Deburring
Removes sharp edges, burrs, and machining residues left after cutting or forming. Essential for safe handling, assembly fit, and downstream coating adhesion.
Finishing Guide
A surface finish determines how a part performs in the field as much as how it looks coming off the line. Corrosion resistance, wear life, electrical conductivity, paint adhesion, and cosmetic acceptance are all governed by the finish specification — not the base material alone. CipherFAB offers a comprehensive finishing portfolio as a value-added service across sheet metal fabrication, pipe and tube fabrication, CNC machining, and additive manufacturing, with every finish backed by DFM review to flag dimensional build-up, masking requirements, and material compatibility before production begins. Finishes are organised below by category: mechanical, conversion coating, and applied coating, followed by a full colour reference for powder coating, electroplating, and PVD.
Surface Finishing for Manufactured Components
A surface finish determines how a part performs in the field as much as how it looks coming off the line. Corrosion resistance, wear life, electrical conductivity, paint adhesion, and cosmetic acceptance are all governed by the finish specification — not the base material alone. CipherFAB offers a comprehensive finishing portfolio as a value-added service across sheet metal fabrication, pipe and tube fabrication, CNC machining, and additive manufacturing, with every finish backed by DFM review to flag dimensional build-up, masking requirements, and material compatibility before production begins.
Finishes are organised below by category: mechanical, conversion coating, and applied coating, followed by a full colour reference for powder coating, electroplating, and PVD.
Mechanical Finishes
Mechanical finishing modifies surface texture through abrasive or cutting action. No additional material layer is deposited — the substrate surface itself is altered.
Grinding
Produces flat, dimensionally controlled surfaces and removes material to a defined finish. Used when surface flatness and Ra consistency are critical to function.
Sand Blasting / Shot Blasting
Abrasive blast cleaning that strips scale, oxide, and contaminants while creating a uniform matte texture suitable for paint, powder coat, or inspection.
Brushing and Polishing
Directional brushing creates a controlled grain; polishing increases reflectivity and reduces surface roughness for cosmetic or hygiene-critical components.
Electropolishing
Electrochemical removal of a thin surface layer from stainless steel, producing a bright, ultra-smooth, micro-burr-free finish with improved corrosion resistance. Commonly specified for medical, pharmaceutical, and food-grade components where surface cleanliness and contamination resistance are critical.
Conversion Coatings
A chemical process that converts the metal surface into a thin, adherent oxide or phosphate layer. Conversion coatings improve corrosion resistance and provide a base for subsequent coating adhesion. No material is sprayed or plated — the coating forms from the substrate itself.
Anodizing Aluminum
Electrochemical oxide layer growth on aluminium, forming a hard, porous surface that can be dyed and sealed. Type II (sulfuric) for corrosion resistance and colour; Type III (hardcoat) for wear resistance up to 50–70 µm. Seal options: nickel acetate, hot water, or dichromate. Used across aerospace, electronics, and consumer products.
Chromate Conversion Coating (Chem Film)
Thin chemical film applied to aluminium for corrosion protection and paint adhesion. Available clear or yellow. Hexavalent chromate (MIL-DTL-5541 Type I) remains the aerospace standard; trivalent (Type II) alternatives meet RoHS/REACH requirements. Preserves electrical conductivity — preferred for electronics grounding and EMI shielding applications.
Passivation
Nitric or citric acid treatment of stainless steel that removes free iron and restores the chromium-rich passive oxide layer. ASTM A967 / AMS 2700 compliant. Improves corrosion resistance without changing dimensions or appearance. Specify for 300-series stainless in marine, medical, and food-processing environments.
Phosphating
Zinc or manganese phosphate conversion layer applied to steel as a paint primer and corrosion inhibitor. Creates a crystalline surface that mechanically locks paint and powder coatings. Widely used in automotive and industrial steel fabrication before coating.
Black Oxide
Alkaline black oxide conversion on steel and stainless steel, producing a dark matte appearance with mild corrosion resistance when oiled. Preserves dimensional accuracy (coating ~1 µm). Commonly specified for tools, fasteners, and mechanical assemblies where a dark cosmetic finish is required without significant dimensional build-up.
Applied Coatings
Applied Coatings
Applied coatings deposit a distinct material layer onto the substrate. Coating thickness, adhesion, and uniformity are governed by surface preparation, coating chemistry, and application method.
Powder Coating
Dry polymer powder electrostatically applied and cured under heat to form a dense, cross-linked protective film. Standard film build is 60–80 µm for interior applications and 80–120 µm for exterior-grade specifications. Epoxy powders offer strong adhesion and chemical resistance but degrade under prolonged UV exposure; polyester powders are the standard outdoor specification. Gloss is measured in gloss units (GU) at 60° — below 10 GU is matte, 10–70 GU is semi-gloss, above 70 GU is high gloss.
Liquid Spray Painting
Wet paint systems for complex geometries and specific protective chemistries, including two-pack epoxy-polyurethane systems for heavy industrial and marine environments. Coating systems are specified by corrosion category per ISO 12944 and applied as primer, intermediate, and topcoat layers to a defined dry film thickness (DFT).
Electroplating
Electrodeposited metal coatings — zinc, nickel, chrome, copper, and gold — applied via electrolysis for corrosion protection, wear resistance, or decorative finish.
Zinc Plating
Cathodic protection for mild steel in moderate corrosion environments, typically 5–25 µm depending on rack or barrel plating method. Hydrogen embrittlement relief (baking) is required for high-tensile fasteners per ASTM F1941.
