Sheet Metal RFQ Checklist: Drawings, Materials, Tolerances and Supplier Questions

A sheet metal RFQ is not only a request for price. For OEM buyers, it is the control package that tells a supplier what must be built, what can be optimized, what must be inspected and what commercial assumptions are allowed.

When the RFQ is incomplete, suppliers either quote with hidden assumptions or add contingency. Both create problems: the low quote may miss coating, hardware, packaging or inspection scope, while the high quote may price risks that could have been clarified in one email.

The practical answer - A strong sheet metal RFQ should include the 3D model, 2D drawings, material and finish requirements, tolerance and inspection expectations, annual volume, prototype quantity, packaging needs, destination, lead-time target and a clear list of supplier questions. If the part is an enclosure, frame, tray, bracket, panel or kit, also define hardware, assembly state and cosmetic zones.

Why sheet metal RFQs fail

Most RFQ problems are not caused by the supplier refusing to quote. They are caused by missing decision inputs.

Common gaps include:

• 3D model without controlled 2D drawings.
• Drawing notes that conflict with the CAD model.
• Material grade written broadly, such as “stainless steel” instead of 304 or 316L.
• Finish listed only as “powder coat” without color, texture, thickness or masking notes.
• Tolerance blocks copied from machined parts and applied to formed sheet metal.
• PEM hardware shown in CAD but missing from the bill of materials.
• No cosmetic face definition.
• No packaging requirement for finished or clean parts.
• No annual volume, prototype quantity or target delivery date.

The result is quoting noise. One supplier may include deburring, hardware insertion, coating and export packaging. Another may quote only cut-and-bend parts. The unit prices are then not comparable.

Sheet metal RFQ checklist

Use this checklist before sending the package to a supplier.

RFQ item	What to include	Why it matters
3D files	STEP, Parasolid or native CAD if acceptable	Defines geometry and assembly relationships
2D drawings	Revision, material, thickness, tolerances, finish, critical notes	Controls manufacturing and inspection
Flat pattern	Include only if approved by engineering	Avoids supplier guessing bend deduction incorrectly
Material	Grade, thickness, temper and approved substitutions	Affects forming, corrosion, cost and lead time
Finish	Color, gloss, texture, masking, coating thickness, passivation or anodizing notes	Prevents cosmetic and functional mismatch
Hardware	PEM nuts, studs, standoffs, hinges, latches, fasteners and supplied-by rules	Prevents missing purchased parts and assembly delays
Welding	Weld type, visible seams, grinding level and distortion limits	Controls appearance, strength and rework risk
Tolerances	Critical dimensions, datums and inspection state	Lets cost follow real function instead of blanket precision
Quantity	Prototype, pilot and annual volume	Changes process route, tooling decision and pricing
Quality records	FAI, material certificates, COC, coating report, inspection report	Prevents missing documentation after shipment
Packaging	Individual wrap, surface protection, kit packout, export carton or pallet	Prevents finish damage and receiving confusion
Delivery terms	Destination, Incoterms, target shipment date and preferred logistics	Makes total landed cost comparable

Drawings: what suppliers need to see

A supplier can quote simple parts from a 3D model, but production control usually needs a drawing. The drawing should identify:

1. Material and thickness.
2. Bend radius or acceptable forming method.
3. Critical dimensions and datums.
4. Threads, hardware and hole types.
5. Cosmetic surfaces.
6. Finish and masking.
7. Inspection requirements.
8. Drawing revision.

If the part is part of a larger assembly, send the assembly view as well. A bracket tolerance that seems excessive in isolation may be critical when it locates a sensor, hinge, rail, gasket or cable path.

For formed parts, review our minimum bend radius and relief guide and K-factor explanation before locking dimensions that depend on bend behavior.

Materials and finish: avoid vague notes

Material and finish notes have a large effect on both price and manufacturability.

Better RFQ inputs include:

• “5052-H32 aluminum, 2.0 mm” instead of “aluminum.”
• “304 stainless steel, No.4 brushed visible face” instead of “stainless.”
• “Powder coat RAL 9005, matte, 60-90 microns, mask grounding studs” instead of “black powder coat.”
• “Zinc plated steel, indoor service” instead of “corrosion-resistant steel.”

If corrosion resistance is important, define the environment. Indoor electrical equipment, washdown food equipment, outdoor telecom cabinets and coastal battery enclosures need different material and coating strategies.

Related references: 304 vs 316 stainless steel, aluminum grades for sheet metal, powder coating pretreatment and stainless passivation explained.

Tolerances: separate critical from normal

One of the fastest ways to inflate a quote is to apply tight tolerances everywhere. Sheet metal parts are cut, bent, welded, finished and sometimes assembled. Each process adds variation.

Define:

• Which dimensions are critical to fit or function.
• Which holes locate the part.
• Whether dimensions apply before or after finishing.
• Whether the part is inspected free-state or restrained in an assembly.
• Which cosmetic or non-mating dimensions can use normal fabrication tolerance.

