hot runner will affect the die life. Improper start-up will lead to mold expansion, resulting in the need for formwork removal and maintenance. Prior to production, manually operate the valve gate to verify proper setting and good working condition.
The material in the hot runner is exported through the guide plate and its temperature is measured to verify whether the material temperature meets the requirements. During hot runner closure, the hot runner temperature should be reduced immediately to reduce the risk of material degradation.
● path 6: reasonable mold cooling setting ●
Too high mold temperature will have a negative impact on mold life, so limiting mold temperature to the minimum requirements of acceptable part appearance is an effective way to improve mold life.
In addition, it should be ensured that the temperature difference between the moving die side and the fixed die side does not exceed 6 ℃. The temperature difference higher than this range will lead to the difference of the thermal deformation between the two sides of the mold is too large, resulting in the problem of the opening and closing of the mold is not smooth, resulting in the wear or damage of the mold.
● path 7: mold cleaning and maintenance ●
Each shift should check, clean and lubricate the mold in the production environment at least once. During the process, pay attention to the wear signs of the mold, such as scratch, parting line wear, burr and metal chips.
Develop regular preventive maintenance plans, keep mold maintenance records, and review repetitive maintenance events to establish preventive maintenance frequency, which will help reduce unplanned maintenance events. Check whether the chute is lubricated and whether the slide rail works normally. Pay attention to brake failure and signs of loose hook head.
After each cleaning and inspection, when leaving the mold, confirm that the sliding position is correct. When the use time of the mold is not more than 6 hours, use anti rust agent, and thoroughly smear the texture and polishing area to prevent rust damage.
