The short answer A laser marks metal in one of four ways: annealing, which darkens stainless without removing metal; white marking on anodised aluminium and dark coatings; ablation, which burns away paint or powder to reveal the metal; and deep engraving, a fibre-laser recess of 0.05 to 0.5 millimetres. Bare stainless and anodised aluminium survive best. Two lasers, two jobs The first decision...

The short answer Specify the process by a named standard, give a thickness range rather than one number, state how it is measured, list the surfaces that must stay bare, and say whether dimensions are met before or after finishing. A note that says copper plate 10 microns but names no standard, method or masking will be quoted differently by every shop. Why a thickness note fails Most surface ...

The short answer Bead blasting fires fine glass or ceramic beads at the surface to leave a uniform, non-directional matte finish at roughly 1.0 to 3.2 micrometres Ra. Brushing drags an abrasive belt or wheel in one direction to leave a directional linear grain at roughly 0.4 to 1.2 micrometres Ra. Blasting hides fingerprints and takes paint; brushing gives the satin look. Two families of mecha...

The short answer Passivation is a chemical bath, citric or nitric acid, that dissolves free iron left on stainless steel by machining, forming and welding, so the natural chromium oxide layer can re-form. It adds no coating and changes no dimension. It is specified per ASTM A967 and confirmed by a copper sulfate, humidity or salt-spray test. Why stainless steel still rusts Stainless steel resi...

The short answer Powder coating is the default finish for metal. A dry powder is sprayed electrostatically and baked at 180 to 200 degrees Celsius into a 60 to 120 micron film that resists 500 to 2,000 hours of salt spray and releases no solvent. Choose wet paint for a custom colour, a non-conductive part, or field touch-up. Two processes, one decision Both finishes protect metal, and the gap ...

The short answer Phosphating converts a steel surface into a crystalline phosphate layer in a dilute phosphoric acid bath. Zinc phosphate at 1 to 7 grams per square metre is the paint primer; manganese phosphate at 5 to 30 grams is a wear and oil-retention layer for gears and shafts; iron phosphate at 0.2 to 1 gram is a thin adhesion base. What phosphating actually is Phosphating is a chemical...

The short answer Electrophoretic coating, usually called e-coating, immerses the part in a water-borne paint bath and uses a few hundred volts to deposit resin on every wetted surface. The film self-limits at 15 to 35 microns because the coating insulates the part as it builds. That even build reaches internal cavities and edges that spray and powder coating miss. How electrophoretic depositio...

The short answer Electrolytic nickel uses an electric current, so it plates thickest on edges and thinnest in recesses and cannot reach inside blind holes. Electroless nickel uses a chemical reducing agent instead, so the deposit is uniform to about plus or minus 2 microns on every wetted surface, including internal bores, and it is a nickel-phosphorus alloy with better corrosion resistance. T...

The short answer Type II is the corrosion and cosmetic finish; Type III, hard anodizing, is the wear finish. Type II builds 5 to 25 microns and dyes in any colour. Type III runs a chilled bath near 0 to 5 degrees Celsius, builds 25 to 125 microns, reaches 400 to 500 HV and is realistically only black or grey. The process difference in one paragraph Both types are sulfuric acid anodizing, and b...

The short answer Anodizing is an electrochemical conversion that grows an aluminium oxide layer out of the aluminium itself. The part is the anode in a sulphuric acid bath, and the oxide grows roughly half into the metal and half out of it. Type II builds 5 to 25 microns; Type III builds 25 to 125 and hardens to 400 to 500 HV. Why anodizing is a conversion, not a coating Anodizing is often des...

The short answer Finishing adds 2 to 50 percent to the as-machined price. Bead blasting is 2 to 5 percent, Type II anodizing 5 to 10, powder coating 8 to 15, and electropolishing or hard anodizing 15 to 30. A batch minimum dominates small orders: a 150 dollar tank charge is 15 dollars a part at ten pieces and 0.30 at five hundred. Two different numbers, and they diverge Every finishing quote c...

The short answer CNC machined parts can be finished in about a dozen ways, and the substrate narrows the list first. Aluminium takes anodizing in Type II or Type III; steel and stainless take plating, passivation or electropolishing; plastics take bead blasting, vapour smoothing or paint. The function you need, not the look, decides which one. What a finish actually does to a CNC part Every fi...