Causes For The Injection Molds Manufacturing Difficulty
Analysis of the injection molds manufacturing difficulty
The cavity and core are three-dimensional.
The external and internal shapes of plastic parts are directly formed by the cavity and core. It’s more difficult to process these complex three-dimensional profiles, especially the blind-hole inner molding surface processing of the cavity.
If using traditional processing methods, workers are required to have a great skill. In addition, many auxiliary tools and fixtures are necessary and with a long processing cycle.
A high precision and surface quality with a long service life are required.
At present, the dimensional accuracy of general plastic parts is required to be IT6-7, and the surface roughness is Ra0.2-0.1μm. The corresponding dimensional accuracy of injection mold parts is required to reach IT5-6, while the surface roughness is less than Ra0.1μm.
The roughness of the recording surface of the laser disc must reach the level of mirror processing of 0.02-0.01μm. And that requires the surface roughness of the mold to be below 0.01μm. Long-life injection molds are necessary to improve efficiency and reduce costs. At present, the service life of injection molds generally requires more than 1 million times.
Precision injection molds need to use a rigid mold base and increase the thickness of the template. Also, add support columns or tapered positioning elements to prevent the mold from deforming under pressure. Sometimes the internal pressure can reach 100MPa.
The ejector device is an important factor that affects the deformation and dimensional accuracy of the product. Therefore, the best ejector point should be selected to make the demolding uniform. Most of the high-precision injection molds adopt inlaid or full-assembled structure. That requires the processing accuracy and interchangeability of mold parts to be greatly improved.
The process flow is long and the manufacturing time is tight.
For injection molded parts, most of them are not complete products and it need to be matched with other parts to assemble the final product. Because it’s required that the shape or dimensional accuracy of the products must be high. Because of the different characteristics of the resin materials, after the mold is manufactured, it is necessary to repeatedly try and modify the mold, which makes the development and delivery time very tight.
Design and manufacture in different places.
Mold manufacturing is not the final goal, but the final product design proposed by the user. The mold manufacturer designs and manufactures the mold according to the user’s requirements. In most cases, the injection production of the product is in other manufacturers. This results in a situation where product design, mold design and manufacturing, and production of the plastic product are carried out in different places.
Professional division of labor, dynamic combination.
Mold production is small in batches and generally belongs to single-piece production. But molds require a lot of standard parts, ranging from mold bases to small ejector pins. These cannot be completed by one manufacturer alone because the manufacturing process is complex. Common equipment and CNC Equipment usage is extremely uneven.