The deformation caused by internal forces in die parts. There are only two approaches: stress relief and mechanical reprocessing or a combination of the two.

The so-called inspection design level of precision mold is the rationality of the design and whether the optimization of the complexity into the simplicity is the best. This point, at present, there is a big difference in China's mold manufacturers.
The so-called inspection equipment level, is to see whether you have regular CNC equipment and use the right process to process. At present, the world's advanced mold manufacturing equipment, can be seen in China. The general Chinese mold manufacturer is basically OK on the equipment.
For management level and quality assurance system. We can only say that more and more enterprises realize its importance.
Here we focus on the processing technology to achieve this requirement of some experience.
First of all, to work in the processing center 3-4 hours after finishing the mold parts, the effect will be the best. Secondly, it is necessary to solve the problem of deformation of die parts due to internal stress in all processing processes, so that the deformation in the process of processing is minimal.
In the mold parts cutting processing, due to the processing of tools, electrodes, cutting wire, hot and cold changes, fastening tools on materials, etc., the material is processed in the internal accumulation of the resulting stress; At the same time, the internal stress is trying to release under the continuous accumulation. When the accumulated internal stress reaches a considerable degree, it overcomes the rigidity of the material, changes the shape of the workpiece to be processed, and produces deformation. It is inevitable that the material being processed will accumulate internal stress in the cutting process, so it is inevitable that the internal stress will cause the deformation of the die parts. We know that the accumulation of internal stress in die parts is the most deep hole, grinding, rough machining and electrical machining stage, as well as welding machining stage.
To overcome the deformation caused by internal force in die parts. There are only two approaches: stress relief and mechanical reprocessing or a combination of the two.
The removal of internal stress is usually done by heat treatment, which is commonly referred to as "stress elimination treatment". Generally steel parts into the furnace, 6-12 hours gradually heating up to 590℃, insulation for 2-6 hours (depending on the size and thickness of the workpiece, but also according to the local seasonal temperature), and then with the furnace cooling. This process usually takes 24-48 hours. General aluminum parts into the furnace, gradually heating up to 290℃ within 6 hours, heat preservation for 2-4 hours (depending on the size and thickness of the workpiece, but also according to the local seasonal temperature), and then with the furnace cooling. The process usually takes 24 hours.
In mechanical processing, especially rough processing, the force of fastening tools must be uniform, generally using multiple times, diagonal fastening, tight-loose-tight method. Our usual processing method is to identify a datum level, the process from beginning to end unchanged, with which to process other parts of the base. In fact, this base level is also deforming due to the deformation caused by the accumulation of internal stresses during machining. And the deformation of the datum will cause a lot of changes in the rest of the shape. During assembly, there are many changes through trimming, which accumulate and affect the quality and life of the mold.
In order to make the performance of the mold to meet the design requirements of the state, we should solve in the process of processing to overcome the internal stress caused by the deformation of the mold manufacturing process of the common disease.
In general, we choose several surfaces with different directions as the observation surface to self-detect the degree of three-dimensional deformation during rough machining. If one is not available, it can be attached and removed when finished. The additional observation surface should not be too small, too small to observe accurately. The principle is: big makes big, easy to cut. For example: in the three-dimensional size of 1000×800×300mm parts, generally the best set of observation surface length should not be less than 900mm, 600mm, 260mm. The smaller the observation surface, the greater the error between the measured value and the actual value. Under normal circumstances, if the length of the observation surface is only 50% of the actual length of the workpiece, the measured value will be 1-2 times different from the actual value.
After rough machining, the measurement of the observation surface and record the data, as far as possible to completely relax the fastening tool, but not change the workpiece in the table surface position, then measure the workpiece each observation surface of the actual data, two contrast, generally can know the deformation of the workpiece.
Secondary fastening: tighten each fastening tool again until it does not move during processing. This is the hardest. Then a small amount of cutting is carried out on each observation surface so that it can correctly play the real and correct role of the second reference (commonly known as the transition reference).
Workpiece turning: according to the deformation data measured after rough machining, the original datum surface dressing processing, must be the workpiece flat. If there is no flat processing, will make other parts of the shape offset, resulting in some parts of the cutting amount is too large, some parts without cutting amount or even negative concave. This machining is to overcome the deformation of the datum level so that it can continue to function as the first datum level. After the first "abatement" (rough machining), the datum surface is reworked. It is different from the following procedure. The processing of the first datum plane causes it to be inconsistent with other planes. In order to solve this contradiction, the workpiece then turn over, fastening: this fastening, the workpiece is best placed in situ. The original detection surface which has been processed twice is tested again. The error with the new datum surface is generally caused by the second tightening. With experience, this error will get smaller and smaller. The parts of the original processing are semi-finished. When done, check. Check no problem, move to the next process.
If proper machining allowance is reserved in the parting surface in advance, the third machining is carried out on the datum surface and parting surface after the three-dimensional reference of the cavity (space 0 bit) is measured by the three-coordinate machine before polishing. Here, a point needs to be made. It's very common for us to use 3D software now. But there are two design benchmarks we use: center 0-bit benchmarks and corner 0-bit benchmarks. The former is with the development of CAD and popular, for beginners, the entry is slow, but very accurate, not easy to make mistakes. The latter is to follow the traditional design method, prone to error. The "measurement of cavity 3D datum (space 0 bit) by CMM" I refer to here refers to the design and detection by "center 0 bit datum". You'll see what I mean. Generally according to this process, it can overcome the deformation caused by the internal stress produced by the processing. Parting surface can avoid the manual leveling process.