The demand for small and light parts has made thin-wall injection moulding the most demanding performance of injection moulding machines. “Thin wall” is usually defined by lightweight electronic parts with a wall thickness of less than 1 mm. For large automotive parts, the “thin wall” can be 2mm.
In summary, thin-walled products require changes in the processing: higher pressures and speeds, shorter cooling times, changes in part ejection and gate alignment. The following are the requirements for injection moulding machines and moulds for thin wall injection moulding.
Standard injection machines can be used to produce a variety of thin walled products. The performance of the new injection machine is currently more than 10 years ago. Advances in materials, gate technology and design have further broadened the performance of standard injection machines for filling thin-walled parts. However, due to the ever-decreasing wall thickness, a more special injection machine with high speed and high pressure performance is required. For example, an electronic part having a thickness of less than 1 mm is normal for a filling time of less than 0.5 seconds and an injection pressure of more than 210 MPa.
The hydraulic injection machine for thin-wall injection moulding is designed with an accumulator that can frequently drive injection moulding and mould clamping. Full electric injection machines and electric/hydraulic injection machines with high speed and high pressure performance are also available. In order to withstand the high pressure of the new injection machine, the minimum clamping force must be 5-7 tons/inch (projected area).
In addition, large formwork helps reduce bending as wall thickness reduces injection pressure. The ratio of the tie rod to the template thickness of the injection machine for thin-walled products is 2:1 or lower. In the production of thin-walled products, infinite loop control of injection speed and pressure, as well as other processing parameters, helps control filling and holding pressure at high pressures and speeds.