Tungsten Machining Processes
Six processes cover almost every machined tungsten part. Which one a shop uses depends on the grade, the feature and the tolerance. Tolerances below are typical, not guaranteed.
| Process | Used for | Grades | Typical tolerance |
|---|---|---|---|
| CNC turning | Round parts: shafts, sleeves, counterweight bodies | Heavy alloy, tungsten copper. Pure tungsten with care. | ±0.01 to ±0.025 mm |
| CNC milling | Pockets, slots, collimator bores, flats, contours | Heavy alloy, tungsten copper, pure tungsten with care | ±0.01 to ±0.025 mm |
| Drilling and boring | Through holes, collimator channels, bores | Heavy alloy, tungsten copper | ±0.01 to ±0.025 mm |
| Threading and tapping | Fastener threads, mounting holes | Heavy alloy, tungsten copper | Class of fit per drawing |
| Grinding | Tight faces, bores and outside diameters | All grades, primary process for carbide | ±0.005 mm or better |
| Wire EDM | Thin walls, sharp internal corners, brittle grades | Pure tungsten, carbide, tungsten copper, heavy alloy | Often ±0.01 mm or tighter |
Why tungsten machines differently from steel
Tungsten is dense, abrasive and in some grades brittle. A part weighs over twice what the same shape weighs in steel, which affects workholding and fixture design. The hard tungsten grains wear cutting edges faster. Chips have scrap value and are usually collected separately. None of this needs an exotic machine, but it needs a shop that has cut the material before. See what is possible in tungsten machining.
Process by grade
Heavy alloy (W-Ni-Fe and W-Ni-Cu) turns, mills, drills and taps on standard CNC equipment with carbide tooling. Grinding finishes the faces and bores that need a tighter tolerance. Start with the heavy alloy machining guide and the speeds and feeds guide.
Pure tungsten is brittle at room temperature. Edges chip and thin walls crack, so shops use light cuts, sharp tooling, grinding and wire EDM for fine features. Parts for furnaces and vacuum systems are the usual use, covered in the pure tungsten furnace components guide.
Tungsten copper cuts cleanly, closer to a hard bronze. See the tungsten copper machining guide.
Tungsten carbide is too hard to mill after sintering. It is ground and wire EDM cut, or shaped before sintering. See carbide versus heavy alloy machining.
Start from the blank
The process starts earlier than the machine. A pressed and sintered near-net blank leaves little to cut. A part cut from solid bar turns expensive material into chips. Read sintered versus wrought blanks and standard bar and plate sizes before you fix the geometry.
Finish, inspection and defects
- Tolerances and surface finish: what to call out and what to leave open
- Surface treatments for heavy alloy parts
- Machining defects and their causes
- How to inspect a machined tungsten part
- Drawing mistakes that add cost
Frequently asked questions
Can tungsten be machined on a standard CNC machine?
Heavy alloy and tungsten copper, yes. Heavy alloy cuts much like hard cast iron with carbide tooling. Pure tungsten is brittle and carbide is extremely hard, so those two lean on grinding and wire EDM, and need a shop that has run them before.
Which process holds the tightest tolerance?
Grinding. Typical turned and milled tolerance on heavy alloy is ±0.01 to ±0.025 mm. Ground faces and bores go tighter, and tungsten carbide is routinely ground to ±0.005 mm or better.
When is wire EDM the better choice?
When the profile is thin, sharp-cornered or in a brittle grade such as pure tungsten or carbide, where a cutting edge would chip the part. Wire EDM cuts with sparks, so it puts almost no force on the workpiece.
Do I need to choose the process in my RFQ?
No. Send the drawing, grade and quantity. The shop picks the process. Mark only the tolerances and finishes that matter so the shop does not grind a face that never needed it.