Guides / Choosing a Supplier
How to Qualify a Machine Shop for Semiconductor Equipment Work
September 26, 2026
A shop that machines aerospace brackets to a tight tolerance is not automatically a shop that can make a chamber liner. The machines are often the same. What differs is everything that happens after the spindle stops.
Qualification in this niche is therefore not a machine audit. It is a check on handling, on finishing control, on paperwork, and on whether the fiftieth piece looks like the first one.
What you are actually qualifying
Four things, in this order.
Handling. What the part touches between the last operation and the bag. Blast media, cloths, gloves, benches, the hands that move it.
Finishing control. Anodize, electropolish and passivation are outside processes for almost every shop. You are qualifying how the shop chooses and manages those vendors, not whether it has a list of them.
Paperwork. Mill certs, heat lots, dimensional reports. Whether they travel with the job as it runs, or get assembled the day you ask for them.
Consistency. Whether the process is written down and repeatable, or whether the good first article was one careful person on one careful day.
An aerospace shop starts closer to this than a general job shop. It is used to certs, to first article reports, to being audited, and to the idea that the paperwork is part of the product. Where it usually falls short is cleanliness culture. Blast media control, a silicone free rule and cleanroom bagging are new habits even for a shop with an excellent quality system, because nothing in aerospace work ever forced them.
Questions to ask on the first call
Five questions, and the answers take about five minutes. They tell you more than any capability list.
Which of these do you do in house: anodize, electropolish, passivation, precision clean, bagging? You are not looking for all five. You are looking for an honest split and a clear answer about who does the rest.
How do you control blast media between jobs? A shop that runs semiconductor work has a real answer, usually dedicated media or a documented changeover. A shop that has never been asked will hear this as a strange question, and that reaction is the information.
What is your rule on silicone in the building? There either is a rule or there is not. A shop with a rule will tell you about mould release, sprays and hand creams without being prompted.
How do you store and hand over material certs and heat lots? The answer you want describes where certs live while the job runs. The answer that should worry you is that they can get them from the supplier when you need them.
Can you show me a dimensional report from a similar part, with the customer details removed? This is the single most useful request on the call. You learn their report format, their inspection habits and whether they have actually made something like your part.
Documents worth asking for
Ask for four things, and keep the request small so it gets answered quickly.
| Document | What it tells you |
|---|---|
| Quality manual table of contents | Which processes are controlled. Do not ask for the manual itself, nobody sends it and nobody reads it |
| A sample first article report | Their inspection depth and format, before it matters. The AS9102 layout is common and easy to read |
| Calibration status of the CMM and the surface finish gauge | Whether the numbers on the report mean anything |
| The written cleaning procedure | Whether cleaning is a process or a habit |
The last one is the one that separates shops. A written cleaning procedure, even a short one, means somebody decided what clean means here. No written procedure means the answer changes with whoever is on shift.
The sample part
Pick the sample carefully. The instinct is to send the hardest part in the program, and that is the wrong test.
Choose a part with one genuinely hard face, not your most difficult geometry. A part with one Ra 0.4 um sealing face, a cert requirement, a cleaning level and a packing standard tests the whole process without the shop having to perform a heroic setup to survive it.
Send the full note set. Finish against faces, coating before or after, cleaning level, packing standard, cert requirement. If you soften the notes to help them pass, you have qualified them for a part you are not going to order.
Measure the bag before you measure the part. Is it double bagged, is the label on the outside, was the inner bag opened. This takes ten seconds and tells you whether the packing note was read or priced and ignored.
Then measure the part, and check the report against what you measured rather than reading it for reassurance.
Order a second article about a month later. This is the part of qualification that cannot be compressed. The first part tells you the shop can do it. The second one, run by whoever happens to be on shift, made after the novelty has worn off, tells you whether the process is written down. Most shops pass the first and only some pass the second.
Answers that end the conversation
Four answers mean stop, regardless of how good the rest of the call was.
“Tolerance is no problem” in response to a cleanliness question. They heard a precision question because that is the only kind of question they have been asked before. The gap is not skill, it is that the topic is not on their map.
No written cleaning procedure. Everything else can be built. This one means the shop has no definition of clean, so there is nothing to hold them to when a part arrives with residue in a pocket.
Certs produced on request instead of held with the job. It means traceability is reconstructed rather than maintained. It works until the day a heat lot question arrives about a part delivered eight months ago.
The finishing vendor chosen per order by price. Anodize and electropolish results vary by vendor. A shop that shops the process around every time cannot give you a consistent part, and will not know why the results moved.
A shorter path
Running this screen on every shop that answers an enquiry is a real amount of work, and it is work done before you know whether the shop is even interested in your quantity.
That is the job this site does. An RFQ that arrives here is screened against the same points before it goes anywhere: the part class, the pressure the part sees, the finishing chain, the cleaning level, and whether the shops it goes to already run that class of work. It then goes to a capped number of shops, stated on the RFQ page, who quote you directly.
Free for you, no commission on the order. Send the drawing and see what comes back.
Frequently asked questions
How long does it take to qualify a new shop?
One call, one document request and two sample parts a month apart. The gap between the two samples is the part that cannot be shortened, because consistency is the thing you are buying and a single good part does not show it.
Should I send my hardest part as the sample?
No. Send a part with one genuinely hard face and the full set of notes: finish, cleaning, packing, certs. You are testing the process, not the machine, and a monster part only tells you whether they can survive it once.
Is an ISO certificate enough to skip this?
It tells you a quality system exists and was audited. It does not tell you how blast media is controlled between jobs or whether silicone is allowed in the building, and those are the failures that reach a fab.
Have a part like this?
Send the drawing. We match it with up to 3 shops that already run semiconductor equipment parts and reply within 24 business hours.
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