How To Avoid The Deformation That Occurs in Wire-cut Machining?

I. Reasons for deformation of workpiece by wire-cut machining
Split a bamboo from the center, both halves of the bamboo piece will become bent, the big half of the bend less, the small half of the bend more. This is the material itself will have stress, the process of splitting breaks the balance of the original stress of the material, through the deformation to restore the balance. Wire cutting workpiece deformation is the same reason, the cutting process breaks the original stress balance of the workpiece.
The size of the deformation of the wire cutting process has a relationship with the structure of the workpiece. Narrow and long shape of the concave mold, convex mold is easy to produce deformation, the size of its deformation and shape complexity, aspect ratio, etc.; Thin wall thickness of the workpiece is easy to produce deformation.
If the deformation is very small, the deformation is almost negligible within the precision range of processing requirements. However, if the deformation exceeds the processing accuracy requirements, it will make the size of the obvious deviation, affecting the shape of the workpiece processing.
The causes of deformation are manifold, such as material problems, heat treatment problems, structural design problems, process arrangement problems, and wire-cutting workpiece clamping and cutting path selection problems, and so on. These various reasons will lead to the deformation of the material by internal stress.
Second, the workpiece processing deformation of preventive measures
Certain measures can be taken to control the deformation of wire cutting processing and prevent the occurrence of deformation phenomenon.
1. Rough machining or stress relief cutting before cutting
If it is necessary to cut a large area on a piece of material, it will make the relative equilibrium state of the residual stress inside the material be damaged, and the material will produce great deformation. We can eliminate most of the stresses in the material first, by either roughing (rough machining) to remove most of the residual first, or by making a stress-release path cut.
For EDM wire cutting of large concave molds, we can do two main cuts, first increase the offset of the main cut by 0.1-0.2mm on one side for the first main cut, let the stress be released, and then use the standard offset for the second main cut.
2.Processing of threading holes
When cutting the convex mold, if you don't process the perforation holes and cut directly from the outside of the material, the deformation will occur due to the stress imbalance of the material, which will result in the deformation of the open mouth or closed mouth deformation. It is possible to process the perforation holes in the material for closed contour machining.

Third, optimize the processing path
In general, it is best to arrange the processing of the starting point near the clamping end, the workpiece and its clamping part of the separation of the cutting section arranged at the end of the machining path, the pause point is located near the clamping end of the blank parts. Some processing due to processing path arrangement is not reasonable, is also caused by wire cutting processing deformation.
Fourth, multiple cutting
Some workpieces in the adoption of certain measures, there are still some deformation, in order to meet the precision requirements of the workpiece, you can change a cut to the size of the traditional habits, the use of multiple cutting methods. Fast walking wire cutting processing using multiple cutting methods, mainly to achieve better surface roughness, but the use of multiple cutting methods to reduce the deformation of mold parts due to stress problems brought about by a very important practical significance.
Fifth, set the amount of multi-stage temporary
Large, complex shape of the workpiece processing situation, should set two or more of the amount of temporary retention, set more than one starting point. Programming to open the shape of the way processing, programming before the graphic decomposition into a number of segments, and were connected up, processing the first contour, and finally processing the amount of temporary parts.