How To Control The Wall Thickness Of Rotational Molded Products
1. Raw material selection
Material fluidity: Different materials have different melt fluidities, which directly affects the uniformity of wall thickness and control strength. Therefore, choosing the right raw materials is the first step in the mold production of rotational molded products. It is necessary to select plastic raw materials with appropriate fluidity according to the specific requirements and process characteristics of the product.
2. Mold design
Structural optimization: The design of the mold plays a key role in controlling the wall thickness of rotational molded products. During the design process, factors such as the structural form of the product and material fluidity should be fully considered. Through reasonable internal structural design and optimization of the mold, the approximate size of the wall thickness can be controlled to improve product quality and production efficiency.
Preheating treatment: For slender rotomolded products, especially those with thin ends and thick middle, the end of the mold can be preheated before molding to increase the temperature to ensure the amount of material loaded at both ends and reduce the wall The difference is large, thereby destroying the deformation phenomenon.
3. Production process control
Heating, melting, and extrusion processes: During the production process, each link should be strictly controlled, especially in the process steps of plastic heating, melting, and extrusion. Parameters such as temperature, speed, and pressure need to be carefully controlled to ensure that the plastic is inside the mold. Flow evenly to ensure the consistency and accuracy of the wall thickness of the product.
Cooling method: The cooling method also has an important impact on the wall thickness uniformity of rotational molded products. Cooling methods that expand the temperature difference (such as comprehensive forced air cooling, water cooling, etc.) should be avoided, and natural cooling methods should be used as much as possible, with local air cooling used for parts with higher temperatures and local reheating used for parts with lower temperatures. Adjust the temperature difference to avoid large deformation of the product.
4. Detection technology
Real-time detection and adjustment: Use advanced detection technology (such as laser thickness measurement device, etc.) to detect the wall thickness of rotational molded products in real time, and adjust production process parameters in a timely manner based on the detection results to ensure the uniformity and accuracy of wall thickness.
5. Other factors
Load-bearing conditions: The wall thickness of rotational molded products needs to be reasonably designed based on their load-bearing conditions in use. Since the plastic is heated for a long time during molding of rotomolded products, its strength (such as tensile strength, bending strength, impact strength, etc.) may be slightly lower than injection molded products of the same plastic. Therefore, when designing rotational molded products, this factor should be considered and the wall thickness should be appropriately increased to meet the load-bearing requirements.
Thermal degradation: The melt-rolling characteristics of plastics and long-term heat exposure can cause severe thermal degradation, which limits the range of wall thicknesses that can be used in rotomolded products. Therefore, the thermal stability of plastics also needs to be considered when controlling wall thickness.
To sum up, the wall thickness control of rotational molded products is a comprehensive process that requires comprehensive consideration and optimization adjustments from raw material selection, mold design, production process control, detection technology, load-bearing conditions and thermal degradation.