This document discusses the design of mechanical spindle speeders used to increase the rotational speed of machine tool spindles. It presents optimal designs for spindle speeders based on power, speed ratio, and other factors. The designs are evaluated based on minimum volume and kinetic energy. Constructional solution A, which uses simple planets, is found to be most optimal with the lowest volume and kinetic energy across speed ratios and powers. Solution C can be used for high speed ratios over 1:10. Tables and graphs show comparisons of solutions and provide recommended designs.

1. Presented by : Guided by :
Harshal R. Borole D. P. Hujare
Roll no. ME11804

2. Introduction
Machining - a form of subtractive manufacturing in which
a collection of material working processes are used with a
sharp cutting tool to physically remove material to achieve
desired geometry.
All of the current trends in machining, from high-speed
machining (HSM) to knowledge-based systems are geared
towards maximising production capabilities.
HSM is growing rapidly as it provides several advantages
like reduced machining time, reduced mechanical stresses,
reduced heating of workpieces, high surface quality etc.

4. Obvious answers are, either….
Buy a new HSM centers
Upgrade an existing lower speed machine tool

6. Significance of Spindle
The spindle is one of the main mechanical
components in machining centers, since its design
directly affects the finished quality of workpieces and
machining productivity.
The spindle shaft rotates at different speeds and holds
a cutter, which machines a material attached to the
machine tool table.
The structural properties of the spindle depend on
the dimensions of the shaft, motor, tool holder,
bearings, and the design configuration of the overall
spindle assembly.

7. A compact gearbox, low cost option that
allows the increase of speed of a conventional
machine tool to the speed that of a High
Speed Machining

8. Common range of speed ratios for which
mechanical spindle speeders are designed is a
multiplication factor from 3.5 to 8 and up to
10.
Maximum output: 40,000RPM @ 2KW power
input

9. Spindle Speeder Gearbox
Functionality of spindle speeder gearbox depends
directly on its constructional solution
(arrangement, volume) and K.E. of transmission.
For optimum functionality, it is desired that
volume & K.E. should me minimum which also
ensures long working life.

11. To give a set of optimal designs of mechanical
spindle speeders based on different powers
and speed ratios which would help
manufacturers and engineers involved in
marketing and design of mechanical spindle
speeders.

13. Advantages of PGT
Compactness.
Ensure high proportion of energy transmitted.
Even Load distribution- greater stability.
Torque capability increased.
In-line transmission.

17. Figure D is more economic since it offers the advantage of
not using a ring gear
Fig A is more advantageous since it is constructed with
simple planets with ring gear as fixed member
What advantage……?
Rotational Kinetic energy,
Thus, K.E is directly proportional to mass
Hence, B,E and F are not appropriate configurations
2
2
Where,
2
1
.
rmI
IEK Rot
×=
××= ω

18. Choose an optimal number of planets for required
power and speed ratio
Number of planet members (Np) can vary from two to
three, four or even more, depending on application
for which it is being designed.
Thus, reduce the weight & kinetic energy of
transmission, ensuring good distribution of load on
each of planet gears
Planets must be arranged concentrically around the
PGTs principal axis to balance mass distribution

21. Module, m
Constraint: For gears to mesh, module for all
gears must be equal
Face Width, b
Constraint: 9m ≤ b ≤ 14m
T
D
m =

22. Gear Tooth Ratio, Znl
Where Znl is the ratio of gear pair formed by linking
members n and l
Constraint:
The tooth ratios can take any value, but in practice, they
are limited mainly for technical reasons because of
assembling gears outside of a certain range of gear ratios.
In this work, the constraint on tooth ratio is as proposed by
“Muller” and AGMA norms,
0.2 ≤ Znl ≤ 5 for external gear mesh
-7 ≤ Znl ≤ -2.2 for internal gear mesh
l
n
nl
Z
Z
Z =

23. Ratio of Diameters Constituting Double planet,
Constraint:
Where, d’4 is the diameter of the planet gear that meshes
with member 2 and d4 is the diameter of the planet
gear that meshes with member 1
Minimum Number of Tooth on Pinion, Zmin
Constraint: Zmin ≥ 18
3
d
d
3
1
'
4
4
<<

