Vetting a Machine Shop You Have Never Visited
You cannot walk the floor, so you have to make the shop show you the floor. Almost everything that decides whether a machining order goes well can be established from a laptop, if you ask for evidence rather than assurances. This is the sequence that works, in the order that filters fastest.
Start with the machine list, not the company profile
Ask for a machine list before anything else: make, model, quantity, travels and year. A shop that runs your work every week answers this in one message. A shop that is brokering your part to someone else gets vague, or sends a list that does not match the photos on its website.
What you are checking is simple:
- Does the work envelope actually fit your part, with room for fixturing
- Is there more than one machine that could run it, or does your delivery depend on one spindle being free
- Milling, turning or both, depending on what your part needs
- Whether a 4th or 5th axis exists, if your part has features on more than two faces
Then ask for a photo of the specific machine your part would run on, taken today. Not a brochure image. This single request separates real shops from intermediaries faster than any questionnaire.
Ask what they buy locally
Material availability is the quiet constraint on any machining order in Vietnam, and it is the thing buyers forget to check. Ask which grades the shop buys from local stockists and holds without a special order.
Common aluminium and stainless grades, mild steel and the usual engineering plastics are normally straightforward. A specific temper, a tool steel, a nickel alloy or a certified aerospace grade may have to be imported, which adds cost and weeks before a chip is cut. A shop that says “we can get anything” without naming a supplier or a lead time has not priced that in, and you will find out when the delivery slips.
Check the inspection side harder than the machining side
Most shops can cut metal. Fewer can prove what they cut. Ask for:
| Ask for | What it tells you |
|---|---|
| Photos of the inspection room | Whether measuring happens somewhere controlled, or on the machine bed |
| List of measuring equipment | CMM, height gauge, bore gauge, surface tester, and what range each covers |
| A sample dimensional report from a past job | Whether they record numbers or just tick boxes. Redacted customer details are fine |
| Calibration certificates | That the gauges were checked by someone, with dates |
| Who signs off a part | A name and a role, not “quality department” |
If the tightest tolerance on your drawing is finer than anything in the equipment list, they cannot verify your part even if they can machine it. That mismatch is worth finding before the order, not after. The tolerances guide covers how to decide which features genuinely need to be that tight, and the quality documents guide covers what to ask them to record.
Send a paid sample, not a free one
Free samples attract the wrong answer. A shop that gives away a sample is either absorbing the cost to win a large order, in which case the sample gets the owner’s full attention and tells you nothing about normal production, or it is cutting corners to keep the giveaway cheap.
Pay for a small first batch at the real price, with a first article inspection before the rest of the batch runs. You learn three things at once: whether they can hold the tolerance, whether they measure honestly and how they behave when something is out of specification. The third one matters most. A shop that tells you a dimension is 0.03 mm over before you find it yourself is worth keeping.
Small orders look expensive per piece because setup lands on few parts. Ask for a price break table rather than a single number, so you can see the real production price behind the trial one, as set out in the minimum order quantity guide.
Watch the communication, because it is the product
Over a border, the shop’s engineering communication is most of what you are buying. Track these on your first exchange:
- Do they ask questions about the drawing? A shop that quotes a part with an ambiguous datum scheme without asking is going to guess again later.
- How fast is a reply, and from whom? A sales contact who relays everything to an engineer adds a day to every question for the life of the relationship.
- Do they write numbers or adjectives? “We can hold that” is worse than “we hold plus or minus 0.02 mm on that bore with a reamer, plus or minus 0.05 mm if you want it milled”.
- What happens when you change something? Send a small revision mid quote and see whether the price and lead time update, or whether the change disappears.
Red flags that end the conversation
- The machine list, the website photos and the address do not line up.
- They quote before asking anything about a drawing that clearly needs a question.
- They will not name the port they normally ship from or the forwarder they use.
- They ask for full payment before production on a first order.
- Every answer is yes.
That last one is the most common. A shop that has never declined a part has not read your drawing.
Score them, rather than forming an impression
Three shops all sound reasonable over email. Fill in a table instead and the differences appear.
| Check | Evidence you asked for | Pass |
|---|---|---|
| Machines fit the part | Machine list plus a photo taken today | |
| Material bought locally | Named stockist and a normal delivery time | |
| Inspection covers your tolerance | Equipment list and a sample report with numbers | |
| Secondary processes | Where each one happens and how far away | |
| Export experience | Port, forwarder and which documents they have issued before | |
| Communication | Did they ask a question about the drawing | |
| Honesty | Did they decline anything, or flag anything on the drawing |
The last two rows predict the relationship better than the first five predict the parts. A shop that asked one good question about your datum scheme has already told you more than a shop that returned a price in an hour.
Where a shop sits also tells you which subcontractor pool it can reach, which is covered in the guide to where machine shops are located in Vietnam.
Then check the boring things
Finally, the administrative layer that decides whether a good part can actually reach you: a business registration number you can check, an export history in the sense of having shipped internationally before, a bank account in the company name rather than a personal one, and a willingness to sign an NDA before receiving files. None of these prove machining ability. All of them prevent the kind of problem that no amount of machining ability fixes.
When you are ready to compare shops rather than read about them, send the drawing and we will pass it to up to three shops in Vietnam that fit the part. They quote you directly, and you run the vetting above on the ones that answer.
Frequently asked questions
Do I have to visit the factory before ordering?
Not for a first small order. Photos of the machine your part will run on, photos of the inspection room and a first article report tell you most of what a walkthrough would. Visit or pay for a third party audit before you move an annual volume, not before you buy 50 pieces.
Is ISO 9001 enough proof?
It proves there is a documented system, not that the system is followed or that the shop can hold your tolerance. Treat it as one input. A shop with no certificate that sends you a clean measured first article is a better bet than a certified shop that will not measure anything before shipping.
What if the shop will not answer my questions?
That is your answer. A shop that avoids naming its machines, its inspection equipment or its material supplier is either brokering the work to someone else or is not confident it can win it. Both are reasons to move on.
Need a quote for a part like this?
Send the drawing. We shortlist up to 3 machine shops in Vietnam, manage the order if you want us to and reply within 24 business hours.
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