Buyer Resources · RFQ Guide
How to Write an RFQ for CNC Machined Parts
A request for quote is not a formality. It is the specification a machine shop prices against. Every item you leave out is either a question we have to email you (delay) or an assumption we have to protect ourselves against (padding). This guide lists exactly what a quoting engineer needs, why each item changes the number, and the handful of habits that get you a faster, sharper quote. If you only read one section, read the checklist in section 02.
In This Guide
- 01What a Shop Actually Does With Your RFQ
- 02The RFQ Checklist
- 03Files: 3D Model + 2D Drawing (Why You Need Both)
- 04Quantity, Lot Structure & Repeat Orders
- 05Material & Specification Call-Outs
- 06Tolerances, Surface Finish & What "Standard" Means
- 07Secondary Operations: Heat Treat, Finishes, Hardware
- 08Quality & Documentation Requirements
- 09Schedule, Delivery & Commercial Terms
- 10ITAR & Export-Controlled Work
- 11The 60-Second RFQ Template
- 12Quick Reference Card
What a Shop Actually Does With Your RFQ
When an RFQ lands at C&W, an estimator rebuilds your part in their head from the inside out: What stock does it start as? How many times does it get flipped in the vise? Which features set the cycle time? What happens after it comes off the machine (heat treat, anodize, inspection)? And how many are we making, which decides how the fixed costs get spread? Each of those questions maps to a line on the quote.
The point is that a quote is a chain of inputs, and the chain is only as good as the weakest one. A perfect 3D model with no quantity gets priced at qty 1. A quantity with no material gets priced at an assumed alloy. A material with no spec gets priced as commercial grade with no certs. None of those are wrong, exactly. They are just not your part, and the number will move when the details arrive. A complete RFQ collapses that loop: one quote, one number, no revisions.
The 80/20 of RFQs
Five inputs drive roughly 80% of a machining quote: the model, the quantity, the material (with spec), the tolerances, and the secondary operations. Everything else refines the number. If you are short on time, get those five airtight and we can work out the rest with you.
The RFQ Checklist
Twelve items. Not every RFQ needs every line, but every line you can fill in removes an assumption from the quote. Use it as a pre-send check.
| Item | What to include | Why it changes the number |
|---|---|---|
| 1. 3D model | STEP (.stp/.step) or IGES per part, named by part number and revision. One file per part; assemblies are fine if the BOM is clear. | Geometry sets stock size, setups, and cycle time. Without it we are guessing from a picture. |
| 2. 2D drawing (PDF) | Dimensioned print with tolerance block, datums, thread callouts, finish, notes, revision. Same rev as the model. | Tolerances, threads, and notes live here, not in the model. They drive inspection time and process choice. |
| 3. Quantity | Firm quantity, or price breaks (e.g. 1 / 5 / 25 / 100). Say if it is a prototype, a one-time buy, or a recurring part. | Programming and setup are fixed; per-part price falls sharply with quantity. |
| 4. Material | Alloy + temper/condition + governing spec + form. Example: 6061-T651 plate per AMS 4027, not "aluminum". | Alloy sets machinability and stock cost; the spec sets what certs we must buy. |
| 5. Tolerances | Title-block default (e.g. ±0.005" / ISO 2768-m) plus any tighter callouts and GD&T. | Tight features add inspection, slower feeds, sometimes grinding or EDM. |
| 6. Surface finish | Ra callouts per surface where it matters; default "as machined" elsewhere. | Fine finishes mean extra passes or secondary ops. |
| 7. Secondary operations | Heat treat, anodize, chem film, plating, paint, passivation, with spec, type/class, color, and masking. | Outside processing is bought, scheduled, and shipped; each step adds cost and lead time. |
| 8. Hardware & inserts | Helicoils, PEM fasteners, dowels, bearings: part numbers and who supplies them. | Purchased parts plus install labor; MIL-spec inserts need lead time. |
| 9. Quality documentation | C of C, material certs, process certs, FAI (AS9102), CMM report, source inspection, DFARS flow-downs. | Paperwork is real engineering time and can double inspection effort. |
| 10. Need date | Required delivery date, or "standard lead time is fine." Mention if partial shipments help. | Expedites cost more; flexibility costs less. |
| 11. Ship-to & packaging | Destination, carrier preferences, special packaging (bagging, bar-coding, kitting). | Freight is quoted separately; special packaging is labor. |
| 12. Export status | Is the part ITAR / EAR controlled? Is an NDA required before we see data? | Controlled data must travel a secure path. See section 10. |
Files: 3D Model + 2D Drawing (Why You Need Both)
The 3D model tells us what the part is. The 2D drawing tells us what the part must be. Machinists program from the model and inspect against the drawing, so a quote from one without the other is half a quote.
