Briefly Describe The Measures To Solve The Warping Deformation Of Rotational Molded Products
1. Analysis of the causes of warping of roto-molded products
Although roto-molded products are non-pressure-molded, they are not easy to warp and deform compared with other pressure-molded methods.
However, roto-molded products are generally complex in shape, uneven in wall thickness, and not completely symmetrical.
This makes the cooling rate and shrinkage rate of different parts of the product inconsistent, and warping and deformation occur in large planes and parts with large wall thickness differences.
PE products have a relatively large shrinkage rate after roto-molding, generally 2% to 3%, or even as high as 3% to 5%.
The dimensional accuracy is poor, and the shrinkage rate is even higher in parts with large local linear dimensions.
The shrinkage of the product is also related to factors such as the heating temperature, cooling and setting temperature, cooling rate, and product demoulding temperature during product molding.
These factors are not easy to accurately control during roto-molding.
Especially in the process of demoulding of products, many manufacturers start demoulding when the product temperature is 70 to 80°C or even higher in order to pursue production efficiency.
Then the product shape is controlled by post-forming treatment. Since the factors of human control in the demoulding process are too strong, the shrinkage of the product is more difficult to control.
For products with strict requirements on the shape and deformation of the product.
In addition to taking targeted measures in the rotational molding process, the post-forming process is also important.
In order to produce higher quality products, emphasizing the stability and uniformity of the production process should be an important concept throughout the entire manufacturing process.
2. Solutions for warping and deformation of roto-molded products
When designing roto-molded products, try to avoid large planes.
Structural forms such as reinforcing ribs, steps, overlaps (bridges) or surface groove decorations can be used to reduce the plane area, thereby controlling warping.
Adjust the position of the mold on the mold frame to eliminate factors that increase the wall thickness difference and affect the uniformity of heating and cooling.
According to the structural characteristics of the product, make a shaping tooling or fixed tooling with active parts to shape the product in the post-cooling and sectioning stage.
For products with special shapes, you can also combine simple shaping tools to pass compressed air into the product to force the product to shape and shape, which has a better effect.
Take reasonable cooling measures to try to make the cooling rate of each part of the product consistent.