Plastic has super high fluidity, which makes it difficult to produce the size of plastic injection molded parts in strict accordance with the requirements of the drawings, especially for some injection molded parts with high dimensional accuracy requirements, the dimensional accuracy of plastic injection molded parts refers to the degree of conformity between the size of the obtained plastic parts and the size of the product drawings, that is, the accuracy of obtaining the size of plastic parts.
Firstly, there are many factors affecting the dimensional accuracy of plastic parts, firstly, the accuracy of mold manufacturing and the degree of wear of mold, secondly, the fluctuation of plastic shrinkage rate and the change of process conditions during molding.
Therefore, in order to reduce the processing difficulty of the mold and the manufacturing cost of the mold, the dimensional accuracy of plastic parts should be designed as low as possible under the premise of meeting the requirements of the injection molded parts.
The dimensional tolerance of plastic injection molded parts can be designed according to SJ1372-78, the standard of tolerance value of plastic parts for injection molding processing. According to this standard, the injection molding accuracy of plastic parts is divided into 8 precision levels, of which 1 and 2 belong to the technical level of precision injection molding processing, which can only be used under special requirements, the standard only stipulates the standard tolerance value, and the basic dimensional deviation can be assigned according to the matching nature of plastic parts.
For the dimensions that are greatly influenced by the moving part of the mold, such as the height dimension of the compressed part, due to the influence of the thickness of the overflow edge of the horizontal type surface, the tolerance value is taken as the sum of the tolerance value and the additional value in the table, and the additional value is 0.05mm for the level 2 precision, 0.10mm for the level 3~5 precision, and 0.20mm for the level 6~8 precision.
In addition, for the unannotated tolerance size, it is recommended to use the standard level 8 precision. Only by strictly following the standard of tolerance value of plastic injection molded parts can we ensure the dimensional accuracy and quality of plastic parts.
In order to meet the human pursuit of injection molding processing material, the performance of products in various industries is constantly improving, the products are composed of accessories, which requires the product parts to be more and more precise, and greatly make the product parts to reach the initial design size, injection molding processing industry is also the same, and precision injection molding processing has become the major outstanding injection molding enterprises compete in the field.
Nowadays, many products are not able to reach their initial design life, which has many reasons, one of which is that the product parts can not reach the initial design size, a complete product is composed of several or even tens of thousands of parts, the size is not able to reach the design requirements, which makes problems in the process of use, and even a long time, it is necessary to replace the parts.
For example: each accessory on the spacecraft is selected by thousands of manufacturing, perhaps a small size problem can lead to a big accident, so in recent years various industries are increasing investment in precision manufacturing, who can master the precision manufacturing technology, who will be able to dominate the competition in the future.
In recent years, the precision injection molding processing industry in the injection molding industry is also developing relatively quickly, but to meet the conditions of precision injection molding processing generally need what aspects.
One: advanced injection molding machine equipment, injection molding machine as the basis of injection molding, the foundation is not good, it is absolutely not good products.
Second: the manufacture of molds, injection molding industry is inseparable from the mold, superior performance of the mold can add a lot of points for precision injection molding processing.
Third: the injection molding operator, without an excellent injection molding engineer, then the best equipment is also futile.
Fourth: the purchase of raw materials, the same kind of plastic, the process of its different, resulting in different performance of plastic, injection molding processing.
Post time: Nov-18-2022