1. Features of precision injection molding products

(1) The dimensional accuracy of the parts is high and the tolerance is small, that is, there are high-precision dimensional boundaries;

(2) The product weight has high repetition accuracy, and the dimensional stability of day, month and year is required;

(3) The material of the mold is good, and the rigidity is sufficient. The dimensional accuracy, smoothness and positioning accuracy between templates are high;

(4) Replace conventional injection machines with precision injection machines;

(5) Adopt precision injection molding process;

(6) Select materials suitable for precision injection molding.

The important technical index for evaluating products is the precision of injection molded products (dimensional tolerance, geometric tolerance and surface finish of products). In order to inject precise plastic products, strict control should be carried out from four factors: material selection, mold design, injection molding process, and operator's technical level.

Precision injection molding machines require that the dimensional accuracy of products is generally within 0.01~0.001 mm. Many precision injection molding machines also require high injection pressure and high injection speed; The clamping system is required to have sufficient rigidity and high clamping accuracy. The so-called clamping accuracy refers to the high uniformity, adjustability, stability and repeatability of the clamping force, and the high precision of the opening and closing positions; It is required that the pressure, flow, temperature, metering, etc. can be accurately controlled to the corresponding accuracy, and multi-stage or stepless injection is used to ensure the repeatability of the molding process reproduction conditions and product dimensions.

2 Factors affecting the dimensional accuracy of products

(1) Die precision;

(2) Molding shrinkage;

(3) The temperature, humidity and fluctuation range of the product using environment.

Keyword: precision injection molding

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