Wear Rings and Strip

Wear rings and strip

Wear rings and guide strips accommodate radial loads of forces acting on the cylinder assembly and guide the rod in the cylinder head as well as guide the piston in the cylinder bore.

Guides are generally made of a polymer material which avoids metal-to-metal contact between moving parts in a working hydraulic cylinder. Compared to metal guides, polymer guides provide the following advantages in hydraulic cylinders.

• Significantly longer service life
• Work more smoothly against the cylinder tube and sealing surfaces
• Avoid wear of cylinder surfaces despite the presence of contamination particles
• High resistance to insufficient lubrication at low speeds
• Provides larger contact area due to higher degree of elastic deformation which distributes the load more evenly and reduces stress to the counter surface
• Provides certain self-lubricating ability

Materials

The most common materials for wear guides are listed below.

• Glass fibre reinforced polyamide (glass filled nylon)
• Phenolic/fabric composites
• PTFE (bronze filled)

Polyamide

Glass fibre reinforced polyamide (glass filled nylon) guides are suitable for medium to heavy duty applications and are characterised by the following properties:

• Wide temperature range
• Wear resistant
• Reduces vibrations
• Protects seals from particles
• Protects components from dieseling effect
• Easy to install
• Tight tolerances
• Able to withstand heavy side loads
• Able to withstand high cycling speeds
• Polyamides are prone to moisture swell. Therefore they should not be used with water based hydraulic fluids

Phenolic/Fabric composite

Phenolic/fabric composite consists of cotton fabric bound with thermoset phenolic resin. Its structure and ability of the fabric fibres to absorb a certain amount of oil make phenolic guides almost self-lubricating. However, phenolic guides should not be used at high stroke speeds over 0.5m/s (1.6 ft/s). Phenolic wear rings are suitable for medium to heavy duty applications and are characterised by the following properties:

• Wide temperature range
• Wear resistant
• Reduces vibrations
• Protects seals from particles
• Protects components from dieseling effect
• Low thermal expansion
• Easy to install
• Tight tolerances
• Able to withstand high cycling speeds
• Moisture resistant. Suitable for use with water based hydraulic fluids

PTFE (40% Bronze + MoS2)

PTFE is typically used in wear rings where low friction and resistance to chemicals, heat and wear are essential. However, PTFE should only be used in applications with low surface pressure. To obtain optimal wear resistance, PTFE materials are available with different fillers such as bronze and carbon powder. PTFE wear rings are characterised by the following properties:

• Wide spectrum of chemical resistance
• Wide temperature range
• Low friction
• Anti-adhesive, low breakout friction
• Good wear resistance
• Reduces vibrations
• Protects seals from particles
• Protects components from dieseling effect
• Tight tolerance machined wear rings available

WR Imperial Wear Rings

These standard guide rings can be used in piston and rod applications. WR imperial wear rings are made of glass fibre reinforced polyamide as standard. Non-standard wear ring materials can be made to order.

Material: Glass Filled Nylon