For more detail, see GD&T basics for sheet metal, ISO 2768 tolerance guide and sheet metal laser cutting tolerances.

Hardware and assembly state

If the supplier must install hardware, include a clear BOM. Hardware ambiguity is a common cause of late quotes and assembly problems.

Specify:

• PEM part number or approved equivalent.
• Thread size and material.
• Installation side.
• Stud height or standoff height.
• Torque or push-out requirement if needed.
• Whether hardware is installed before or after finish.
• Whether the supplier provides fasteners, hinges, locks or gasket material.

The hardware insertion guide covers the design rules that prevent inserts from being too close to bends, cut edges or other hardware.

Packaging and kit control

Packaging belongs in the RFQ, not after the purchase order. Finished parts can be ruined by poor packout even when fabrication is correct.

Define:

• Whether cosmetic faces need film or individual wrapping.
• Whether stainless parts must avoid carbon-steel contact.
• Whether parts ship loose, bagged, carton-packed or palletized.
• Whether kits must be grouped by product model, drawing revision or assembly sequence.
• Whether photos of final packaging are required.

For clean or high-finish parts, read packaging sheet metal parts for export and cleanroom sheet metal packaging.

Questions to ask a sheet metal supplier

Add these questions to your RFQ when supplier capability is part of the decision:

1. Which process route do you propose: laser, punching, bending, welding, finishing and assembly?
2. Which drawing notes increase cost or lead time?
3. Which tolerances should be relaxed if they are not functional?
4. Which material or finish alternatives are available locally?
5. Which hardware is standard and which requires sourcing approval?
6. What inspection records are included in the price?
7. How will finished surfaces be protected during shipment?
8. What assumptions are excluded from the quotation?

A supplier that answers these clearly is easier to manage than one that only returns a unit price.

How to compare quotations

Do not compare only unit price. Compare the scope:

• Are material grade, thickness and finish identical?
• Are hardware and assembly included?
• Are inspection reports included?
• Are coating tests or certificates included?
• Is export packaging included?
• Is the quoted lead time based on prototype or production quantity?
• Does the quote include tooling, fixtures or one-time engineering charges?
• Are Incoterms and destination the same?

If quotes differ widely, ask each supplier to list assumptions and exclusions. That usually exposes the real difference.

Add the evidence required for the actual part family

A generic quotation checklist becomes useful only when it identifies the interface, record and approval boundary for the product being sourced. Use the same controlled drawing package, but add the application-specific inputs below.

Sourcing scope	Add these RFQ inputs	Commercial fabrication page
Perforated facade and cladding panels	Panel marks, pattern continuity, open area, folded returns, bracket coordinates, finish zones and pack sequence	Architectural facade panels
Robot enclosures, sensor brackets and part kits	Platform revision, shared datums, hardware, sensor orientation, module BOM and first-article checks	Robotics sheet metal parts
Aerospace mounting brackets	Released alloy and temper, material traceability, critical holes, finish and project-defined inspection records	Laser-cut aerospace brackets
Stainless equipment housings	Approved 304 or 316 grade, weld finish, cosmetic grain, door fit, gasket interface and hardware schedule	Custom stainless steel enclosures
Medical control housings and cover kits	Component drawings, electronics mounting interfaces, removable covers, service access and kit revision	Medical device sheet metal housings
Complete medical mechanical enclosures	Assembly drawing and BOM, frame-to-panel datums, door fit, hinges and latches, finish zones and the quoted assembly state	Medical equipment enclosures

For medical equipment, distinguish a finished mechanical enclosure from a finished medical device. List electronics, displays, seals and purchased hardware as supplier-provided, customer-supplied or excluded. Define which door gaps and mounting interfaces are checked on individual parts and which are accepted after assembly. The equipment OEM retains the approved design, cleaning-method validation and final device approval; a fabrication quote should state the mechanical work and records it actually includes.

Buyers preparing a building-envelope package can also use the architectural facade panel RFQ checklist; equipment buyers can start with the editable custom sheet metal enclosure RFQ template. Certification, installed-system compliance, robot safety and final product validation must be agreed with the responsible owner rather than inferred from a supplier quotation.

How DRAmetal reviews RFQ packages

DRAmetal reviews custom sheet metal RFQs for manufacturability, cost risk and production control before quoting. For a package that spans several processes, start with our precision sheet metal fabrication services and identify the required delivery state. The agreed scope can include laser cutting, punching, bending, welding, surface finishing, hardware insertion, assembly and export packaging.

Useful related guides:

• Design for manufacturing sheet metal
• Custom sheet metal cost guide
• Reduce sheet metal costs
• Supplier factory audit checklist

If you need a quote, send the 3D model, 2D drawings, material and finish notes, hardware list, quantity, inspection needs and delivery destination through our contact page. We will review the package and clarify assumptions before pricing.