注塑件设计准则(injection moulding design guidelines).pptVIP

Lighting system design rules For headlamps with second surface parting lines, there must be 1mm additional clearance between parting line surface and adjacent surfaces above and beyond minimum normal surface to surface clearance. 7. Undercut A feature prevent the part from directly removing from the core or cavity. They are categorized into internal and external undercuts, where external undercuts are on the exterior of the part and interior undercuts are on the inside of the part. Design rules: ? Enough space for a lifter or slider near by the undercut. Be careful to add the radius at the edge. ? Use the tool shut-off to avoid undercut. Draft angle in the lifer/slider movement direction. Risks/potential issues: Parting line on the A surface. Thin lifter or slider. 8. Shut off angle Design rules: When an opening is desired (such as to accommodate a snap-fit), and is to be formed without core pulls, a 5° angle mating of the core and cavity is required. Risks/potential issues: The core and cavity wear quickly, hence flash appears. Shut off to avoid to use lifter or sliders in the tool. Shut off to avoid to use lifter or sliders in the tool. Shut off surface Core insert Cavity insert 9. Analytical Mold Flow Design rules: Use the CAE software to help decide the gate position. Predict weld line and vent locations (weld lines are not located in high stress areas. Weld lines and vents are not located on surface with stringent cosmetic quality requirement) Predict temperature distribution - temperature difference does not exceed 10°C or per benchmark analysis. Risks/potential issues: Appearance, functional, structural issues not found until 1st shot parts are made. 10. Shrinkage Design rules: Material/resin: Crystalline and semi-crystalline materials exhibit higher shrinkage than amorphous materials. Unreinforced plastics have higher shrinkage than reinforced grades. Select grade of material before the mold is constructed and specify proper mold shrin