Ultra High Molecular Weight Polyethylene Rod (UHMW-PE Rod) Description
Ultra-high molecular weight polyethylene (UHMW-PE) rods are semi‐crystalline thermoplastics. They are characterised by molecular weights ranging from 3 500 000 to 7 000 000 g/mol. The material demonstrates a crystallinity between 50% and 85% with folded-chain lamellae (10–50 nm thick) and amorphous regions. An impact strength of ≥200 J/m (notched Izod test at 23°C) is recorded, while the tensile yield strength is approximately 20 MPa and the elongation reaches 50%.
The tribological properties of UHMW-PE are quantified as follows:
Coefficient of friction: 0.05–0.30 (dynamic, measured against steel; self-lubricating)
Abrasion resistance: <0.1 mg weight loss (ASTM D1044, 1 000 cycles)
PV limit: 0.3 MPa·m/s (dry running)
Thermally, the rods possess a melting point of 130°C and a glass transition temperature near –120°C. Continuous service is limited to 80°C (HDT: 50°C @0.45 MPa) given that the modulus decreases sharply above the glass transition. The coefficient of thermal expansion is 19×10⁻⁵ K⁻¹, and the thermal conductivity is 0.41 W/m·K.
Chemically, the rods resist exposure to concentrated acids and alkalis, chlorinated solutions and hot water (90°C) owing to non-polar chains and high crystallinity. Exposure to hydrocarbons induces a slight swelling (≤3% in hexane), whereas ketones and aromatics cause stress cracking. UV degradation is mitigated by stabilisation measures (for instance, carbon black incorporation extends outdoor service life beyond 10 years).
Electrically, the volume resistivity is on the order of 10¹² Ω·cm and the dielectric strength is 45 kV/mm. Surface tracking resistance is moderate (CTI: 200–400 V). Compliance with FDA/EEC standards permits the material to be used in food contact applications.
Ultra High Molecular Weight Polyethylene Rod (UHMW-PE Rod) Applications
UHMW-PE rods are utilised as engineering components in environments with high wear, chemical exposure and low friction. Their abrasion resistance (ASTM D1044 wear index <0.1 mg) and self-lubricating nature (coefficient of friction between 0.05 and 0.30 against steel) support their use in material handling systems. Applications include conveyor wear strips, chain guides and hopper liners in mining and aggregate operations, where recorded lifespans exceed those of steel by more than five times in abrasive conditions. The food and pharmaceutical industries employ precision-machined rods for FDA-compliant bearings, star wheels and valve seats, leveraging chemical inertness against acids, alkalis and hot water (up to 120°C short-term).
In industrial machinery, the rods are applied for low-maintenance cam followers, gears and piston rings in hydraulic systems. Reduced friction corresponds to energy consumption reductions of between 15% and 30% when compared with metal parts. In chemical processing, the rods serve in pump sleeves and tank stirring paddles, with resistance to concentrated acids (for example, 70% H₂SO₄) and chlorinated solvents. An impact strength of 200 J/m permits use in safety components such as dock bumpers and lifting pad inserts, with the capacity to absorb three times more energy than nylon.
Limitations include a continuous service temperature limit of 80°C (with creep deformation exceeding 5% at 10 MPa over 1 000 h) and a low tensile modulus (680 MPa). Consequently, support structures become necessary for load-bearing applications. Performance is maximised by utilising the anisotropic properties of the material (axial tensile strength is approximately 1.5 times higher than transverse strength) in sliding wear applications. These features enable UHMW-PE rods to function as cost-efficient replacements for metals, nylons and acetals in high-abrasion, chemically aggressive environments without requiring additional lubrication.
Ultra High Molecular Weight Polyethylene Rod (UHMW-PE Rod) Packaging
Our products are packaged in customised cartons of varying sizes based on the dimensions of the material. Smaller items are securely packed in PP boxes, whereas larger items are placed in custom wooden crates. The packaging customisation and use of appropriate cushioning materials are strictly adhered to, thereby ensuring optimal protection during transportation.
Packaging: Carton, Wooden Box, or Customized.
Kindly review the packaging details provided for reference.
Manufacturing Process
1. Testing Method
(1) Chemical Composition Analysis – Techniques such as GDMS or XRF are employed to verify conformance with purity requirements.
(2) Mechanical Properties Testing – Tensile strength, yield strength and elongation tests are conducted to assess material performance.
(3) Dimensional Inspection – Measurements of thickness, width and length are taken to ensure adherence to specified tolerances.
(4) Surface Quality Inspection – Visual and ultrasonic examinations are performed to detect defects such as scratches, cracks or inclusions.
(5) Hardness Testing – The material hardness is determined to confirm uniformity and mechanical reliability.
Please refer to the SAM testing procedures for further details.
Ultra High Molecular Weight Polyethylene Rod (UHMW-PE Rod) FAQs
Q1. How can precision machining be achieved without causing melting or burning?
The use of sharp carbide tools with a rake angle of at least 15° is required. Cutting speeds should be maintained between 300 and 500 m/min with feed rates of 0.1–0.5 mm/rev. Compressed air cooling must be applied because coolants result in swelling. Tool dwell time must be minimised to prevent local temperatures exceeding 80°C. Subsequently, an annealing process at 70°C for 2 hours is recommended to relieve machining-induced stresses.
Q2. What is the maximum PV limit for dry bearing applications?
For dry running, the limit is ≤0.3 MPa·m/s (for example, a load of 0.5 MPa at 0.6 m/s). For applications exceeding 0.3 MPa·m/s, water lubrication (PV limit ≤1.0) or grease (PV limit ≤0.7) must be employed. Exceeding the limit results in transfer film failure and rapid wear (>0.5 mm/100 h).
Q3. What are the chemical resistance limits for acids and alkalis?
The material resists 98% H₂SO₄ at 23°C, 50% NaOH at 80°C and chlorine bleach. Exposure to oxidising acids (nitric acid at concentrations greater than 30%), ketones (such as acetone) and aromatics (such as toluene) must be avoided, as these conditions cause stress cracking within 24 hours. Swelling in hydrocarbons is limited to ≤3%.
Related Information
1. Common Preparation Methods
UHMW-PE rods are produced by fusing ultra-high-molecular-weight polyethylene powder under heat and pressure. Virgin polymer powder (with a molecular weight exceeding 3 500 000 g/mol) is dried and loaded into cylindrical moulds. The material is compressed while being gradually heated to between 200°C and 250°C. The sintering process bonds the particles without fully melting them, which is a characteristic procedure for UHMW-PE due to the considerable chain entanglement.
Converters & Calculators
