October 19, 2021 Author: MDO Contributor Network
These 0.001 inch tungsten filament filaments are used to make tungsten mechanical cables. [Photo courtesy of Carl Stahl Sava Industries]
Connor Chiuchiolo and Scott Dailey, Carl Stahl Sava Industries
The mechanical cables in the motion control systems of most modern surgical robots are so small that it is almost impossible for the naked eye to see the individual filaments themselves.
The wires made up of tungsten cables used in surgical robots are so small that the diameter of individual strands they contain is as small as a quarter of the thickness of a sheet of paper.
When a surgical robot designer comes to a cable manufacturer that uses tungsten cable applications, the cable must meet a specific set of standards. For example, cables must withstand precise loads while maintaining a small diameter, as well as a critical safety factor. After all, tungsten cables must bear their load requirements without becoming too large to fit the compact shape of today's surgical robots. Therefore, manufacturing tungsten cables for surgical robots involves a delicate process of understanding how tungsten wires behave under extremely small diameters after being twisted into a spiral cable structure.
Although engineers must design the manufacturing process to prevent the mating components from damaging the ultra-fine tungsten cables, they must also ensure that the mating components are combined with the actual environment to provide world-class motion drives in life-threatening situations.
Simply put, as engineers introduce additional components, stresses, and other external conditions during the design process, the behavior of miniature tungsten cables becomes more complicated.
Just like the continuous development of miniaturization of surgical products, manufacturing tungsten cables for surgical robots is a very complex engineering process, which is more challenging due to its smaller and smaller footprint and complex behavior characteristics.
19×19 0.5mm tungsten steel cable with plasma welding end [photo courtesy of Carl Stahl Sava Industries]
Surgical robot designers use tungsten cables in more and more of their products because of the unique ability of this material to withstand high loads and traverse small radii.
The pulleys in these surgical miracles may be as small as the tip of a crayon. Therefore, the mechanical cable that needs to bypass such sharp turns must have the quality that enables the product to withstand cable bounce. The cable will withstand thousands of cycles without worrying about premature degradation.
Tungsten (also called tungsten) is ideal for these applications because it has the highest tensile strength of any natural metal on earth.
Tungsten cables are flexible in behavior, as shown in this 7×37 0.021 inch. Tungsten cable. [Photo courtesy of Carl Stahl Sava Industries]
When engineers use sleeves, ball joints, or other cable joints in combination with tungsten cables, the natural characteristics of tungsten stranded wires will change in and around these joints. The changes produced by these mating components are often essentially unnecessary to completely unacceptable. In short, this is the challenge that engineers face when designing miniature tungsten cables for surgical robots.
An 8×19 0.5mm tungsten steel cable with a flat ball or "hockey" accessory in the middle. [Photo courtesy of Carl Stahl Sava Industries]
The designers of future surgical robots care about the diameter, position and performance of the ball, as well as the tungsten cable assembly itself. However, cable design experts must pay attention to the above requirements and the tools, processing and manufacturing processes that can create the perfect product every time.
Remember that cable design engineers not only need to solve the temporary and predictable complex problems that arise when dealing with tungsten cables, but also need to be solved on a large scale so that robot manufacturers can expand in the extremely aggressive and fast-growing global market compete.
This article was written by Connor Chiuchiolo, Associate Design Engineer at Carl Stahl Sava Industries, and Scott Dailey, Vice President of Marketing. For more information about Carl Stahl Sava Industries in Riverdale, New Jersey, please visit www.savacable.com.
The views expressed in this blog post are only those of the author and do not necessarily reflect the views of MedicalDesignandOutsourcing.com or its employees.
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