8. Friction force calculation formula

8. Friction force calculation formula		Symbol description and unit
(1)Sliding friction	f₀=μ₀*R　[kgf] f₀=	μ₀： Maximum coefficient of static friction
(1)Sliding friction	f₀=μ₀*R　[kgf] f₀=	R： Force applied perpendicular to the surface[kgf]
(2) Dynamic friction force	f'=μ*R　[kgf] f'=	μ： Dynamic friction coefficient
(2) Dynamic friction force	f'=μ*R　[kgf] f'=	R： Force applied perpendicular to the surface[kgf]
(3) Rolling friction force	M_ρ=ρ*R　[kgf] M_ρ= M_ρ： Moment that hinders rotation	ρ： Rolling friction coefficient
(3) Rolling friction force	M_ρ=ρ*R　[kgf] M_ρ= M_ρ： Moment that hinders rotation	R：Force applied perpendicular to the surface[kgf]

References: "Machine Official Collection" (co-authored by Masaaki Oishi / Tatsuo Inami) Industrial Mechanics, page 35, refer to frictional force.