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 molding machines for filling thin-walled parts. However, due to the continuous decrease in wall thickness, a more special injection machine with high speed and high pressure performance is required. For example, an electronic part with a thickness of less than 1 mm has a filling time of less than 0.5 seconds and an injection pressure of more than 210 MPa. The design of a hydraulic injection machine designed for thin-wall injection molding is frequently driven by the accumulator to inject and mold. All-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 molding machine, the minimum clamping force must be 5-7 tons per square inch (projected area). In addition, when the wall thickness reduces injection pressure increases, large stencils help reduce bending. The ratio of tie bars to stencil thickness for injection molding machines for thin-wall products is 2:1 or lower. When producing thin-walled parts, closed-loop control of injection speed and pressure, as well as other processing parameters, helps to control filling and holding pressures at high pressures and speeds.
As for the injection volume, large-diameter barrels are often too large. The simple injection volume is 40%-70% of the cylinder capacity. Electric shortening of the overall molding cycle of thin-walled products may reduce the minimum injection volume to 20%-30% of the barrel capacity. The user must be very careful in injection molding because the small injection volume for the material means that the material stays in the barrel longer, which can lead to a decrease in the performance of the product.
Speed ​​is one of the key factors for successful thin-wall injection molding. Rapid filling and high pressure can inject molten thermoplastic material into the mold cavity at a high speed to prevent gate freezing. If a standard part is filled in two seconds, the thickness is reduced by 25% for exactly 1 second.
One of the advantages of thin-wall injection molding is that when the thickness is reduced, less material needs to be cooled. As the thickness decreases, the molding cycle can be cut in half. The rational arrangement of the melt conveyor means that the hot runners and runners do not prevent shortening of the molding cycle. Using hot runners and sprue bushings helps to minimize molding cycles.
Mold materials should also be considered. P20 steel is widely used for the molding of conventional products, but due to the higher pressure of thin-wall injection molding, the mold must be made very strong. H-13 and other hard steels add additional safety factors to thin-walled dies. However, the cost of a strong mold may be higher than that of a standard mold by 30% - 40%, but the increased cost is usually offset by the increased production performance.