Specifications

AA.. CCyylliinnddrriiccaall IInneerrttiiaa
1. Outer Diameter (OD) = ________Inches
2. Inner Diameter (ID) [= 0 if Solid]
3. Weight (W) = ________Pounds
or Length (L) = ________Inches
Density (d) = ________lb/in
3
W = PI x ((OD ÷ 2)
2
) - ((ID ÷ 2)
2
) x L x d = ________Pounds
4. Total Inertia (J System)
= .5 x W ((OD ÷ 2)
2
) + ((ID ÷ 2)
2
) = ________lb-in
2
5. Total Friction Torque (F total) = ________oz-in
AA.. LLeeaaddssccrreeww SShhaafftt IInneerrttiiaa
1. Shaft Diameter (D) = ________Inches
2. Shaft Weight (W Shaft) = ________Pounds
or Shaft Length (L) = ________Inches
Shaft Density (d) = ________lb/in
3
3. Shaft Inertia (J Shaft) Calculation
= (W Shaft x (D ÷ 2)
2
) ÷ 2g or
= PI/32g x d
4
x L x d = ________lb-in
2
BB.. RReefflleecctteedd LLooaadd IInneerrttiiaa
1. Load Weight (W Load) = ________Pounds
2. Leadscrew Pitch (P) = ________Rev/in
3. Efficiency (E) = ________%
4. Load Inertia (J Load) Calculation
= (W Load ÷ (E x P
2
) x (1 ÷ (2 x PI))
2
= ________lb-in
2
CC.. TToottaall IInneerrttiiaa
1. Add leadscrew shaft = ________lb-in
2
Inertia and load inertia
J System = J Shaft + J Load
DD.. FFrriiccttiioonn
1. Friction Force = ________lb
F force = µ x W load
µ = Coefficient of Friction
2. Total Friction Torque = ________lb-in
F total = (F force) ÷ (P x E x 2 x PI)
Reference
Inertia Worksheet for Braking & Reversing Applications
Friction Coefficients (Sliding) µ
Steel on steel .58
Steel on steel (greased) .15
Aluminum on steel .45
Copper on steel .36
Brass on steel .44
Plastic on steel .2
Linear bearings .001
Mechanism Efficiencies %
Acme screw (brass nuts) .35–.65
Acme screw (plastic nuts) .5–.85
Ball-Screw .85–.95
Preloaded ball-screw .75–.85
Spur or bevel gears .9
Timing Belt .96–.98
Chain and sprocket .95–.98
Worm gears .45–.85
Material oz lb gm
Densities in
3
in
3
cm
3
Aluminum 1.57 .098 2.72
Brass 4.96 .31 8.6
Bronze 4.72 .295 8.17
Copper 5.15 .322 8.91
Plastic .64 .04 1.11
Steel 4.48 .28 7.75
Hard wood .46 .029 .8
Soft wood .28 .018 .48
A
side
= L x h
V = L x h x w
J = x (h
2
+ W
2
)
A
end
=π
2
V = A
end
x L
J = =
J =
A
end
= x (D
o
2
- D
i
2
)
J = x (r
o
4
- r
i
4
)
J = x (D
o
2
- D
i
2
) =
x (r
o
2
- r
i
2
)
V = volume
L = length
h = height
w = width
J = inertia
m = mass
W = weight
D = diameter
r = radius
g = gravity = 386 in/s
2
d = density
A = area
π = 3.14
W
12g
m D
2
8
W r
2
2g
π
4
m
8
W
2g
π Ld
2g
π Ldr
4
2g
AA.. MMoottoorr PPuulllleeyy IInneerrttiiaa
1. Diameter (D Pulley) = ________Inches
2. Weight (W) if known = ________Pounds
or calculate weight:
Length (L) = ________Inches
Density (d) = ________lb/in
3
W = PI x (D Pulley ÷ 2)
2
÷ 2 x L x d = ________Pounds
3. Pulley Inertia (J m System) Calculation
= W x (D Pulley ÷ 2)
2
÷ 2 = ________lb-in
2
BB.. LLooaadd PPuulllleeyy IInneerrttiiaa
1. Diameter (D Load) = ________Inches
2. Weight (W) if known or calculate weight:
Length (L) = ________Inches
Density (d) = ________lb/in
3
W = PI x (D Pulley ÷ 2)
2
÷ 2 x L x D = ________Pounds
3. Pulley Inertia (J 1 Pulley) Calculation
= W x (D Pulley ÷ 2)
2
= ________lb-in
2
CC.. EExxtteerrnnaall LLooaadd DDrriivveenn bbyy LLooaadd PPuulllleeyy
1. Load Weight (W) = ________lbs
2. Load Inertia = ________lb-in
2
J load = W x (D Load ÷ 2)
2
DD.. GGeeaarr RRaattiioo
G = (D Load)/(D Pulley) = ________
EE.. TToottaall IInneerrttiiaa
J system = J m Pulley +
(J 1 Pulley) ÷ G
2
+ (J Load) ÷ G
2
= ________lb-in
FF.. TToottaall FFrriiccttiioonn TToorrqquuee
(F Total) = ________oz-in
1. LEADSCREW MECHANICAL SYSTEM 2. CYLINDRICAL MECHANICAL SYSTEM
3. PULLEY MECHANICAL SYSTEM
0 91
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K
REFERENCE