How to specify
a stainless steel part.

Start with the finished part

Attach a dimensioned drawing that identifies the part number, revision and units. Describe the component’s function and the surface or feature that locates it in the assembly. If you send a photograph or scan, include the complete drawing and readable dimensions; the photo itself is not a dimensional reference.

Use the custom part directory to find a component-specific parameter checklist. A mounting plate needs hole datums; a Z bracket needs a finished offset; a saddle-cut tube needs the mating tube and intersection angle.

304, 304L, 316 and 316L: name the exact grade

Outokumpu describes 304 as a general-purpose austenitic grade and 304L as its low-carbon alternative. Its 316 / 316L range includes molybdenum for improved corrosion resistance. Grade selection still depends on the environment and engineering requirements. See Core grade information and Supra grade information.

These are designation references, not a declaration of interchangeability under every purchasing standard. If a project needs a material certificate, heat identification or a particular specification, request it during quotation. We confirm the actual material and documentation scope for the order.

Flat parts: define the contour and feature function

• Envelope: length, width, outside diameter or a fully defined irregular profile.
• Thickness: nominal sheet thickness and any functional thickness requirement.
• Holes: diameter, center location, count and datum; distinguish clearance holes from locating bores.
• Slots: width, length, end radius and adjustment direction.
• Mating features: tab-slot clearance, bolt circle, register opening or contact surface.

Give tolerances for the dimensions that control the assembly. Do not apply a machining tolerance to every cut feature by default. Threads, precision fits and countersinks should be called out as separate finished features for review.

Explore mounting plates, mounting rings and tab-and-slot connector plates.

Bent parts: dimension the formed geometry

Supply finished leg lengths, bend direction, angle, inside radius and the critical relationship between mounting faces. Explain whether the leg dimensions refer to the inside, outside or theoretical bend intersection. Include a flat pattern if available, while keeping the finished drawing as the reference.

Feature proximity to a bend can affect the result. Protolabs’ sheet metal design toolkit discusses holes near bends, reliefs and forming geometry. Its numeric limits reflect its own processes and tooling; they are not INDMCH production specifications.

For U brackets, show inside clearance and side-hole alignment. For Z brackets, dimension the functional offset between mounting planes. For trays, define the corner construction and any liquid-retention requirement.

Tube parts: name the face and end datum

Specify outside section dimensions, wall thickness, cut length and end profile. Place each hole or slot along the tube axis from a named end datum, then identify its face or angular position. A single-wall opening is different from a hole through both walls.

TRUMPF’s tube part design guide illustrates how cut features can support positioning and tube connections. For your part, provide the mating geometry and assembly sequence so the end shape and clearance can be reviewed.

A mitered member needs a length convention, such as long-point or centerline length. A saddle-cut end needs the mating diameter and tube intersection angle.

Surface finish and cut-edge condition are different

worldstainless distinguishes 2B cold-rolled, BA bright-annealed and brushed or polished finishes. A sheet’s face finish does not by itself specify the cut edge. Ask separately for deburring, exposed-edge treatment and visible-face requirements.

What a complete RFQ contains

1. Original drawing, part number, revision and units.
2. Material grade, specification and thickness or tube section.
3. Quantity by part number, plus expected repeat volume if known.
4. Critical dimensions, mating parts and inspection requirements.
5. Finished surface, edge condition and packing requirements.
6. Delivery destination and requested date.

We accept JPG, PNG, PDF and DXF on the inquiry page. A clean DXF supports a flat cut contour; images and PDFs communicate dimensions and notes. Formed parts and tubes can be submitted for technical review even when the automatic preview cannot represent their full geometry.

References and scope

Reviewed 7 October 2026. The linked primary sources provide material, finish and design background. The component-specific checklists are INDMCH’s original inquiry guidance. Dimensions, tolerances, available finishes and lead times are confirmed for each drawing; this article does not publish machine limits or certify an application.

• Outokumpu — Core 304 / 304L grades — Material grade reference
• Outokumpu — Supra 316 / 316L grades — Material grade reference
• worldstainless — Surface treatment — Finish terminology
• Protolabs — Sheet metal design toolkit — Feature placement and forming
• TRUMPF — Tube part design — Tube feature and connection design