Precision Measurement & Dimensional Inspection for Technical Ceramic Components
CMM contact probing · 2.5D vision · surface roughness · X-ray · helium leak test
Precision measurement is how a ceramic part is proved to match its drawing — every critical dimension, flatness and surface measured on the method that suits that feature, and the numbers delivered with the parts. LONGYI inspects its advanced ceramic components in-house with a bridge-type coordinate measuring machine (CMM), a 2.5D vision measuring machine, a surface roughness tester, X-ray inspection and a helium leak detector, and every shipment leaves with its measurement data. Whether your team calls them advanced, technical or fine ceramics, the question is the same: can the supplier show you the numbers, and explain how they were taken?
We often write the inspection standard — because the drawing rarely does
Many of the parts we make arrive as a sample to reverse-engineer, a sketch, or a drawing that gives dimensions but not how to check them. So the inspection plan is settled at drawing review, before machining starts: which dimensions are critical, which faces are the datums, and whether each feature is measured by contact probe, by vision or by leak test. That plan goes into the measurement report, so the numbers you receive can be repeated on your side. A certificate on the wall cannot tell you how your flatness was measured; this report does. The trade-off is honest: a measurement is only comparable when the method is the same, so if your incoming inspection uses a different method, tell us — we will state ours on the report and help you reconcile the two.
Five Inspection Methods, Chosen per Feature
No single instrument measures everything well. Each method below is used where it gives the most trustworthy number, and the method for each critical feature is named on the report.
3D Coordinate Measuring Machine (CMM)
Contact probingA probe touches the actual surface on a granite-based bridge machine. On white or translucent ceramics, where light scatters into the material and edges look soft to a camera, contact probing reads the true geometry.
2.5D Vision Measuring Machine
Non-contact opticalA camera and stage measure outlines, hole positions and small features without touching the part — fast enough for many features per part, and safe for thin or delicate ceramics.
Surface Roughness Tester
Stylus profileA stylus traces the surface to give Ra. Seal faces, sliding surfaces and vacuum chuck faces are checked against the roughness called out on the drawing.
X-ray Inspection
Internal structureShows what a caliper and a camera cannot: internal cracks, voids and braze coverage inside joined ceramic-to-metal assemblies, without cutting the part.
Helium Leak Detector
HermeticityBrazed, vacuum-tight assemblies are tested with helium on our own leak detector. Leak rate is the only measurement that proves a seal — dimensions alone cannot.
The Inspection Plan Starts at the Drawing
How a part will be measured is decided before it is made. Six steps, one supplier responsible for both the part and its data.
Drawing review
We mark the critical dimensions, datums and tolerances that decide whether the part works in your machine — and ask when the drawing is silent.
Sample or reverse engineering
No drawing? We measure your existing part and propose a drawing with tolerances for you to approve before production.
Method per feature
Each critical feature is assigned to CMM, vision, roughness, X-ray or leak test — the method that gives a repeatable number for it.
Manufacture
Parts are formed, sintered and finished by CNC 5-axis machining and grinding to the agreed plan.
Final inspection
The agreed features are measured in our quality control room on the assigned method, and every result is recorded for the report.
Ship with data
Every shipment leaves with its measurement report, so your team can accept the parts on evidence, not on trust.
What Every Measurement Report Contains
Each critical dimension with its nominal value, tolerance, measured result and pass/fail — the page your incoming inspection checks first.
Measured values plotted against the design value and tolerance band, so trends across a batch — not just single failures — are visible at a glance.
The measuring method and datums used for each feature, likely sources of deviation and, where useful, recommendations for the design or the next batch.
Why Your Numbers and Ours May Differ
It is one of the most common questions we get, and usually neither side is wrong. The difference comes from how the part was measured, not from the part.
Vision systems find an edge from light contrast. White and translucent ceramics scatter light into the surface, so an optical edge can sit slightly off the physical one. A CMM probe touches the surface itself. On a critical diameter or step, the two can disagree by more than the tolerance.
Measure a hole position from a different face or edge and you get a different number. Agreeing the datums at drawing review removes most disputes before they start.
Flatness taken from a few points can miss a saddle or a dished centre that a full-surface grid will find. For vacuum chucks and work-holding plates, we probe across the whole face.
A thin plate measured clamped, on three points or lying free can give three flatness values. The support condition is stated on our report so it can be repeated.
If your results differ from our report, send us your method and data — we will compare them feature by feature and explain the difference.
When Our Report Is Not Enough on Its Own
The part must function in an assembly you have not described? Dimensions within tolerance do not guarantee fit with mating parts we have never seen. Share the mating drawing or the assembly condition, and we will add the interface dimensions to the plan.
