Sheet Metal Design Guidelines

Our basic guidelines for sheet metal fabrication include important design considerations to help improve part manufacturability, enhance cosmetic appearance, and reduce overall production time.

Sheet Metal Materials                Aluminum Sheet Metal Parts

  • Aluminum
  • Stainless Steel
  • Galvanneal and Galvanized CRS
  • Cold Rolled Steel
  • Brass
  • Copper

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Punched Features

We have the following standard punched features available; rib, louver, bridge lance, embossment, and dimple.

Formed Features

For sheet metal parts, we accept up to 12 bends per part, which are geometry and complexity dependent. Hems are closed up to 36 in. and our offsets are standard heights of 0.062 in. – 0.375 in. Bump forming for radii up to 1 in. at 90 degrees and our internal bend radii standard is 0.030 in.

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Free Design Guide for Sheet Metal Fabrication

Currently designing sheet metal prototypes? Download the sheet metal design guide for design for manufacturability best practices on hems, countersinks, holes and slots, bends, and more.

Tolerances

Tolerances vary depending on part feature such as bends, offsets, holes and inserted hardware. The following tolerances will be guaranteed by Rapid for precision sheet metal fabrications. Our standard angular tolerance is +/- 1 degree and we hold a fractional tolerance of +/- 1/64 in.

Locational Tolerances

Tolerances on One Surface

Bend to bend (2 bends) +/- 0.015 in.
Bend to bend (3 or more bends) +/- 0.030 in.*
Edge to hole (2 bends) +/- 0.015 in.
Bend to hole (2 bends) +/- 0.030 in.*
Bend to hole (3 or more bends) +/- 0.030 in.*
Hole to formed feature or hardware +/- 0.010 in.
Hole to formed feature or hardware (2 or more bends) +/- 0.030 in.*
Edge to formed feature or hardware +/- 0.010 in.
Edge to formed feature or hardware (2 or more bends) +/- 0.030 in.*
Hole to hole (2 or more bends) +/- 0.020 in.*
Edge to edge (2 or more bends) +/- 0.020 in.*
Edge to bend (more than 1 bend) +/- 0.020 in.*
Edge to edge +/- 0.005 in.
Edge to hole +/- 0.005 in.
Hole to hole +/- 0.005 in.
Hole to hardware* +/- 0.010 in.
Edge to hardware* +/- 0.010 in.
Hardware to hardware +/- 0.015 in.
Bend to edge +/- 0.010 in.

Hole Tolerances

Hole diameters +/- 0.005 in.
Hardware hole diameters +/- 0.003 in.
Countersink major diameters +/- 0.005 in.
Countersink minor diameters +/- 0.015 in

*non cumulative

Surface Finishes for Sheet Metal

Typically, we break (deburr) the edges of all sheet metal fabricated parts. In some instances your project may require additional finishes.

Mill Finish

Orbital Sanding

Edge Breaking

A variety of powder coat paint colors are available in textured and non-textured finishes, including RAL colors. Silk screening is also available up to two colors and can be matched to any Pantone number.

Part Marking

We offer two methods of part marking: ink stencil and bag and tag. Ink stencil is a method in which we spray a permanent ink over a stencil to create the marking. Bag and tag is when parts are wrapped and labelled with part number sticker.

Welding

Rapid offers the following single component welding methods: seam, stitch, and tack.

Seam Weld

Seam welding is simply a continuous weld along a joint and is typically the strongest welding method because it completely welds a joint. The main advantage of seam welding is the strength and durability of the weld. A common application for seam welding is in the corners of a folded-up sheet metal chassis. Seam welding the corners gives the appearance of a solid box and makes the chassis stronger. Other applications include brackets for load bearing, areas where there can be no gaps for contaminants to enter, and frame components that will be load bearing.

Stitch Weld

Stitch welding is a weld along a joint that is broken up into equal length and equal spaced welds, giving the weld a stitched look. Stitch welding reduces the amount of heat distortion and also is less costly than a full seam weld. Stitch welding is typically used when the strength or look of a seam weld is not needed.

Tack Weld

Tack welding is the use of small strategically placed beads of weld typically used to secure parts in place before final welding. Tack welding allows the parts or assembly to be adjusted and properly fitted for the final weld to take place. Tack weld can be used to weld where a spot welder cannot reach, for example in long chassis or metal boxes.

 

Seam Weld

Stitch Weld

Tack Weld

Sheet metal seam weld Sheet metal stitch weld

Assembly

We will ship loose components or provide POP riveting up to four components.

Tip: If you have more than four components, we can fabricate them and ship them loose.

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Documentation

The following documentation is available for all sheet metal orders; ISO9001, a certificate of conformance, and material certifications are available upon request.

Sheet Metal Fabrication and CNC Machining

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3D Printing and Injection Molding

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