Typical Applications of Heavy Tungsten Alloys (WHA)(2)

While high density metals are relatively no corrosive, plating Is recommended if used in a corrosive atmosphere. Standard plating procedures for cadmium, nickel, and chromium are used. A copper flash Is sometimes used for better adherence. Plating is suggested if used with aluminum to prevent galvanic reaction,Oxidation starts at approximately 400C (752F), and in high humilities at approximately 66C (150F) showing a blue-black film. To minimize oxidation at high temperatures and high humidity, plating is recommended.MACHINING AND FINISHINGWHAs is similar to machining gray cast iron. A coolant is optional and carbide tools are recommended in most cases.TURNING & BORING — Roughing — use C-2 carbide with cutting depth of .030” to 125’ and .008” to .015 feed, at 200 to 300 SFM. Finishing — .010" to .015" cutting depth and 004" to .010" feed at 250 to 400 SFM.DRILLING— Use high speed steel surface treated drills with plain points. Increased clearance angles and automatic feeds are often used to avoid binding and seizing. Carbide drills will give better tool life. A chlorinated oil Is sometimes used as a coolant.TAPPING — Use high speed steel or carbide, two flute plug spiral point taps. Chlorinated oil or a tapping compound is recommended. GRINDING - Use aluminum oxide or silicon carbide wheels of medium hardness.MILLiNG - Use M-2 high speed steel for light cuts and M-42 high speed steel for deep cuts. Carbide cutter inserts will extend tool life. We recommend when using carbide, feeds .007” to .015” per tooth at speeds of 200 to 400 SFM for roughing, and when finished, feeds .003” to .010 per tooth at speeds of 300 to 700 SFM.High density tungsten alloys are not heat treatable; however, stress relieving is sometimes done on machined parts. We suggest heating at 600F in air for two hours and cool in air or in a protective atmosphere at 900F for 30 minutes.SAWING OR CUTTING — When sawing, use a bi-metai coarse blade at high speeds, or a high speed steel coarse blade at low speeds. Coolant can be used. Material also can be cut using high speed abrasive cutoff wheels.As a result of the materials’ characteristics and especially its low thermal expansion. very close tolerances and fine finishes can be held.JOININGCOPPER BRAZING Is a very good method of joining high density tungsten materials to itself or other materials. Joint strength Is close to that of parent material. One disadvantage is that it should be done in a controlled atmosphere, which is not too practical for most users.DIFFUSION BONDING is an ideal way of joining tungsten alloy material to itself, but It has to be done by the material manufacturer. If parts are finished, there may be some distortion from the process.SILVER SOLDERING for most companies is a practical and efficient method of joining these types of material either to themselves or to steel.SUGGESTIONS: Typically .002 clearance between parts to be joined is required, As the part gets larger, more clearance is required. Parts should be as clean as possible, sand blasting is sometimes used, both parts are fluxed, carefully heated until solder flows. Easy flow 45 is commonly used. A slow uniform cooling is recommended, Uneven cooling could set up stress in the joint and the material.SHRINK FITTING is another good method of joining high density tungsten material to steel. Depending on the size, .0005/.0007 interference fit per side is recommended. The tungsten alloy is chilled In dry ice or nitrogen while the steel is heated. When assembled, a slow cool is necessary, while parts are held by a locating pin or fixture.AVAILABILITY high density tungsten material is stocked in the following sizes:1/8" to 1" dia. in 8" & 12" lengths1 1/8" to 2" dia. in 12" lengths1/4" to 1" square in 8" & 12" lengths1 1/8" to 2" square in 12" lengthsRectangles, discs, and rings are also available.Larger sizes up to 6" dia. or 41/2" square x 30" long, and depending on cross section, longer lengths and sizes can be supplied.
All round bars up to 2" diameter are centerless ground, while all larger diameters are lathe finished.If material is not in stock, delivery is normally 10-14 days, or sooner for emergency requirements.Because we make our own tooling, special shapes and sizes can be made quickly and competitively— finished machined to your requirements or as a near net shaped blank.COPPER TUNGSTEN AND SILVER TUNGSTENRefractory metal composites produced by which are. used for:Resistance Welding Die Inserts and Electrode Facings EDM and ECM ElectrodesElectrical Contacts Semi-Conductor Heat Sinks and Thermal BasesWear Surfaces Requiring High Electrical and Thermal Conductivity

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