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What are the reasons for the uneven wall thickness of the rotational molding mold?

2020-10-28 13:54:32

Many customers call our website to inquire about the solution to the uneven wall thickness of products in the process of rotational molding, so the editor will explain the solutions to the uneven wall thickness of products in the process of rotational molding.

Cause analysis

It is not easy to process products with abrupt wall thickness during rotational molding. The average wall thickness of the product depends on the feed rate. Its uniformity is related to the structure of the die itself and the rolling forming process.

(1) Generally speaking, the thickness of the inner concave corner (the outer convex of the mold) of the rotational molding product is smaller than that of the outer convex corner (the inner concave of the mold) of the product. However, if the angle of the convex part of the product is too small, it is easy to cause the material can not fill the mold, resulting in the corresponding defects such as holes, so the product should not have sharp corners, usually use large flat parts. Sliding arc transition.

(2) The melting and adhesion ability of plastics is mainly related to the mold temperature. When the mold temperature is high, the plastic is easy to melt first, and coating layer by layer with the mold rotation, so there will be more adhesive resin, while the resin adhering to the low temperature part is relatively less, resulting in uneven wall thickness of the product.

(3) The wall thickness of the product is also related to the rotational speed. It is easy to cause uneven wall thickness and irregular speed, so the motor with constant torque or speed and automatic control is usually used to ensure the uniform rotation of main shaft and secondary shaft. When the wall thickness of one part of the product is very different from that of other parts, and the mold can not be modified, it is necessary to seek solutions from the technical point of view.

Rotational molding mold

terms of settlement

(1) It will be fixed in the appropriate position of the mold base to adjust the balance of the mold base.

(2) The speed of the main shaft and the secondary shaft should be proportional and uniform.

(3) The heating furnace can ensure that the mould is heated evenly in all directions.

(4) Heating and cooling process should be reversed once, reverse should be rapid, generally forward and reverse times are the same.

(5) When the thickness of the product needs to be increased, the corresponding part of the mold should be preheated or the influence of heat insulation factor should be reduced.

(6) Teflon plate or asbestos pad is added to the corresponding part of the mold to insulate the parts where the thickness of the product needs to be reduced, so that the molten material is not easy to adhere to the mold or continuously accumulate, so as to reduce the thickness of this part. This method is also used to insulate the mold so that the inner surface of the mold cannot adhere to the resin to obtain the opening, but the openings made by this method are usually irregular.

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