What can I do to get rid of warpage in thin wall plastic products? what are the reasons causes this problem?

Dear Khaled,There are some of the many things you can look into.Check if the part is too much hot during ejection,you have to increase cooling time and ensure balanced ejection.Hold on time and pressure can be increased.Warpage is the result of non uniform shrinkage on the part which may again be because of unbalanced mold cooling and non uniform wall thickness.Melt temperature can be increased to ensure faster and effective filling in the mold cavity.Balancing of runners and gates symmetrically with respect to part geometry is also essential.

What material are you moulding? Is the tool finished?

Thanks in advance for every one who care .I tried rising cooling time & i checked cooling process of mold it was uniform , when i raised holding time this gave me some enhancement but it was not satisfied for me , i also raised barrel pressure to enhance dosage of material , after all this tries i changed the used material , this gave me the required level

i use pp material

Hi Khaled,

Because don't know what shape of your products, difficult to say the real reason.

PP is a highly shrinkage material, so products & mold design is very important to starting from the beginning to prevent warpage & deform.

Try using Cold water for cooling, decrease injection pressure, increase injection speed. (But difficult to fill the thin wall) And use water cooling after injection.

Or if it can, use some modified PP with smaller shrinkage rate instead.

For thin wall molding
1) high pressure is needed to push the melt quickly
2) high injection speed to keep from freezing off to soon
3) higher mold temperature to keep the melt moving
4) thin parts freeze quickly so uniform thermal control is more important than a cool mold
Warpage from molded in stress or differential and unbalanced filling tends to be big issue with thin wall
Often the Press is not capable of providing the required injection speed or pressure. Don't assume the press is capable without doing a study.
There are good thin wall molding guides

For PP material, you may have to use high injection speed of upto 1000 mm/s. A plunge type with plasticizing screw is very helpful in thinwall molding. More than often both speed at high injection pressure are needed to keep ramming the melt into the cavity.