Tenfaye is a well-known enterprise in the manufacturing of large-scale steel castings in China. It undertakes the processing and manufacturing business of a large number of large-scale steel casting bearing seats every year. Bearing seat is a key bearing part of typical large steel castings widely used in rolling mills. It has a complex structure, high processing accuracy requirements, and high external and internal quality requirements for the cast steel material itself, which must meet relevant inspection standards. In actual production, some casting defects of large castings are unavoidable, such as cracks, blisters, sand sticking, pores, shrinkage cavities, sand inclusions, etc. These deficiencies need to be dealt with effectively. This article is about to talk the common defects of steel casting bearing seat.
1. Material of bearing seat
The materials of large bearing seats are generally ZG230-450, ZG270-500 and some alloy steels and other common materials.
2. Determination of defect nature
During the machining process, the product gradually showed some relatively small casting defects. After observation, defects that appear during machining are generally pores and slag inclusions; there are also some crack defects, but they are basically non-penetrating. According to the problems that arise, the nature, location and size of the defects and the different processing processes, corresponding repair plans are proposed.
3. Scope of the defect
Under normal circumstances, the treatment of internal defects that can be repaired after flaw detection of the bearing seat should be done before and after rough machining. Surface defects visible to the naked eye after surface processing of the bearing seat. For bearing seats that have passed ultrasonic flaw detection and re-inspection, surface defects must be controlled and processed before finishing.

4. How to deal with defects
(1) For linear defects (such as cracks, etc.), after UT and MT inspection, determine the size, location and depth of the defect. Most defects are removed by machining. In the rough machining state, the removal depth should in principle not exceed 2/5 of the wall thickness of the plane where the defect is located. The crack removal depth at the round hole should be less than 50mm. In the semi-finishing state, the excavation depth should not exceed 1/3 of the wall thickness of the plane where the defect is located, and the crack excavation depth at the round hole should be less than 35mm.
(2) Nonlinear defects (such as slag inclusions, blisters, pores, looseness, etc.), if the defects are small, choose the pistol drill method to remove them. For blisters, you can first tap the blisters with a punch to loosen them, and then use an alloy grinding head to polish until the defects are removed. For relatively large surface defects, machine tool processing is required to remove the surface defects in this area. In principle, the depth of rough machining should not exceed 2/5 of the wall thickness of the plane where the defect is located. The excavation depth in the semi-finishing state shall not exceed 1/3 of the wall thickness of the plane where the defect is located.
(3) After finishing to the finished product, there may still be scattered point defects such as tiny pores and blisters on the surface. After removing the defects by manual grinding, argon arc welding is used to directly repair these areas. After the repair welding is completed, use polishing The repair welding surface is manually polished by machine.
(4) After surface defects or internal defects are excavated until the defects are no longer visible to the naked eye, the excavated parts shall be color-coded and flaw-detected, and repair welding shall be carried out after confirming that there are no defects. 
Tenfaye is a professional to produce steel casting bearing seat. High qualtiy is the first requirement. Email:mischa.wang@tenfaye.com