What are the requirements for bolt production

① The bolts of the extruder should be made of steel alloy with low thermal deformation, wear resistance and corrosion resistance. Commonly used materials are 38CrMoAlA alloy steel or 40Cr steel, and repair parts can also be made of 45 steel.

②The blank of screw material should be formed by forging method.

③After the screw is processed, the outer circle accuracy should reach the level 8 (GB 180-79) accuracy and quality requirements.

④The concentricity error between the surface of the screw's working shaft and the connecting part of the drive shaft and the outer circle of the thread should not be greater than 0.01mm.

⑤Roughness of the machined surface of the threaded part. Value: The two sides of the thread should not be larger than 1.69m, and the bottom and outer circle of the thread should not be larger than 0.8/1m.

⑥ If the screw is made of low-carbon alloy steel, in order to improve the hardness, corrosion resistance and wear resistance of the threaded surface, the thread surface should be nitrided. The depth of the nitriding layer is 0.3~0.6ram, and the surface hardness is 700~840HV. The brittleness does not exceed level 2.

The connection of the inner hole of the screw shall be subjected to a water pressure test of 0.3 MPa, and no water leakage shall be allowed within 5 minutes.

Dongguan Jingnai Screw Machinery Co., Ltd. specializes in producing extruder screws, injection molding machine screws, bi-alloy screws and other screw and barrel series products.