Carl Stahl Sava Industries has been manufacturing coated steel cable for 50 years now using nylon (PA), vinyl (PVC), Teflon® (FEP), polyurethane (PU) and polyethylene (PE). The benefits to coating cable are many, but largely deal in sealing-in lubricants, in prolonging cable life, achieving a desired aesthetic appearance, as well as keeping dirt and debris from contact with the bare cable strand itself and mitigating safety concerns.
But beyond these more obvious advantages to coated cable, extrusion also cushions the cable from shock and pressure, protects from pulleys from abrasion and is easy to clean.
Nylon cable, also known as polyimide (PA) coated cable, is among the most popular cable coatings in the industry and with good reason. For one, nylon jacketed cables have been shown to extend the life of mechanical cable by a factor three, which taken without any other nylon benefits, makes this extrusion material ideal. Nylon is also hard and durable, secondly. Its toughness and resilience make it the go-to coating for cables in cyclical applications, where cables are being directed over pulleys.
Sava lubricates our cables beneath the nylon extrusion, which further extends the life of the cable in cyclic applications. This lubricant dampens the bending stresses in the wire rope, promising longer cable life and cost-effectiveness of the overall mechanical system.
In push-pull applications, nylon coated cable, also impregnated with lubricant, reduces the friction present in the push-pull assembly. This allows for lower forces required to actuate devices.
Vinyl Coated Cable
Like nylon, vinyl coated cable material is wildly common. However, unlike nylon, Vinyl (PVC) is not as durable or resilient in applications where cables are being repeated cycled over pulleys. When using vinyl over pulleys, the coating doesn’t adhere to its substrate (cable), due to the manner in which is processed onto the cable. Unmoving or static cable applications, where protecting the cable from the elements is important, would make vinyl an ideal choice.
Despite its vulnerabilities to movement, vinyl coated cable has wide-ranging utilitarian applications, nonetheless. No matter how dry or wet, exposed or not the vinyl cable is, PVC extrusion performs exceptionally well in most environments. Accompanied by UV inhibitors, vinyl coated cable will remain stable under excessive sunlight, making it well-suited for outdoor applications.
FEP cable, which is commonly known as Teflon® coated cable, is best-known for its frictionless and chemical inertness, meaning that this extrusion material requires less force to achieve movement and can withstand a variety of chemical environments. While other coated cables may offer minor levels of chemical resistance, Teflon® coated cable offers chemical compatibility, including hydrochloric and hydrofluoric acid, along many extremely corrosive chemicals.
Teflon® cable also offers continuous service temperatures, up to 400 degrees Fahrenheit and negligible moisture absorption, making this extrusion material ideal in high-temperature and humid environments.
Medical devices using mechanical cable commonly use FEP coated cable. The benefits to Teflon® in these complex endoscopic and surgical instruments are the low coefficient of friction and chemical compatibilities required in such devices.
Polyurethane cable is ideal in mechanical cable applications where resistance to a wide host of particulates and invasive material are present. Polyurethane, or PU coated cabled, is highly resistant to oils, water, exposure to the harsh conditions created by the ozone, artificial or natural and is largely unaffected by the presence of radiation.
But beyond even the environmental benefits, cable jacketed with polyurethane is also highly tolerant of abrasion, making it a perfect extrusion material where cables make contact with pulleys or other mechanical components. PU is lightweight, easily colored, moldable and is less expensive
with which to coat mechanical cable. Combined with its exceptional load-bearing and tear-resistance, polyurethane is an excellent and cost-effective solution when needing more from extruded material.
PE cable, similar to polyurethane cable, provides superior protection against water and vapor exposure, while also being lightweight, wildly customizable and cost-effective. But what makes polyethylene cable a unique proposition for extruded mechanical cable is its impact tolerance. Used in virtually any application where impact, or continued contact with potentially harmful surfaces is present, polyethylene acts as a durable and time-tolerant barrier from outside elements and objects.
Polyethylene cable also stands up to oxidation and chemical exposure, further making it an enduring jacket material for cables in a host of solutions where exposure to unwanted particulates is constant. If the cable application calls for ease with which the cable or motion control system is cleaned, polyethylene is also nicely suited. It is easily cleaned where either optics, function or both demand a squeaky-clean presentation of the cable.
Lastly, but critically, polyethylene coated cable is eco-friendly. Unless discarded improperly, as compare with many other extruded materials, polyethylene has no verifiable environmental or health concerns, nor negative impacts on ecosystems.