Guides / Process

How to Inspect a Machined Tungsten Part

Updated September 26, 2026 · Reviewed September 26, 2026

Inspection catches problems before a part goes into service, and tungsten has a few inspection points that matter more than they would on a more common material. This guide covers what to check, what to ask your shop for, and what a complete inspection report should contain.

Dimensional inspection

Standard dimensional inspection, using calipers, micrometers, gauges or a coordinate measuring machine depending on the tolerance, applies to tungsten the same way it applies to any machined metal. What differs is less the method and more the stakes: because tungsten parts cost more to remake, catching a dimensional problem before a part ships matters more than it would on a cheaper material, and it is worth confirming your shop’s inspection process before the job starts rather than after a part fails to fit.

Density verification

Density is often a functional requirement on tungsten parts, particularly for shielding and counterweight applications where the whole point of the part is its mass within a given volume. Verifying density on a finished part typically involves measuring mass directly and calculating or measuring volume, either from the part’s known geometry for simple shapes or by a displacement method for complex ones. The result is compared against the expected density range for the specified grade and ASTM B777 class. If density is critical to your application, ask for this explicitly; it is not always included in a standard inspection package.

Surface and edge condition

Tungsten, particularly pure tungsten, is more prone than steel to chipped edges and micro-cracking from machining stress, especially around sharp corners, thin sections and drilled holes. A visual inspection under good lighting, sometimes supplemented by dye penetrant inspection for parts where surface cracking is a real risk, catches these issues before the part goes into service. Heavy alloy is less prone to this than pure tungsten, but it is still worth a careful visual check, particularly on parts with fine features or tight internal corners.

Material certification and traceability

A material certification documents the composition, grade and source of the tungsten used in your part, typically traceable to a specific heat or lot from the mill. This matters most for regulated applications, medical, aerospace or anywhere your customer requires documented material traceability. If your project needs this, request it explicitly in the RFQ, since it is not automatically included in every quote and adds a small amount of cost and lead time. For what a certification document should actually contain and how to check it, see how to read a tungsten material certification.

Testing beyond standard inspection

Some applications call for testing beyond dimensional and density checks:

Radiographic inspection, checking for internal voids or inclusions, most relevant for shielding parts where internal integrity affects performance.
Magnetic permeability testing, confirming a W-Ni-Cu part is genuinely non-magnetic where that property is critical, such as near MRI equipment.
Hardness testing, occasionally requested for parts with a structural or wear-related function.

None of these are standard by default. Match the testing you request to what your application actually requires, since each additional test adds cost and time.

What a complete inspection report should contain

Different shops format inspection reports differently, but a report that actually lets you verify the part against the drawing usually includes:

Report element	What it should show
Dimensional results	Each toleranced feature, the measured value and pass or fail against the drawing tolerance
Measurement method	Which instrument or method was used for each feature, especially for tight tolerances
Density result, if applicable	Measured density against the expected range for the grade and class
Material certification reference	Heat or lot number, traceable to the mill, if certification was requested
Visual or surface inspection notes	Any chipping, cracking or finish issues observed, even if within tolerance
Inspector and date	Who performed the inspection and when, for your own records

Ask for this before the job starts rather than assuming a particular format. A shop with a clear, complete report is usually a good sign about their process generally.

Inspection method by feature type

Which inspection method fits depends on the feature and the tolerance, not on tungsten specifically, but the table below is a useful starting point when you are deciding what to ask for.

Feature type	Typical method	When to consider something tighter
General length and diameter, ±0.05 mm or looser	Calipers or micrometer	Not usually needed at this tolerance band
Precision bore or shaft diameter, ±0.01 to ±0.025 mm	Micrometer, bore gauge or CMM	CMM for complex geometry or multiple related features
Positional or geometric tolerances (true position, flatness, parallelism)	Coordinate measuring machine	Always, since these are difficult to verify manually with confidence
Overall mass or density	Scale plus volume calculation or displacement method	Displacement method for irregular shapes where calculated volume is unreliable
Surface or subsurface cracking	Visual inspection under magnification	Dye penetrant inspection on pure tungsten or safety-critical parts

None of this is unique to tungsten. What is worth remembering is that a scrapped tungsten part costs more to remake than a scrapped steel part, so it is usually worth choosing the more thorough method when a feature is close to the boundary between the two columns.

What to ask your shop for before the job starts

What dimensional inspection method they use, and whether it matches the tolerance on your drawing.
Whether density verification is included, and if not, whether it can be added.
How they check surface and edge condition, particularly on brittle grades like pure tungsten.
What certification and traceability documentation they provide by default, and what can be added on request.
Turnaround time for any additional testing, since some tests, like radiographic inspection, may be sent out rather than done in-house.
Whether first article inspection is available, particularly on a new part or a new setup, before a full lot is run.

Common gaps that show up after delivery

A few inspection gaps come up often enough to flag before they happen rather than after:

A part arrives within tolerance but the buyer expected a density check that was never requested. Density is not automatically part of a standard dimensional inspection.
A certification is provided, but it does not trace to the specific parts shipped. Ask that any certification reference the actual heat or lot used for your order, not a general material data sheet.
Surface cracking on pure tungsten is found only after the part is in service. A visual check under good lighting before shipment, and dye penetrant inspection for higher-risk parts, catches most of this earlier.

Confirming these upfront, as part of your RFQ, avoids a surprise at delivery when you expected documentation that was never part of the original quote. When your drawing is ready, send your RFQ with your inspection and certification requirements stated clearly. For what to include in a complete RFQ generally, see how to write an RFQ for a machined tungsten part. For grade-specific tolerance expectations, see what tolerance and finish you can hold on a tungsten part.

Inspection is the last step of the sourcing path described in our guide to custom tungsten parts.

See also: NDT of tungsten parts, for which method finds which defect.

Frequently asked questions

Does a tungsten part need different inspection than a steel part?

Dimensional inspection methods are the same. What differs is that tungsten parts more often warrant a density check, since density is frequently a functional requirement, and edge and surface condition matters more because tungsten, especially pure tungsten, is more prone to chipping and micro-cracking than steel.

How is density verified on a finished part?

The standard method is measuring the part's mass and volume, either directly for simple geometries or using a displacement method for complex shapes, then comparing the result against the expected density for the specified grade and class.

Should I request a material certification, a test report, or both?

It depends on what your application needs. A material certification confirms the composition and source of the tungsten used. A test report documents specific measurements, such as density or dimensional results, on your actual part. Ask for whichever, or both, your project requires.

What is the difference between first article inspection and normal lot inspection on a tungsten order?

First article inspection is a full dimensional and, where relevant, density check on the very first part made from a new setup, meant to catch a process problem before an entire lot is run. Normal lot inspection samples ongoing production at a lower rate, since the process has already been validated. Tungsten's higher scrap cost makes first article inspection worth requesting even on smaller orders.

Can I inspect a tungsten part myself, or do I need the shop to do it?

You can inspect basic dimensions yourself with calipers or a micrometer if you have them. Density verification, coordinate measuring machine inspection and any nondestructive testing generally require equipment most buyers do not have on hand, so those are normally done by the shop or a third-party lab and reported to you.

Sources

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