How to get rid of warpage for PBT material (ultradur B4300G6LS Bk 15073). Is there any who have experience in PBT material to support, currently we are facing a big problem due to warpage, can any one giude us on this issue

You have to know why the warpage happens,because different thickness(cause of stress) or eject issue?You can do moldflow analysis.Change the gate`s location/type and optimize injection parameter,etc.

Please, explain about preheat material. Do you mean dry the material in a resin dryer?

Unsuitable mold temperatures and unfavorable switch over point from injection to holding pressure may be causes of warped molding of PBT either filled or unfilled grades.
heat the mold halves to different temperatures for resolve this problem.

Thanks a lot for the all of your comment, let me sum up some more info,we have been facing this problem for the last 9 months, we have tried out all the possible way like mold flow analysis, but in the mold flow it self we get the part warped, the change temperature of both halves still no positive result, we tried out by different gate position and different types of gate , that too could not solve this, we played with the process like high packing, increase cooling time reducing cooling , injection pressure what ever can be done to our knowledge we have applied still no positive result,
we do secondary process ie: jigging but , at the time of jigging we get it with in 0.3 with in two days we go back to 0.8 and above , is there any jigging method that can resolve this, as we came to know that tooling and process cant help us,
if you all think there is any other remedy or solution kindly share, and if any body know any jigging process that can reduce the warp kindly advice. now after jigging with in 2~3 day it again warp.
The resin we use is 30%glass filled.

Cold runner? Hot runner? Gate methods tried? Dimensions of the part? Units of measure is mm? Ribs? Thin to thick sections, hard transition? Ribs, bosses or inserts? How is the mold cooled? Water lines as close as possible to cavity? Fill time?

Sounds like part is not designed for "moldability"?

The PBT with glass is difficult to control the warpage in molding. It couldn't eliminate the warpage in molding completely. But may get better improvement by molding as below:
1> Increase the mold temperature, But mold temperature below 100 degree.
2> Add some rib, Use the molding pressure to make the warpage tend to the rib side.
3> Use outside tool, as fixture to hold the sample. Use heater sourcing to back of warpage to keep the side temperature after the sample is taken out from machine.

you have to preheat the material at 110 c for three hour then try .

I have made the fog lamp housing for the Porsche Cayenne. Well I learned a lot by making a good flow and warpage analyses. From that moment I was convinced that a good flow analyze is a trend setter for your mould construction and later process. The main problem is that only a few are capable of making a goof flow analyze. If you find somebody with product design skills, mould developed skill and process determination skills then you get a very good trend setting flow analyses. I have made may fog lamp housing afterwards and the optimization cost and lead time reduced to the minimum.