November 17, 2021 Author: MDO Contributor Network
19×19 0.5mm tungsten steel cable with plasma welding end [photo courtesy of Carl Stahl Sava Industries]
Connor Chiuchiolo and Scott Dailey, Carl Stahl Sava Industries
When manufacturing tungsten mechanical cables for surgical robots, tungsten itself has huge mechanical advantages, including extraordinary tensile strength captured in an astonishingly small diameter.
More importantly, the tungsten twisted into an ultra-fine mechanical cable has significant ductility that is not available in stainless steel alternatives.
The combination of strength and flexibility of tungsten makes it the material of choice for manufacturers of surgical robots. But tungsten (also known as tungsten) is very brittle as a pure metal, which makes it a challenging material for cable design engineers.
Take a 19×19 tungsten wire cable as an example. It consists of 361 wires. Imagine that the cable design engineer solved the bird cage problem that appeared on each side of the pressure ball joint. In this case, the industrial press exerts too much pressure on the accessories, and then crushes, separates and even cuts the brittle filaments of the cable strands. Although the accessory fixes the cable, excessive pressure on the accessory can damage the strength, durability, and even shorten the length of the component.
The typical danger in tungsten cable manufacturing is that solving one challenge often brings other challenges. Experienced tungsten cable design engineers anticipate such a situation and prepare for it.
If the birdcage problem occurs due to the excessive force applied by the industrial press to the mating accessories, the tensile strength and even the cable length may be affected. Therefore, when this unnecessary damage to the cable filament is resolved, it cannot be at the expense of other inherent qualities of the tungsten cable. Therefore, cable design engineers must continue to change the manufacturing process until all problems are eliminated.
Since the accessories used in the manufacture of tungsten cable assemblies are almost the same as those used in other markets, the experienced cable design engineers who produce tungsten surgical robot cables draw on decades of experience in the use of variable alloys with components such as balls. Until it reaches a perfect and delicate balance, the strength, life and geometry are all perfected. Therefore, applying the necessary pressure to the ball fitting is an exercise in formulating changes to the characteristics and settings of the cable and the machinery that produces the cable.
The correct study of pressure, dimensional tolerances and small adjustments to pounds can ensure that the tungsten wire is not damaged, as well as additional ball accessories that meet the expectations of the strength level and life cycle testing.
Tungsten cables are flexible in behavior, as shown in this 7×37 0.021 inch. Tungsten cable. [Photo courtesy of Carl Stahl Sava Industries]
Reducing the number of changes in the manufacturing process is one of the main ways for tungsten cable design engineers to reduce the risk of one solved manufacturing problem introducing another. Although it seems simple, reducing processing is one of the easiest ways to reduce variation.
But if cable design engineers avoid handling cables when producing cables, how can they make complex cables to help surgical robots reduce hospital stays and complications? The answer is simple: engineers must develop lean manufacturing processes to limit the frequency and extent of tungsten cable processing during the production process.
As mentioned earlier, tungsten cables are incredibly strong once installed in a surgical robot. However, for all the tensile advantages of tungsten, outside of its application environment, tungsten mechanical cables are extremely vulnerable to damage during handling. Simply moving the thumb and index finger along its length will cause the filament to separate immediately and render the cable assembly useless.
The spiral wires of tungsten cables are very easy to separate. Even the excessive processing from the manufacturing unit to the packaging to the final transportation will cause irreversible damage to these complex components. For these reasons, the handling of tungsten cables used in surgical robots is no more or less than absolutely necessary to produce the components themselves. More importantly, even the packaging, transportation and delivery of tungsten cables must bear as little pressure as possible.
Therefore, engineers experienced in tungsten cable manufacturing must also ensure that the lean manufacturing process can transport finished products on a large scale between production departments and between couriers and other potentially harmful contact points.
As a mechanical cable material, tungsten is a niche solution. Due to its natural resistance to high temperatures, it has a long history of supporting the crystal growth industry, but today there are few practical mechanical cable applications.
Supporting the pitch and yaw functions of the explosive surgical robot market, tungsten has quickly become the alloy of choice in today's industry. But its unique and unparalleled benefits as a motion actuator in a small space are also related to its manufacturing and engineering challenges.
Therefore, this contradictory material represents an elegant, reliable and impressive solution for surgical robot designers, and at the same time represents a groundbreaking rich manufacturing achievement that makes tungsten cables a rare engineering miracle, worth mentioning .
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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