CNC Milling Kovar from VT machining delivers precision Kovar parts produced to your exact drawing. Multi-axis milling cutters remove material to produce prismatic features, pockets, slots and contoured 3D surfaces, and we tune every parameter to the behaviour of Kovar, which is matched thermal expansion for glass/ceramic seals.
Starting Parameters for CNC Milling Kovar
| Cutting speed (carbide) | 35-75 m/min |
|---|---|
| Feed per tooth | 0.021-0.063 mm |
| Spindle speed, Ø10 mm end mill | 1110-2390 rpm |
| Insert / tool class | ISO S — sharp PVD-coated carbide |
| Coolant | Flood emulsion; sulphurised oil for tapping |
| Thermal growth, 100 mm part, +10 °C | 5.1 µm (CTE 5.1 µm/m·K) |
Shown for Kovar, the most common Kovar grade we see for CNC Milling. Starting values for Kovar, Annealed; optimised on the first article.
CNC Milling Capability for Kovar
- 3-, 4- and 5-axis capability
- Tolerance to ±0.01 mm
- Pocket/slot/contour features
- Spindle speeds to 12,000+ rpm
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 Milling Kovar Works
Rotating multi-flute cutters remove material as the Kovar workpiece is driven through programmed tool paths on 3-, 4- or 5-axis machining centres. Climb milling, step-over and depth-of-cut are set so chip load stays in the ideal band for the alloy.
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 Milling Kovar
| Feature | Standard | Precision |
|---|---|---|
| Linear dimension (< 100 mm) | ±0.05 mm | ±0.010 mm |
| Linear dimension (100–300 mm) | ±0.10 mm | ±0.025 mm |
| Hole diameter (reamed) | H9 | H7 |
| True position of hole pattern | ±0.10 mm | ±0.025 mm |
| Flatness over 100 mm | 0.05 mm | 0.015 mm |
| Perpendicularity | 0.10 mm | 0.020 mm |
| Surface finish, as machined | 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.
Design Tips for CNC Milling Kovar
We are happy to suggest design tweaks that improve manufacturability. Generous internal radii, sensible pocket depth-to-width ratios and avoiding very thin unsupported walls all reduce cost and improve accuracy in Kovar. If you send your model early, we will return practical DFM feedback before you commit to production.
CNC Milling Tolerances & Surface Finish
For CNC Milling, dimensional and positional tolerances around ±0.01 mm are routine, tightening toward ±0.005 mm on precision setups. Surface finish on machined faces typically falls in the Ra 0.4–1.6 µm range depending on tooling and pass strategy.
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.
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.
Applications of CNC Milling Kovar
Customers order CNC Milling 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.
Typical Kovar Parts for CNC Milling
Illustrative examples of CNC Milling Kovar parts and the callouts that usually drive the process plan. They show the kind of work that fits this process; they are not specific customer orders.
Heat sink base
- Material
- Kovar
- Size
- 200 × 100 × 8 mm
- Key callouts
- Fin thickness 1.2 ±0.05 mm, base flatness 0.03 mm
- Batch
- 500 pcs
Fins cut with a slotting cutter in one pass to avoid the deflection a step-over leaves.
Manifold block
- Material
- Kovar
- Size
- 120 × 60 × 45 mm
- Key callouts
- Cross-bore intersection ±0.05 mm, ports G1/8", leak-tested to 10 bar
- Batch
- 80 pcs
Deburred internally with a brush tool; a burr at a cross-bore is what fails the leak test.
Robot end-effector bracket
- Material
- Kovar
- Size
- 180 × 90 × 30 mm
- Key callouts
- Bore pair concentric within 0.02 mm, weight reduction pockets
- Batch
- 120 pcs
Pockets ganged so wall thickness never drops below 2 mm at the load path.
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 Milling 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 Milling
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
Can VT machining make custom Kovar parts to my drawing?
Yes. Kovar machining 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.
What tolerances can you hold for CNC Milling Kovar?
Achievable tolerances for Kovar machining depend on the alloy, geometry and feature size. Milling holds positional and dimensional tolerances to around ±0.01 mm, tighter with precision setups. Exact figures are confirmed against your drawing callouts.
Does CNC Milling Kovar require dedicated tooling?
Most Kovar machining work uses standard cutting tools and CNC programs; dedicated fixtures are made only when geometry or volume requires them.
What material thickness or size range suits CNC Milling Kovar?
We machine Kovar across a broad size range; share your part envelope for confirmation.
Which industries use CNC Milling Kovar parts?
CNC Milling Kovar parts are used across aerospace, medical, automotive, electronics, semiconductor and general industrial sectors — anywhere precise Kovar components are required.