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Motor Selection Guide

Basic DATA for Calculation

Total weight of table & work	W =	kgf
Total mass of table & work	m =	kg
Coefficient of Friction	μ =
Ball Screw Operation Efficiency	η₈ =	90%
Pre-load Coefficient of internal friction of Nut	μ₀ =
Ball Screw Diameter	D =	cm
Ball Screw whole length	L =	cm
Ball Screw Pitch	P =	cm
Ball Screw Material Density	ρ =	kg/cm
Travel Distance	ℓ =	cm
Positioning Time	t₀ =	sec
Time of Acc/Dec	t₁ =	sec
25% of Position setting time is appropriate.

External Force	F_E =	kgf
Gravitational acceleration	g =	m/sec²
sin α	=
cos α	=
Basic Step Angle	=	°
Encoder Resolution	=	ppr
Installation angle	α =	˚
Gear Ratio	R =	Without Gearbox R=1
Gear Efficiency	η_R =	90% (Without Gearbox ηR=1)
Safety Factor	S =
Angle Resolution	Δθ =	˚

If you enter values in the yellow fields, the rest of the values are calculated automatically.

Refresh Calculate

Operation Speed and Acceleration Calculation

Work linearvelocity V =	I	=		= cm/sec
	t₀ - t₁		-
Ball Screw Rotation Speed ω_R = (V/P) × 60 = rpm
Operation Motor Revolution Velocity ω_M = (V/P) × 60 = rpm
Operation Motor Revolution Angular Velocity ω_M = (V/P) × R × 2π = rad/sec
Operating Motor Resolution Angular Acceleration = =	ω_M	=		= rad/sec²
	t₁
Ball Screw Acc/Dec Angular Velocity = ω_R =	V	× 2π =		× 2π = rad/sec
	P

Motor Selection


Just consider Rotor's Inertia Moment as J₀ = 0,
Motor Operation Torque	T_M =	so, from FASTEH Motor Torque curves
Operating motor revolution velocity	ω_M =	rpm at
Operating Torque is	T_M =	Select motor offers over N.m from curves

See Torque Curves of Selected Motor

Verify validation of selected motor


From selected motor spec, need to file out inertia moment J₀
J₀ = gcm² = kgcm² = kgm²
Motor's operating Torque re-calculation with consideration of motor inertia moment
T = N·m

[ Verify validation of selected motor ]
From selected motor's torque curve
Selected motor's revolution velocity	ω_M =	rpm at
Selected motor's torque is	T =	is over : OK.
Selected motor's torque is	T =	is less than : NG.
Repeat Motor selection and Verify Validation width increasing motor's length or size

Refresh Calculate

Check Load’s Intertia Moment Ratio K


K =	J_L	=		=
	J₀ × R²		× ²

Check Load's Intertia Moment Ratio K
Can operate but motor's inappropriate opation (vibrating at Acc/Dec) can be happened So, please input enough Acc/Dec and need to decrease operation speed If you can't control Acc/Dec and need to decrease operation speed, please increase one level of motor's length or size, We would like to recommend to choose bigger motor has higher inertia moment. In case of using reducer, even selected motor's operation torque is enough but load inertia moment ratio "K" is not satisfied, We would like to recomment to choose incrased ration of reducer.