When it comes to manufacturing products, several different methods can be used: compression molding, injection molding, and extrusion.

Not all molding processes are the same. Each of these methods has its unique benefits and drawbacks. In this blog post, we’ll discuss the differences between compression molding vs injection molding. Let’s get started!

The custom injection molding process is to close the mold before charging, the plastic resin’s raw material is heated in a separate charging cavity, is molten, injection molding moves the material through a screw and a hopper, whereas compression molding does not. and then pressed into the heated mold cavity at high speed through the pouring system of the mold under pressure, and continues to be heated and pressed in the mold and cured into the injection molds.

What is compression molding?

The compression molding process uses the characteristics of each stage of the resin curing reaction to mold the product, i.e., the molding material is plasticized, flows and fills the mold cavity, and the resin is cured.

During the flow of the molded material filling the mold cavity, not only the resin flows, but also the reinforcing material, so the molding pressure of the low-cost molding process is higher than that of other processes, and it is a high-pressure molding.

Therefore, it requires both a hydraulic press that can control the pressure and a metal mold with high strength, high precision, and high-temperature resistance.

Applications

It is mainly used as structural intricate parts, connecting complex parts, protective parts, and electrical insulation parts. They are widely used in automotive industry, agriculture, transportation, electrical, chemical, construction, machinery, and other fields. Due to the reliable quality of molded products, they are also used in weapons, aircraft, missiles, and satellites.

Advantages of compression molding

(1) The loss of raw materials is small and does not cause excessive loss (usually 2%~5% of the product mass).

(2) The internal stress of the product is very low, the warpage deformation is also very small, and the mechanical properties are more stable.

(3) The wear and tear of the mold cavity are very small, and the maintenance cost of the mold is low.

(4) The cost of molding equipment is low, the mold structure is simple, and the manufacturing cost is usually lower than that of injection mold or transfer molding mold.

(5) Large flat products can be molded. The size of the products that can be molded by molding is only determined by the clamping force of the existing molding machine and the size of the template.

(6) The shrinkage of the product is small and repeatable.

(7) A large number of mold cavities can be placed on a given mold plate, resulting in high productivity.

(8) It can adapt to automatic filling and automatic removal of products.

(9) High production efficiency, easy to realize specialized and automatic production.

(10) High accuracy of product size and good repeatability.

(11) Smooth and clean surface, no need for secondary finishing.

(12) Can form complex structure products at one time.

(13) Mass production, relatively low price.

Disadvantages of compression molding

(1) The molding cycle of the whole production process is long and inefficient, and it has a large physical consumption for the staff.

(2) It is not suitable for complex products with depression, side slopes or small holes, etc.

(3) In the production process, it is difficult to fill the mold and there are certain technical requirements.

(4) At the end of the curing stage, different products have different stiffness, which has an impact on the product performance.

(5) For products with high dimensional accuracy requirements (especially for multi-cavity molds), the process has a shorthand.

(6) The final product has thicker flying edges, and the workload of removing the flying edges is large.

(7) The disadvantage of molding the is that mold manufacturing process is complicated and the investment is large, and it is limited by the press, so it is most suitable for mass production of small and medium-sized composite products.

What is injection molding?

Injection molding is a kind of injection technology and molding method. It is the most utilized manufacturing process for the fabrication of plastic parts. Melted plastic is injected into a mold, where it gradually takes shape.

The advantages of the injection plastic molding options method are high production speed and efficiency, automatic operation, variety of colors, simple to complex shapes, large to small sizes, accurate product sizes, easy product replacement, and the ability to form complex-shaped parts.

Injection molding service is suitable for mass production and complex shaped products and other molding processing fields.

At a certain temperature, the plastic heated material is completely molten by screw mixing, injected into the mold cavity with high pressure, and cured by cooling to obtain the molded product.

This method is suitable for the mass production of complex-shaped parts and is one of the important processing methods.

Advantages of the injection molding process

(1) Efficient production speed and high efficiency

(2) The operation can be automated

(3) Wide variety of colors

(4) The desired shape can be simple to complex

(5) The size can be from large to small, and the product size is accurate

(6) Consumer products can be easily updated

(7) It is suitable for mass and high volume production and complex-shaped products in the molding process

Disadvantages of the injection molding process

(1) Large investment cost

(2) Long cycle time for injection mold making

(3) High requirement for operator’s operation skills

Summary

Through this article, you should have a certain understanding of molding and injection molding.

If you are going to custom plastic molding project, determine which process is more suitable, compression molding or injection molding, by the size of the product, the complexity of the structure, the material, and the quantity of the product.

If you are not quite sure which process to choose, you can also seek help from Zetarmold, with Zetar, you can have your project come true in a matter of days.

With more than 20 English speakers and 7 experienced engineers on hand to support the process from idea to reality – let us help turn your dream into a reality!