In CNC machining, the choice of surface treatment process directly affects the functionality, aesthetics and durability of parts. The following are common surface treatment technologies and their characteristics:

First, mechanical surface treatment

. Sandblasting
Medium: glass beads (80-400 mesh), alumina, silicon carbide
Effect: Matte texture (Ra1.6-6.3μm), eliminating slight finish marks

Applications: Aluminum alloy housing, medical equipment

. Polishing

Mirror polishing: Diamond grinding paste (Ra≤0.05μm) for optical parts

Vibration polishing: Batch deburring of ceramic abrasives, suitable for small complex parts

. Lapping

Precision surface grinding: monocrystalline silicon (flatness ≤0.001mm)
Superfinishing: Reduce surface corrugation (such as automotive camshafts)

Second, chemical/electrochemical treatment
. Anodizing
Hard anodizing: Film thickness 50-100μm (HV≥800) for aviation components
Color anodizing: coloring by electrolysis (e.g., iPhone aluminum body)

. Passivation
Stainless steel passivation: nitric/citric acid removes free iron and improves corrosion resistance

Electrolytic polishing: micro-levelling (Ra reduction by 50%+), suitable for food grade equipment

. Electroless Plating

Electroless nickel plating: uniform coating (hardness HV500-700), repair wear parts

Third, coating technology

PVD coating (physical vapor deposition)

TiN/TiAlN coating: Tool surface hardness HV2000-3000

DLC diamond-like coating: friction coefficient < 0.1 (automobile piston ring)

. Thermal Spray

Plasma spraying: Zirconia thermal barrier coating (turbine blade)
Supersonic Flame spraying (HVOF) : WC-Co abrasion resistant coating

. Special function processing
.Laser surface treatment
Laser cladding: Repair of high value parts (e.g. die cutting edge)

Laser Texture: Custom micron surface patterns

. Micro Arc Oxidation (MAO)

Magnesium alloy treatment: in situ formation of ceramic film (corrosion resistance improved by 10 times)
. Dacromet
.Chromium-free zinc-aluminum coating: Salt spray resistance 1000h+ (automotive chassis parts)

. Composite Technology (cutting-edge technology)

Nano composite plating: SiC/Al₂O₃ nanoparticles are added to enhance the coating

Ion implantation: Surface alloying (such as medical titanium alloy antibacterial treatment)

Cold spray additive manufacturing: low temperature deposition of copper/aluminum conductive layer