- Start from the feature, not the company list
- Six questions that separate shops fast
- Read tolerance, volume and material claims for what they omit
- Five red flags in a first quote
Start from the feature, not the company
Write down the three hardest things about your part — the tightest tolerance, the thinnest wall, the material. Then look for a shop that can do those three, not a shop with the biggest banner. The feature is the spec; the company is just the delivery mechanism.
Six questions that separate shops fast
1. Which feature, in which material, at what volume? A real answer names the feature. 2. What is the report format? A real answer shows you one. 3. What is your rework rate on parts like mine? 4. How do you handle a nonconformance? 5. What does your DFM note look like? 6. Who signs the first-article report? If the answers are general, you are reading a quote machine, not a shop.
Reading capability claims
Tolerance: 'we hold ±0.001 mm' without a feature, material and volume is a red flag — a claim without context. Volume: 'prototype to production' is only meaningful with a climb plan. Material: an aluminum specialist shows mill-cert records for 6061 and 7075; a generalist shows a list. Ask for the evidence behind each claim.
Communication and documentation signals
Response time, DFM quality, and readable English reports are soft signals that predict the hard outcomes. A shop that answers a drawing with three questions is better than one that answers with only a price. You are buying a relationship that survives a schedule slip and a spec change, not a one-off transaction.
China versus local
China wins on cost, capacity and material availability; local wins on iteration speed and face time. The right split is usually: iterate locally, produce in China. If you go offshore, choose a shop that communicates in English and documents in English — the language of the report is the language of your audit.
Red flags in a first quote
A single blended number with no material/cycle-time breakdown. No questions about GD&T or finish. A price that returns in seconds. A refusal to show a sample report. A tolerance claim that ignores your hardest feature. Any two of these, and you should keep looking.
How do I de-risk a first order?
Start with a small batch, require a first-article report, and consider third-party inspection on the first lot. A shop that welcomes that is a shop that expects to pass it.
What should I send to compare shops fairly?
The same 3D and 2D, the same quantity and finish, and the same tolerance call-outs — to every shop, so the quotes are comparable, not just the prices.
Apply the six questions and see who answers like a shop.
Send a 3D file to [email protected] · +86 13126536955
Standards referenced on this page
- ASTM B211/B211M-19 — Standard Specification for Aluminum-Alloy Rolled or Cold Finished Bar, Rod, and Wire
- ISO 9001 — Quality management systems — Requirements
- ASTM E8/E8M-21 — Standard Test Methods for Tension Testing of Metallic Materials