Factors Affecting Thin-Walled Parts

- Sep 08, 2018-

Thin-walled plastic products are widely used in aerospace, table and medical and electronics industries due to their ease of recycling and environmental pollution. High-speed thin-wall injection molding saves time and is one of the important production processes for plastic products in the future.


The cost of plastic raw materials usually accounts for about 50-80% of the cost of the product, which is quite amazing. Thin wall manufacturing helps to reduce this ratio. In particular, the daily plastic parts related to consumer lunch boxes, medical supplies, and electronic products are becoming thinner and thinner. Thin walling has become a new research hotspot in the plastic molding industry due to its advantages of reducing product weight and external dimensions, facilitating integrated design and assembly, shortening production cycle, saving materials and reducing cost.


A thin-walled member refers to a workpiece having a relatively thin wall thickness and is referred to as a thin-walled member. In the industry, a workpiece having a wall thickness of less than 1 mm is referred to as a thin-walled member.


In the injection molding process, the definition of thin wall is related to the process/wall thickness ratio, the viscosity of the plastic, and the heat transfer coefficient. The distance from the main channel of the mold to the farthest point of the finished product is called the process (indicated by L), divided by the wall thickness of the finished product (indicated by t), called the flow/wall thickness ratio. When L/t>150, it is called thin wall. If the thickness of the process is inconsistent, the process/wall thickness ratio can be calculated in stages. 


Thin wall material requirements and reasonable control of cooling time


Thin-wall high-speed injection molding materials must have the following characteristics: good fluidity; high impact strength; high heat distortion temperature; good dimensional stability; high heat resistance; good flame retardancy; high mechanical assembly; Good quality results.


At present, the commonly used materials for thin-wall injection molding are polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS) and PC/ABS blends. The materials suitable for thin-wall injection molding must have a high flow. Sex, once the raw material fluidity is not good, it can only be improved from the equipment, such as increasing the material temperature, high speed and high pressure, using oil temperature machine or hot runner effect to improve the fluidity of raw materials and achieve the purpose of producing qualified products.


The cooling time accounts for 80% of the injection molding cycle. Accurately evaluate the cooling time of the plastic parts to accurately estimate the molding cycle of the plastic parts. The cooling time is related to the raw materials, product wall thickness, injection temperature, and mold temperature.