1. Barrel temperature (raw material temperature)
Considering the thickness of raw materials and articles, the temperature of the barrel should normally be set at a level 10-200 CD above the nominal melting temperature of the material. Amorphous materials such as PS and ABS have no specified melting point, so the barrel temperature should refer to the melt flow index (MI) and spiral process line (SPR). Recently, with the emergence of plastic products of various sizes, L/T (feed flow length/product temperature) has become a very important parameter. If L/T is large, the temperature of the barrel must be set. More general temperatures stimulate flow.
2. Injection pressure
Injection pressure and pressure retention are very important conditions to determine the quality of injection products. Injection pressure refers to the pressure required to fill the plastic melt throughout the mold. As the melt enters the mold, it gradually cools along the wall. Therefore, if the flow is long, the wall is thin, the plastic temperature is low, and the mold temperature is low, higher injection pressure is required. In addition, high injection pressure is required when rapid filling is required.
Injection pressure and injection speed can be set arbitrarily. In general, the injection pressure can be set conservatively and the injection speed can be set as required (the required filling time, the solution if the product is defective). With the standard model, the initial setting of the injection molding machine can be set in the center of the machine and the fill status and mold status can be checked.
For thin plastic parts with wall thicknesses of less than or equal to 2 mm, it is important to increase injection speed when melt enters the mold and solidifies along the mold wall, which increases flow resistance and makes filling difficult. If the injection speed cannot be set according to the Settings. After completion, the injection pressure should be increased. In other words, a typical jet project is a speed-control project and therefore requires sufficient oil pressure to control speed.
3. Exit velocity
Concept of injection speed: Injection speed is usually the speed at which the screw moves forward, but what really matters is the speed at which the melt moves in the cavity relative to the cross-sectional area of the flow direction.
Determination of injection speed: In principle, the injection speed should be determined by the cooling rate of the melt and the viscosity of the melt as soon as possible, and the melt with high cooling rate or high viscosity should use high injection rate. The cooling rate depends on the properties of the material itself, wall thickness and mold temperature.
Injection speed is so fast that it is easy to produce focused, pulsating edges, internal bubbles or melt-blown, injection speed is too slow, flow marks, welding marks are easy to produce, the surface is rough and fuzzy.
Initial setting of injection speed: Standard model should be set to about 40% lower than medium speed.