You accept parts by on-machine trial only? Many teams have no CMM and judge parts by how they run. That works — but tell us which dimensions your machine is sensitive to, so they are measured and reported rather than discovered in production.
The seal must be hermetic? Dimensions cannot prove it. Brazed and metallized assemblies need a helium leak test as well, and we run it on our own detector.
See the Measurements Being Taken
Three short videos from our quality control room — vision measurement, flatness measurement of thin parts on a vacuum chuck, and helium leak testing.
Vision measurement of ceramic parts
The vision system measures outlines, hole positions and small features without touching the part — quick for parts with many features, and gentle on thin ceramics.
Thin parts held flat on a porous ceramic vacuum chuck
Thin and perforated parts bend under clamps, so they are held by a porous ceramic vacuum chuck with a fixture plate — uniform suction, no clamping force.
Edges are imaged in high-contrast black-and-white by the add-on camera on the CMM, then the probe measures the surface for flatness.
Brazed rings tested below 1×10⁻⁹ mbar·l/s
Brazed ceramic rings are tested on our own helium leak detector. A seal is proved by its leak rate, not by its dimensions — more on ceramic brazing.
From Measurement Back to Manufacturing
The same team makes the part and measures it
Measurement closes the loop on forming, sintering, machining and grinding. The full process chain is on our advanced ceramics manufacturing page, and the machining step on CNC 5-axis machining.
Precision ceramic manufacturer in Taiwan since 2007
LONGYI supplies ceramic components and assemblies to equipment builders in semiconductor, vacuum and precision automation. Learn more about LONGYI and our OEM & ODM service.
Send your drawing or an existing sample. Tell us which dimensions matter in your machine and how you inspect incoming parts — we will set the inspection plan with you before quoting.
Request an Inspection PlanPrecision Measurement — FAQ
What is precision measurement for ceramic components?
Precision measurement for ceramic components is the dimensional and functional inspection that proves a finished ceramic part matches its drawing — using CMM contact probing, vision measurement, surface roughness testing, X-ray and helium leak testing, each on the features it measures best. LONGYI performs all five in-house and ships every order with its measurement data.
Which measuring methods do you use in-house?
A bridge-type coordinate measuring machine (CMM) for flatness, heights and 3D tolerances; a 2.5D vision measuring machine for outlines and hole positions; a surface roughness tester for Ra; X-ray inspection for internal defects and braze joints; and a helium leak detector for vacuum-tight assemblies, verified to better than 1.0×10⁻⁹ mbar·l/s.
What does the measurement report include?
Every shipment includes a data table of critical dimensions with nominal, tolerance and measured values; charts comparing actual results with the design; and notes on the measuring method, datums and any sources of deviation, with recommendations where useful.
Why are our measurement results different from yours?
Usually because the parts were measured differently. Optical systems detect edges by light contrast, which white and translucent ceramics can blur; a CMM probe touches the surface. Different datums, flatness taken from a few points instead of a full grid, and different support conditions also change the result. Send us your method and data and we will compare them feature by feature.
Our drawing does not say how to inspect the part. Can you define it?
Yes, and it is common. At drawing review we propose the critical dimensions, datums and measuring method for each feature, and you approve the plan before production. If you only have a sample, we measure it and propose a drawing with tolerances.
We do not have a CMM. How can we accept the parts?
Use our measurement report as the acceptance record, and tell us which dimensions your machine is most sensitive to so they are measured and reported. Many teams combine the report with an on-machine trial run.
How do you inspect brazed joints and features you cannot see?
With X-ray inspection for internal cracks, voids and braze coverage, and with a helium leak test for hermeticity. Both are run on our own equipment, so brazed and metallized assemblies are verified before they ship.
Do you measure surface roughness?
Yes. Ground and lapped faces — seal faces, sliding surfaces and vacuum chuck faces — are checked with a stylus surface roughness tester against the Ra on your drawing. If the drawing gives no roughness, we will ask what the surface has to do and propose a value.
Related processes
Parts we measure
Materials
Also known as: ceramic dimensional inspection · ceramic metrology · CMM inspection of ceramic parts · coordinate measuring machine · contact probe measurement · 2.5D vision measuring machine · video measuring system · optical measuring machine · flatness measurement · surface roughness Ra measurement · X-ray inspection of brazed joints · helium leak test · hermeticity test · measurement report · incoming inspection · reverse engineering from sample · Keramik Messtechnik · 3D-Koordinatenmessung · 三次元測定 · 画像測定機 · 精密量測 · 三次元量測 · 影像量測儀 · 表面粗度量測