The solution for molded part easy breaking

The solution for easy breaking molded part. The part is very simple, and almost it is a flat product. It seems everything is easy and smooth. First mold test is on 25th day. Sample photo is following:

3D mould - The solution for molded part easy breaking

Project information:

  • Part size: 70.25 x 46.28 x 7.87mm (L+R)
  • Part weight: 5g
  • Mold base: LKM
  • Steel: P20
  • Plastic: ABS(ChiMei PA-757)
  • Cavities: 2+2
  • Runner system: Cold
  • Cycle time: 30s
  • Tolerance: +/-0.5mm
  • Dimensions: 270 x 350 x 271mm
  • Mold life: 300,000 shots
  • Lead time: 25 days
  • Spruce: Sub φ1mm

Molded sample feedback

The average wall thickness is 2.54mm, and the min thickness is 2.29mm. First sample is shipping by DHL to customer after 25 work days,  and core and cavity are waiting for texture. 3 days later, it is said it is bad, as it is easy break, see follow picture:

sample feedback1 300x227 - The solution for molded part easy breakingsample feedback2 300x227 - The solution for molded part easy breaking

It is unlucky, everyone though it is simple project before. Chinese New Year is coming, customer want 5,000 shots molding product urgent. We have meeting and test the sample in hand, the test result is follow:

The part is fragile and very easy break. It is broken just in first bend, specialized for gate location. ABS is good and popular use for normal plastic molding part. It should be ok but not. What is wrong???

Maybe the spruce is too small, as it must be cut automotive with runner. Maybe high pressure flow in part and it can’t be welding well after molding. It should be a little bigger.

Solution 1: Gate is change into 1×1.4mm in steady for φ1mm. Fan gate should be a little better. Thinking is good but result is bad. It is the same as before. It can’t solve break problem.

Solution 2: We try to use other plastic material, normal PC and PA+30%GF. It is bad, both are easy break either

PC sample 300x227 - The solution for molded part easy breakingPA630GF 300x227 - The solution for molded part easy breaking

After calling with our consultant, Tony, he suggest us to use special PC, which is Lexan* Resin FXE1414, the shrinkage is the same as ABS. It will be no problem for specification. Lucikly, it solve easy breaking problem. Thanks goodness, thanks Tony. Following is good sample.

special PC 1 - The solution for molded part easy breaking

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