Why add a film such as PVC between the mold and the molding material?

The mold is specific to the contact pair between the forming mold and the raw material or semi-finished product of the workpiece. Due to the huge difference between the molding load and the material to be formed, several measures are adopted to solve the problem of the workpiece strain, in addition to considering the effectiveness of the effect, it must also be Considering the batch size of the product, the difficulty of realization and its economical aspects, the following will be discussed in detail.

To solve the problem of strain in the forming process of the workpiece, we should improve or solve the problem of the strain of the workpiece by changing the properties of the contact pair in accordance with the basic principle of reducing adhesive wear. The three parties that constitute this pair of contact pairs, that is, the raw material of the workpiece to be formed, the workpiece and the mold, and the mold are analyzed separately.

By surface treatment of the raw material, such as phosphating, spraying, or other surface treatment, a non-metallic film can be formed on the surface of the material to be molded, which can greatly reduce or eliminate the problem of workpiece strain. This method often costs Higher and needs to add additional production equipment and increase the production process, although this method is sometimes effective, the actual production is rarely used.

Adding a layer of films such as PVC between the mold and the molding material can sometimes solve the problem of workpiece strain. For the production line, the film can be continuously supplied through the mechanism, and for the cyclical production stamping equipment, each workpiece is produced. A film needs to be added, which affects the production efficiency. This method is generally costly and generates a lot of waste. It is advisable to use this method for the production of small batches of large workpieces.

In some occasions where the forming load is small, sometimes the problem of workpiece strain can be solved by adding lubricating oil or lubricating oil with EP (extreme pressure) additives.