Highest density.
Radiation shielding.
Compact counterweights.

Pure tungsten: very hard, brittle, nearly impossible to machine with conventional tools. Typically wire EDM or grinding used for final shapes. Heavy metal (W-Ni-Fe): tungsten powder sintered in nickel-iron matrix. Machinable with conventional carbide tooling, though tool wear is significant. For most custom tungsten parts, we use heavy metal. Pure tungsten only specified when maximum density (0.5 g/cc higher) or maximum temperature is required.

Density: tungsten 19.3 g/cc, lead 11.3 g/cc. Tungsten shields provide same radiation attenuation in 65% of the thickness. Advantages of tungsten: compact size (smaller package), lead-free (environmental/handling concerns), harder (survives impact, drops). Disadvantages: 10-15× more expensive than lead, harder to machine, more difficult to cast complex shapes. For portable/compact/lead-free shielding (medical cabinets, precision instruments), tungsten wins despite cost.

Tungsten counterweights used wherever compact high mass matters. Golf club heads: tungsten in specific locations optimizes center of gravity without increasing overall size. Race cars: minimum allowed weight distribution controlled with tungsten inserts. Aerospace control surfaces: mass balance maintained with compact tungsten weights. Watch movements: tungsten rotor weight for self-winding. For each application, the density premium justifies itself through compact packaging.

Pure tungsten raw: $80-150/kg. Heavy metal W-Ni-Fe: $60-120/kg. Machining cost: 2-3× equivalent steel due to tool wear and difficulty. Typical finished part cost: 5-10× equivalent brass or copper part. For applications where density is required, cost is rarely the limiting factor — tungsten enables the design. Alternative materials (lead, DU, or larger non-tungsten parts) each have their own constraints.

Tungsten itself is considered environmentally benign — not bioaccumulative like lead, not radioactive. Tungsten dust: mild respiratory irritant during machining. Heavy metal containing nickel: more concerning (nickel is carcinogenic). Machining: wet coolant, HEPA collection, proper PPE. Finished parts: safe to handle without restrictions. Tungsten is increasingly chosen over lead specifically to avoid lead's handling restrictions.

Heavy metal W-Ni-Fe: 4-6 weeks including material sourcing. Pure tungsten: 6-10 weeks depending on specific grade and form. Machining time: 2-3× equivalent steel. Finishing (grinding, plating): additional 1-2 weeks. Total: 8-16 weeks typical for tungsten projects. Plan ahead for tungsten-critical designs.