Products involved in science and technology electronic products, plastic molds, automobile parts, fine gifts, office supplies for teaching, civil plastic products, fine toys and many other industry sectors. Higher requirements for the manufacture of molds. Requirements for mold manufacturers to provide mold mold parting surface shall not have hand-polished traces, and many domestic factories are unable to do this requirement. In fact, general mid-range molds (small and medium-sized) should meet this requirement. This requirement is to examine the mold manufacturer's design level, equipment level, process level, management level, quality assurance system and staff quality of one of the comprehensive indicators.

Precision mold so-called examination of the design level, is the rationality of the design and the optimization of complexity into simplicity is the best. This point, there is still a big difference in the Chinese mold manufacturers.

The so-called examination of the level of equipment, that is, to see whether you have formal CNC equipment and the use of the correct process to process. Currently, the world's mold manufacturing equipment can be found in China. General Chinese mold manufacturers are basically in the equipment is OK.

For the management level and quality assurance system. Can only say that more and more enterprises recognize its importance.

Here focus on the machining process to achieve some of the experience of this requirement.

First, to work in the machining center 3-4 hours after the mold parts for finishing, the results will be the best. Secondly, to solve the problem of deformation of mold parts due to internal stress in all machining processes, so that the minimum deformation in the machining process.

In the mold parts cutting process, due to the processing of tools, electrodes, cutting wire, hot and cold changes, fastening tools on the material of the application of force, etc., the material being processed in the internal accumulation of the resulting internal stress; at the same time, the internal stress in the continuous accumulation of attempts to release. When the accumulated internal stress reaches a considerable degree, overcoming the rigidity of the material, changing the shape of the machined part, resulting in deformation. The material being processed in the cutting process accumulation of internal stress is inevitable, then the internal stress to cause deformation of mold parts is also inevitable. We know that the mold parts in the accumulation of internal stresses in the most, is to play a deep hole, grinding, roughing and electrical processing stage, as well as welding processing stage.

Overcome the deformation caused by internal forces in the mold parts. No more than two ways: eliminate internal stress and mechanical reprocessing or a combination of both.

Elimination of internal stress is generally to take the heat treatment method, that is, we usually say “elimination should be dealt with”. General steel parts into the furnace, 6-12 hours within the gradual warming to 590 ℃ or so, holding 2-6 hours (depending on the size and thickness of the workpiece, but also according to the local seasonal temperature at the time), and then cooled with the furnace. This process generally takes 24-48 hours. General aluminum parts into the furnace, 6 hours to gradually warm to 290 ℃ or so, holding 2-4 hours (depending on the size of the workpiece and thickness, but also according to the local seasonal temperature at the time), and then cooled with the furnace. This process generally takes 24 hours.

In machining, especially rough machining, the force of the fastening tool must be uniform, generally using multiple times, diagonal fastening, tight - loose - tight method. We are generally accustomed to the processing method is to identify a reference surface, the processing process from start to finish unchanged, to use it as a benchmark to process other parts. In fact, due to the deformation caused by the accumulation of internal stress during processing, this reference surface is also deformed. The deformation of the datum surface will cause many changes in the shape of the rest. In the assembly by trimming, and produce many changes, these cumulative, it affects the quality and life of the mold.

In order to make the performance of the manufactured mold to meet the design requirements of the state, we should solve the deformation caused by internal stress in the processing to overcome this common disease in the mold manufacturing process.

We generally choose a few faces in different directions as observation surfaces for self-testing the degree of three-dimensional deformation during rough machining. If there is no ready-made, can be attached, to be removed when finishing. Additional observation surface can not be too small, too small observation is not accurate. The principle is: as large as possible, easy to remove. For example: in the three-dimensional dimensions of 1000 × 800 × 300mm parts, it is generally best to set the length of the observation surface should not be less than 900mm, 600mm, 260mm. the smaller the observation surface, the greater the error between the measured value and the actual. In general, if the length of the observation surface is only 50% of the actual length of the workpiece, the difference between the measured value and the actual will be 1-2 times.

In the rough machining is completed, measure the situation of the observation surface and record the data, try to completely relax the fastening tool, but shall not change the position of the processed parts in the worktable, and then measure the actual data of the observation surface of the processed parts, the two sides of the comparison, generally know the deformation of the processed workpiece.

Second fastening: again tighten the fastening tools to the processing will not move until. This is the most difficult. Then a small amount of cutting on the observation surface so that it can correctly play the second benchmark (commonly known as transition benchmark) of the true and correct role until.

Workpiece turning: According to the deformation data measured after rough machining, the original datum surface for finishing processing, be sure to pad the workpiece flat. If it is machined without pad leveling, it will make other parts of the shape offset, resulting in excessive cutting in some parts and no cutting or even negative concavity in some parts. This machining is to overcome the deformation of the datum surface so that it can continue to function as the first datum surface. After the first “abrasion treatment” (after roughing), the datum surface is re-machined. This is not the same as the following process. The machining of the first datum surface creates an error between it and the other surfaces. In order to solve this contradiction, the workpiece is turned over again and fastened: this time, the workpiece is preferably placed in its original position. Each of the original testing surface that has been processed twice, and then tested. Its error with the new reference surface, generally more than the second fastening is too tight caused by. With the accumulation of experience, this error will become smaller and smaller. Semi-finish machining of the original machined parts. When finished, inspect. If there is no problem with the inspection, move to the next process.

If appropriate machining allowances are reserved on the parting surface in advance, the datum and parting surface will be machined for the third time after measuring the three-dimensional datum (space 0 position) of the cavity with a three-coordinate machine before polishing. Here, a problem needs to be emphasized. We are now using three-dimensional software has been very popular. But we use the design of the benchmark but there are two kinds: the center of the 0-bit benchmark and the corner of the 0-bit benchmark. The former is popularized with the development of CAD, for beginners, slow to start, but very accurate, not easy to make mistakes. The latter is to follow the traditional design method, easy to make mistakes. I refer to the “three-coordinate machine to measure the cavity three-dimensional reference (space 0),” means that the “center 0 reference” design and testing. You will understand what I mean if you experience it. Generally, by following this procedure, the deformation caused by the internal stress generated by machining can be overcome. The parting surface can avoid the process of manual flattening.