Guides / Choosing a Supplier
Seven Questions That Separate a Ceramic Shop From a Metal Shop
August 31, 2026
In metal, a shop that overreaches delivers a part out of tolerance and you argue about it. In ceramic, a shop that overreaches chips the part on the last pass, eight weeks into a twelve week lead time, and you start again.
That asymmetry is why qualification matters more here. These seven questions take twenty minutes and tell you most of what you need.
1. Which grades do you machine every week?
Not which can you machine. The list of materials on a website is aspirational. The list of materials with dressed wheels on the shelf is real.
Listen for: specific grades and suppliers, and an opinion about them. “We run a lot of 99.5 alumina and 3Y zirconia, less SiC because our wheel cost gets ugly” is a good answer.
Warning sign: a materials list with twenty entries and no preferences.
2. Do you green machine, hard grind or both, and what do you subcontract?
Both routes are legitimate. Confusion about which one they are quoting is not. Ask explicitly whether firing, lapping, metallising and coating happen in house or at a partner, and how that affects lead time.
Listen for: a clear split and named partners.
Warning sign: vagueness about where the part physically goes. See green machining or hard grinding.
3. What shrinkage factor do you use for this grade, and how did you measure it?
Only relevant if they green machine, and it is the single most revealing question you can ask a green machining shop.
Listen for: a number, a statement that it is measured per powder lot and an explanation of how they verify it on first articles.
Warning sign: a generic “about 20 percent” with no measurement story. The background is in sintering shrinkage explained.
4. What inspection do you own?
CMM, profilometer, optical flat, interferometer, density measurement. Owning it matters because subcontracted inspection slows feedback and gets skipped under schedule pressure.
Listen for: named equipment, calibration intervals and an understanding that probe force and tip wear are different on ceramic. See how ceramic parts should be inspected.
Warning sign: “we inspect everything” with no specifics.
5. What is your scrap rate on a part like this, and who carries it?
Ceramic scrap is normal. Hidden ceramic scrap is not, because it turns into schedule slip that nobody warned you about.
Listen for: a range tied to geometry, a policy on who pays and a willingness to price a pilot batch honestly.
Warning sign: “we do not scrap parts.”
6. What do you decline?
The best question in the list. Every real ceramic shop has a list: internal corners below a radius, walls below a thickness, aspect ratios, hole sizes, tolerances they will not chase.
Listen for: immediate, specific limits, and a suggestion for how to redesign around them. The common ones are in 12 design rules for a ceramic part.
Warning sign: “send us anything, we can do it all.”
7. Can you show a report from a similar part?
Redacted is fine. You are looking for the shape of the report, not the customer name.
Listen for: a dimensional report with methods, a material certificate and a chip acceptance standard.
Warning sign: a photograph instead of a report.
What we check before matching
We are a matching service, not a shop, so our job is to filter before your drawing goes anywhere. Before a request is sent to anyone we confirm the grade and route are regular work, the envelope and tolerance are inside what they hold, the inspection exists and the shop replies to buyers quickly. We send each RFQ to at most three shops, and the ones who quote are the ones that fit.
If you would rather run this yourself, use the seven questions above. They are the same ones we ask. The rest of the buying process is in the buyer guide.
Which type of supplier to call comes before these seven questions; see buying machined ceramic parts and technical ceramics manufacturer or grinding shop.
Send your drawing and we do the filtering for you. Reply within 24 business hours.
Frequently asked questions
How can I tell if a shop really machines ceramic?
Ask what they decline. A shop that grinds ceramic weekly will immediately name features it will not quote, such as sharp internal corners or unsupported thin walls. A shop new to it says yes to everything.
Does a ceramic shop need to own a kiln?
Not necessarily. Many excellent shops only hard grind sintered blanks and buy blanks in. What matters is that they are clear about which steps are in house and which are subcontracted.
What is a normal scrap rate on a ceramic part?
It depends entirely on geometry. A simple ground disc is close to zero. A thin walled part with cross holes can run in the double digits. What matters is that the shop can tell you the number and say who carries it.
Need a quote for this part?
Send the drawing. We match you with up to 3 shops that grind this grade and reply within 24 business hours.
Get matched with a ceramic shop