We nitrided screw barrel by ourselves,that we could control the hardness strictly by ourselves. And also avoid the damages in transportations.
Some other small company,who don't own the Nitrogenation Oven,they need to nitride screw barrel in nitriding company,that have 2 disadvantages:
1.products are always damaged in transportations,especially the screw flight
2.They also can't control the quality,because nitriding company will put all half-finished products from different companys different product lines in the Nitrogenation Oven.