Sheet Metal Finishing for Custom Fabricated Parts

Deburring and Edge Condition

Deburring removes projections left by cutting or punching. An edge break softens the transition between faces. Neither term establishes a universal radius.

Where an edge affects sealing, handling, assembly, or a mating component, define the required condition on the drawing. Excessive material removal can alter small holes, slots, and thin features.

Grain, Weld Blending, and Cosmetic Faces

Brushing creates a directional texture. Orbital finishing produces a less directional appearance. For adjacent panels, grain orientation can be as noticeable as color.

Identify visible faces and define acceptable weld appearance, scratches, support marks, and texture. An agreed reference sample and viewing conditions are more useful than an undefined “cosmetic finish” requirement.

Weld blending removes material. The desired appearance must remain compatible with the wall thickness and joint requirements.

Surface Roughness

A roughness value does not define a complete cosmetic finish. Surfaces with similar Ra values can differ in gloss, grain, color, and visible marks.

Specify the roughness parameter, units, measurement direction, and location where these affect acceptance.

Coating Thickness and Finished Dimensions

A deposited coating on both walls of a bore reduces its diameter by approximately twice the local film thickness. Coating on an external diameter increases that diameter.

Anodizing requires a different allowance because the oxide grows both into and outward from the original surface.

Identify whether critical dimensions apply before or after finishing. Review threads, slip fits, locating holes, and sliding interfaces together with the selected treatment.

Masking and Grounding Areas

Define surfaces, holes, and threads that must remain free of a treatment. Masking boundaries need particular attention near bends, hems, recesses, and welds.

Anodic oxide is electrically insulating. Aluminum conversion coatings used for electrical contact applications require the appropriate specified class and acceptance criteria. A bare or selectively treated grounding area also needs a defined final surface condition.

Hardware and Process Contact Points

Hardware installation sequence depends on the fastener, substrate, finishing process, and installation access.

Installation before treatment may expose hardware to chemicals or coat threads. Installation afterward may damage the finish or change installation conditions. The fastener manufacturer’s requirements and joint design govern the choice.

Electrolytic processes need electrical contact, and powder coating needs a grounding route. Define acceptable support or contact locations where resulting marks could affect appearance or function.

Aluminum Treatments

Anodizing is commonly selected for protection and a metallic appearance. Hardcoat anodizing is considered where wear is a stronger design driver.

Alloy composition, weld filler, and prior surface treatment can produce visible differences within an assembly. Thickness and dimensional growth must be assessed separately from the color designation.

Conversion coatings can provide a paint base or a protective treatment for specified electrical contact applications. A non-hexavalent process designation alone does not establish compliance for an entire product.

Stainless Steel and Plated Parts

Stainless steel passivation addresses free iron contamination. Substantial weld oxide removal is a separate preparation consideration.

Electroless nickel can provide relatively uniform deposition across accessible wetted surfaces, but recesses and trapped gas still matter. Zinc protects steel sacrificially; service conditions and supplementary treatments influence performance.

For susceptible high-strength steel, plating-related hydrogen embrittlement requirements need attention during process selection.

Powder Coating, Wet Paint, and Markings

Exterior-grade polyester powder systems are commonly considered for UV exposure. Epoxy systems can suit selected indoor and chemical environments but tend to chalk under UV. Chemical or immersion suitability depends on the actual coating system.

Deep recesses can be difficult to coat evenly. Cure temperatures also affect seals, adhesives, and purchased components. A suitable liquid coating system may offer a different cure route where heat exposure is a constraint.

For printed legends or laser marking, define artwork, contrast, location, and abrasion exposure. Laser marking can alter or remove a protective layer, so corrosion requirements must be considered alongside identification.

ShincoMetal’s project review records the agreed finish requirements and inspection responsibilities before production release. 

For externally processed finishes, ShincoMetal coordinates the agreed specification and required documentation with the finishing partner. 

The quotation identifies which inspection records, finish certificates, or test reports are included and which require a separate arrangement. 

A material test report addresses the base metal; it does not replace a finish certificate or coating test report. Similarly, an ASTM B117 salt spray result describes behavior under specified test conditions and does not directly predict years of field service.

A reference sample helps communicate color, gloss, texture, and grain. A finished first article can also reveal interference at mating features or differences around welds and formed areas.

Where sample approval is required, include sample preparation, customer review, and possible revisions in the project schedule.

Finishing price and lead time depend on preparation, geometry, masking, coating selection, quantity, and acceptance requirements. Custom colors, special testing, and documentation can add work beyond the coating operation.

For repeat orders, define which appearance references and approved requirements must remain consistent between batches.