Defect injection 1

[campp]

Hello,

I have two parts (cavity 1 and 2) with different appearance (matte area on a larger surface on one part compared to the other) and I do not know if the injection parameters determined this effect and how they can influence the mechanical properties of parts?
It is possible the melt front cooling more quickly for one of the parts (the injection point to be asymmetrical compared to the two parts?).
It can be differences in crystallinity between glossy and matt zones?

Thank you.

 

[MacGyverS2000]

That line looks to be WAY too straight to be due to cooling effects... but I'm not a molder, so what do I know. It just looks like a line in the mold where shotpeening was masked off.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[hendersdc]

I agree with MacGyver, that looks like a mold surface finish difference to me too.

 

[Pud]

How is this part fed? There are three of what looks like hot tip feeds on the top surfaces. (Two of which are crossed by your nearly vertical red line). Unless they are some design feature? What size is the part?

www.tynevalleyplastics.co.uk

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[campp]

total length - 260mm

 

[Pud]

campp: is it hot tip fed?


www.tynevalleyplastics.co.uk

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[Paulkuklych]

It looks like surface finish on the mould.

Take a look at the mould cavities, if it looks the same then that is your answer.

Paul Kuklych

http://www.improve-your-injection-molding.com

 

[campp]

I don't know tip fed, I am sorry.

Thank you all.

 

[WKTaylor]

All... Yes, the 'line' is obviously straight in each part: however, assuming they came from the same mold, why is the 'line' in two completely different locations???????

Campp... Have You done the obvious and 'sectioned thru/across these line-areas' to examine material flow/fusion... and mechanically tested Ftu, Fty, Fcy, FSy, strain, etc] at/across these 'line-areas' [as-well-as characterizing 'other areas away from this line'].... while looking for obvious physical and mechanical inconsistencies?

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[cowski]

All... Yes, the 'line' is obviously straight in each part: however, assuming they came from the same mold, why is the 'line' in two completely different locations???????

The parts were molded in different cavities as evidenced by the in-molded "1" and "2" visible in the picture. The question becomes "why are the 2 cavities different?". If the surface finish isn't clearly called out on the print, I'd guess that the tool maker took some liberties - perhaps to help part ejection (or some other manufacturing parameter).