24. Simple Planet
Where, Z1 is the number of teeth on sun gear and Z2 is the
number of teeth on the ring gear (Sign depends on turning
direction of the sun & ring gear with arm fixed)
For Double Planet
&
Where, Np is the number of planet gears
integeran
N
Z
P
12
=
± Z
integeran
N
PPZ
P
1122
=
± Z
2
1
4
'
4
PZ
PZ
=

25. Hertz Contact Stress (As per ISO norms),
Allowable Hertz contact Stress
Hence,
Bending Stress (As per ISO norms)
Allowable Bending Stress
Hence,
u
u
db
F
ZZZZKKKK t
EHHHVAH
1+
×
×
××××××××= βεαβσ
XWVRLNHHP ZZZZZZ ××××××= limσσ
βεαααβσ YYYY
mb
F
KKKK SF
t
FFVAF ××××
×
××××=
XrelTNTSTFFP YYYY ××××= δσσ lim
HPH σσ <
FPF σσ <

26. Volume Function
( )
( ) ( )
( ) ( ) 'D'For,2max
4
'C'For2,2max
4
PlanetsimpleFor2
4
2
241'2414
2
'4241'2414
2
4141
dddbbV
ddddbbV
ddbV
D
C
A
+×+×=
++×+×=
+××=
π
π
π

27. Kinetic Energy Function
( ) ( )
2
N
V
2
N
2
1
PlanetDoubleFor
2
1
2
1
N
2
1
PlanetSimpleFor
2
4'44
P2
4
'
44
P2
11
2
44
2
44P
2
11
ωω
ωω
IImmIKE
IVmIKE
CD
A
++++××=






××+××+××=

28. The design variables are of constructional solution
chosen from those of Fig. A,C,D
Number of planet gears Np
Module of the gear mi
Number of teeth on each gear Zi
Face width bi
Helix angle βi
When these design parameters are determined by
minimizing the above objective functions, the PGT
is perfectly defined

33. Conclusions from Table 1 & 2 (For constructional solution of
A)
Gears designed with different module have greater
difference in kinetic energies (i.e. KE2-KE3)
Gears designed with same module have lesser difference in
kinetic energies (i.e. KE2-KE3)
Diameter based on minimum K.E design is always smaller
than diameter based on minimum volume design
Thus, the inference from above statement is that
mechanical spindle speeders must be designed based on
minimum KE solution.

34. Conclusions from Table 3 & 4 (For constructional
solution of C & D) and Graph
When compared with constructional solution of A
(Table 1&2), C & D have more volume and K.E’s
Graph gives comparison between A v/s C/D
K.Ec<<K.Ed and Vc<<Vd. Thus, solution D is poorer
than C.
Ratio between volume and kinetic energy falls as
speed ratio increases.

35. Adaptable to any machine:
Transfer machines
Special machines
Machining centers milling machines
Drilling machines
Lathe machining centers
Grinding machines

36. The best design of a mechanical spindle speeder is
based on the constructional solution of Fig. A which
is the most often used by mechanical spindle speeder
manufacturers
For Fig. A, each speed ratio, power and maximum
output speed, the results given in Table 1 and 2 offer
the most appropriate solution i.e. minimum volume
and minimum kinetic energy solutions.
The constructional solution of Fig. C can be used for
high speed ratios (>1:10)

40. Salgado DR, Alonso FJ (2009) Optimal mechanical spindle
speeder gearbox design for high speed machining. Int. J Adv
Manufacturing Technology.
Salgado DR, Alonso FJ (2007) Optimal machine tool spindle
drive gearbox design. Int. J Adv Manufacturing Technology
Maeda O, Cao Y, Altintas Y (2005) Expert spindle design
system. Int J Mach Tools Manuf
J. Jedrzejewski, W. Kwasny, Z. Kowal, W.Modrzycki
Wrocław Operational behavior of high speed spindle unit.