Practical Guide to Preventing Deformation and Cracks in Stainless Steel Casting Processing: Materials, Processes and Operation Points

In the field of industrial manufacturing, stainless steel castings are widely used due to their corrosion resistance and high strength. However, during the processing process, deformation and cracking problems occur frequently, which directly affects the qualification rate of finished products. How to avoid these problems through reasonable process design and operation control? This article combines practical experience to systematically analyze solutions from material properties, processing parameters to post-processing links.

1. Root cause analysis of deformation and cracks

1. Material factors

• Stainless steel castings (such as 304, 316L) have poor thermal conductivity, and local heat accumulation during processing can easily lead to thermal deformation.

• There may be residual stress inside the casting, and the release of stress during the cutting process may cause deformation or micro-cracks.

2. Process design defects

• The cutting parameters (such as rotation speed, feed rate) do not match, resulting in excessive cutting force or excessive heat.

• The clamping method is unreasonable and uneven local stress causes plastic deformation.

2. Key measures to prevent deformation

1. Processing in stages to reduce cutting stress

• Roughing and finishing are carried out separately, with a margin of 0.5-1mm reserved during roughing, and a multi-pass strategy with a small depth of cut (0.1-0.3mm) used for finishing.

• Example: During the processing of a certain valve casting, the deformation is controlled within 0.05mm in three passes.

2. Optimize clamping plan

• Use flexible clamps or hydraulic clamps to disperse pressure and avoid local extrusion and deformation.

• When processing thin-walled parts, add auxiliary support, such as a machining center with vacuum suction cups for fixation.

3. Control temperature and cooling

• Use water-based coolant and make sure it is fully poured to avoid overheating the cutting area.

• Large castings can be pre-cooled to 20-25 degrees Celsius before processing.

3. Key points of anti-crack process

1. Tool selection and wear monitoring

• Use sharp carbide tools (such as YG8), and the rake angle must be greater than 15 degrees to reduce cutting resistance.

• Check the tool wear after every 50 pieces of processing to avoid cracks caused by dull knives pulling on the material.

2. Cutting parameter adjustment

• The recommended linear speed is 80-120m\/min, and the feed rate is 0.05-0.1mm\/r. The specific requirements need to be adjusted according to the hardness of the casting.

• Case: During the processing of a certain pump body, after the feed rate was reduced from 0.15mm\/r to 0.08mm\/r, the crack rate decreased by 70%.

3. Post-processing to relieve stress

• Stress relief annealing is performed immediately after processing (heating to 300-400 degrees Celsius and holding for 2 hours).

• Vibration aging treatment can also replace traditional heat treatment with lower cost.

4. Common misunderstandings and user questions and answers

• Misunderstanding:"Increasing cutting speed can improve efficiency" → In fact, it intensifies the risk of thermal deformation.

• User asked:How to repair deformed castings?
  answer: It can be corrected by cold correction (press adjustment) or local heating, but care must be taken to avoid secondary damage.