Requirement authority
Name the drawing, specification and revision that govern the material requirement. A family label alone does not establish authority.
Materials selection
Select the material as a controlled requirement—not a familiar family name.
A defensible material decision connects application, exact grade and condition, manufacturing route, verification evidence and substitution authority.
Control sequence
Six decisions connect selection to released evidence.
Use the sequence during design review and RFQ preparation. Unknown inputs are questions to close—not neutral assumptions.
Exact identity
Record alloy or polymer designation, standard and any customer-specific grade. Trade names need an agreed technical equivalence basis.
Condition or temper
Heat treatment, temper, hardness, moisture state, filler and other condition details can change both performance and processing.
Process interaction
Check whether machining, forming, moulding, joining, finishing and heat input preserve the required properties and geometry.
Evidence route
Define the certificate, lot identity, test report or inspection record needed to connect delivered parts to the specified material.
Substitution control
A proposed alternative remains a change request until the relevant technical authority has compared and approved the differences.
Decision matrix
Compare material families through the requirement and evidence route.
These rows guide clarification. They are not a universal compatibility table or a statement of supplier capability.
| Material family | Decision basis | Evidence to define |
|---|---|---|
| Aluminium alloys | Weight, strength, corrosion, thermal behaviour, finishing and machining response. | Alloy + temper, governing standard, lot certificate where required, finish compatibility. |
| Stainless steels | Corrosion environment, strength, fabrication route, weld condition, surface state and cleaning. | Exact grade, product form, condition, heat/lot identity and required passivation or surface record. |
| Engineering plastics | Temperature, moisture, chemical exposure, creep, wear, dimensional stability and certification. | Base polymer, grade, filler/additive, colour, conditioning state and batch identity. |
| Sheet metals | Grade, thickness, temper, grain direction, bendability, weldability and cosmetic zone requirements. | Coil/sheet identity, thickness basis, direction requirements and certificate or incoming check. |
| Tool and alloy steels | Hardness, toughness, wear, heat-treatment route, distortion and machinability. | Grade, supply condition, heat-treatment specification, hardness result and trace identity. |
| Copper alloys | Electrical/thermal conductivity, strength, forming, joining, oxidation and finish needs. | UNS/EN designation, temper, conductivity or chemistry evidence when specified, and finish record. |
Claim boundary
Selection guidance is not release authority.
This guide does not certify a material, finish, supplier or part. The controlled drawing/specification, validated process route and authorised technical decision remain decisive.
Source notes
External engineering context used for this guide.
01TWI — What is Materials Selection?02Industrial Metallurgists — Materials Selection: Design Requirements
Sources provide general context. Customer specifications, standards and verified project evidence govern each release.
Apply it to a live requirement