PP40CaCo3 in PP30GF Mold

[madhan_rm]

Hello,

Looking for few suggestions on what are the possibilities to use PP40Caco3 in the mold built for PP30GF. Though shrinkage % is different, but is there any way this compensation can be balanced in mold?

Thanks.

[bernor_mf · Accepted solution]

@madhan_rm 

Hi,
changing from fiber filled material to filled with Calcium carbonate, or chalk, it will affect part shrinkage in different
directions, hence warpage and part deflection as fiber filled material has high anisotropy.

To affect shrinkage of plastic part in already designed mold, there is only process conditions left.

Adjusting melt temperature, mold temperature, packing pressure, cooling time during molding could appropriately change shrinkage of plastic parts.

In general:
Higher melt temperature, the greater the amount of shrinkage.
Mold temperature: changes the mold size due to CLTE, temperature expansion - But: mold temperature also affect part freeze off, hence shrinkage.
A rule-of thumb here is that a 10% change in mold temperature can result in a 5% change in original shrinkage.
Packing time and pressure level: longer and higher to pack the part more and reduced shrinkage.

Changing process conditions could also lead to other unwanted results of surface appearance and part deflection.

Suggest to run Moldflow to get an understanding of the shrinkage difference between materials and change of process condition and the effects on part deflection.

Hope this helps.
Regards,
Berndt

[madhan_rm · Accepted solution]

Thanks for the suggestions..