How to Choose Sheet Metal for Stamped Parts

How material choice shapes the whole part

Before a die is designed, the material sets the rules. Strength and hardness affect forming force, tool wear and springback; corrosion behavior decides whether a finish is optional or mandatory; conductivity and weight may be functional requirements in their own right.

Choosing material early, and keeping it fixed, keeps the rest of the project stable, because changing material later shifts bend radii, tolerances and finishing decisions.

Cold rolled steel (SPCC)

Cold rolled steel is the economical default for many brackets, panels and housings. It forms easily, welds well and takes paint or powder coating nicely. Its main limitation is corrosion: bare cold rolled steel rusts, so it almost always needs a protective finish.

Stainless steel (SUS304, SUS301)

A deep-formed cover and a spring clip should not receive the same “304/301 stainless” callout. Annealed 304 can be a starting point for forming; cold-worked 301 strip can provide higher strength for a spring application, but the harder condition changes bendability and springback. Specify the supplied condition instead of relying on the grade number alone. [1, 6]

For a clip, define the installed deflection and required force, then verify the finished part’s force, permanent set and expected cycling. For a cover, check forming cracks, surface condition and fit. Higher material strength alone does not demonstrate spring life, and stainless grade alone does not establish hygiene or medical suitability.

• [1] Atlas Steels — 301/301L/301LN data sheet (2021), pp. 1–2
• [6] Outokumpu Core — 304 formability and material condition

Aluminum (5052, 6061)

For a bent cover, compare actual sheet conditions such as 5052-H32 and 6061-T6. 5052 is strengthened by cold work; H32 specifies a strain-hardened and stabilized condition. 6061-T6 is solution heat treated and artificially aged. Their supplied conditions give different strength and forming responses. Check the datasheet for the purchased thickness and product form. [2, 3]

If a tight bend governs the design, review the required radius and bend direction before replacing 5052-H32 with 6061-T6. If 6061 is selected for strength, confirm that its forming and joining route preserves the required properties. A cover made from either alloy still needs its own fit, stiffness and finish checks; a grade name cannot settle those questions.

• [2] Atlas Steels — 5052 data sheet (2021), pp. 1–3
• [3] TWI — Aluminium alloys: work hardening, heat treatment and welding

Copper and brass

High-conductivity copper and brass are not equivalent electrical choices. The Copper Development Association lists about 101% IACS for C11000 and 28% IACS for C26000 at 20°C; IACS is a conductivity reference, not a current rating. Use those typical values only to understand why equal-sized parts may have different electrical resistance. [4, 5]

For a busbar or terminal, check the current path, cross-section, temperature rise, contact area and joining or plating. For a spring contact, add required force, deflection and durability. C26000 properties vary with temper, so selecting a harder strip for spring strength also changes forming behavior. Neither conductivity nor hardness alone establishes contact reliability.

• [4] Copper Development Association — C11000
• [5] Copper Development Association — C26000

Galvanized and electrolytic steel (SGCC, SECC)

These are steels with a zinc or electrolytic coating already applied, giving built-in corrosion protection for chassis and structural panels. The thing to plan for is that cut and pierced edges expose bare steel, so edge protection or a secondary finish may still be needed where corrosion resistance is critical.

Tinplate and nickel silver

Tinplate can suit shielding, solderability and other application-specific requirements where its coated surface is part of the design. Nickel silver combines corrosion behavior, appearance and spring-contact possibilities for selected electronic components.

Neither should be treated as a generic substitute for steel or copper. Specify the functional reason, grade and material condition so forming and contact requirements can be reviewed.

Thickness, formability and finish

Choose thickness from load, stiffness, forming geometry, contact requirements and available product specifications. A broad thickness range cannot describe what is feasible for every grade, temper and shape. Review bend direction, edge condition and springback on the actual material before releasing tooling.

Decide material and finish together. Coatings alter dimensions and contact surfaces; exposed edges, joining and the service environment affect corrosion. Keep the purchased material condition and the finished-part acceptance requirements in the same review.

How to decide during part design

Use the dominant function to shortlist candidates: forming and fit for a cover, force and deflection for a clip, or conductivity and contact temperature for a terminal. Compare finished parts under the same load, environment, geometry and finish requirements; a stronger or more conductive datasheet entry is only one input.

Once a candidate works, record grade, supplied condition, product form and thickness. Use the alloy and stainless guides for grade detail, then transfer the approved choice into the material RFQ specification. A proposed alternate should trigger a review of forming, fit and function before purchase.