GUIDE TO SELECTING NYLON STOCK SHAPES FOR WEAR-RESISTANT APPLICATIONS
For wear-resistant applications, nylon's
toughness, low coefficient of friction and good abrasion resistance make it an
ideal replacement for a wide variety of materials from metal to rubber (see
- Nylon weighs about 85% less than bronze.
- Nylon reduces lubrication requirements, and
eliminates galling and corrosion problems.
- Nylon provides good sound dampening characteristics.
- Nylon is available in a broad range of grades and
stock shape sizes, including both extruded shapes and near-net shapes.
While there are many basic types of nylons,
the two most widely used grades are type 6/6 and 6. Various grades of each are
available to meet specific end-use requirements.
Nylon 6/6 stock shapes are extruded and
available in a variety of cross sections including rod, strip, tubing, custom
profiles and plate.
Nylon 6 products are cast from caprolactam.
It is typically supplied in rod, plate, tubular bar or custom shapes including
near net castings and finished parts.
Nylon is easily fabricated into precision
parts using standard metalworking equipment. Standard tooling is acceptable for
cast nylon, extruded 6 and 6/6, including molybendenum disulfide-filled,
talc-filled and calcium carbonate-filled grades. Carbide, carbide-tipped or
polycrystalline diamond tooling is suggested for glass fiber reinforced, carbon
fiber reinforced and graphite filled nylon.
Nylon has a proven record of outstanding
service in a multitude of parts for such diverse fields as paper, textiles,
electronics, construction, mining, metalworking, aircraft, food and material
Of the two major types of nylons, 6/6 is
slightly more heat resistant than 6. The short-term heat resistance of 6/6 is
about 250°F, under no load (230°F for 6). The long-term temperature
limit (continuous service temperature, CST) for 6/6 is 210°F (200°F for
Slightly higher CST is possible with heat
stabilized and filled grades. For example, molybendenum disulphide (MoS2)-filled
nylon 6/6 has a CST of 220°F; and, heat-stabilized nylon 6 has a CST of
Nylons have excellent resistance to
hydrocarbon fuels, lubricants, and many organic solvents. They are, however,
attacked by strong acids, oxidizing agents and concentrated solutions of certain
Nylon 6/6 and 6 absorb moisture in high
humidity or when submerged. Strength and wear resistance also decrease with
increased water content. Equilibrium moisture content of nylon 6/6 and 6 at 50%
relative humidity is approximately 2.5% and can be as high as 8% at saturation.
Part size Considerations
In general, small parts are most economical
to machine from extruded nylon stock shapes. Large parts are more economical to
machine from near-net cast nylon shapes. Near-net shapes, which require minimal
finish machining, increase savings by reducing material cost and machining time.
Like injection molding, casting allows the one-piece part combines several parts
into one, thus reducing manufacturing, assembly and maintenance costs.
Small general purpose wear and structural
parts -- Of all the unmodified nylons, extruded nylon 6/6 is the strongest,
most rigid and has one of the highest melting points. Unmodified nylon 6/6 is
stocked in both natural and black. Other colors are available on a custom basis.
Unmodified nylon 6/6 stock shapes are FDA, USDA, NSF and 3-A Dairy compliant.
Small parts with improved load-bearing
capability -- MoS2-filled nylon offers improved strength and rigidity. With
a lower coefficient of linear thermal expansion than nylon 6/6, MoS2-filled
nylon parts maintain better fit and clearances, and have less tendency to seize
Small parts with improved load capacity or
for improved frictional characteristics -- For applications requiring higher
compressive strength and rigidity, 30% glass reinforced nylon 6/6 is available.
It is stocked in diameters ranging from 10-mm to 150-mm (or .394 in. to 5.910
Large general purpose wear and structural
parts -- Heat stabilized nylon 6 offers long-term thermal stability to
260°F. It is blue in color.
Unmodified type 6 nylon offers the highest
strength and hardness of the nylon 6 grades. Natural (off-white), it is FDA,
USDA and 3A-Dairy compliant.
Large parts with improved load bearing
capability - Nylon 6/6 that contains finely divided particles of MoS2 offers
enhanced load bearing capabilities, while maintaining the impact resistance
inherent to nylon. It is the most commonly used grade for gears, sheaves,
sprockets and custom parts. It is gray-black in color.
Large parts having the best wear resistance
and lowest coefficient of friction -- Nylatron® NSM Nylon -- Proprietary
type 6 nylon formulation produced using DSM's Monocast® process. Solid
lubricant additives impart self-lubricating, high pressure/velocity and superior
wear resistance characteristics. Nylatron NSM was developed specifically for
demanding applications where larger size parts are required. It is ideal for
bearings, gears and wear pads. In wear applications, Nylatron NSM lasts up to 10
times longer than standard type 6 nylon.
Large parts with improved load capacity or
for improved frictional characteristics - Oil/MoS2-filled nylon 6/6 combines
load capacity and improved frictional characteristics. It excels in higher
pressures, and at low speeds-up to 40 fpm. It offers 20% lower coefficient of
friction, 50% greater limiting PV, and a lower "k" factor than
MoS2-filled nylon, and the lowest "slip-stick" of any nylon product
making it ideal for slide pads, thrust washers and trunion bearings. It is dark
blue in color.
|Typical Wear-Resistant Applications for Nylon Stock Shapes|
|Application||Material||Material Replaced||Benefits Gained With Nylon|
|Pivot bushing for mining truck||Solid lubricant filled nylon 6||Bronze||Excellent wear resistance and very low coefficient of friction|
|Wear pads for telescoping boom||Solid lubricant filled nylon 6||UHMWPE covered steel||Smooth, continuous movement of the boom and high load-capacity|
|Gears for printing equipment||Solid lubricant filled nylon 6||Bronze||Elimination of lubrication system and reduced gear noise|
|Nozzle for water treatment equipment||Heat stabilized nylon 6||Stainless steel||Lightweight results in easier installation and reduced cost|
|Rollers on conveyor||MoS2/oil-filled nylon 6/6||Ball bearing assembly||Elimination of external lubrication, longer life, and lower cost|
|Sheaves in marine lifting equipment||MoS2 filled nylon 6||Steel||Reduced weight, excellent corrosion resistance and increased life for wire rope|
|Berry harvesting tines||Nylon 6/6||Wood||Longer service life and reduced manufacturing cost|
|Sprockets for food processing equipment||Nylon 6||Stainless steel||Reduced noise and increased chain life|
|Dryer gears for paper processing equipment||Heat-stabilized nylon 6||Steel||Noise reduction and better property retention than possible with cast nylon|
For more information, contact Michael Oliveto, DSM Engineering
Plastic Products, 2120 Fairmont Ave., Reading, PA 19612-4235, 800-366-0300, Fax:
800-366-0301, e-mail: firstname.lastname@example.org, Web: www.dsmepp.com.