Wear Rings

Advantages
  • Very good anti-friction-behavious
  • No stick-slip effect
  • Good dry running characteristics
  • Good wear resitance, long service life

Wear rings are designed to guide the piston and piston rods of power cylinders and to absorb lateral forces where they occur. They also prevent metal to metal contact between sliding parts. Wear rings are available in tape or machined rings.

An important advantage is that metallic siezure cannot occur with the correct design. The most frequently used non-metallic wear rings are filled PTFE and compounds of PTFE and fabric materials.

Wear rings are easily fitted into the closed grooves on the piston or in the glands. The number of wear rings to be used will depend on the radial forces and the permissible surface pressure of the wear ring material, in addition to the length of stroke, the diameter and other design factors.

Table for Type M80 and M81
Tape Ring Rod Ø
C f8
Groove Ø
​D + 0.08
Groove
Width L+0.2
Diametral
Clearance
E Max*
Groove Ø
B - 0.05
Cylinder Ø
​A H9
Tape Ring
M8003C M8103C 8-20 C + 3 3.2 0.4 - 1.0 A - 3 10-25 M8003A M8103A
M8804C M8104C 15-35 C + 5 4.2 0.5 - 2.0 A - 5 20-40 M8004A M8104A
M8006C M8106C 20-75 C + 5 6.3 0.5 - 2.0 A - 5 25-80 M8006A M8106A
M8008C M8108C 30-250 C + 5 8.1 0.5 - 2.0 A - 5 40-270 M8008A M8108A
M8009C M8109C 50-300 C + 5 9.7 0.5 - 2.0 A - 5 60-320 M8009A M8109A
M8010C M8110C 50-300 C + 5 10.1 0.5 - 2.0 A - 5 60-320 M8010A M8110A
M8015C M8115C 120-900 C + 5 15.0 0.5 - 2.0 A - 5 120-900 M8015A M8115A
M8020C M8120C 200+ C + 5 20.0 0.5 - 2.0 A - 5 200+ M8020A M8120A
M8025C M8125C 300+ C + 5 25.0 0.5 - 2.0 A - 5 300+ M8025A M8125A
M8030C M8130C 300+ C + 5 30.0 0.5 - 2.0 A - 5 300+ M8030A M8130A
M8040C M8140C 300+ C + 5 30.0 0.5 - 2.0 A - 5 300+ M8040A M8140A
M8050C M8150C 300+ C + 5 30.0 0.5 - 2.0 A - 5 300+ M8050A M8150A

Calculating Wear Ring Lengths and Gaps

Calculating Wear Ring Length and Gaps Calculating Wear Ring Widths
H:     F
___________
Fg x A
L = Length H = 0.5
C = Rod ø  
A = Bore ø    
S = Wear Ring Thickness where  
Z = Gap between ends of installed H = Ring Width
  Wear ring (mm) (see table A) F = Side Load (Kp)
    Fg = Material Specific Load (Table B)
Then:   A = Cylinder ø or C = Shaft ø
L = 3.142 (C + S) +/- Z for Rod
L = 3.142 (A + S) +/- Z for Piston
Table A:
Dia A or
C mm
Z mm up to
°120C
Z mm at 200°C
50 0.00 -1.00
100 1.00 -1.00
200 2.00 +1.50
300 4.50 +4.00
600 10.00 +9.00
800 13.00 +13.00

 

Table B:
Code
No
Composition Temp
°C
Material Load
kp/mm2
Application Coeff.
Friction
05 PTFE/Carbon Graphite -250 to +320 0.85 at 50°C
0.65 at 85°C
Water/Air 0.10
07 PTFE/Bronze -150 to + 290 1.60 at 50°C
0.90 at 85°C
Hydraulic Oil 0.08
10 UHMW - PE -150 to +80 16.5 at 50°C Water 0.11
99 PTFE/Polyester -150 to +145 340 at 50°C Water, Air, Hydraulic Oil 0.10

Cut Styles

Bearing capacities are given for speeds up to 1.5 m/s, Above this value, consult Moontown. Moontown wear rings can be used in all hydraulic oil media.

PTFE materials have a low coefficient of friction but also low load characteristics. They are therefore more suitable for low load applications.

Thermoplast materials have a higher friction coefficient but also high load characteristics, and can be used in high pressure.

Wear rings are made with different cuts: x for reciprocating, y for rotary and z for reciprocating or rotary movements in contaminated systems to protect the seal.

In extremely contaminated systems, consideration should be given to the use of code 99 material position inboard of the seal with any other wear ring material situated in the outboard position if required.

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