Painting

Painting applies liquid coatings to parts for color, basic corrosion protection, and branding, suited to large surfaces and moderate durability requirements.

Overview

Painting deposits a controlled layer of liquid coating—usually by spray, dip, or brush—onto metal or plastic parts after fabrication. It provides color, branding, and moderate corrosion protection, and can hide minor surface defects. Coating thickness is usually in the 25–75 µm range, so it changes dimensions slightly but does not control them precisely.

Use painting when you need cosmetic appearance, standard environmental protection, and a broad range of colors and gloss levels at reasonable cost. It works well for enclosures, machinery, and structures where aesthetics and brand colors matter more than extreme wear or chemical resistance. Tradeoffs: adhesion and durability depend heavily on surface prep and cure, paint can chip or scratch under impact or abrasion, and tight fits may need masking or post-paint sizing. For harsh chemicals, high temperatures, or heavy wear, more specialized coatings may be required, but for general industrial and commercial products, painted finishes are often the most economical choice.

Common Materials

  • Mild steel
  • Aluminum 6061
  • Stainless steel 304
  • Cast iron
  • ABS plastic
  • Polycarbonate

Tolerances

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Applications

  • Machine frames and guards
  • Sheet metal enclosures and panels
  • Structural steel brackets and weldments
  • Consumer product housings
  • Control cabinets and electrical boxes
  • Automotive and off-road body panels

When to Choose Painting

Choose painting when you need a colored, uniform cosmetic finish with moderate corrosion protection at low to medium cost. It’s especially effective for large parts, enclosures, and weldments where film thickness variation is acceptable. Ideal for indoor or mild outdoor environments and volumes from prototypes through high production with consistent color standards.

vs Machined Surface Finishing

Choose painting over leaving a machined finish when you need consistent color, branding, and corrosion resistance rather than visible toolpaths. Painting also helps visually unify welded or assembled components made from mixed materials. Use it when cosmetic requirements go beyond a bare-metal appearance.

vs Polishing

Choose painting instead of polishing when appearance is color-driven, not reflectivity-driven, and when you need corrosion protection in addition to cosmetics. Painting is also more practical for large weldments or structural parts where polishing would be expensive and still leave visible weld discoloration.

vs Coatings

Choose painting over more specialized coatings when operating conditions are moderate and you don’t need extreme wear, chemical, or temperature resistance. Painting is cheaper to apply and easier to touch up, making it suitable for general industrial equipment and housings where aesthetics and basic protection are the priorities.

vs Surface Texturing & Marking

Choose painting when the primary goal is overall surface coverage, color, and protection, not logos, part IDs, or localized textures. You can combine painting with marking, but painting alone is better when you want to change the entire visual character and corrosion performance of the part.

vs Hard Coatings

Choose painting instead of hard coatings when impact, abrasion, or high-temperature resistance are not critical, and cost and color flexibility matter more. Painting suits covers, guards, and cosmetic structures, while hard coatings are overkill for parts that see only light handling or indoor environments.

Design Considerations

  • Specify paint system, color (RAL/Pantone), gloss level, and environment (indoor, outdoor, chemical exposure) clearly on the drawing to avoid ambiguity
  • Call out surfaces and features to mask, especially tight-tolerance holes, threads, and grounding/earthing points, and provide clear masking drawings if needed
  • Avoid sharp edges and burrs; specify edge breaks of at least 0.2–0.5 mm to improve paint adhesion and reduce chipping
  • Account for paint thickness (typically 25–75 µm) in clearance fits, gasket lands, and snap features, especially on plastic parts
  • Define surface preparation requirements (e.g., blast profile, phosphating, solvent cleaning) because adhesion and corrosion resistance depend heavily on prep
  • Group parts by material and color where possible to reduce color changeovers and setup costs and to get more accurate painting quotes