SCREW NUT COLLAR FRICTION TABLE

Collar friction and screw & nut friction table for lead screws.

Friction Coefficient [f] for Screw and Nut
Screw Material	Nut Material
Screw Material	Steel	Bronze	Brass	Cast Iron
Steel, dry	0.15-0.25	0.15-0.23	0.15-0.19	0.15-0.25
Steel, machine oil	0.11-0.17	0.10-0.16	0.10-0.15	0.11-0.17
Bronze	0.08-0.12	0.04-0.06	-	0.06-0.09
Source : From Shigley's Mechanical Engineering Design [Ref 1] and Mechanical Design and Systems Handbook [Ref 2]

Thrust-Collar Friction [fc] Coefficients
Combination	Running	Starting
Soft steel on cast iron	0.12	0.17
Hard steel on cast iron	0.09	0.15
Soft steel on bronze	0.08	0.10
Hard steel on bronze	0.06	0.08
Source : From Shigley's Mechanical Engineering Design [Ref 1] and Mechanical Design and Systems Handbook [Ref 2]

Budynas.R , Nisbett.K. (2008) . Shigley's Mechanical Engineering Design . 8th edition. McGraw-Hill
Rothbart H. A. (1985), Mechanical Design and Systems Handbook , 2nd edition, McGraw-Hill