The injection molding process is a complex processing process that involves many factors such as mold design, mold manufacturing, raw material properties and raw material pretreatment methods, molding process, injection molding machine operation, and is closely related to processing environmental conditions, product cooling time, and post-processing process. Therefore, the quality of the product depends not only on the injection precision and metering precision of the injection molding machine, but also on the quality of the mold design and the precision level of the mold processing. Generally, it is also affected and restricted by other factors mentioned above.

Under the constraints of so many complex factors, the appearance of defects in injection molding products is inevitable. Therefore, it is particularly important to find the internal mechanism of defects and predict the location and types of defects that may occur in products, and to guide mold design and improvement, summarize the rules of defects, and formulate more reasonable process operating conditions. We will elaborate the mechanism and solution of injection molding defects from three main factors that affect the plastic material characteristics, mold structure, injection molding process and injection molding equipment in the injection molding process.

Classification of common defects of injection molding products

The plastic materials used in the injection molding process are various, and the types and forms of mold design are also varied. In addition, the familiarity of the operators with the specific injection molding machine and the operating skills and practical experience of the workers are also different. At the same time, the objective environment (such as ambient temperature, humidity, air cleanliness) will also vary with the seasons, These objective and subjective conditions jointly determine the defects of injection molding products.

Generally speaking, there are three main aspects to evaluate the performance of plastic products:

First, appearance quality, including integrity, color and gloss;

Second, the accuracy between size and relative position, that is, size accuracy and position accuracy;

Third, the mechanical properties, chemical properties, electrical properties, etc. corresponding to the use, namely, functionality

Therefore, if there is a problem in any of the above three aspects, it will lead to the generation and expansion of product defects.

Classification of common defects of injection molding products

Appearance defects: craze discoloration, weld mark

Process problems: flash, shrinkage, lack of glue

Performance problems: warpage and embrittlement