Mitsubishi Chemical Advanced Materials UHMW-PE STERRA DRYSLIDE is a solid-lubricant-modified ultra-high-molecular-weight polyethylene stock shape supplied as plate, rod, and custom profile for dry-running guide rails, wear strips, and bearing components in packaging, bottling, and food-processing equipment. The grade designation is STERRA DRYSLIDE; no separate model number is published in the public datasheet. The base polymer is UHMW-PE, defined by ASTM D4020 as having an average molecular mass above 3.1 × 10⁶ g/mol. A proprietary dry lubricant additive is compounded into the matrix to modify the sliding interface; the exact additive chemistry is not stated in public literature. Published product-specific mechanical and tribological values are limited, so application thresholds should be confirmed against lot-specific certificates and the manufacturer’s technical datasheet. The product is positioned for dry sliding where external oil, grease, or silicone spray is excluded by hygiene, product-contact, or maintenance constraints.

Selection of STERRA DRYSLIDE for a replacement part is usually validated on a production conveyor trial rather than by tensile or hardness data alone. On high-speed beverage lines, UHMW-PE wear-strip failure is frequently observed as edge rounding, localized melting at transfer points, or black wear debris adhered to the mating stainless steel. Those field signatures indicate that the interface temperature exceeded the low thermal conductivity limit of UHMW-PE; the base polymer is often assigned a continuous service temperature of 80 °C in air. The solid lubricant in STERRA DRYSLIDE is intended to reduce frictional heat generation at start-up and during intermittent slipping, not to raise the bulk thermal endurance of the polyethylene. Thermocouple placement at the sliding surface is required when line speed or guide pressure is increased beyond the original installation parameters.

How Does STERRA DRYSLIDE Differ from Unmodified and PTFE-Filled UHMW-PE?

Unmodified UHMW-PE exhibits high impact toughness, low moisture absorption, and broad chemical resistance, but it can generate high breakaway friction after dwell periods and can slip-stick at low speeds. PTFE-filled UHMW-PE lowers dynamic friction but often reduces tensile strength and can produce inconsistent wear rates if the PTFE phase is poorly dispersed; some PTFE-filled grades also generate white wear debris that is visually objectionable on starch-based packaging lines. STERRA DRYSLIDE is formulated to reduce the static-to-dynamic friction differential, suppress stick-slip, and preserve the base polymer’s abrasion resistance under dry running. Direct substitution should be tested with the mating surface roughness and contact pressure of the actual installation because filler-modified grades can show different transfer-film formation rates. Lot certificates should state the friction coefficient obtained under a recognized method such as ASTM D3702 or ASTM G99; the two methods do not yield directly comparable values.

If Start-Up Friction and Stick-Slip Control the Conveyor Duty Cycle

In dry-running side rails and chain guides, service load is often below the compressive yield strength of UHMW-PE, but the start-up friction peak determines actuator sizing and surface wear. Field data from bottling conveyors show that unmodified UHMW-PE guide rails can exhibit a static friction event high enough to stall low-torque drives after extended shutdown, especially when the rail surface is scratched and the mating belt is new. STERRA DRYSLIDE reduces the breakaway load and the static-to-dynamic friction differential; it is therefore specified for indexing chains, star-wheel guide plates, and transfer tables that move intermittently. Contact pressure should remain below the yield strength of the specific formulation; for extruded UHMW-PE grades, compressive yield strength is typically 20–25 MPa per ISO 604. Product-specific values should be verified on the lot certificate. Initial surface break-in at reduced speed is used to establish a transfer film on the stainless steel counterface.

Compliance Documentation for Hygienic and Dry-Running Installations

Food-contact suitability is a property of the compounded article, not of the base resin alone. Unmodified UHMW-PE is commonly covered by FDA 21 CFR 177.1520 for olefin polymers and by EU Regulation (EU) No 10/2011 subject to migration testing. For STERRA DRYSLIDE, the solid lubricant additive must be verified against the applicable positive list, and the final stock shape must be declared compliant by the manufacturer for the intended food-contact condition. Lot-specific certification should include the material designation, production date, and any applicable 3-A Sanitary Standards or USDA acceptance letters if the installation is in dairy, meat, or poultry processing. The product is not claimed to be compliant in all jurisdictions; importers and converters are responsible for confirming national legislation and the specific migration limit for the lubricant additive. In dry-running applications, compliance documentation should also address wear debris because the material is consumed at the sliding interface.

Machining of STERRA DRYSLIDE stock shapes requires carbide or polycrystalline diamond tooling with high rake angles and sharp cutting edges. UHMW-PE has a high coefficient of thermal expansion and a low modulus; excessive cutting depth or blunt tools produce burrs, smear the surface, and close machined slots after part cooling. The material is usually machined dry, and coolant use is unnecessary at standard cutting speeds. Dimensional inspection should be performed after a stabilization period because the stock shape may continue to move after machining. General tolerances are assigned per ISO 2768-1 or the customer drawing, with additional allowance for thermal growth.

The linear thermal expansion coefficient of unmodified UHMW-PE is often reported between 1.5 × 10⁻⁴ K⁻¹ and 2.5 × 10⁻⁴ K⁻¹ per ISO 11359-2; the lubricant additive in STERRA DRYSLIDE may shift this value slightly. In a 2 m guide rail, a temperature rise of 30 K can produce expansion of approximately 9–15 mm if the rail is fully restrained. Slot clearances and end gaps must be calculated from stock-shape expansion data, not from steel guide rail allowances. Moisture absorption is below 0.01% per ISO 62 for unfilled UHMW-PE, so dimensional changes in wet wash-down areas are primarily thermal rather than hygroscopic.

