Fine blanking originates from ordinary stamping, but it is not just a stronger version of ordinary stamping. The essential difference between fine blanking and stamping lies in the fact that ordinary stamping cannot effectively avoid the generation of section tearing during punching and cutting, while fine blanking tries to suppress the occurrence of plate tearing as much as possible during punching and cutting.
Now let's compare the differences between fine blanking and ordinary stamping from the perspective of workpiece characteristics and mold structure.
Ordinary stamping can process almost any material as long as the die steel has sufficient strength and the press has sufficient pressure.
However, the materials used for fine blanking require good plasticity, low yield strength ratio and high elongation in order to effectively transfer pressure stress between material crystals to suppress cracks; They need to have a good organizational structure. Uneven material structure is difficult to produce uniform suppression under constant pressure conditions; The tensile strength is usually below 600 MPa~700 MPa, and the material structure of too hard materials is relatively coarse (such as martensite). When selecting materials, you can choose based on the following three conditions:
1. When the carbon content of the material is less than 0.35%, it can be fine blanked directly.
2. When the carbon content (carbon equivalent) of the material is between 0.35%~0.7%, it needs to be spheroidized annealed.
3. You can choose high-strength nano-grain alloy steel.
1. Low carbon steel: DC03, DC04, etc.
2. Low-alloy high-strength steel: H420LA, S500MC, etc.
3. Quenched and tempered steel: 16MnCr, 42CrMo4, etc.
The fine blanking mold is a composite mold. Unlike ordinary molds, the composite mold can complete multiple forming or separation actions through one mold station in one press cycle.
In short, the mold structure of fine blanking is more complicated than that of ordinary stamping. It has an additional gear ring pressure plate and ejector, and the clearance between the punch and die is extremely small, and the die edge has a round corner.
Ordinary stamping equipment generally provides unidirectional power (there are also double-action presses for processing special-shaped products), that is, cutting force. The table difference is also very large. For example, the table length of an 800T press can be from around 2m to around 5m.
A fine blanking machine can provide three powers: punching force, trimming force, and counter force. And the fine blanking equipment has a compact structure, and the table is small, with an 800T fine blanking machine table length generally around 1m.
Of course, like ordinary stamping machines, fine blanking machines also require other supporting auxiliary equipment. Generally, the necessary auxiliary systems for fine blanking machines include uncoiling leveling feeding machines, mold lubrication systems, and waste separation systems.