How to shape EVA material?

Generally, EVA with vinyl acetate content of less than 5%, its main products are films, wires and cables, LDPE modifiers, adhesives, etc., EVA products with vinyl acetate content of 5% to 10% are elastic films, etc. EVA with a vinyl acetate content of 20% to 28% is mainly used in hot melt adhesives and coating products.

How to process EVA material? The processing technology of EVA products includes injection molding, extrusion molding, blow molding, calendering, rotational vacuum thermoforming, foaming, coating, heat sealing, welding and other molding processes.

The required uses for processing EVA are:

LDPE can produce expanded foam products, which are harder and have no resilience. They are mainly used for foam insulation, slippers, bags, etc.

EPDM: Increase flexibility.

Natural rubber: increase non-slip performance.

Selection of EVA processing pigments:

Color masterbatch, good dispersion, correct color

Toner: low price, poor dispersion, operating environment pollution

Color sand: better dispersion and less pollution

EVA processing foaming agent:

High temperature, with better magnification, but will affect the color of the product

Medium temperature, suitable for injection molding and small models

EVA foam generally has three processes: injection, traditional flat large foam and small in-mold foam.

1. Injection

This process is more advanced and can be completed in only one process. The product requires high precision of the mold and will become the mainstream in the future. Its principle is similar to the injection molding in the plastics industry, but the difference is that the injection mold is opened immediately And the temperature of the mold is different, that is, the injection process of EVA only adjusts the plastic injection.

2. Small foam in the mold

Mainly used for shoe materials. The first foaming of sports shoes is the midsole. Its function is to weigh the material and put it into the opened mold. The difficulty lies in the symmetry of the mold and the formula, and the amplification must be controlled at the same time. The magnification and hardness, according to the shape and structure of the product, the foaming conditions of this method are more flexible, of course, mainly change with time, and the temperature changes little.