Finally, the support shaft for American customers has been processed. This support shaft is used by customers to overhaul the steel plate leveler and replace the old shaft on the steel plate leveler. Material: 4140 alloy steel, quantity: 40 pieces, shaft size ￠ 220 * 485.

Raw material --- Forging--- Rough machining ---Quenching and tempering----Final Machining -- High-frequency Induction Surface Quenching----Grinding 

The raw material is alloy steel 4140 (Chinese Grade 42CrMo, European Grade 42CrMo4) forged into round bar, and then machined. 2 times heat treatment have been arranged in between. The diameters on the both end of shaft for bearings installation, it has to be precise, so it has to be grinded by Cylindrical grinder to reach precise tolerance and fine roughness, and the final processing is completed.

1. Raw materials: the rough is provided by Jiangsu Yonggang Group Co., Ltd., and the chemical composition of the test is as follows. 4140. The following table shows the chemical composition. 

2. Forging: the raw material is forged round bar, and ultrasonic examination comply European standard EN 10028-3 Level 2.  All outer diameters leave 2 -3 mm machining allowance.

3. Rough turning: then rough turning all outer circles and end faces, leaving 1mm on one side of all faces, the diameter of ￠ 220  is drum shape, so it has to be machined by CNC lathe to process spherical shape.

4. Intermediate tempering heat treatment: then overall tempering heat treatment, hardness BHN 270-300, core hardness not less than BHN 230. The heat treatment is oil cooling. After testing, the surface hardness is between 270-300. The pictures below show the shafts after rough turning and before tempering.

5. Finish turning: after heat treatment, finish turning all outer circles and machining with CNC Lathe will be arranged. The diameter of drum shaped part shall be turned to the drawing size, and 0.2mm grinding allowance shall be reserved for the part which for bearing installed at both ends.

6.      Surface quenching: after finishing turning, the surface of the drum shaped part shall be quenched (because the drum shaped diameter ￠ 220 surface is in contact with the large roller, and bear the big pressure from the big roller, so the hardness is required to be high), the depth is 10 mm, and the surface hardness is BHN 470-500. Because only the surface quenching treatment will not cause the deformation of the whole shaft, so only grinding allowance is left for the shaft diameter of the bearing installed at both ends. After the surface quenching treatment, the hardness is checked to be Bhn 470-530, meeting the drawing requirements.

7.      Then arrange the external grinder to grind the diameter part for the bearings, the dimension is ￠ 90, the tolerance is required to be 0-0.05mm, and the roughness is Ra1.6. After the detection, there are 3 out of tolerance, after communication with the customer, the customer agrees to spray repair, and then grind to the dimensional accuracy.

8.      Packing: the surface is coated with antirust oil and then packed. to be finished.