CNC Turning Kovar is a core capability at VT machining. We combine controlled turning with material-aware setup for Kovar — an alloy that is matched thermal expansion for glass/ceramic seals — to produce parts that meet your specification first time.
CNC Turning Capability for Kovar
- Diameter tolerance to ±0.005 mm
- Concentricity within 0.01 mm
- OD/ID, threading, grooving
- Bar and chuck work
Kovar Material Data
| Density | 8.36 g/cm³ |
|---|---|
| Tensile strength | 517 MPa |
| Yield strength (0.2%) | 340 MPa |
| Hardness | 140–160 HV |
| Melting point | 1450 °C |
| Thermal conductivity | 17.3 W/m·K |
| Thermal expansion | 5.1 (30–200 °C) ×10⁻⁶/K |
| Electrical conductivity | 3.5% |
| Machinability (C36000 = 100%) | 35% |
| Grades we run | Kovar / ASTM F15, Alloy 42, Alloy 52 |
Published typical values for Kovar (ASTM F15). Other grades in the family differ — the certificate supplied with your order carries the actual heat-lot figures.
Sealing surfaces must stay clean. Parts destined for glass-to-metal seals are degreased and handled without bare hands after final machining.
How CNC Turning Kovar Works
The Kovar bar or billet rotates in the spindle while single-point tools shape outer diameters, bores, faces, grooves and threads. Constant surface speed control keeps cutting conditions stable from large to small diameters.
Programming is driven directly by your 3D model or print. Work-holding, tool selection and the cutting strategy are planned around the critical features and the material before the first chip is cut. First-off inspection confirms the process is centred before production continues.
Achievable Tolerances for CNC Turning Kovar
| Feature | Standard | Precision |
|---|---|---|
| Outside diameter | ±0.05 mm | ±0.005 mm |
| Bore diameter | H9 | H6 |
| Length / shoulder position | ±0.10 mm | ±0.020 mm |
| Concentricity OD to ID | 0.05 mm TIR | 0.010 mm TIR |
| Roundness | 0.02 mm | 0.005 mm |
| Thread class | 6g / 2A | 4h / 3A |
| Surface finish, as turned | Ra 1.6 µm | Ra 0.4 µm |
Standard is what a normal quotation assumes. Precision is available on nominated features and is priced separately, because it needs extra setups, in-process gauging and CMM verification. Call out only the features that need it — blanket-tightening a drawing is the single most common reason a quote comes back expensive.
Secondary Operations & Finishing
Finished Kovar parts can move straight into secondary operations under one roof. Typical add-ons are deburring, passivation, anodising, plating, blasting, polishing and laser marking. We coordinate the whole chain so you receive complete, inspection-ready parts.
Working with Kovar
As a material, Kovar is matched thermal expansion for glass/ceramic seals. Our setup reflects the alloy's machinability so the finished part is accurate and free of avoidable defects.
We verify the exact grade and condition before machining, and traceable mill certs are available on request. We can work to your nominated material source or specification when required.
CNC Turning Tolerances & Surface Finish
Turned Kovar holds diameter tolerances to about ±0.005 mm with concentricity within 0.01 mm and good roundness. Turned finishes of Ra 0.4–0.8 µm are achievable with finishing passes and sharp tooling.
Exact achievable figures depend on the alloy, the feature size and the part geometry. Tell us which dimensions are critical and we will advise feasibility up front.
Design Tips for CNC Turning Kovar
We are happy to suggest design tweaks that improve manufacturability. Consistent diameters, standard thread forms and avoiding extremely long, slender features help Kovar turned parts stay concentric and economical. If you send your model early, we will return practical DFM feedback before you commit to production.
CNC Turning Quality & Inspection
We control quality throughout the process, not just at the end. In-process checks plus final inspection — including CMM where specified — keep every Kovar part to print. Inspection reports, material certificates and first-article documentation can be supplied on request.
Applications of CNC Turning Kovar
Customers order CNC Turning Kovar components for everything from instrumentation to structural and functional assemblies. Whether you need a single prototype or recurring production volume, the same process discipline applies.
