Tungsten Machining Glossary: Grades, Processes and Terms

ASTM B777: The standard specification for tungsten base, high-density metal. It defines four classes of tungsten heavy alloy by minimum tungsten content, density and mechanical properties. Read the full guide.
Balance Weight: See Counterweight.
Ballast: Dense mass added to a vehicle or structure to set or adjust total weight, distinct from a counterweight, which offsets a specific rotating or moving mass. Read the full guide.
Boring Bar: A long, thin cutting tool used to enlarge a hole from the inside. Tungsten heavy alloy bodies are used to raise the tool’s natural frequency and reduce chatter on deep, small-diameter bores. Read the full guide.
Bucking Bar: A handheld dense metal tool that backs up a rivet during aircraft assembly, absorbing the impact energy of the riveting hammer. Tungsten heavy alloy lets the bar stay compact for tight access points. Read the full guide.
CNC Machining: Computer numerical control machining: turning, milling, drilling and tapping on programmed equipment. Tungsten heavy alloy and tungsten copper run on standard CNC equipment; pure tungsten needs lighter, more controlled cuts. Read the full guide.
Collimator: A precision-machined aperture that shapes a radiation or particle beam by absorbing everything except what passes through a defined opening. Used in medical imaging and in industrial and research instrumentation. Read the full guide.
Conflict Minerals (3TG): Tin, tantalum, tungsten and gold, minerals subject to responsible sourcing reporting requirements because of their historical association with conflict financing in certain regions. Buyers with reporting obligations ask suppliers for sourcing documentation. Read the full guide.
Counterweight: A machined mass added to offset the weight or moment of another part, commonly in rotating assemblies, control surfaces or crankshafts. Tungsten heavy alloy lets a counterweight fit more mass into a fixed envelope than steel or lead. Read the full guide.
Density: Mass per unit volume, expressed in g/cm³ for tungsten materials. Pure tungsten runs about 19.3 g/cm³, tungsten heavy alloy 17.0 to 18.5 g/cm³ depending on class, against 11.3 for lead and 7.85 for steel. Read the full guide.
Dimensional Weight: A freight pricing method based on a package’s volume rather than its actual weight. Dense tungsten parts usually ship on actual weight instead, which can make a small part cost more to ship than a bulkier, lighter one. Read the full guide.
Downhole Tool: Equipment run inside an oil or gas well, such as a sinker bar or logging tool weight. Tungsten heavy alloy adds mass within the fixed diameter of the tool string. Read the full guide.
Green State: The pressed but not yet sintered condition of a powder metallurgy part, including tungsten carbide before firing. Some features are easier to machine in the green state than after the part reaches full hardness. Read the full guide.
Grinding: Material removal using an abrasive wheel rather than a cutting edge. The primary process for shaping sintered tungsten carbide and for holding the tightest tolerances on pure tungsten and heavy alloy. Read the full guide.
Hardness: Resistance to surface deformation, measured on the Rockwell or Brinell scale. Tungsten heavy alloy is tough rather than surface-hard, which is why it is chosen for mass and damping rather than as a wear-resistant tooling material on its own. Read the full guide.
Heavy Alloy: Short for tungsten heavy alloy. See Tungsten Heavy Alloy.
Lead Time: The time from RFQ to shipped part. Tungsten lead time is affected by material sourcing, blank type (bar stock versus near-net blank) and any required testing or certification. Read the full guide.
Magnetic Permeability: A material’s response to a magnetic field. Shops verify a W-Ni-Cu part is genuinely non-magnetic with a permeability meter rather than assuming it from the grade alone. Read the full guide.
Material Certification: A mill test report documenting a material’s grade, composition, density and mechanical properties, traceable to a specific heat or lot. Requested when a part needs documented material traceability. Read the full guide.
Molybdenum (TZM): A refractory metal lighter and less dense than tungsten, sometimes used instead of tungsten where high-temperature strength matters more than mass. TZM is a molybdenum alloy with added strength and creep resistance. Read the full guide.
Near-Net Blank: A pressed and sintered blank shaped close to a part’s final geometry, leaving only a few millimeters to machine. Reduces material waste and machine time on higher-quantity orders, at the cost of upfront pressing tooling. Read the full guide.