The model
Send a neutral format: STEP (AP214 or AP242) is the standard; IGES works. Native SolidWorks, Inventor, or Fusion files are fine as a supplement, but a STEP guarantees we open exactly what you modeled. Check three things before you export: the model is at the final revision, the units are right (a part modeled in millimeters but exported as inches is a classic RFQ killer), and the file name carries the part number and rev (
12345-002_RevB.step). If the part is one body of an assembly, export the body you want quoted, or send the assembly and tell us which components are machined versus purchased.The drawing
A PDF print is the contract. It should carry a tolerance block, datum scheme, thread callouts with depth and class (
1/4-20 UNC-2B ↧ .500), surface finish symbols, material and finish notes, and a revision block that matches the model. Drawings that say "see model for dimensions" are acceptable for profile features, but tolerances, threads, and notes still have to be on the print, because nobody inspects to a STEP file.Do
One STEP + one PDF per part number, both at Rev B, file names that match the title block, units confirmed. Quote arrives in a day.
Avoid
A screenshot of the model, a drawing from a different revision, and a note saying "dimensions are roughly per the sketch." Three emails before anyone can price it.
Revision mismatches are the #1 RFQ error we see
When the PDF says Rev C and the STEP is Rev B, we stop and ask, because quoting the wrong one wastes everyone's time. Before you hit send, open both files and check the rev block. Thirty seconds on your side saves a day on the calendar.
Quantity, Lot Structure & Repeat Orders
Quantity is the single biggest lever on per-part price, because programming, fixturing, first-article inspection, and machine setup are fixed costs that get divided across the lot. Ten parts rarely cost ten times one part; they often cost two to three times one part.
Tell us how you actually intend to buy:
Prototype / one-off. Say so. We will quote the fastest sane process and skip the fixture investment that only pays off in production.
Price breaks. Ask for two or three quantities (1 / 5 / 25 is common) and we will show you where the curve flattens. That is free information for your make-or-buy decision.
Recurring part. If this will be released in lots over a year, tell us the annual usage and lot size. We can quote a blanket with releases, and we keep programs and fixtures on file so repeat orders carry little or no NRE.
Assemblies. List every machined component and its quantity per assembly, and flag which parts are purchased hardware. "Quote this assembly" without a BOM means we count bodies and guess.
Price breaks. Ask for two or three quantities (1 / 5 / 25 is common) and we will show you where the curve flattens. That is free information for your make-or-buy decision.
Recurring part. If this will be released in lots over a year, tell us the annual usage and lot size. We can quote a blanket with releases, and we keep programs and fixtures on file so repeat orders carry little or no NRE.
Assemblies. List every machined component and its quantity per assembly, and flag which parts are purchased hardware. "Quote this assembly" without a BOM means we count bodies and guess.
Why the curve flattens
Once the lot is long enough that machine time dominates setup, price per part tracks cycle time and material almost linearly. For most milled parts that happens somewhere between qty 10 and qty 50. Ask for a break on either side of where you think you'll land.
