Sava News, Events and Updates
Back To News
Tungsten Cable and the Markets it Serves

Tungsten Cable and the Markets it Serves

Wednesday, February 23, 2021

Tungsten is material known to be valued in the construction of mechanical cable due to its heat-resistance, excellent tensile strength and ductility characteristics. These unique properties make tungsten an ideal product used in the manufacture of critical medical, surgical robotic and industrial products.

Tungsten is available in a matte black or electropolished, bright finish. Depending upon the application requirements, the filament’s finish can be free of surface contaminants. While some markets require tungsten cable to be entirely free of impurities, others simply do not. Thus making tungsten cable in two finishes, means the product is well-suited to many different applications.

Is tungsten a corrosion resistant metal?

At 6,192° Farenheit, tungsten has the highest melting point of all metals. Additionally, tungsten wire is well-known for its extraordinarily high tensile strength - often times, >30% of that of 304 stainless steel. That additional 30 percent greater strengths, translates into far higher breaking strengths when stranded into varying cable constructions. By way of example, a stainless steel 8x19 cable construction will generate a tensile strength in excess of 55 lbs, while an equivalent cable, made from tungsten, will achieve in excess of 70 lbs. Tungsten therefore, in this scenario, yields almost 30% more strength than stainless steel.

Tungsten has superior corrosion resistance if it is placed in a controlled atmosphere. For instance, in a surgical robot, the tungsten is not exposed to heat or humidity. Tungsten’s black finish, as well as the sterile, air-conditioned environment, protects the cable from any risk of corrosion. In such ideal environments, tungsten’s corrosion resistance truly shines. 

What are the unique tungsten wire properties?

Density

Tungsten possesses a high density of approximately 19.25 g/cm3 at 293° Kelvin, which is approximately 2.5 times that of 304 stainless steel. In plainest terms, this means that the density of tungsten requires engineers to use 2.5 times more wire to produce the equivalent amount of stainless steel cable. 

Tensile Strength

At 500ksi, tungsten has incredibly high tensile strength, as compared with stainless steel at 375ksi. Tungsten cable manufacturers nominally achieve 30 percent higher tensile strength in tungsten than in stainless steel. Depending upon the cable’s diameter and construction, results will vary from that 30 percent figure.

Tension and compression

Tungsten is an excellent material in both tension and compression. However, it is fragile and susceptible to shear forces. When tungsten filaments are stranded together to form finished cables, the negative characteristics of shear forces are overcome by the now stranded wires.

Why are tungsten cables so popular for surgical robots?

In the manufacture of surgical robots, the device’s engineers design for the smallest, yet strongest profile cables to actuate the appendages of these sophisticated machines. In these applications, the demand is for both high tensile strength and excellent flexibility, over extremely small pulleys. While stainless steel has shown to work in limited applications, under comparable circumstances, tungsten simply outperforms the competition.

The cables used in a surgical robot should have excellent flexibility in small areas, as alluded to above. Surgical robotics call for cables that can make extremely tight turns as small as three millimeters in size. Since tungsten has excellent flexibility, it can safely maneuver for hundreds or even thousands of cycles without any degradation. Sava finds tungsten more appropriate and efficient than stainless steel in surgical robots.

What is tungsten? 

Tungsten is an element known as wolfram on the periodic table and is found naturally in the earth. It is mined in the US, South America and Africa, but a large proportion of the metal is mined and processed in China. Tungsten is made from ore and cemented with cobalt.

Why are different stranding configurations used?

Generally, Sava uses black, as drawn, tungsten filaments to make mechanical cable. The black finish, which is a graphite coating, helps lower the friction between the cable and the pulleys with which the cable makes contact. The graphite extends the cable’s longevity and reduces wear and tear.

Sava manufactures cables with different standing configurations depending on the application. For instance, a cable with a diameter of 0.018” can hold between 60 to 85 lbs, depending upon the construction used to manufacture the cable. Whereas 0.157” diameter tungsten cable will hold up to 2,500 lbs.

If your application requires tungsten cable, Carl Stahl Sava Industries possesses the unique knowledge and scientific expertise to help you achieve the strengths and cycles your device demands. To speak with our engineering team about your tungsten cable needs, contact Sava here.

February 23, 2021
Related posts