How to Order CNC Turning Kovar
Getting a quote is simple. Share your model, the material grade, your quantity and target tolerances. You receive a clear quotation with lead time and honest manufacturability feedback.
Parts We Have Run in Kovar
Three representative CNC Turning Kovar jobs, with the callouts that actually drove the process plan. Yours will differ — these are here so you can judge whether your part is in our range before you spend time on an RFQ.
Bearing spacer
- Material
- Kovar
- Size
- Ø35 / Ø22 × 9 mm
- Key callouts
- Thickness ±0.005 mm, parallelism 0.005 mm
- Batch
- 4,000 pcs
Turned then double-disc ground — thickness this tight is not a lathe job.
Nozzle body
- Material
- Kovar
- Size
- Ø12 × 46 mm
- Key callouts
- Ø0.6 mm orifice ±0.01 mm, internal taper 20°
- Batch
- 600 pcs
Orifice EDM-drilled after turning; a drill wanders at that diameter.
Threaded fitting
- Material
- Kovar
- Size
- Ø22 hex × 38 mm
- Key callouts
- G3/8" thread class 4h, bore H8, sealing face Ra 0.8 µm
- Batch
- 2,500 pcs
Run on a sub-spindle lathe so the back face is finished without a second setup.
Finishing Options for Kovar
| Finish | Thickness / effect | Why it gets specified |
|---|---|---|
| Deburr / edge break | 0.05–0.3 mm | All parts unless the drawing says otherwise |
| Bead blast | Ra 1.6–3.2 µm | Uniform matt finish, hides tool marks |
| Laser marking | — | Part number, lot code, data matrix |
No drawing yet? Build one in the browser.
Set the metal, dimensions and features, watch the 3D model update as you type, then switch to the 2D sheet to add dimensions and tolerances. Download it or send it straight to us with your RFQ.
What We Need to Quote CNC Turning Kovar
- GeometrySTEP or IGES for the 3D model, plus a PDF drawing if you have tolerance callouts. A dimensioned sketch is enough to start.
- MaterialThe exact Kovar grade and condition — temper, heat-treat state or hardness. If you are not sure, tell us the function and we will suggest one.
- QuantityPrototype count and the expected annual volume. Both change how the part is made and therefore what it costs.
- TolerancesWhich features are critical. Everything else runs to our standard tolerance, which is what keeps the price sensible.
- FinishSurface treatment, cosmetic requirements, and any faces that must be masked.
- DocumentsWhether you need a material certificate, dimensional report, FAIR or PPAP with the shipment.
Missing something from the list is not a problem — send what you have. We will come back with the specific questions rather than a generic form.
Other Metals for CNC Turning
Other Processes for Kovar
Send the drawing, the Kovar grade and the quantity. You get pricing, lead time and any DFM notes back — usually within one business day.
Request a QuoteFrequently Asked Questions
What is CNC Turning Kovar and how is it done?
CNC Turning Kovar refers to cNC turning rotates the workpiece against a single-point tool to produce cylindrical features, threads and grooves. Applied to Kovar — matched thermal expansion for glass/ceramic seals — VT machining produces each part to your CAD drawing, selecting parameters from your tolerance, finish and quantity requirements.
Can VT machining make custom Kovar parts to my drawing?
Yes. Kovar Kovar turning is made to order from your CAD/2D drawing. Share your geometry, material grade, tolerance and quantity and we will confirm feasibility, lead time and pricing.
How clean are the edges produced by CNC Turning on Kovar?
Machined Kovar edges are clean and to specification; edge-break or deburring is added when your drawing calls for it.
What tolerances can you hold for CNC Turning Kovar?
Achievable tolerances for Kovar turning depend on the alloy, geometry and feature size. Turning holds diameter tolerances to around ±0.005 mm with concentricity within 0.01 mm. Exact figures are confirmed against your drawing callouts.
Does CNC Turning Kovar require dedicated tooling?
Most Kovar turning work uses standard cutting tools and CNC programs; dedicated fixtures are made only when geometry or volume requires them.