Material & Specification Call-Outs
"Aluminum" is not a material callout. "Steel" is not a material callout. A complete callout has four parts: alloy, temper or condition, governing specification, and product form. Each one changes what we buy, what it costs, and what paperwork comes with it.
| Incomplete | Complete | What the spec adds |
|---|---|---|
| 6061 aluminum | 6061-T651 plate per AMS 4027 (or ASTM B209) | Temper fixes strength; plate vs bar fixes stock; the spec fixes the cert. |
| 7075 | 7075-T7351 plate per AMS 4078 — or 7050-T7451 per AMS 4050 w/ UT Class A | Thick-section aerospace plate may require AMS 4050 and ultrasonic inspection. See the 7050 guide. |
| Steel | 1018 cold-drawn bar per ASTM A108 — or A36 plate per ASTM A36 | Same chemistry family, different form and properties. See A36 vs 1018. |
| 4140 | 4140 per ASTM A29, pre-hard 28–32 HRC — or annealed, Q&T to 36–40 HRC after rough | Condition decides whether heat treat is in the quote. See 4140 vs 4340 vs 4130. |
| Stainless | 17-4 PH per AMS 5643, Condition H900 — or 316L per ASTM A276 | An H-condition on 17-4 is a heat-treat instruction. See 303 vs 304 vs 316 vs 17-4 PH. |
| Inconel 718 | 718 per AMS 5662 (annealed) with aging per AMS 2774 to AMS 5664 | Machining strategy flips with the condition. See Inconel AMS specs and machining Inconel. |
| Titanium | Ti-6Al-4V per AMS 4911 (sheet/plate) or AMS 4928 (bar), annealed | Grade and form drive both cost and certs. See titanium grades. |
| Plastic | Delrin 150 (acetal homopolymer) natural — or UHMW PE, FDA/USDA compliant | Detectable and food-grade variants cost more. See UHMW vs Delrin. |
Certs, traceability and customer-supplied stock
If you need material certifications (mill certs, chemical and physical test reports) say so in the RFQ; certified stock is a different purchase than commercial stock and it is priced accordingly. If the material must be DFARS-compliant (domestic or qualifying-country melt) or require full lot traceability, that goes in the RFQ too. And if you are supplying the material yourself, tell us the form, size, quantity, and when it will arrive; we will quote labor only and plan the schedule around your delivery.
Exotic alloys: quote them early
Nickel superalloys and titanium have long stock lead times and volatile prices. If your part is in Inconel, Hastelloy, or titanium, send the RFQ as soon as the material is decided, even if the drawing is still being finalized. We can lock stock while you finish the print.
Tolerances, Surface Finish & What "Standard" Means
Every drawing has a default tolerance in the title block, and most features should live there. Common defaults are ±0.005" on decimals (±0.010" on fractions) or ISO 2768-m for metric drawings. Those are "standard machining tolerance": no extra inspection, no special process. Tighter callouts (±0.001", true position of 0.002", flatness of 0.0005") are where cost hides, because they change how the feature is made and how it is measured.
In the RFQ, make three things explicit: what the default is, which features are tighter and by how much, and whether GD&T is per ASME Y14.5. If the print is silent, we will assume ±0.005" and say so on the quote. If your application genuinely needs a tight feature, call it out on that feature only, not on the whole drawing. Our DFM guide covers the tolerance cost curve, thread depth, and corner radii in detail; it is worth a read before you finalize the print.
Surface finish
"As machined" on a CNC mill is typically 63 µin Ra (1.6 µm) or better. If a surface needs 32 or 16 µin Ra, a sealing face, or a cosmetic finish, put the symbol on that surface. A blanket "32 Ra all over" note makes every face a finish pass and can add hours to a part that only needed one good face.
A useful sentence to put in any RFQ
"Unless otherwise noted, tolerances per title block; surface finish as machined; break all edges .010–.020." That one line answers three questions every estimator would otherwise have to ask.
Secondary Operations: Heat Treat, Finishes, Hardware
Anything that happens after the chips stop flying is a secondary operation, and most of it is bought from a certified outside processor. Each step adds cost, a shipping leg, and calendar days, so the RFQ needs to name it precisely.
Finishes and coatings
Call out the specification, type, class, and color, plus any masking. Examples that an estimator can price without asking: Anodize per MIL-A-8625, Type II, Class 2, black; Chem film per MIL-DTL-5541, Type II, Class 3; Passivate per AMS 2700; Zinc plate per ASTM B633, SC2, Type III; Powder coat, RAL 7035, mask threads. "Anodize" alone leaves type, thickness, and color open, and each changes the processor's price.
