Checklist: Verifying Metal Service Bureau Quality

Why verification matters before you outsource metal AM

Procurement teams often select a metal service bureau based on price, lead time, or machine count. Those factors matter, but they do not tell you whether the bureau can hold tolerance, meet material specifications, or deliver a part that will pass your incoming inspection. A weak partner can turn a design into a non-conforming part, a failed prototype, or a recall risk.

This checklist gives you a practical way to audit a service bureau before you sign an agreement. It is organized by the areas where quality problems most often appear: materials, process controls, post-processing, inspection, documentation, and communication.

Use it as a pre-award questionnaire. Send it to the bureau, ask for written responses, and follow up with a site visit or a small trial order.

1. Material traceability and certification

Every part you outsource starts with a raw material. For metal AM, that means verifying the feedstock, confirming the alloy, and checking that the material was certified for the intended application.

• Ask for the mill certificate or heat lot number for each material lot.
• Confirm whether the bureau uses certified powder or only recycled powder.
• Ask how they manage material segregation between alloys.
• Check whether they keep records that link a specific print job to the exact powder lot used.
• If your part requires a specific heat treatment, ask how they ensure the material condition matches that requirement.

Red flags to watch for:

• The bureau cannot produce a heat lot number on request.
• They mix different alloys in the same build chamber without explanation.
• They cannot tell you whether the powder is virgin, recycled, or a blend.
• They provide no material traceability beyond a simple part number.

Metal AM parts are often used in aerospace, medical, energy, or defense applications. In those industries, a missing heat lot number is not a minor paperwork gap. It can block acceptance, delay certification, or void a material guarantee.

2. Process parameters and build control

The build process itself is where design intent becomes a physical part. A service bureau should be able to show you how they control powder density, laser power, layer thickness, scan strategy, and chamber conditions.

• Ask for a typical process parameter sheet for the material you are using.
• Confirm whether they run qualification builds before production.
• Ask how they validate a new part or a new material.
• Check whether they log build parameters for every job.
• Ask what they do when a build shows anomalies such as porosity, delamination, or poor surface finish.

Red flags to watch for:

• They use the same generic settings for every material and part.
• They cannot explain how they handle support structure design.
• They have no documented process for handling failed builds.
• They do not log build parameters or do not keep them for a reasonable period.

Support design is a common source of metal AM problems. If a part has thin features, undercuts, or high thermal gradient zones, the support strategy matters more than the machine itself. Ask them to show a support plan for a complex part from your portfolio. A strong bureau will walk you through how supports are placed, how they are removed, and how they minimize distortion.

3. Post-processing and heat treatment

Most metal AM parts need post-processing. That can include support removal, machining, heat treatment, surface finishing, and final inspection. The quality of these steps often determines whether the part is fit for use.

• Ask for a post-processing list for each part type.
• Confirm whether heat treatment is done in-house or by a third party.
• Ask for the heat treatment profile, including temperature, time, and atmosphere.
• Check whether they perform dimensional inspection after heat treatment.
• Ask how they handle surface finish requirements such as Ra value or coating.

Red flags to watch for:

• They outsource heat treatment without providing the provider details.
• They do not re-inspect parts after heat treatment.
• They cannot give you a surface finish specification or method.
• They treat post-processing as an afterthought rather than a controlled step.

Heat treatment is one of the most common sources of dimensional drift. A part that measured correctly before heat treatment may move, warp, or change density after it cools. A good bureau will inspect the part after heat treatment and document the final dimensions. If they cannot do that, do not accept the part without your own verification.

4. Inspection and testing

Inspection is the proof. If a bureau claims high quality, it should be able to show you how it inspects parts. That includes dimensional checks, material verification, surface analysis, and sometimes non-destructive testing.

• Ask what inspection methods they use for each part type.
• Confirm whether they use CMM, CT, optical scanning, or manual gauging.
• Ask for sample inspection reports from similar parts.
• Check whether they test for porosity, inclusions, or other internal defects.
• Ask what acceptance criteria they apply and whether they are based on your drawing or internal standards.

