Feature	Typical Tolerance
Bend angle	±1°
Bend radius	±0.25 mm
Hole diamete	±0.1 mm
Part outline accurac	±0.2 mm

Effective sheet metal design is crucial for manufacturability, cost-efficiency, and functional performance. Below are key guidelines and best practices used by engineers and fabricators.

     · Standard sheet thickness: 0.5 mm – 6 mm

     · Use uniform thickness throughout a design to reduce cost and complexity.

     · Consider material bendability (e.g., aluminum bends more easily than stainless steel).

     · Minimum Bend Radius: Typically 1× sheet thickness for most materials (check specific alloy requirements).

     · Bend Relief: Add relief cuts near bends to avoid tearing in tight corners: Slot length ≥ material thickness; Slot width ≥ bend radius.

     · Bend Orientation: Orient all bends in the same direction when possible to reduce setup time.

     · Avoid placing holes too close to bends; use this rule: Distance from hole to bend edge ≥ 2× sheet thickness + bend radius.

The bend radius should match or exceed the material thickness to avoid cracking. General guideline:

     · Bend radius ≥ 1× material thickness

For example, a 1.5 mm thick aluminum sheet should have a bend radius of at least 1.5 mm.

     · Holes near bends should be spaced at least 2× the material thickness away.

     · Avoid placing slots or cutouts along the bend line.

     · Maintain a minimum hole diameter of 1.5× material thickness.

Bending stretches the outer material and compresses the inner material. The K-Factor (typically 0.3 to 0.5) helps calculate bend allowances. Use accurate K-Factor values in your CAD software to prevent part deformation.

    · Keep notches at least 3× material thickness deep.

    · Tabs should be longer than they are wide and evenly spaced.

Simpler designs reduce tooling costs. Use:

     · Straight bends over curves

     · Fewer cutouts or embossed features

     · Flat faces when possible for better clamp fit

The performance, durability, and appearance of a sheet metal part heavily depend on the material and surface finish chosen. Selecting the right combination ensures that parts meet both functional and aesthetic requirements.

Mild Steel

    · Pros: Strong, cost-effective, easy to weld and machine

    · Cons: Prone to corrosion without finishing

    · Common Grades: ASTM A36, A1008, A1011

    · Applications: Frames, brackets, structural parts

Stainless Steel

    · Pros: Corrosion-resistant, durable, good strength

    · Cons: Higher cost, harder to cut/form

    · Common Grades: 304, 316

    · Applications: Food equipment, medical devices, outdoor enclosures

Aluminum

    · Pros: Lightweight, corrosion-resistant, easy to machine

    · Cons: Softer, less strong than steel

    · Common Grades: 5052, 6061

    · Applications: Aerospace, electronics, automotive panels

Copper

    · Pros: Excellent electrical/thermal conductivity, antimicrobial

    · Cons: Expensive, soft, oxidizes quickly

    · Applications: Electrical components, heat sinks

Brass

    · Pros: Decorative, corrosion-resistant, easy to machine

    · Cons: Costly compared to steel

    · Applications: Hardware, trim, plumbing

Finishing enhances corrosion resistance, aesthetics, and wear properties. Choose finishes based on the product’s environment and usage conditions.

Protective Finishes

Aesthetic Finishes

Functional Finishes

Choosing the Right Combination

Successfully sourcing custom sheet metal parts requires careful planning, clear documentation, and effective communication with your fabricator. Here's a step-by-step guide to help you move from concept to production smoothly.

Start by clearly specifying what the part needs to do:

     · Function: Structural support? Enclosure? Aesthetic cover?

     · Environment: Indoors, outdoors, high humidity, temperature extremes?

     · Mechanical needs: Load-bearing, vibration resistance, precision fit?

Tip: The more details you provide, the fewer revisions and delays you’ll face.

Design your part using CAD software with sheet metal-specific tools (e.g., SolidWorks, Fusion 360, AutoCAD).

Key considerations:

     · Choose standard material thicknesses (e.g., 1.5 mm, 2 mm, 3 mm)

     · Use consistent bend radii and avoid tight bends near cutouts

     · Include:

          ○  Bend lines

          ○ Hole dimensions

          ○  Flat pattern drawings if possible

Tip: Overly tight tolerances or unnecessary complexity unless absolutely needed.

Your documentation package should include:

Tip: Include callouts for material type, finish, quantity, and critical tolerances.

Choose a supplier that matches your needs in:

    · Capabilities (laser cutting, bending, welding, coating)

    · Experience (industry-specific knowledge)

    · Certifications (ISO 9001, AWS, RoHS, etc.)

    · Lead Time & MOQs (minimum order quantities)

Sources:

     · Local shops for fast turnaround

     · Online platforms with brand effect

     · Overseas suppliers have cost-effectiveness advantages

Submit your design package with:

     · Quantity

     · Material preference

     · Finish type

     · Required delivery date

     · Any certifications or inspection requirements

Tip: Get multiple quotes for price comparison and capacity checks.

Some fabricators will offer Design for Manufacturability (DFM) suggestions:

     · Modifying tight bends

     · Suggesting alternate fasteners

     · Recommending stock material sizes

Take this seriously—it can reduce cost, lead time, and risk.

For complex or high-volume projects:

     · Ask for a First Article Inspection (FAI) part

     · Test fit and function before full production

     · Make any final revisions

Once you approve the prototype or quote:

     · Submit purchase order

     · Confirm lead time and shipping method

     · Track progress and communicate frequently with your supplier

When you receive parts:

    · Inspect dimensions and surface finish

    · Test fit and function

    · Review accompanying documents (CoC, test reports, etc.)

If issues arise, work with the supplier quickly on rework or replacement.

Reducing machining costs—especially for sheet metal fabrication—requires a blend of smart design, material choices, and manufacturing awareness. Here’s a list of practical, high-impact suggestions to reduce cost without compromising quality.

    · Reduce the number of bends.

    · Avoid tight bend radii and complex contours.

    · Combine parts where possible.

    · Use common hole sizes.

    · Maintain consistent material thickness across parts.

    · Avoid custom tooling (embosses, lances) unless necessary.

    · Use aluminum instead of stainless steel when corrosion resistance is not critical.

    · Consider cold-rolled steel with powder coating for strength and affordability.

    · Design for functionality, not aesthetics alone.

    · Overly tight tolerances or unnecessary finishing will drive up costs.

    · Ordering in larger volumes reduces per-part setup and handling time.

    · Group similar parts together to minimize sheet waste.

    · Ask for Design for Manufacturing (DFM) feedback.

    · Involve fabricators early in the design process to identify cost-saving opportunities.

Sheet metal fabrication is a versatile and powerful manufacturing process, but getting it right depends on thoughtful design and practical material choices. By adhering to industry standards, optimizing part geometry, and working closely with suppliers, engineers and designers can produce high-quality parts at competitive costs.