Heat treatment
State the target condition or hardness and the governing spec: Q&T to 28–32 HRC per AMS 2759; Age to H900 per AMS 2759/3; Solution and age per AMS 2774 to AMS 5664. For parts that are heat treated after machining, say whether finish dimensions apply before or after treatment; that decides if we rough, treat, then finish (see sequence of operations).
Hardware and inserts
Helicoils, keenserts, PEM studs and nuts, dowel pins, bearings and bushings: list the part number and quantity per part, and say who supplies them. MIL-spec inserts (MS21209, NAS1130) can carry multi-week lead times, so flag them early. Include the install callout on the print (
MS21209-F1-15 insert, 4 places) and we will price both the hardware and the installation labor.Marking, assembly and packaging
Part marking (laser mark P/N and rev per AS478), sub-assembly, kitting, bagging and tagging are all quotable, and all invisible unless the RFQ mentions them.
Quality & Documentation Requirements
Documentation is engineering time. A part that ships with a packing slip and a part that ships with a full AS9102 first-article package can have identical geometry and very different prices. Tell us what your quality system needs, and we will build it into the quote instead of finding out at shipment.
| Deliverable | What it is | Typical for |
|---|---|---|
| Certificate of Conformance | Our statement that parts meet the drawing and PO. Standard with every shipment. | Everything |
| Material certs | Mill test reports traceable to the heat/lot used. | Aerospace, defense, pressure, food contact |
| Process certs | Certifications from heat treat, plating, anodize, NDT processors. | Any part with secondaries |
| First Article Inspection (AS9102) | Full dimensional and documentation package on the first production part, per AS9102. | AS9100 supply chains, new part numbers, rev changes |
| Inspection report / CMM data | Measured values for called-out features; 100% or sampled per your plan. | Tight-tolerance and critical parts |
| Source inspection | Your inspector (or government) witnesses inspection before shipment. | Defense primes, flight hardware |
| Flow-downs | DFARS, ITAR, counterfeit-parts, special process approvals (e.g. Nadcap) you require of us. | Defense and aerospace purchase orders |
C&W is AS9100D and ISO 9001:2015 certified, so every item above is routine. The only thing we need from you is to name it in the RFQ. If your purchase order will carry quality clauses, attach them (or the clause list) with the RFQ: it is far easier to price a clause than to absorb one after award.
Schedule, Delivery & Commercial Terms
Need date. Give a real required date, not "ASAP." If standard lead time works, say that; if you need it faster, say by when, and we will quote an expedite honestly (sometimes it costs nothing, sometimes it costs overtime). If partial shipments would help you start assembly, tell us; splitting a lot is often free.
Shipping. Destination address, preferred carrier or your account number, and any dock or receiving constraints. Freight is quoted separately from parts unless you ask for a delivered price.
Terms. Payment terms you expect (net 30 is typical for established accounts; new accounts may start on credit card or prepayment), whether an NDA must be in place before we open files, and how long you need the quote to remain valid. Our written quotes state their validity period; if you need longer, ask and we will tell you which line items are exposed to material price changes.
Contacts. Who answers technical questions (the engineer) and who answers commercial ones (the buyer). Half the delay in quoting is finding the right person to ask a two-minute question.
ITAR & Export-Controlled Work
If the part is on the USML (ITAR) or is EAR-controlled technical data, the RFQ itself is controlled. Do not attach controlled drawings or models to a plain email, and do not upload them to a public quoting tool. Instead, send a short non-technical note (part number, material, quantity, need date, and that the data is ITAR/EAR) to our contact page or by phone, and we will set up a secure transfer and confirm the access controls before any technical data moves.
C&W is ITAR registered, holds a CAGE code, and operates under NIST 800-171 / CMMC controls, so controlled work is part of the normal day. It just has to start on the right channel.
When in doubt, treat it as controlled
If you are not sure whether a drawing is export-controlled, ask your program's export compliance contact before you send it anywhere. The cost of an extra phone call is minutes; the cost of an inadvertent export is not.
The 60-Second RFQ Template
Copy this into the body of your email. Fill in what you know; write "TBD" for what you don't, and we will flag it on the quote rather than guess.
