What are the plastic mold structures

Thu Feb 23 14:38:29 CST 2023

It mainly includes a concave mold with variable cavities consisting of a concave mold combination substrate, a concave mold assembly and a concave mold combination plate, and a convex mold with variable cores consisting of a convex mold combination substrate, a convex mold assembly, a convex mold combination plate, a cavity cut-off assembly and a side cut-off combination plate.

In order to improve the performance of plastics, various auxiliary materials, such as fillers, plasticizers, lubricants, stabilizers, colorants, etc., are added to the polymer to become a good performance plastic.

1、Synthetic resin is the most important component of plastic, and its content in plastic is generally from 40% to 100%. Because of the large content and the fact that the nature of the resin often determines the nature of the plastic, people often see the resin as a synonym for plastic. For example, polyvinyl chloride resin is confused with polyvinyl chloride plastic and phenolic resin with phenolic plastic. In fact, resin and plastic are two different concepts. Resin is a raw, unprocessed polymer that is used not only in the manufacture of plastics, but also as a raw material for coatings, adhesives, and synthetic fibers. And plastic except for a very small part of the resin containing 100%, the vast majority of plastics, in addition to the main component resin, but also need to add other substances.


Filler is also called filler, it can improve the strength and heat resistance of plastics, and reduce costs. For example, the addition of wood flour in phenolic resin can greatly reduce the cost of phenolic plastic to become one of the cheapest plastics, but also significantly improve the mechanical strength. Fillers can be divided into two categories of organic fillers and inorganic fillers, the former such as wood flour, rags, paper and various fabric fibers, the latter such as glass fiber, diatomaceous earth, asbestos, carbon black, etc.


Plasticizers can increase the plasticity and softness of plastics, reduce brittleness, so that plastics are easy to process molding. Plasticizers are generally miscible with resin, non-toxic, odorless, light and heat stable high boiling point organic compounds, the most commonly used is phthalate esters. For example, when producing PVC plastics, if more plasticizers are added, soft PVC plastics can be obtained, and if no or less plasticizers are added (dosage <10%), hard PVC plastics can be obtained.


In order to prevent the decomposition and destruction of synthetic resin by light and heat during processing and use, and to prolong the service life, stabilizers are added to the plastic. Commonly used are stearate, epoxy resin, etc.

5、Coloring agent

Coloring agents can make plastics with a variety of bright, beautiful colors. Organic dyes and inorganic pigments are commonly used as colorants.


The role of lubricant is to prevent the plastic from sticking to the metal mold when molding, and to make the surface of plastic smooth and beautiful. Commonly used lubricants are stearic acid and its calcium and magnesium salts. In addition to the above-mentioned additives, flame retardants, foaming agents, antistatic agents, etc. can also be added to plastics.