UHMW-PE is resistant to sodium hydroxide, sodium hypochlorite, and many dilute acid cleaning agents used in food plants. STERRA DRYSLIDE is generally used at ambient wash-down temperatures because the maximum continuous service temperature of the base polymer is close to 80 °C. Exposure to steam above 90 °C can cause dimensional movement and local softening. Oxidizing media such as concentrated hydrogen peroxide or chlorine dioxide at elevated temperatures may attack the polyethylene matrix; the lubricant additive should be tested separately for extraction. Strong oxidizing acids should be excluded from the service environment unless compatibility is documented by the chemical supplier.

Wear factor is a system property, not a material constant

Any single coefficient-of-friction value has limited transferability. In qualification programs, STERRA DRYSLIDE is evaluated against an unmodified UHMW-PE control on a thrust-washer test at a fixed pressure and velocity. The output is a wear factor K in mm³/N·m or in³-min/ft·lb·hr, and the friction coefficient is recorded after the transfer film stabilizes. Unmodified UHMW-PE often exhibits a wear factor in the range 1–10 × 10⁻⁶ mm³/N·m under non-melting conditions; the dry lubricant modification may shift the wear rate within the same order of magnitude. Published data for STERRA DRYSLIDE in this specific configuration are limited, so direct substitution requires a back-to-back test. The mating counterface should be stainless steel with surface roughness 0.4–0.8 µm Ra and should be cleaned of polishing residues. If the wear surface shows curls or molten smears, the PV has exceeded the heat removal capacity of the polyethylene.

Machined STERRA DRYSLIDE wear strips are not recommended for static structural components because UHMW-PE creeps under sustained compressive load. The compressive modulus of UHMW-PE is typically 600–900 MPa per ISO 604, lower than acetal or nylon, and creep occurs at ambient temperature. Threaded inserts, bolt holes, and counterbored fasteners should include generous bearing washers and oversize clearance holes to accommodate thermal expansion. For heavily loaded static joints, a metal or acetal structural rail should carry the load while the STERRA DRYSLIDE component functions as the wear face.

Inspecting Wash-Down Failure Signatures on Dry-Running Conveyor Guide Rails

On production lines that combine dry sliding with frequent wash-down, failure often appears not as surface wear but as crack initiation at bolt holes and cutouts. Thermal expansion of UHMW-PE can exceed the clearance in rigidly bolted guide rails; after repeated wash-down cycles, the material can form radial cracks from fastener holes. Field inspection of dry-running conveyors has documented this mode when fixed holes and steel backing bars restrain the polymer. STERRA DRYSLIDE does not significantly alter the thermal expansion behavior of UHMW-PE, so hole design remains critical. For a 1 m rail length and a service temperature swing of 40 K, a linear expansion of approximately 6–10 mm is expected. Fastener slots should be oriented along the direction of expansion, and restrictively tight bolts should be avoided.

Acetal and Nylon Are Not Direct Substitutes for STERRA DRYSLIDE in Dry-Running Conveyor Systems

When a stainless steel or acetal guide is replaced with STERRA DRYSLIDE, the installation must account for the lower modulus and higher thermal expansion of polyethylene. Acetal homopolymer typically has a flexural modulus near 2 800 MPa per ISO 178, whereas UHMW-PE is substantially more flexible, with flexural modulus often below 1 000 MPa. Nylon absorbs moisture and may swell in wash-down areas; UHMW-PE does not absorb moisture to the same extent. The resulting difference is reduced breakage of glass containers, lower sliding friction, and improved resistance to cleaning agents at ambient temperatures. STERRA DRYSLIDE is therefore used where low friction and impact resilience are more important than dimensional rigidity. If the guide must span long unsupported distances or hold tight index tolerances, a stiff backing rail or an acetal structural component may be required.

The dry lubricant is intended to form a low-shear transfer film on the counterface. Transfer-film formation depends on sliding speed, load, and temperature. If the film is repeatedly removed by abrasive wear or by acid cleaning, the friction coefficient rises until the film is re-established. This explains why STERRA DRYSLIDE may show a transient increase in friction during the first minutes after cleaning; run-in should be scheduled after any acid or bleach wash.

The presence of the solid lubricant additive reduces the weldability of STERRA DRYSLIDE compared with unmodified UHMW-PE. Hot-gas welding and extrusion welding are possible on unfilled UHMW-PE components with polyethylene welding rod, but filler migration at the weld interface can reduce joint strength. Adhesive bonding is not a primary joining method for UHMW-PE after corona or plasma pretreatment. Mechanical fastening is the preferred joining method. When replacing an existing UHMW-PE part with STERRA DRYSLIDE, welding procedures must be revalidated on coupons cut from the same lot because filler distribution affects flow and fusion. Published data for this specific configuration is limited.

A procurement specification for STERRA DRYSLIDE should list the grade, form, dimensions, compliance requirements, and friction-test reference. Without a specified standard, a supplier may report the lowest coefficient of friction obtained under a different speed and pressure than the application. The specification should also require lot certification for density, hardness, tensile yield stress, and food-contact compliance where applicable. Machining drawings should identify the sliding surface, fastener direction, and required clearance for thermal expansion.