Injection molding design issues should be noted

Posted August 6, 2015 by cnmoulding

Cnmoulding plastic mould factory and injection molded plastic products maker in China. Manufactures and exports quality OEM plastic injection molding parts and plastic moulds for injection molding &mould making

1. Injection should be consistent with the outer surface smooth Requirements: High visibility area, A level surface, the local tangent continuous. Less visible areas, grade B surface, tangent continuous. Invisible area, grade C surface, continuous position.

2. Injection to smooth the edges, and other pieces of gap should be uniform.

3. Surface do striae member draft angle greater than 5 °. Structural strength, reliable, secure and stable installation.
Surface quality interior trim pieces demanding surface defects are not allowed. Most of the current use of injection molding, compression molding process for forming the inner trim, interior trim to consider outside surface should be in the direction of releasing no "negative" to ensure that in the mold design, mold parting lines are not assigned On the surface of the door trim panel, so as to ensure the surface quality of the outer surface of the door trim board. Determine the draft direction injection molded parts should also consider whether there are avoidable negative angle to reduce costs. After the interior molding surface does not allow flawed, sink marks, so the design should guarantee for the wall thickness, ribs strengthen the rational distribution, rib thickness should be less than 1/2 of the maximum can not be greater than 1 / 1.6.

4. Injection skeleton material thickness is generally 2.5-3 mm,

5. In general, small parts with snap, catches connection, large parts or parts to increase the force and increase the need to strengthen the screw connection
Structure. Snap snap connection should consider the amount of axial rebound 0.5 mm, the amount of compression side pressed into 0.75 mm, snap common vias φ8 (φ6.5) card withhold the end of the large diameter φ9.5 (φ8). Brackets size recommended modifications compensation snaps. Where zero is designed components and peripheral parts in contact with the touch should be zero, and should leave enough local non-contact sufficient space; the supporting surface should be considered when designing plastic parts require a larger plane as the bearing surface, if the Omo as a whole by the bearing surface, in the manufacturing process is not easy to meet the requirements.

6. Aperture shape and position size should be rounded, aperture in line with standardized, serialized.

7. Check the manufacturing process: the appearance of molded parts to be uniform thickness; interior trim is a large thin-walled injection molded parts, requiring the materials
Have better liquidity, along with high precision parts and resistance to UV stability, the general use of modified polypropylene. In the structural design of plastic parts, to avoid excessive use acute and right angles, since stress concentration at sharp corners, easy to crack, the impact strength of the workpiece; in order to avoid stress concentration should be used arc transition, which for mold manufacturing, life is very advantageous. General plastic parts each connection should be 0.5-1mm rounded, and large rounded corners imposed transition, to reduce stress, and to ensure consistent wall thickness. Hole vias should generally be designed to avoid ф5 less blind holes. The bottom of the blind hole should be designed hemispherical or conical surface, in order to facilitate the flow of materials, pore size and depth ratio is generally 1: 2-1: 3. The length of the larger parts should minimize the length direction on both sides of the mold slide stroke. Pulling the slider injection should be considered within the smallest space. Plastics welding process should also consider whether it is reasonable. Rib design is reasonable. Plastics welding process is reasonable

8. Structural strength analysis: the force components higher strength material should be used, the part in the force area should consider reinforcing structure,
CAE strength analysis carried out if necessary. In large part locally 160 × 160 range without additional support should be considered when the support structure, or foam support blocks. The rim flange parts generally should be designed, firstly, to increase strength, the second is to avoid the flash. Flanging should be added to the appropriate stripping slope.

9. Motion check: moving parts must be checked for motion to prevent interference and determined movement parting gap.

10. Analysis of the final assembly process must carry out parts assembly process analysis, analysis of parts are smooth installation and removal, mainly to have a removal tool installation space and parts activities smooth place. Parts should normally positioning guide structure.
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Last Updated August 6, 2015