Direct answer: A useful custom sheet metal RFQ defines the drawing revision, material grade and thickness, annual volume, critical dimensions, bend and weld requirements, surface finish, inspection records, assembly interfaces and packaging limits. The supplier should then explain the proposed manufacturing route and the controls for burrs, springback, weld distortion, coating buildup and final fit. A short request for “sheet metal parts” is not enough to quote risk accurately.
The RFQ package is the starting point for manufacturability review. Missing information does not only delay the quotation; it can produce a price based on the wrong material, tooling route, inspection effort or packaging assumption.
| RFQ input | What the supplier should review | Risk when missing |
|---|---|---|
| 2D drawing and 3D model | Revision, datums, critical-to-quality dimensions, hole pattern and assembly interfaces | Conflicting geometry or an incorrect tolerance interpretation |
| Material and thickness | Exact grade, temper or condition, sheet thickness, grain direction when relevant and certificate requirements | Wrong bend response, weld behavior, corrosion resistance or material cost |
| Prototype and annual volume | Laser cutting and bending, punching, stamping, dedicated tooling or a mixed route | A process that is economical for samples but unsuitable for production, or the reverse |
| Tolerances and datums | Which dimensions control function, fit, flatness, hole position and stack-up | Over-tolerancing, unstable inspection or parts that pass dimensions but fail assembly |
| Weld and joining requirements | Joint type, weld location, cosmetic limits, distortion risk, grinding and downstream assembly | Heat distortion, weak access, appearance variation or extra rework |
| Surface finish | Finish type, color or texture, appearance surface, masking, coating thickness and corrosion environment | Thread, hole or mating-feature interference after finishing |
| Inspection evidence | First-article report, material certificate, dimensional report, visual standard, gauge plan and functional check | Different acceptance criteria between sampling and production |
| Packaging and delivery | Scratch protection, part separation, deformation risk, labeling, lot traceability and shipment quantity | Good parts damaged or mixed after final inspection |
No single process route is correct for every sheet metal part. The supplier should explain why a route matches the geometry, tolerance, surface requirement and production volume instead of listing equipment without connecting it to the drawing.
This route is often practical for prototypes, lower volumes and designs that may still change. The review should cover cut-edge condition, heat-affected appearance where relevant, bend radius, bend relief, hole-to-bend distance, forming sequence and access for press-brake tooling.
Punching and stamping can support repeatable features or higher production volumes, but tooling decisions require stable geometry and an agreed change-control process. Buyers should ask how the supplier controls tool wear, burr direction, formed features, strip or blank layout, first-piece approval and maintenance records. For higher-volume formed parts, see Zhengna Technology's custom stamping capability.
Welding and fastening introduce a second tolerance system after individual components are made. Fixture datums, weld sequence, heat input, access, fastener installation and post-weld inspection should be defined before production. Cosmetic grinding should not remove functional material or hide an uncontrolled joint.
Some assemblies need machined datums, bearing seats, threads or precision interfaces that are not economical or stable in the sheet-metal operation alone. In that case, the drawing should identify which features are created or finished after forming and how the supplier preserves the datum relationship. Related capability: custom CNC machining parts.
Bend radius and relief geometry must match material behavior, thickness and tooling access. Holes, slots and tabs placed too close to a bend can distort during forming. The drawing should identify whether a dimension is required before or after bending and which datum controls its final position.
Springback varies with material grade, thickness, bend angle, tooling and grain direction. It should be managed through process planning and verified on the actual part. A general material table cannot guarantee the final angle or flatness of a specific geometry.
Large panels, asymmetric forms and welded frames may move after cutting, bending or welding. Buyers should identify the functional flatness zone, the assembly restraint and the stage at which the part is measured. A supplier should not promise flatness from machine capacity alone.
Powder coating, plating, anodizing and other finishes can change hole size, thread fit, electrical contact and mating clearances. Specify masked areas, appearance surfaces and functional interfaces. If coating thickness is important, define how and where it will be measured.
“Deburr” is not a complete acceptance standard. The buyer should define edge condition where parts are handled, wired, sealed or assembled. Burr direction may also affect stacking and fit. Inspection and packaging should protect the accepted edge condition through shipment.
| Production stage | Typical control | Buyer evidence to request when relevant |
|---|---|---|
| Incoming material | Grade, thickness, condition and lot identity | Material certificate or incoming record |
| Cutting and punching | Profile, holes, burr direction and edge condition | First-piece dimensional record and visual standard |
| Bending and forming | Angle, radius, hole position, height, flatness and feature orientation | First-article report tied to drawing datums |
| Welding and assembly | Fixture location, distortion, joint appearance, fastener fit and assembly interface | Fixture check, weld visual criteria or functional fit record |
| Surface finish | Color or texture, coverage, masking and functional clearance | Approved sample, appearance limit or coating check when specified |
| Final release | Critical dimensions, appearance, quantity, labeling and packaging | Final inspection report and lot traceability when required |
The inspection method must match the requirement. Calipers may be suitable for some dimensions, while a height gauge, optical system, coordinate measuring machine, fixture, thread gauge or functional assembly check may be more appropriate for others. The drawing and control plan should identify the critical characteristics instead of requiring unnecessary measurement of every feature.
A prototype proves that a geometry can be produced once under a particular route. Production approval should also address repeatability, tooling condition, material lot control, fixture strategy, inspection frequency, change control and packaging. If the route changes from laser-cut prototypes to production stamping, the buyer should expect a new first-article review because edge condition, forming behavior, datums and tooling effects may change.
Before SOP, agree on drawing revision, approved samples, critical dimensions, defect limits, inspection records, packaging and the escalation path for nonconforming parts. These controls make quotation assumptions visible and reduce disputes after production begins.
Zhengna Technology can review manufacturing feasibility and quote against buyer drawings, but the buyer remains responsible for the product-level design requirements, regulatory obligations and application validation unless a separate written scope assigns those responsibilities. Material certificates, finish standards, corrosion tests, weld qualifications, enclosure ratings and industry-specific approvals should be requested explicitly when the application requires them. A manufacturing page or sample part does not by itself prove NEMA, IP, medical, aerospace or other product-level compliance.
For production capability and quotation routing, review custom sheet metal parts manufacturing. To submit a controlled RFQ, contact Zhengna Technology with your drawing and requirements. For the site's inspection overview, see quality control.
Send the current drawing and 3D model, material grade and thickness, quantity, critical tolerances, finish, inspection requirements, assembly conditions and packaging needs. Identify any unresolved design assumptions instead of leaving the supplier to guess.
Stamping may be worth evaluating when geometry is stable, repeatability or formed features matter and production volume can justify dedicated tooling. Laser cutting and bending are often more flexible for prototypes, lower volumes or designs that may change. The final decision requires part-specific cost and risk review.
Define the functional surface, datum, measurement condition, assembly restraint and production stage. The supplier should then review fixture strategy, weld sequence, heat distortion and the inspection method. A general flatness statement without these conditions can be interpreted differently.
Request only records that control application risk, such as material certificates, first-article reports, critical-dimension reports, visual standards, coating checks, functional gauges, assembly-fit records and lot traceability. The drawing or quality agreement should define the required format and frequency.
No. A supplier page describes manufacturing capability. Product-level ratings, tests and regulatory approvals depend on the final design, materials, assembly, test method and documented scope. Buyers should specify each required certificate or validation separately.
EN