Fineblanking tooling is unique in its construction. When compared to conventional stamping tooling, there are a few specific features that set fineblanking tools apart. They are:
The V-ring is a raised V-shaped ridge usually on the stinger plate that has the same contour as the blanking punch and is located close to it, roughly a distance equal to 50% of material thickness. In some cases the V-ring is placed on the die plate, sometimes on both the die and the stinger plate, and at times no V-ring is used.
In the initial stage of the fineblanking cycle, the V-ring is pressed into the material to prevent lateral movement of the material in the piercing and blanking operations. The V-ring also ensures that enough material is packed into the die cavity to create fully sheared, straight edges.
Close punch-die clearance:
This is another important feature of fineblanking tooling, which enables the unique characteristics of fineblanked parts to be created. Generally the clearance between punch and die is 0.5% of material thickness - per side. In some cases, depending on the material and application, zero clearance between punch and die is used. The minimal punch-die clearance is the key to obtaining the fully sheared edges that fineblanked parts are noted for. This compares with a typical clearance of 10% of material thickness per side for conventional stamping tools.
The die-cavity in
a fineblanking tool is straight - not tapered. This helps ensure
the cleanly sheared edges and results in cut edges that are tapered
approximately only 0.5°. Such a minimal taper enables tight
dimensional control through the full thickness of the piece part.
The straight die
cavity also ensures that after the die plate is ground during regular
die maintenance, the size of the die cavity does not grow (as it
would if the die cavity was tapered). This ensures that the parts
produced in every production run will maintain the same nominal
dimensions as when the part was first made.
Radiused cutting edges:
Fineblanking is as much an extrusion process as a stamping process. The cutting edges of the die cavity are not sharp - they are radiused. This allows the metal to flow into the die cavity.
Fineblanking tools are compound dies, meaning that the part is ejected out of the die cavity. Most fineblanking dies are single station dies, with all features created at one time with a single stroke of the press. Parts made in a single station tool have extremely consistent relationships between features. The use of progressive fineblanking dies is increasing rapidly, in an effort to provide more and more complex features on parts right out of the tool - eliminating secondary operations and enhancing design possibilities.
Because of the extremely close punch and die clearances and the pressures inherent in the process, fineblanking tools must be produced with very tight fit among all tool components.
There are two types of fineblanking tools: sliding punch and fixed punch. Generally, sliding punch tools are used for smaller and less complex parts, while fixed punch tools are used for larger and more complex parts. Sliding punch tools are less expensive to build, set-up, and maintain, but are not as rigid as fixed punch tools - and cannot be used in every application.
To see how the fineblanking die works, please visit the How it Works section of this website.