elements of difficulties in manufacturing injection mold
The cavity and core are three-dimensional.
The external and internal shapes of the plastic parts are directly formed by the cavity and core. It is difficult to process these complex three-dimensional surfaces, especially for the blind hole internal forming surface of the cavity. If the traditional processing method is adopted, it requires not only high technical level of workers, more auxiliary tools, more cutting tools, but also long processing cycle. High precision and surface quality requirements, long service life requirements.
At present, the dimensional accuracy of general plastic parts is required to be it6-7, the surface roughness Ra 0.2-0.1 μ m, the dimensional accuracy of corresponding injection mold parts is required to be it5-6, and the surface roughness Ra 0.1 μ m or less.
The roughness of the recording surface of the laser disk should be 0.02-0.01 μ m of the mirror processing level, which requires that the surface roughness of the mold should be less than 0.01 μ M. Long life injection mold is necessary to improve efficiency and reduce cost. At present, the service life of injection mold generally requires more than 1 million times.
For precision injection mould, the mould base with large rigidity shall be used, the thickness of the mould shall be increased, and the supporting column or cone positioning element shall be increased to prevent the mould from deforming under pressure. Sometimes the internal pressure can reach 100MPa.
Ejecting device is an important factor that affects the deformation and dimensional accuracy of products. Therefore, the best ejecting point should be selected to make all parts demoulded evenly. In the structure of high-precision injection mold, most of them adopt the splicing or full splicing structure, which requires the processing accuracy and interchangeability of mold parts to be greatly improved. Long process and short manufacturing time.
For injection parts, most of them are complete products matched with other parts, and in many cases, they have been completed in other parts, waiting for the matching of injection parts to be listed. Because of the high requirements for the shape or size accuracy of products, and because of the different characteristics of resin materials, after the completion of mold manufacturing, it is necessary to test and modify the mold repeatedly, which makes the development and delivery time very tight. Design and manufacture in different places.
Mold manufacturing is not the ultimate goal, but the end product design is put forward by the user. According to the user's requirements, mold manufacturers design and manufacture molds, and in most cases, injection production of products is also in other manufacturers. In this way, the product design, mold design and manufacturing and the production of products are carried out in different places. Professional division and dynamic combination.
The mould production batch is small, generally belongs to the production of single piece, but the mould needs a lot of standard parts, ranging from mold base to thimble, which cannot and cannot be completed by only one manufacturer alone, and the manufacturing process is complex, and the use of common equipment and numerical control equipment is extremely uneven.