1. Selection of mold materials

When choosing mould materials, the selection should be made according to different production batches, process methods and processing objects. In mass production, long life mould materials should be selected, such as hard alloy, high toughness and high abrasion resistant steel (e.g. Yg15, yg20). The test system of small batch or new product can be used in mould materials such as zinc alloy and bismuth tin alloy. High strength and high toughness materials (t10a) are required for common mold with easy deformation and rupture failure. The hot forging die should be made of materials with good toughness, strength, resistance to mould and cold and heat fatigue. The die casting mould should adopt the alloy steel with high thermal fatigue resistance and high temperature strength (such as 3cr2w8v). The plastic mould should choose easy to cut, the organization compact, the polishing performance good material. In addition, in the design of punch and die, appropriate chooses different hardness or mold matching of different materials, such as: punch tool steel (t10a), die with high carbon high chromium steel (such as cr12, cr12mov), mold can improve the service life of 5 ~ 6 times.

2. Reasonable mold structure

Mold design principle is to ensure sufficient strength, stiffness, concentricity, to neutral and rational blanking clearance, and reduce the stress concentration, to ensure that the mold to produce parts meet the design requirements. So the main work zero of mould (such as convex and concave die of punching die, injection mold, die, stamping die of upper and lower mould, etc.) for its high accuracy and good concentricity and neutral of guidance and blanking clearance is reasonable.

When designing the mould design, the main consideration should be:

1. When designing the convex mold, it must pay attention to guide support and protection. In particular, the design of the eyelet punch can prolong the die life.

2. In order to reduce stress concentration, to reduce stress concentration, the circular arc radius should be 3~5mm.

3. For complex concave mold of structure, it can also reduce stress concentration.