Nickel Plating
Electroless nickel deposits a uniform alloy layer on steel, aluminium, and copper, plating evenly into bores and recesses without an external current. Medium-phosphorus (6–9% P) is standard for general corrosion resistance; high-phosphorus (>10% P) for maximum corrosion resistance in acidic environments.
Chrome Plating
Hard, decorative, low-friction surface with high wear resistance, commonly specified for shafts, hydraulic components, and decorative hardware.
Copper Plating
Often used as a base or strike layer beneath nickel or chrome to improve adhesion and levelling, also specified standalone for electrical and decorative applications.
Gold Plating
Decorative and functional plating for connectors, electrical contacts, and high-end hardware requiring conductivity and tarnish resistance.
PVD Coating (Physical Vapour Deposition)
Vacuum-deposited ceramic thin-film coating bonded at the atomic level, producing significantly greater hardness and wear resistance than conventional electroplating at a fraction of the coating thickness (typically 2–5 µm). PVD does not use pigments or dyes — colour is generated by the optical properties of the coating compound itself, which is why PVD colours remain stable and fade-resistant over the life of the part. PVD bonds most reliably to stainless steel and brass substrates; aluminum and mild steel typically require a nickel or chrome strike layer prior to coating.
PVD colour is controlled by the choice of target metal — titanium, zirconium, or chromium — combined with the reactive gas atmosphere (nitrogen, oxygen, acetylene) during deposition.
PVD Coating Colours
| Colour | Coating Compound | Character |
|---|---|---|
| Gold | Titanium Nitride (TiN) | Warm, bright gold — the most stable and widely produced PVD colour |
| Rose Gold | Titanium Carbonitride (TiCN), tuned | Soft pink-gold tone, highly sensitive to film thickness control |
| Champagne Gold | Zirconium Nitride (ZrN) | Muted, upscale gold tone, common in architectural and sanitary fittings |
| Black / Gun Black | Titanium Carbonitride or high-acetylene Chromium-based | Deep metallic black-grey from high optical absorption rather than true matte black |
| Gunmetal Grey | Chromium Nitride (CrN) | Cool-toned grey, between silver and black |
| Bronze | Custom-tuned Titanium/Zirconium deposition | Warm, industrial antique-metal tone |
| Copper / Sunset Copper | Custom-tuned deposition, higher red shift than rose gold | Deeper, redder, more industrial than rose gold |
| Silver | Chromium and/or Titanium with Argon (inert) | Bright, white-metal tone resembling polished stainless or white gold |
| Graphite | Chromium Nitride, darker formulation | Dark grey, slightly lighter and warmer than full black |
| Blue | Titanium Nitride with controlled nitrogen variation | Cobalt-toned, used for accent and decorative applications |
| Purple | Specialty gas-tuned deposition | Niche decorative colour, less common in industrial production |
| Multicolour / Gradient | Variable gas and thickness control during deposition | Colour-shift effect (e.g. gold fading to black) for high-end decorative parts |
Surface preparation changes how each colour reads: mirror-polished substrates produce a deep, saturated, reflective tone; brushed or satin substrates mute and soften the colour; sandblasted substrates scatter light for a textured, sparkle-like effect. Gold, rose gold, champagne gold, gunmetal, and black are the most production-stable colours. Purple, blue, and multicolour gradients carry tighter process tolerances and should be sampled before a full production run.
Powder coating colour follows the RAL Classic system, the global standard for industrial and architectural coatings. The full RAL palette is available; the most commonly specified groups are:
Powder Coating Colours (RAL)
| RAL Group | Range | Typical Use |
|---|---|---|
| RAL 1000 series | Yellows | Safety equipment, agricultural machinery |
| RAL 2000 series | Oranges | Safety equipment, high-visibility components |
| RAL 3000 series | Reds | Fire safety equipment, branding |
| RAL 5000 series | Blues | Industrial machinery, structural steel |
| RAL 6000 series | Greens | Agricultural and outdoor equipment |
| RAL 7000 series | Greys | The most widely specified industrial range — enclosures, panels, machine frames |
| RAL 9000 series | Whites and Blacks | RAL 9005 (jet black) and RAL 9010 (pure white) are the two most ordered colours across all industries |
Gloss level is specified independently of colour: matte (below 10 GU), semi-gloss (10–70 GU), or high gloss (above 70 GU), measured at a 60° viewing angle.
Electroplating Finish Options
| Colour | Coating Compound |
|---|---|
| Zinc | Clear/bright, yellow chromate, black chromate, olive drab (military spec) |
| Nickel | Bright nickel (decorative), satin nickel, electroless nickel (matte grey, uniform on complex geometry) |
| Chrome | Bright chrome (mirror), satin/brushed chrome |
| Copper | Bright copper, satin copper |
| Gold | Bright yellow gold, available in various karat-equivalent tones |
How to Specify a Finish
Finish specification errors are one of the most common causes of part rework. When placing an order, include:
Process —
coating type (e.g. Type II anodise, powder coat polyester, PVD gold)
Colour or Grade —
RAL code, standard class, or PVD colour designation
Thickness —
minimum and maximum coating build in µm or mil
Masked Areas —
threaded features, bores, or mating faces to remain coating-free
Standard Reference —
applicable specification (e.g. MIL-A-8625, ISO 12944, ASTM A967)
If a drawing does not specify a finish, CipherFAB's engineering team flags this during DFM review before the order proceeds to production.