SpecialFocus
Heavy Industrial
Equipment Applications Feature Cast Nylon 6
Heavy Equipment
By Bernd Nussdorfer, Cast Nylons Ltd.
S

ince the early 1970s, cast nylon 6 has been recognized as a qualifying substitute for metals. Mechanical engineers were initially astonished by the performance of this thermoplastic material’s performance and started using it as a substitute for cast iron, steel and aluminum. Significantly lighter than steel, approximately 1/7th its specific weight and 30 percent lighter than aluminum, cast nylon 6 offers a multitude of advantages and is used in a variety of ways.

Following the advancement of the casting process, cast nylon 6 can be molded into various shapes and wall thicknesses thar are not possible with traditional extrusion or injection molding technology. Through the implementation of various additives, the properties of the cast nylon material can be designed for specific applications. This versatility makes cast nylon 6 an excellent choice for industrial usage.

Originally used as a bearing material, cast nylon is now an industrial favorite for a wide variety of applications. From bushings and wear pads to heavy loaded sheaves for steel ropes, numerous applications are possible.

Material advantages
Many performance plastics are used in industrial applications, so why use cast nylon 6?
an all terrain crane using cast nylon sheaves and wear pads parked at a construction site
An all terrain crane uses cast nylon sheaves and wear pads, reducing the weight of the equipment without sacrificing performance.
Three Gorges Dam
Three Gorges Dam, one of the largest dams in the world, used cast nylon sheaves.
Cast nylon 6 is produced through the anionic polymerization of e-caprolactam. In a 2-component system, the e-caprolactam is mixed with an activator and a catalyst and under a short exothermal reaction the material solidifies in a heated tool. Due to its low viscosity (like water), the material takes the shape of any tool. The process allows the production of low quantities in inexpensive tools, making it affordable for industrial use. Different material thicknesses in a part are possible with almost no existing residual stress.

Extrusion or injection molding processes do not offer this flexibility in sizes, geometries or cycle times. This enables cast nylon 6 to be used more cost effectively than other polymer materials.

In addition, cast nylon 6 does not corrode and has good chemical resistance, which is a huge advantage over most metals.

Industrial applications
Cast nylon 6 is used in various industries. From mining and drilling to lifting and transport, the material is being used for numerous applications. As a true substitute for metals, cast nylon 6 is an established option for use in the heavy equipment industry. Here is a look at some examples.

Cranes

The crane and lifting industry uses cast nylon in many ways, such as high loaded sheaves carrying steel ropes, wear pads for telescopic booms and outrigger floats that guarantee the integrity of a crane to stand while operating.
cast nylon sheaves in crane setup at Three Gorges Dam
Cast nylon sheaves in crane setup at Three Gorges Dam. Each crane in the photo on the right is 80 meters high.
graph of a look at the coefficient of friction and wear rates of various lubricant infused cast nylon materials
A look at the coefficient of friction and wear rates of various lubricant infused cast nylon materials.
While cranes driving over the roads can lift heavier loads every year, the maximum gross weight per axle for the open road is limited. With a maximum allowable gross weight per axle in the United States of 20,000 pounds and in Europe at 22,000 pounds, the manufacturers of this equipment are challenged with staying within the weight limits. The use of cast nylon sheaves and wear pads in telescopic booms have reduced the overall weight significantly; in some cases, the weight reduction is by more than several tons.

A cable crane carying a 25 ton payload with a concrete bucket during the construction of the Three Gorges Dam in China (www.lcs-cablecranes.com/en/projekt/three-gorges-dam/) operated with sheaves with a diameter of 1.5 meter made from nylon while the wire rope span for more than 1 mile over the Yangtze River.

The chemical makeup of cast nylon 6 allows for customization for specific applications. For example, wear pads for telescopic cranes made from cast nylon 6 material are infused with solid or liquid lubricants to enhance the coefficient of friction and ultimately its wear rate. Using lubricant-infused cast nylon instead of bronze bushings provides for smoother operating without the use of additional grease.

Pile driving

Pile driving equipment is used to drive piles made from steel, concrete or wood into the soil to build a pole-supported structure such as bridges or buildings.
birds eye view of Pier 55 (Little Island) in New York, NY, USA
Pier 55 (Little Island) in New York, NY, USA.
NYCAST® cushion pads in yellow and light blue
NYCAST® cushion pads were used for pile driving in the construction of Pier 55/Little Island.
a Cast Nylons NYCAST seal in a valve

A valve assembly in the oil and gas industry.

The concrete pillions of Pier 55 (aka Little Island) in New York, NY, USA were piled into the rock bed of the Hudson River with pile hammering equipment. Each concrete tube is 132 feet long and weighs 80 tons (176,000 pounds). There are 270 concrete tubes piled into the Hudson River to support the new island. Visit https://littleisland.org/design-construction/ to see a video about the design and construction of Little Island.

Cushion pads made from rubber-nfused cast nylon were used in the piling equipment and ensured that the process went smoothly and the piles were not damaged.

Oil and gas

In the oil and gas industry, cast nylon 6 is being used as backup rings in valves. The material must withstand high pressure and maintain its form under load. The strength the cast nylon 6 allows for use in huge valve systems.

Additional applications include:

  • Pipe in pipe spacers (centralizers)
  • Bundle clamps
  • Riser clamps
  • ROV thruster nozzles
  • Sheaves for launch and recovery systems
a Cast Nylons NYCAST seal in a valve
A Cast Nylons NYCAST seal in a valve.
wear liners for working rolls used in steel mills
Wear liners for working rolls used in steel mills.

Steel mills

The steel industry was one of the first to recognize the usefulness of cast nylon 6 and replaced traditional bronze or brass bushings and slipper pads for universal couplings with cast nylon. Applications in steel mills include:

  • Friction bearings made from oil infused cast nylon 6 to support the spindles in the stands.
  • High impact resistant grades are used in universal spindles as slipper pads, acting as the defined breaking mechanism to ensure costly spindles weren’t harmed.
  • Wear plates replacing stainless steel or bronze are used for outer plates in roll assemblies.
Environmental advantages

The use of special lubricated cast nylon requires less grease in applications, which is a significant environmental improvement.

Due to its dampening factor, cast nylon 6 has been used to reduce noise in various applications.

Cast nylon 6 is fully recyclable. It can be granulated and added to extrusion or injection molding process at a certain percentage. Due to its general UV stability, the material does not degrade over time.

Cast nylon 6 is also used in direct food contact and due to its high abrasion resistant you will find no particles in food if used correctly.

Bernd Nussdorfer is the chief techology officer for Cast Nylons Ltd. For more information, contact Cast Nylons Ltd. at 4300 Hamann Parkway, Willoughby, OH 44094-5626 USA, (800) 543-3619 or (440) 269-2300, fax (440) 269-2323, cnlmail@castnylon.com or www.castnylon.com.
Back to issue