Guides / Choosing a Supplier
Everything a Ceramic Shop Needs Before It Can Price Your Part
September 17, 2026
A ceramic quote that comes back as a question list is not a slow shop. It is usually an RFQ missing three or four items. Here is the whole list, in the order a shop reads it.
The twelve items
- Part description in one sentence. What it does, where it sits, what it touches.
- Drawing, dimensioned. PDF is fine. A STEP file alongside it helps.
- Grade, or the environment. Name the ceramic if you know it. If not, give temperature, chemistry, load, voltage and vacuum level and ask for a recommendation. The property table on materials compared is a good starting point.
- Which features are ground. Mark them. Everything else is as fired at about 1% of the dimension.
- Tolerances that matter, and only those. Each tight callout is grinding time and inspection time.
- Surface finish by face. Ra, flatness and parallelism belong on the faces that seal, slide or mount, not in a blanket note.
- Edge treatment. A defined chamfer, not a deburr note, and an acceptable chip limit.
- Quantity now and annual volume. The route changes with volume, so both numbers move the price.
- Date needed. Blank availability, not machining, usually sets the calendar.
- Inspection and documents required. First article report, material certificate, cleanliness, packing.
- Assembly context. Is the part brazed, metallised, plated, potted or bolted afterwards?
- Commercial basics. Delivery terms, destination country and whether an NDA is needed before files are shared.
The four omissions that cause the biggest swings
No indication of which features matter. A shop that cannot tell will either grind everything, which prices you out, or grind nothing, which delivers a part that does not fit. This single item moves quotes more than any other.
No annual volume. A drawing quoted as ten pieces gets the grinding route. The same drawing with 3000 pieces a year on it may justify pressing tooling and green machining, which changes the piece price entirely. See green machining or hard grinding.
No date. Shops assume standard lead time and buy the blank that is convenient. Given a date, they can propose a grade or size that is on a shelf now.
No function sentence. “Seal face runs against carbon, vacuum on one side” tells a shop which surfaces to protect and which to leave alone. Without it every surface looks equally important.
What good looks like
Insulator ring, alumina 99.5%, minimum 3.9 g/cm3. Sits between an RF electrode and a grounded flange in a vacuum chamber. 62 mm OD x 40 mm ID x 8 mm. Bore and face A ground, marked G. Face A lapped flat within 0.005 mm, Ra 0.1 µm max. All other surfaces as fired, ±1%. All edges chamfered 0.2 x 45 degrees. 40 pieces now, about 150 a year. Needed in 10 weeks. First article report and material certificate required. Cleaned and double bagged. NDA available on request.
That paragraph is enough for three shops to quote the same part and for you to compare the quotes meaningfully. The comparison itself is covered in how to compare ceramic quotes.
What you do not need to include
- A process specification. Say what the part must do, not how to grind it. Shops choose the route
- A material you are unsure about. An uncertain grade name produces a confident wrong quote
- Every tolerance from the metal version of the part. Most of them do not apply
Send it once
Our whole job is that you write this once rather than eight times. We read the RFQ, decide the route, then put it in front of up to 3 shops that already run that grade. They quote you directly and you order from whoever you like.
The RFQ is one step in a longer path; our guide to buying machined ceramic parts follows it from the quote to the first approved parts.
Send your RFQ and we reply within 24 business hours.
Frequently asked questions
Do I need a 3D model or is a drawing enough?
A dimensioned drawing is enough to quote. A STEP file speeds up programming later and reduces the chance of a misread feature, so send both when you have them.
Should I tell a shop my target price?
It helps more than it hurts. A target lets a shop propose a different route, grade or tolerance set that reaches it, instead of quoting the drawing as written and losing.
How much does an RFQ cost me?
Nothing here. Buyers pay nothing to send an RFQ or to receive quotes. Shops pay us for matched requests, so the cost sits on the supplier side.
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.
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