Red flags to watch for:

• They only provide a visual inspection.
• They cannot produce a sample inspection report.
• They do not specify tolerance levels or acceptance limits.
• They use uncalibrated equipment or cannot show calibration records.
• They treat inspection as a final step rather than an integrated process.

For critical parts, ask whether they can provide X-ray CT or ultrasonic testing. These methods can reveal internal porosity, cracks, or inclusions that dimensional inspection will not catch. The cost is higher, but it may be necessary for pressure vessels, aerospace brackets, or medical implants.

5. Documentation and quality management

A service bureau that can produce a good part is useful. A service bureau that can produce a good part and prove it is what you need for procurement.

• Ask for their quality management system documentation.
• Confirm whether they hold certifications such as ISO 9001 or industry-specific quality standards.
• Ask how they control changes to process, material, or equipment.
• Check whether they provide a traceability package with each delivery.
• Ask how they handle non-conforming parts and corrective actions.

Red flags to watch for:

• They cannot produce a quality manual or process flow.
• They do not have a defined corrective action process.
• They provide no traceability package beyond a packing list.
• They have no record of customer complaints or non-conformances.
• They resist providing documentation or sample reports.

Documentation is not bureaucracy. It is the difference between a part you can defend and a part you cannot. If your customer, regulator, or internal audit team asks for proof, you need it. A bureau that does not keep records will make your job harder, not easier.

6. Communication and change control

Even a technically strong bureau can fail you if communication is weak. Parts change. Tolerances get tightened. Materials get swapped. A good bureau has a clear process for handling those changes.

• Ask how they handle engineering changes.
• Confirm whether they require written approval for any change.
• Ask how they communicate build status and anomalies.
• Check whether they provide a single point of contact for your account.
• Ask how they manage revisions and version control for drawings.

Red flags to watch for:

• They make changes without approval.
• They provide no build status updates.
• They do not have a clear escalation path.
• They treat revisions as informal email exchanges.
• They cannot show you how they manage multiple versions of the same part.

A small change in a drawing can create a large problem in production. If your engineering team revises a tolerance, the bureau needs to know immediately. If they do not, you may receive a part that does not match your current design.

7. Trial order and site visit

Before you commit to volume work, test the bureau. A small trial order is the fastest way to see whether their quality claims match reality.

• Order one or two representative parts, not just simple brackets.
• Include a part with tight tolerances and a part with a complex geometry.
• Require full documentation with the delivery.
• Inspect the parts against your drawing and acceptance criteria.
• Ask for a debrief on what went well and what did not.

A site visit is also valuable. You do not need to see everything, but you should see the build area, the post-processing area, and the inspection area. Ask to see a sample inspection report and a material traceability record. Watch how they talk about failures. A strong bureau will describe what went wrong and what they changed. A weak bureau will deflect or minimize.

If the trial order passes, you can move to production. If it fails, you have your answer without losing a large order.

Quick reference: key verification items

Verification area	What to ask	What to look for
Material traceability	Heat lot number, mill certificate, powder source	Certified heat lot, clear record of powder source
Process control	Build parameters, qualification builds, anomaly handling	Logged parameters, documented qualification process
Post-processing	Heat treatment profile, surface finish, re-inspection	Documented heat treatment, post-heat inspection
Inspection	CMM, CT, surface analysis, acceptance criteria	Sample reports, calibrated equipment, clear tolerances
Documentation	Quality manual, traceability package, change control	ISO 9001 or equivalent, full traceability, defined change process
Trial order	One representative part, full documentation, debrief	Part meets spec, documentation is complete, debrief is honest

Final check before you sign

Before you award the work, ask yourself three questions. Can this bureau prove the material is what it says it is? Can they show you how they control the build and post-processing? Can they produce a document that would satisfy your incoming inspection and your customer? If the answer to any of those is no, do not move to volume. A small delay now is cheaper than a failed part later.