thyssenkrupp Materials NA Canada offers Acetal plastic, a thermoplastic made from POM (polyoxymethylene) resin which has excellent dimensional stability and is easy to machine to close tolerances due to its unique properties of moisture absorption, high tensile strength, and low creep. Acetal’s physical properties stay constant in a variety of environments and in temperatures up to 180ºF. Along with its excellent abrasion resistance, acetal plastic is one of the most widely used engineered plastics on the market. Acetal plastic is a popular choice for replacing parts that are traditionally machined from metals.
We offer two primary versions of acetal: homopolymer and copolymer. Chemically they are approximately 90% identical, however each acetal variety offers its own unique benefits. In addition, filled versions of acetal are available to help meet specific application requirements.
Benefits of Acetal Homopolymer
- Rigid
- Thermoforms easily
- Can be used in a wide variety of applications
- Impact resistant
- Good chemical resistant
- Low moisture absorption
- Stiffer than acetal copolymers, with higher flexural modulus at ambient temperature and in elevated temperature applications
- Higher impact strengths, at both ambient temperature and low temperatures
- Roughly 10-15% higher tensile strength than copolymers
- Higher continuous use temperature than copolymers (95°C vs. 90°C)
- Benefits of Acetal Copolymer
- More flexible and pliable than homopolymer
- Resistant to cracking at lower temperatures
- No moisture absorption
- FDA compliant
- Can be welded
- Can be bonded
- Greater dimensional stability than acetal homopolymer, due to lower crystallinity
- Better chemical resistance with high pH solutions (bases)
- Lower centerline porosity (see below) in extrusions
Other trade names for Acetal include: Celcon®, Delrin®, Ensital®, Pomalux®, Polyacetal®, POM (PolyOxyMethylene) Sustarin®, Tecaform®, Ultraform®, Unital®, and ZL 900.
Features of Acetal
- Excellent for general purpose parts in wet environments
- Machines to tight tolerances
- Homopolymer and Copolymer versions available to fit different applications
- Filled versions available including PTFE and lubricants*
- Available in FDA and USDA compliant grades
Acetal Applications
In addition to its general properties, acetal is resistant to a wide range of neutral chemicals, solvents, and hydrocarbons. Common applications for acetal plastic include:
- Bearings, bushings, rollers, and gears
- Wear pads and wear strips
- High speed conveyor lines
- Valves and manifolds
- Scraper blades in food processing applications
- Orthotic and Prosthetic applications, especially upper and lower limb prosthetics
- Food Processing applications requiring FDA compliance for food contact
- High moisture environments
Testing by manufacturers has shown that acetal bearings can outperform nylon bearings 4 to 1 in high moisture or submerged applications. Individual testing for your applications should always be done first.
Acetal Centerline Porosity
Most common in thicker extrusions and extruded rods, centerline porosity is visible as a lighter-shaded discoloration of the material, running down the center of the extrusion/rod for its entire length. In extruded slab, centerline porosity appears as a line along the center of each cut edge; in extreme cases, the slab may appear to be two separate pieces glued or laminated together. The main cause of this porosity difference is shrinkage caused by thermal inconsistencies. As it is extruded, the outer skin of the acetal cools and shrinks faster than the interior part of the extrusion. As the interior cools and shrinks, the solidified outer skin restricts the change in interior volume, causing voids to form in the remaining space.
Extreme centerline porosity is undesirable for cosmetic reasons. In some applications, it may compromise structural integrity and present a route for leakage of gas or liquids. The more porous area may also provide a place where build-up or foreign matter can occur, allowing bacteria to grow.
If you are looking for an acetal with no centerline porosity, thyssenkrupp is a stocking distributor of Mitsubishi Chemical Advanced Materials. Mitsubishi Chemical Advanced Materials Acetron® GP is made through their proprietary manufacturing process to create an acetal with no centerline porosity. Acetron® GP is available in acetal sheet and acetal rod formats.
Ask thyssenkrupp about filled acetal grades. Fillers can add and enhance properties to meet specific application needs. Fillers include PTFE and glass fibers that add dimensional stability to acetal sheet and acetal rod applications. Acetal is also available with proprietary internal lubricants that provide enhanced wear resistance.