RFQ — [Company] — [Part number(s)]
Parts: P/N 12345-002 Rev B (STEP + PDF attached)
Quantity: 10 now; please also price 25 and 100. Expected annual usage ~200.
Material: 6061-T651 plate per AMS 4027; material certs required.
Tolerances: Per title block (±.005"); hole pattern ⌖ .005 to datums A/B/C. GD&T per ASME Y14.5.
Finish: As machined; anodize per MIL-A-8625 Type II Class 2 black, mask tapped holes.
Hardware: (4) MS21209-F1-15 inserts, C&W to supply and install.
Quality: C of C, material and process certs, AS9102 FAI on first lot.
Need date: Oct 15; partials acceptable.
Ship to: Turlock, CA — UPS Ground on our account.
Export status: Not controlled (commercial).
Contacts: Technical — J. Engineer (email); Commercial — A. Buyer (email).
Quantity: 10 now; please also price 25 and 100. Expected annual usage ~200.
Material: 6061-T651 plate per AMS 4027; material certs required.
Tolerances: Per title block (±.005"); hole pattern ⌖ .005 to datums A/B/C. GD&T per ASME Y14.5.
Finish: As machined; anodize per MIL-A-8625 Type II Class 2 black, mask tapped holes.
Hardware: (4) MS21209-F1-15 inserts, C&W to supply and install.
Quality: C of C, material and process certs, AS9102 FAI on first lot.
Need date: Oct 15; partials acceptable.
Ship to: Turlock, CA — UPS Ground on our account.
Export status: Not controlled (commercial).
Contacts: Technical — J. Engineer (email); Commercial — A. Buyer (email).
What happens after you send it
We acknowledge the RFQ, review the files for completeness and manufacturability (you get free DFM feedback with every quote), and come back with any questions in one batch rather than a trickle. You receive a written quote with unit price by quantity, lead time, and any assumptions called out explicitly. On award we confirm the revision, issue an order acknowledgement, and for new part numbers schedule first-article inspection before the lot runs. If anything in the quote is not what you expected, tell us: the fastest way to a better number is usually a five-minute call about which requirement is driving it.
Quick Reference Card
The short version. If your RFQ covers these six, it will be quoted fast and quoted right.
Files
STEP + PDF per part number, same revision, units checked, file names that match the title block.
1 STEP + 1 PDF per P/N
Quantity
Firm quantity or 2–3 price breaks. Say if it's a prototype or a recurring part.
1 / 5 / 25 / 100
Material
Alloy + temper + spec + form. Say if certs or DFARS compliance are required.
6061-T651 / AMS 4027 / plate
Tolerances & Finish
Default in the title block, tight callouts on specific features only, finish symbols where they matter.
±.005" unless noted
Secondaries & Quality
Spec / type / class / color for every finish; name the documents you need (certs, FAI, CMM).
MIL-A-8625 Type II Class 2
Schedule & Export
Real need date, ship-to, and whether the data is ITAR/EAR controlled (if so, call first).
Date + destination + status
Ready to send one?
Send your STEP and PDF through the contact page, or call the shop, and an engineer will pick it up. For ITAR work, send the non-technical summary first and we'll set up a secure transfer.
Sources & References
[1]SAE AS9102C, Aerospace First Article Inspection Requirement. Defines the FAI forms and content referenced in section 08.
[2]ASME Y14.5-2018, Dimensioning and Tolerancing. The GD&T standard referenced on most U.S. drawings.
[3]ISO 2768-1, General tolerances for linear and angular dimensions without individual tolerance indications. The common metric title-block default.
[4]MIL-A-8625, Anodic Coatings for Aluminum and Aluminum Alloys; MIL-DTL-5541, Chemical Conversion Coatings on Aluminum and Aluminum Alloys; AMS 2700, Passivation of Corrosion Resistant Steels. Finish specifications cited in section 07.
[5]SAE AS478, Identification Marking Methods. Part-marking callouts referenced in section 07.
[6]C&W Manufacturing estimating practice, Turlock, CA. AS9100D / ISO 9001:2015 certified; ITAR registered.