Views: 3 Author: Site Editor Publish Time: 2026-08-25 Origin: Site
The cheapest quote and the right supplier are rarely the same shop. Vetting is about de-risking a drawing you are about to hand over - checking that the equipment, quality system and contract terms match what your part actually needs. This page is a working, scored checklist you can run before the first RFQ.
Table of Contents
Write down tolerance, material, volume and certification before you talk to anyone. That short brief filters shops instantly - a CNC-only shop cannot help with molded volume, and a toy-grade shop cannot hold aerospace tolerance. Process fit is spelled out in our CNC plastic, metal and injection molding guides.
Score each candidate 0-2 (0 = no, 1 = partial, 2 = yes) and add them up. A shop under ~12 of 16 is a risk for anything beyond a cosmetic copy.
Criterion | What to ask | Red flag |
Equipment | 3-axis or 5-axis? Runs your material? | No 5-axis, no PEEK/Ti experience |
Quality system | ISO 9001? What ships with part? | No cert, 'no report needed' |
Inspection | CMM available? Caliber sheets? | Only 'we check by eye' |
IP / contract | NDA? File-access clause? | Won't sign NDA |
Communication | Replies in your day? | 12h gap, silent on RFQ |
Capacity | Extended shifts for rush? | Fixed single shift only |
Sample / refs | Similar sample? One reference? | None offered |
Quote clarity | Itemized lines? | One lump number, vague |
Match machines to geometry. 3-axis covers most enclosures; 5-axis earns its keep on deep cavities and undercuts. Ask about spindle count and whether they run the material you specified - experience with PEEK or titanium is not universal. Capacity also sets speed; our quick-turn guide depends on shops that actually run extended shifts.
Look for ISO 9001 at minimum, and ask what inspection ships with the part - CMM reports, caliper sheets, or nothing. For bridge tooling specifically, confirm they document mold steel and shot life; our rapid tooling guide covers what good documentation looks like. Material behavior varies; our materials guide helps you judge whether a shop's recommended plastic or alloy fits your test.
A signed NDA and a clause limiting file access to the working team are table stakes for confidential work. Established bureaus handle OEM projects under contract routinely; the question is whether the shop in front of you has the paper and the habit. Never send a production drawing to a shop that will not put IP terms in writing.
A shop that answers DFM questions in your working day saves more time than one that is 12 hours ahead and silent. Test responsiveness on the RFQ itself - slow quotes predict slow fixes. A good supplier pushes back on impossible tolerances at quote stage, not after the cut.
Compare line items, not totals: machining vs finish vs inspection vs freight. The cost levers and hidden charges are in our cost and quoting guide - use it to normalize two offers before you decide.
Q: What certifications should a supplier have?
A: ISO 9001 at minimum; industry-specific certs (medical, automotive) if your part needs them. Ask what inspection ships with the part.
Q: How do I protect my design?
A: A signed NDA plus a clause limiting file access to the working team. Established bureaus do this as standard for confidential OEM work.
Q: 3-axis or 5-axis machining?
A: 3-axis covers most enclosures; 5-axis earns its keep on deep cavities and undercuts. Match the machine to your geometry.
Q: Why compare line items, not totals?
A: Because quotes bundle different things - machining only versus machining plus finish, inspection and freight. Line items reveal the real difference.
Q: Should I ask for a sample?
A: Yes. A sample of similar work and one industry reference tell you more than a brochure about whether the shop can hold your tolerance.
