Factors affecting mold life and methods to improve mold life

The mold life  restricts the application and development of fine blanking technology. Therefore, we must pay attention to the service life of the mold. The following editor will provide you with the factors that affect the mold life and tell you the ways to improve the mold life.

Factors affecting mold life

1. Structural manufacturability of fine blanking parts (sharp corners, thin walls, suspended walls, dimensional tolerances, etc.).

2. Materials of fine blanking parts (material quality, material thickness, hardness, plasticity, surface quality).

3. Structure of fine blanking die (strength, stiffness, die guide, small punch guide, exhaust and lubrication).

4. Mold material (material, carbide size and uniformity, hardness, toughness).

5. Mold manufacturing (mold blank forging, processing technology, heat treatment, wire cutting, grinding, assembly).

6. Production operation (mold height, pressure, speed, feeding accuracy, blank cleaning, lubrication).

7. Mold maintenance (reasonable storage, reasonable grinding, cleaning, stress tempering, rust prevention).

Ways to improve the mold life

1. Review the manufacturability of fine blanking parts. The manufacturability of fine blanking parts (especially the fillet radius) has a certain impact on the life of fine blanking molds. For those with poor manufacturability (especially sharp corners), suggestions for improvement should be made to the design department. Figure 1 shows the relationship between the fillet radius of the part and the die life. Generally, r/t ≥ 0.8 is better. If it is less than 0.25, the die life will be low.

2. Material selection and heat treatment of fine blanking molds. Cr12MoV is generally selected as the material of the main working parts of the fine blanking die. When the thickness of the workpiece is greater than 4mm, W6Mo5Cr4V2 high-speed steel can be used for the punch and die. For punch and die with high working intensity and severe stress, powder metallurgy steel (V4, asp23, asp30) or cemented carbide gt30 is used. The hardness of heat treatment of male and female dies is generally 58~62hrc. For dies with simple shape and wear as the main failure form, 60~64hrc can be taken; For the mold with complex shape and the main failure form of blade collapse, 56~60hrc or even 54~58hrc can be taken.

For the heat treatment of Cr12MoV mold, when the shape of the cutting edge is simple and the thickness of the blanking material is thin (t ≤ 3mm), the one-time hardening process (1020 ° C quenching and 220 ° C tempering) can obtain higher strength and wear resistance. When the shape of the cutting edge is complex and the blanking material is thick (t>3mm), high impact toughness and stability can be obtained by twice hardening process (1080 ° C quenching and 520 ° C tempering). For the heat treatment of W6Mo5Cr4V2 mold, low temperature quenching process must be adopted to obtain high strength and good toughness.

3. Problems that should be paid attention to in the structural design of fine blanking molds. The stress state of the mold should be good to prevent eccentric load, cantilever, one-way stress, etc; The reliable guidance is effective for reducing the wear of working parts, ensuring the uniformity of clearance, avoiding the gnawing of the mold and avoiding the misalignment of the pressure center. For example, when designing the punch for fine punching deep and long holes, the punch sheath structure should be reasonably used. When designing some large dies, small guide posts should be considered in their internal structure to increase the guiding accuracy. The guide of pressing plate and punch is also better. When the material thickness t ≥ 4mm, the concave mold is best to add prestressed sleeve. Due to the precise matching between the components of the fine blanking die and the thick lubricating oil used, it is easy to form a closed space between the bottom surface of the female die and the punching punch, as well as between the punch seat and the base with accurate matching. During the movement of the die, the air in the closed area is not easy to be discharged quickly, so that the heat caused by friction between the modl components is not easy to be taken away with the air, which will affect the movement of the push plate and ejector rod, reduce the production speed, and even cause the uneven phenomenon of the workpiece, affecting the normal life of the precision stamping mold. Therefore, exhaust slots should be opened on the bottom surface of the punch and concave mold, the fixed plate of the punch and the base

4. Assembly of fine blanking molds. In addition to paying attention to the uniformity of the gap between the upper and lower die edges, the coaxiality and the matching relationship between the parts, the assembly of the fine blanking molds should also pay special attention to the phase height of the working parts to ensure the correct position of the molds in the closed state and the open state, so as to ensure the reliability of its work.

5. Production operation and maintenance. When installing the die to adjust the pressure, on the premise of ensuring the quality of fine blanking parts, the pressing force and back pressure should be taken as small as possible. When using the fine blanking continuous molds, the first and last parts of the strip should pay special attention to the force balance of the molds, otherwise the punch is easy to break due to the lateral force. During feeding, attention should be paid to the setting of strip height limit and other devices to prevent the waste from being heavily pressed. When the burr of the workpiece is found to exceed the standard, it should be grinded in time. The grinding amount is generally 0.1~0.2mm, and attention should be paid to the elimination of internal stress.



About Huizhou Dj Molding Co., Ltd

Dj Mold is a China mold maker of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer, mold manufacturer China– plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Person: James Yuan
Company: Huizhou Dj Molding Company Limited
Add:  LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Tel: 86-752-6682869
Email: [email protected]

Site: https://www.jasonmolding.com/custom-injection-molding/

Share this post