What are the differences between injection mold and compression mold
It is well known that the injection mold manufacturing industry is the main pillar of the development of modern industry. With the rapid development of modern industry, the materials of products being developed and applied are also rich and diverse. This has promoted the diversification of the mold industry, including die-casting mold, plastic mold, silicone mold, stamping mold, casting mold, sheet metal mold, and so on. Today, I will explain the difference between die-casting mold and plastic mold in detail, as well as related knowledge.
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The structure of die-casting mold and plastic mold is actually the same. It should be said that if you can make plastic mold, you should be able to make die-casting mold. The main difference between the two is that on the feeding sprue sleeve, the sprue sleeve of the plastic mold is a slender tapered feeding port, and the diameter of the feeding port is relatively small; The feed inlet of the die-casting mold is relatively large, and the diameter of the taper feed inlet of the central feed is much larger than that of the plastic mold. Another feeding port is a straight circular sleeve with a diameter of 30 to 40 mm, which is a structure that is not available in plastic moulds.
Injection mold is a part that gives shape and size to plastics during molding. Although the structure of the mold may vary greatly due to different types and properties of plastics, shapes and structures of plastic products, and types of injection machines, the basic structure is the same.
Injection mold can be divided into thermosetting plastic mold and thermoplastic plastic mold according to molding characteristics; According to the molding process, it can be divided into transmission mold, blowing mold, casting mold, hot forming mold, hot pressing mold (compression mold), injection mold, etc. The hot pressing mold can be divided into overflow type, semi overflow type and non overflow type in the way of overflow, and the injection mold can be divided into cold runner mold and hot runner mold in the way of pouring system; According to the loading and unloading mode, it can be divided into mobile type and fixed type. The classification of dies is also based on different processing technologies. Injection mold is to inject molten plastic into the cavity of the mold with a certain speed and pressure. After the plastic cools, open the mold to take out the molded injection products.
Compression molding die is called compression mold for short_ The plastic raw materials are directly added to the open mold cavity, the mold is closed, the plastic becomes a flowing state and fills the mold cavity under the effect of heating and pressure, and then the products are hardened and shaped through chemical crosslinking or physical cooling.
The plastic pressing mold is used to heat and press the plastic sheet into shape with a heated mold, then open the mold, take out the formed products, and put them into cold water for shaping and cooling. Compression molding is an important technology in the molding process, which is widely used in industrial production and industrial processing, and plays an important role in people’s life. Generally, powder, granular, agglomerated, flaky or even shaped blanks similar to the products are first made, placed in the cavity of the heated mold, and then closed mold pressurization is used to form, cure or vulcanize them, and then demoulded to obtain the products (see figure). This method is particularly applicable to the molding process of thermosetting plastics (see thermosetting resin). The disadvantages are long production cycle, low efficiency and poor dimensional accuracy of products.
In addition, plastic molds and die-casting molds are made of different steels; The plastic mould generally uses 45 # steel, T8, T10 and other steels, while the die casting mould mainly uses heat resistant steel such as 3Cr2W8V. The production of plastic products is first based on the development and design of plastic molds. Plastic molds are a basic tool for the production of plastic products. The precision of molds directly affects the structural integrity and dimensional accuracy of plastic products.
The production of all kinds of plastic products needs to go through plastic mold design and manufacturing, injection molding, surface treatment and other links. The precision mold has complex structure, high requirements for surface quality and technical standards, and belongs to technology and capital intensive products. The production process needs to apply high-speed processing and ultra precision processing technology, rapid prototyping technology, automatic control technology, polymer material processing and application technology, etc., involving machinery, metal materials Polymer materials, chemical materials, electronic and electrical, automatic control and other fields require high technical comprehensiveness.
After the design of the whole mold is completed, the following inspections must be carried out: first, the draft analysis of the insert to see if there is any undercut, and second, the interference inspection of all parts of the mold, which is the most important. Now 3D software has this function, which is very convenient. Then there is the simulation of mold opening and closing. As long as a simple mold is not too clear, it must be simulated in practice. In addition, the machinability of each part of the mold and the assembly process of the mold. Don’t work hard to design a clever structure. The theoretical calculation is OK. After processing, the result cannot be loaded or it is not easy to assemble.
