In injection molding industry, a good mold may often be more expensive than injection molding machine itself. Compared with other molds, injection molds are more complex and precise in structure, have higher requirements for operation and maintenance. Therefore, mold life is an important factor affecting profitability of injection molding enterprise projects.

 

Mold life refers to number of production times (stamping times, molding times) that mold can achieve under premise of ensuring quality of parts. It includes repeated sharpening and replacement of wearing parts until the total number of qualified parts formed by replacement of main part of mold. Life of mold is affected by many factors, including material selection, design quality, use conditions and maintenance. Different types of molds, such as stamping molds, plastic molds, etc., have different life standards and usage times. For example, design life of stamping molds is generally more than 1 million times, and high-quality molds can even reach more than 10 million times; while design life of plastic molds is generally about 10 years, service life is generally between tens of thousands and hundreds of thousands of injection cycles. ‌
Technical measures to improve life of molds include using pure high-performance mold steel and toughening treatment. Material selection has an important impact on life of molds. High-quality mold materials have higher hardness, wear resistance and corrosion resistance, and can provide longer service life. Reasonable mold design can reduce stress concentration and fatigue cracks, improve strength and stability of mold. Proper control of use conditions, such as temperature, pressure and number of cycles during injection molding, can extend service life of mold. Regular maintenance is essential to extend life of mold, including cleaning mold surface, lubricating mold parts, repairing damaged and worn parts.

Path 1. Reasonable setting of clamping force
Correctly setting clamping force of injection molding machine is very critical and important to improve life of mold. Setting clamping force too high or too low will have an adverse effect on life of mold. If clamping force is set too low, injection pressure may exceed clamping force, causing mold to expand or even damage during injection process. If clamping force is set too high, injection molding machine will apply excessive pressure to mold parting line, exhaust area, and mold components, thereby damaging mold.
Path 2: Low-pressure mold clamping setting
Set low-pressure mold clamping on injection molding machine to protect mold.
Path 3: Reasonable mold opening and closing settings
Mold closing speed affects cycle time, but the faster mold closing speed, the better. Because too fast a mold closing speed can cause excessive wear or damage to mold components.
Path 4: Reasonable ejection setting
Incorrect ejection mechanism settings may endanger mold life due to excessive ejection or improper product ejection, resulting in mold compression problems and damage to mold.
Path 5: Reasonable hot runner settings
Hot runner startup and shutdown methods affect mold life. Improper startup can cause mold expansion, resulting in need for mold removal and repair. Before formal production, manually operate valve gate to verify whether settings are correct and whether working condition is good.
Path 6: Reasonable mold cooling settings
Excessive mold temperature will have an adverse effect on mold life, so limiting mold temperature to minimum requirement for acceptable part appearance is an effective way to increase mold life.
Path 7: Cleaning and maintenance of molds
Develop a regular preventive maintenance plan, keep mold maintenance records, and review repetitive maintenance events to establish a preventive maintenance frequency, which will help reduce unplanned maintenance events.

1. By optimizing mold design and strengthening mold maintenance work (Mold should be repaired as little as possible or not at all);
2. Choose steel with high hardness, good rigidity and wear resistance for moving parts of mold to reduce its wear;
3. Install anti-collision blocks on mold parting surface to prevent mold from being crushed;
4. Install wear-resistant blocks on the left and right sides and bottom of mold slider to prevent it from being worn;
5. If mold is pushed back by ejector plate guide column during mold closing, install an "anti-collision pin" on part where ejector plate guide column hits;
6. For molds with large order volumes, cooling water channel needs to be processed with stainless steel to prevent water channel from rusting;
7. Inlay steel with good rigidity and high hardness at stress-bearing part of mold to improve its compression and deformation resistance;
8. Install "three positioning" on mold to prevent guide column and guide sleeve from being worn or deformed and damaged due to excessive force;
9. Optimize design of lifter structure, install wear-resistant inserts on its moving parts, and install the bottom on lifter seat (to prevent wear);
10. Wear-resistant steel is used for glass fiber reinforced plastics to improve its wear resistance and product size stability;
10. Optimize ejector design, use exhaust ejector, ordinary ejector should be in sliding fit state, and improve processing accuracy of ejector hole, ejector head needs to be hardened to reduce ejector wear or burning;
11. For main channel type mold, a support head (support column) needs to be installed in the middle of mold core to prevent mold from "punching" and deformation;
13. For plastics with poor stability and easy to decompose by heat to produce corrosive substances, mold needs to use steel with good corrosion resistance;
14. For molds with large order volume, mold cavity should be made into a block structure as much as possible to facilitate replacement of damaged or worn cavities;
15. For molds with hardware inserts, holes for inserting hardware inserts should be processed with steel with good rigidity, high hardness and wear resistance (extend service life of holes);
16. Increase thickness of mold cavity and core mold plate to improve mold's pressure resistance and impact resistance, extend service life of mold;
17. "Pull buckle" of three-plate mold needs to be a device with good quality and reasonable structure. It is best to use it together with rubber pull buckle to share pull force and reduce its failure.