Difficulties in Processing Stainless Steel Materials

Challenges in Processing Stainless Steel

High Cutting Force and Temperature

Stainless steel materials, such as 1Cr18Ni9Ti and 2Cr13, are known for high cutting forces and temperatures due to their high strength, large tangential stress, and significant plastic deformation-Processing Stainless Steel. Poor thermal conductivity leads to heat concentration near the cutting edge, accelerating tool wear.

Work Hardening

Austenitic and high-temperature alloy stainless steels tend to harden during cutting. This work hardening is significantly greater than in ordinary carbon steels, leading to shorter tool life as tools cut through hardened areas.

Chip Adhesion

Both austenitic and martensitic stainless steels produce strong chips and high cutting temperatures during processing. This can cause chips to adhere to the tool, affecting the surface finish of the machined parts.

Accelerated Tool Wear

Stainless steels often contain high-melting-point elements and exhibit high plasticity, which increases cutting temperatures and accelerates tool wear. Frequent tool sharpening and replacement are necessary, impacting production efficiency and increasing costs.

Processing Techniques for Stainless Steel

Drilling

Drilling stainless steel can be challenging due to poor thermal conductivity and a small elastic modulus. Appropriate tool materials, geometric parameters, and cutting amounts must be selected.

Tool Material

Drill bits made from W6Mo5Cr4V2Al, W2Mo9Cr4Co8, or similar materials are recommended. Although expensive and hard to procure, these materials are effective. Common W18Cr4V high-speed steel drill bits may suffer from inadequate vertex angles, leading to poor chip evacuation and insufficient cooling.

Tool Geometry

Vertex Angle: Increasing the vertex angle to 135°-140° helps concentrate cutting forces at the drill tip and improves chip removal.
Chisel Edge: Grinding the chisel edge to a bevel angle of 47°-55° and a rake angle of 3°-5° enhances cutting resistance.
Relief Angle: To accommodate the high elastic recovery and work hardening of stainless steel, a relief angle of 12°-15° is advisable.
Chip Grooves: Staggered chip grooves on the drill bit’s flank surfaces aid in chip evacuation.

Cutting Amount

Selecting the right cutting speed and feed rate is crucial. A cutting speed of 12-15 m/min is recommended to reduce cutting temperature and tool wear. The feed rate should be 0.32-0.50 mm/r to balance wear and surface roughness.

Cutting Fluid

Using an emulsion as a cooling medium helps reduce cutting temperatures during drilling.

Reaming

Reaming stainless steel often requires carbide reamers with specific geometric parameters different from ordinary reamers.

Tool Geometry

Number of Teeth: Fewer teeth enhance cutter strength and prevent chip clogging.
Rake Angle: A rake angle of 8°-12° is typical, but 0°-5° may be used for high-speed reaming.
Relief Angle: Typically 8°-12°.
Main Deflection Angle: Depends on the hole type—15°-30° for through holes, 45° for blind holes.
Blade Inclination: Increased to 10°-20° for better chip removal.
Blade Width: Should be 0.1-0.15 mm.
Inverted Taper: Larger than ordinary reamers—0.25-0.5 mm/100 mm for carbide reamers and 0.1-0.25 mm/100 mm for high-speed steel reamers.
Correction Part Length: 65%-80% of ordinary reamers, with the cylindrical part being 40%-50%.

By addressing these challenges and utilizing appropriate techniques, the processing quality, production cycle, and cost efficiency of stainless steel parts can be significantly improved.