Artmiz-Group

Diamond turning tools

Five groups, ordered from the most widely used to the most specialised. Values are typical ranges and are indicative. Each quotation includes the manufacturer's datasheet for the exact grade.

GROUP 01

PCD inserts

A layer of sintered diamond grains, bonded with cobalt at high pressure and temperature, on a carbide substrate. The most widely used diamond turning tool, with tool life many times that of plain carbide in aluminium.

Insert shapes: CCGT and CCMT (80° rhombic), DCGT (55°), VCGT (35°), TCGT and TPGT (triangular), SCGT and SPGT (square), RCGT (round). Single-tip, two-tip and full-face versions.

Used for: wheels, pistons, cylinder blocks and gearbox housings in aluminium; copper and bronze parts; MMC; CFRP and GFRP; engineered wood and filled plastics.

Typical specification

Hardnessabout 50 to 80 GPa
Diamond layerabout 0.3 to 1.0 mm, usually 0.5 mm
Thermal conductivityabout 100 to 600 W/m·K
Transverse rupture strengthabout 1000 to 2000 MPa
Maximum working temperatureabout 600 to 700 °C
Rake anglepositive, 0° to 15°

Grain size grades

Fine, about 1 to 2 µmSharpest edge, best surface finish. Finishing, low-Si aluminium, copper.
Medium, about 10 µmGeneral purpose. Aluminium up to 12% Si.
Coarse, about 25 µmLongest wear life. Aluminium above 12% Si, MMC, CFRP.

GROUP 02

CVD diamond-coated carbide

A thin diamond layer grown on a low-cobalt tungsten carbide insert by chemical vapour deposition. It costs less than PCD and can be applied to any insert shape, including chip-breaker geometries.

Compared with PCD: lower cost and more complex geometry, but a rounder edge and a thinner wear layer. Coated inserts cannot be re-sharpened.

Used for: graphite electrodes, fuel-cell bipolar plates, CFRP and GFRP, green (unsintered) ceramics and carbide, high-silicon aluminium.

Typical specification

Coating thicknessabout 5 to 30 µm
Coating hardnessabout 80 to 100 GPa
Grain structuremicrocrystalline (MCD) 1 to 5 µm, or nanocrystalline (NCD) 10 to 100 nm
SubstrateWC-Co, about 6% cobalt
Edge radiusabout 15 to 30 µm
Maximum working temperatureabout 600 to 700 °C

GROUP 03

CVD thick film (TFD)

A free-standing sheet of pure CVD diamond with no binder, cut by laser and brazed onto a carbide insert. It holds a very sharp edge and wears slowly in abrasive material, at a higher price than PCD.

Used for: aluminium above 12 to 17% silicon, metal matrix composites, CFRP, graphite electrodes, green ceramics.

Note: less tolerant of impact than PCD. Avoid heavily interrupted cuts.

Typical specification

Sheet thicknessabout 0.3 to 1.0 mm
Hardnessabout 90 to 100 GPa
Thermal conductivityabout 1000 to 2000 W/m·K
Bindernone
Electrical behaviourinsulating, shaped by laser
Insert shapesCCGT, DCGT, VCGT, TCGT, with wiper options

GROUP 04

Single-crystal diamond

One crystal of natural, HPHT or CVD diamond, oriented, ground and polished, and brazed onto a shank. It is the tool for ultra-precision diamond turning, where surface roughness is measured in nanometres.

Tool forms: radius tools (most common), straight-edge facing tools, V-tools, multi-radius tools.

Used for: aluminium and copper mirrors, optical moulds, NiP-plated moulds, infrared optics in germanium, silicon, ZnSe and ZnS, polymer lenses, hard-disc substrates.

Typical specification

Edge radiusabout 10 to 50 nm
Nose radiusabout 0.1 mm up to several mm, or straight edge
Rake and clearancerake usually 0° (negative for brittle materials), clearance about 5° to 10°
Crystal sourcenatural type Ia or IIa, HPHT type Ib, CVD
Achievable roughnessRa below 5 nm on a suitable machine
Form accuracyabout 0.1 to 0.25 µm PV

GROUP 05

NPD and special tools

Lower-volume tools for particular jobs. Nanopolycrystalline diamond (NPD) is made without binder, from grains of about 10 to 30 nm, with hardness of roughly 110 to 140 GPa and no grain-direction weakness.

Also in this group: PCD grooving and threading inserts, PCD boring cartridges, PCD form tools, and diamond burnishing tools with a single-crystal tip of about 1 to 4 mm radius.

Used for: piston ring grooves, cylinder bores and bushes, profile parts in series, shaft and hydraulic cylinder finishing, hard and brittle materials.

Typical specification

NPD grain sizeabout 10 to 30 nm
NPD hardnessabout 110 to 140 GPa
NPD edge radiusbelow about 100 nm
Grooving widthabout 1 to 6 mm
Availability[CONFIRM WITH SUPPLIER: stock or made to order]

Not for ferrous work. Diamond tools are not suitable for steel, cast iron, nickel alloys or, as a rule, titanium. Ask us about PCBN, carbide and ceramic alternatives.

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