compression mould

MDC mould > compression mould

Compression molding process is based on the characteristics of each stage of the curing reaction of thermosetting plastics or other moulding materials.

Compression mold uses a hydraulic press in which a mold is fixed on the top and bottom platens of the press. The molds can be classified as hand molds, used for trial runs; semiautomatic, in which the press follows a programmed cycle but the operator manually loads and unloads the press, and automatic, which operate under a fully automatic press cycle (including automatic loading and unloading).

The process of compression molding is as follows:

Step1 - Powdery, granular or fibrous plastic is put into the heated metal mold at the molding temperature.
Step2 - Close the mold and apply pressure to force the material into contact with all mold areas.
Step3 - Maintain heat and pressure until the molding material is cured.
Step4 - The product is ejected by ejector, repairing the flash.
Step5 - After demolding, clean the mold cavity to start the next production.

Compression molding Vs Injection molding

Injection molding can produce plastic parts with complex structures. But, the strength of products is not enough, while compression molding allows longer fiber materials with very good strength and toughness. Compression molds are generally simpler than their injection mold counterparts. There is no sprue and runner system in a compression mold and the process itself is generally limited to simpler part geometries due to the lower flow capabilities of the starting thermosetting materials.

Disadvantages of compression molding

1. At present, it is not suitable for molding complex parts with depressions, side slopes or small holes.
2. Burrs must be trimmed manually.
3. For thermosetting plastics, when the molded products have slight defects, they are often unable to be recycled.

Advantages of compression molding

1. Suitable for mass production, short cycle moulding times and high efficiency;
2. Lowest cost molding methods, the loss of raw materials and the mold wear is small, and the maintenance cost of the mold is low.
3. It can be used to form large flat products. High dimensional accuracy, small shrinkage, low internal stress, high strength, the mechanical properties are relatively stable. The surface is smooth without secondary modification.
4. Advanced composite materials are used to ensure better mechanical properties of the products.

The initial charge of molding compound can be in any of several forms, including powders or pellets, liquid, or preform. Materials for compression molding include phenolics, melamine, urea-formaldehyde, epoxies, urethanes, and elastomers. To produce higher quality compression mold, The following are some of MDC's compression mold solutions: 1: Maintain pressure during cooling to avoid uneven surface. 2: Smooth surface mold with a fast cooling rate can prevent the product from sticking to the mold.. 3: ...

Compression mold is one of MDC's largest products. MDC thinks that for compression molds, material, shape, pressure, temperature, part thickness, cycle time must be considered. MDC has mastered and innovated the molding technique, analyzed the characteristics of the materials and the requirements of the products, to ensure the uniform flow of the plastic materials in the cavity of mold and fill all areas to obtain the perfect products.