Rockwell Automation MPAI Heavy Duty Electric Cylinders - Manual (Page 47)

MP-Series Heavy Duty Electric Cylinders 47
Rockwell Automation Publication MPAI-IN001E-EN-P - March 2012
Roller Screw Lubrication
The lubrication interval (t
l
) of a roller screw actuator must be calculated. Factors that influence
the lubrication interval include the following:
• Frame Size - 83 or 110 mm (3.27 or 4.33 in.)
• Screw Lead - 5.0 or 10 mm/rev (0.197 or 0.394 in./rev)
• Basic lubrication interval (t
bl
) based on RMS velocity (V
rms
)
• Load correction factor (K) based on the actuator peak force (F
Xpeak
) and application
maximum commanded force (F
Xn
)
Use only the lubricant the factory recommends for your roller screw application.
Lubrication Interval Calculation
Use these steps to calculate the lubrication interval (t
l
) in hours for your roller screw electric
cylinder.
1. Select the basic lubrication interval (t
bl
) based on the RMS velocity (V
rms
).
t
bl
= 4500 x (V
rms
) -1.57 , hr
The basic lubrication interval (t
bl
) should fall within the range of this graph.
2. Determine the load correction factor (K) based on the ratio of actuator peak force
(F
Xpeak
) to the application maximum commanded force (F
Xn
).
Frame Size 83, 5 mm Roller Screw Load Correction
K
MPAI-x3xxxSM3xx
= 0.24 (F
Xpeak
/F
Xn
)-0.15
IMPORTANT Load Correction (K) must not be greater than one (<1).
100,000
10,000
1000
100
0 1 2 3 4 5 6 7 8 9
Cycle RMS Velocity (in/s)
Lu
bric
at
ion I
nt
er
val
(hr)
Basic Lubrication Interval (t
bl
)