Non-Magnetic Tungsten: Tungsten heavy alloy made with a nickel-copper binder (W-Ni-Cu) instead of the standard nickel-iron binder, removing the mild magnetism that W-Ni-Fe carries. Specified for parts used near MRI equipment or magnetic sensors. Read the full guide.
Passivation: A chemical surface treatment that removes free iron contamination from a metal surface. Less commonly needed on tungsten heavy alloy than on stainless steel, since heavy alloy does not rely on a passive oxide layer for corrosion resistance the same way. Read the full guide.
Pure Tungsten: At least 99.95% tungsten, made by pressing and sintering powder, sometimes forged or rolled afterward. Brittle at room temperature and used where extreme heat resistance matters more than ease of machining. Read the full guide.
Radiation Shielding: A part that absorbs X-ray or gamma radiation to protect equipment, personnel or surrounding material. Tungsten heavy alloy shields achieve the same attenuation as lead in a smaller, lighter package. Read the full guide.
Refractory Metal: A metal with an unusually high melting point and resistance to wear and deformation at elevated temperature. Tungsten, tantalum and molybdenum are the refractory metals most often compared for machined parts. Read the full guide.
RFQ: Request for quote. On this site, a description of a tungsten part (grade, drawing, quantity, tolerance) sent to be matched with shops that can quote it. Read the full guide.
Scrap Value: The resale value of tungsten machining chips and offcuts, which is high relative to the material’s original cost compared with steel or aluminum scrap. Affects how a shop prices material waste into a quote. Read the full guide.
Sintering: Heating a pressed metal powder compact below its melting point until the particles bond into a solid piece. The standard way tungsten heavy alloy and pure tungsten blanks are made before machining. Read the full guide.
Standard Bar Size: A diameter, thickness or length a tungsten mill keeps in regular stock. Specifying a part that fits a standard size, rather than a custom one, usually speeds up a quote and lowers cost. Read the full guide.
Thoriated Tungsten Electrode: A pure tungsten TIG welding electrode alloyed with a small amount of thorium oxide to improve arc starting. A different product category from the machined structural and shielding parts this site sources. Read the full guide.
Tolerance: The allowed deviation from a specified dimension. Typical for tungsten heavy alloy is ±0.01 to ±0.025 mm on turned and milled features; pure tungsten is looser unless finished by grinding. Read the full guide.
Tungsten: A metallic element with the highest melting point of any metal and a density around 19.3 g/cm³ in its pure form. In machined parts, the term covers three distinct materials: pure tungsten, tungsten heavy alloy and tungsten copper. Read the full guide.
Tungsten Carbide: A ceramic composite of tungsten carbide grains in a cobalt binder, too hard to mill or turn after sintering. Shaped by grinding, EDM or machining in the green state before firing. Read the full guide.
Tungsten Copper: A porous tungsten skeleton infiltrated with 10 to 30% copper, combining tungsten’s wear resistance with copper’s conductivity. Used for EDM electrodes, welding electrodes and electrical contacts. Read the full guide.
Tungsten Heavy Alloy: 90 to 97% tungsten held together by a nickel-iron or nickel-copper binder, which makes it far easier to machine than pure tungsten. The standard material for shielding, counterweights and ballast. Read the full guide.
Vacuum Furnace Components: Heat shields, boats, crucibles and hot-zone fixtures machined in pure tungsten for use inside vacuum or inert-atmosphere furnaces, where the material’s high melting point matters most. Read the full guide.
Vibration Damping: Reducing chatter and oscillation in a cutting tool or structure by raising its mass and natural frequency. A key reason tungsten heavy alloy is used inside boring bars and similar tool holders. Read the full guide.
W-Ni-Cu: Tungsten heavy alloy bound with nickel and copper instead of nickel and iron, chosen when a part must be non-magnetic. Read the full guide.
W-Ni-Fe: Tungsten heavy alloy bound with nickel and iron, the more common binder system. Carries mild magnetism from the iron content. Read the full guide.
Wire EDM: Electrical discharge machining that erodes material with a thin traveling wire, used for features too fine or too brittle to mill, such as small deep holes in pure tungsten or apertures in a collimator. Read the full guide.
Wrought Tungsten: Tungsten or tungsten heavy alloy further worked by rolling or forging after sintering, which changes its grain structure and mechanical properties compared with the as-sintered condition. Read the full guide.

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