Carbon Steel Product CNC Machining

Characteristics and selection of carbon steels with different carbon contents: 1) Low Carbon Steel (C≤0.25%): Good plasticity, easy to machine, lower strength, suitable for stamped parts and welded structures; 2) Medium Carbon Steel (0.25%0.6%): High hardness, good wear resistance, but poor plasticity, suitable for manufacturing cutting tools and molds. Selection requires comprehensive consideration of part stress conditions, machining methods, and usage environment.

Carbon steel CNC machining precision: Normal machining can achieve ±0.01mm, precision machining can achieve ±0.005mm. With precision grinding, higher accuracy can be achieved. Surface roughness: Rough machining Ra3.2-6.3μm, semi-finishing Ra1.6-3.2μm, finishing Ra0.8-1.6μm, precision grinding can achieve Ra0.02μm. After heat treatment, carbon steel hardness increases, machining difficulty increases, and precision and surface quality slightly decrease, but high precision can still be ensured with specialized tools and processes.

Methods to prevent carbon steel rusting: 1) Surface plating: Zinc plating, chrome plating, etc., to form protective films isolating air and moisture; 2) Coating: Painting, powder coating, suitable for decorative and non-precision parts; 3) Chemical treatment: Phosphating, blackening to form conversion films improving corrosion resistance; 4) Oiling: Short-term rust prevention for unused parts; 5) Stainless steel cladding: Improves corrosion resistance at higher cost; 6) Environmental control: Store in dry environments avoiding humidity. Selection depends on usage environment, cost, and appearance requirements.

Reasons for re-machining carbon steel after heat treatment: 1) Heat treatment causes part deformation requiring subsequent machining to correct dimensional accuracy; 2) After quenching, material hardness increases significantly making precision machining difficult. Usually adopt "rough machining - heat treatment - finish machining" process; 3) Heat treatment may form oxide layers or decarburized layers on surface requiring machining removal; 4) Certain high-precision mating surfaces require extremely high surface quality needing precision grinding after heat treatment; 5) For complex parts, leave machining allowance before heat treatment to avoid inability to machine due to excessive hardness. For parts with low precision requirements, processes without post-heat treatment machining are also possible.

Differences in machinability between carbon steel and stainless steel: 1) Cutting force: Stainless steel cutting force is 20%-30% larger than carbon steel; 2) Work hardening: Stainless steel has severe work hardening causing fast tool wear; 3) Thermal conductivity: Carbon steel has better thermal conductivity than stainless steel, dissipating heat better during machining; 4) Chip handling: Carbon steel chips break easily, stainless steel chips are tough and tend to wrap around tools; 5) Tool selection: Carbon steel can use high-speed steel tools, stainless steel usually requires carbide tools; 6) Cooling requirements: Stainless steel machining requires stronger cooling; 7) Cost: Carbon steel machining cost is lower than stainless steel. Overall, carbon steel has better machinability than stainless steel with higher efficiency and lower cost.

Differences in machining processes between medium and high carbon steels: 1) Tool selection: Medium carbon steel can use high-speed steel or carbide tools; High carbon steel recommends carbide tools; 2) Cutting parameters: Medium carbon steel can use higher feed rates; High carbon steel uses lower feed rates with moderate cutting speeds; 3) Heat treatment timing: Medium carbon steel can be quenched entirely after machining; High carbon steel usually requires quenching after rough machining followed by finish machining; 4) Cooling requirements: High carbon steel machining requires stronger cooling lubrication; 5) Machining allowance: High carbon steel deforms more after heat treatment requiring larger machining allowances; 6) Surface treatment: Medium carbon steel suitable for plating and painting; High carbon steel suitable for blackening, nitriding, etc. Proper process selection improves efficiency and product quality.