pigment issue, monitoring strategy

[Drhouse77]

Hello all,
I am newbie in this forum.
I am facing an issue related to inomogeneus pigments in one co-molded component founded during microstructure analysis as consequence of a broken part.
Due to the fact that I have to perform an audit on a supplier side, I would like to understand if and how is possible to controll the quantity of pigments during injection and what is influecing the process in terms of parametes or anything else which give as results an inomogeneus parts under microstructure analysis.
Is there any monitoring strategy applicable on the pigments ?

Thanks in advance for your support!

[Pilot]

Hi
I have one question. Do you mean pigment or colour masterbatch?

Pilot

[Drhouse77]

Hi,
I mean colour masterbatch

[brentb]

Hi,
I mean colour masterbatch


gravimetric feeder? Do you perchance mean non homogeneous?

KOM

brent

[Pilot]

If it looks like non homogenity, usualy the percentage is lower than 1%. for most colour masterbatces are 2% OK.
YOu can control process through % on the gravicolor, or through color meassurement on the parts.

Sometimes surface on the fracture looks like dark contour with light core. It is mostly due to melt flow and cooling conditions without influence of colour MB.
In case, that % of colour MB is toooooo high you can see troubles with mechanical properties.

Next Issue is carrier used for colour MB. For ex. material which must be coloured is PP and you can use MB carrier PP (expensive) or PE (usualy cheaper). PE is compatible with PP and due to good shear stress during processing is mixed good enought.
Other situation is when you use PS (or PC) MB carrier for coloring of PP material. It is not compatible and you can have a nonhomogenity in the surface.
Usualy you will get some optical defects on surface, which can shows on problem.

Good colouring is science ......

regards

Pilot