Vishwas Mokashi has over 16 years of experience in quality assurance roles related to gears, mechanical components, and supplier management. He is currently responsible for quality oversight of 90+ local and global suppliers providing 2100 parts. Mokashi has expertise in gear design and manufacturing processes, supplier quality systems, and standards like ISO 9001, IATF 16949, APQP and PPAP. In this presentation, he provides an overview of gear fundamentals including classification, types, nomenclature, manufacturing, accuracy testing and metrology.

1. Introduction: Vishwas Mokashi
Total Experience 16 + years
 Supplier selection (Technical Capability Assessment)
 Suppliers Quality Performance monitoring and improvement
 Measure & improve suppliers quality systems
 Technical support in new part development
 Customer complaint & NC handling related to suppliers
A quality professional with more than
16+ years of overall experience in
diversified domains such as Gears,
Pulleys, Gear Boxes, Pneumatics,
Machining, Fasteners, Bearings,
Technological Components and
Proprietary Parts. Currently managing
90+ local and global suppliers suppling
2100 parts.
Vishwas Mokashi
Experience
Work Experience in
• Gears and Gear Boxes
• Product & process quality
• Supplier Quality Assurance
• Supplier Development
• New part development
• ISO 9001:2015
• IATF 16949
• APQP, PPAP, SPC, MSA, AIAG VDA FMEA, 8D
Present Role & Responsibility

2. Basics of Gears, 03/2023, Vishwas Mokashi
Basics of Gears

3. Topics:
Basics of Gears, 03/2023, Vishwas Mokashi
 Mechanical Drives
 What is Gear
 Classification of Gears
 Types of Gears
 Nomenclature of Gear
 Working Gear Nomenclature
 Gear Manufacturing processes
 Process flow of Gear
 Gear Accuracy
 Gear Metrology
 Terms in lead and profile graph

4. Mechanical Drives:
Basics of Gears, 03/2023, Vishwas Mokashi
The mechanisms which are used to transmit the required motion and power from one shaft to another shaft
are called mechanical drives.
Types of Mechanical Drives:
1. Belt and rope drives
2. Chain drives
3. Gear drives
These three power train elements transfer energy through rotary motion.
Change the speed of rotation
Change the direction of rotation
Change the amount of torque available to do work.

5. We all know gears?
Basics of Gears, 03/2023, Vishwas Mokashi
A gear can be defined as the
mechanical element used for
transmitting power and rotary
motion from one shaft to another by
means of progressive engagement of
projections called teeth.
Advantages of Gear drives:
 Compact as compare to belt or
chain.
 Transmit higher power and speed
as compare to belt or chain.
 Transmit power between shafts
which are parallel / non-parallel,
intersecting / non-intersecting.
 Used for wide range of speed
ratios.

6. Classification of Gears:
Basics of Gears, 03/2023, Vishwas Mokashi
Gears can be broadly classified by looking at the positions of axes such as parallel shafts, intersecting
shafts and non-intersecting shafts.
 Power Transmit in PARALLEL SHAFT
 Spur Gear
 Helical Gear
 Power Transmit in two INTERSECTING SHAFT
 Bevel Gear
• Straight Bevel Gear
• Spiral Bevel Gear
 Power Transmit in NON PARALLEL and NON INTERSECTING SHAFT
 Worm and worm Gear

7. Types of Gears:
Basics of Gears, 03/2023, Vishwas Mokashi
Spur Gear:
Teeth are straight and
parallel to the gear shaft
axis.
transmits motion between
parallel shafts.
Helical Gear:
Teeth are inclined to the axis of
rotation, the angle provides more
gradual engagement of the teeth
during meshing,
transmits motion between parallel
shafts.
Rack & Pinion:
Rack and pinion is type of
spur gear.

8. Types of Gears:
Basics of Gears, 03/2023, Vishwas Mokashi
Bevel Gear:
Gears that mesh at an angle, usually 90°
Changes the direction of rotation
Shafts of the gear and pinion can intersect at
90°or any desired angle.
Straight Bevel Gear Spiral Bevel Gear
Worm and Worm Gear:
Use for high velocity ratio (up to
300:1).
The worm only be driving element.

9. Nomenclature of Gear:
Basics of Gears, 03/2023, Vishwas Mokashi

10. Nomenclature of Gear:
Basics of Gears, 03/2023, Vishwas Mokashi
Pitch Circle : It is an imaginary circle which by pure rolling action would transmit same motion as the
actual gear.
Pitch Circle Diameter(d) : It is diameter of pitch circle.
Module : It is ratio of pitch circle in mm to number of teeth.
Addendum (ha) : It is radial distance between top land of the teeth and pitch circle. Normally addendum =
1 module.
Dedendum (hf) : It is radial distance between bottom land of the teeth and pitch circle.

11. Nomenclature of Gear:
Basics of Gears, 03/2023, Vishwas Mokashi
Whole depth : It is radial distance between Addendum circle and dedendum circle. It is sum of Addendum
and dedendum.
Circular Pitch : It is the distance measured along the circumference of the pitch circle ,from point on one
tooth to corresponding point on next tooth.
Pressure Angle : It is the angle between the common normal to the two gear teeth at point of contact and
common tangent to two pitch circles at pitch point.
Pressure angle is the angle at which pressure from the tooth of one gear is passed on the tooth of another
gear. 14.5°and 20°are standard pressure angle.

12. Working Gear Nomenclature:
Basics of Gears, 03/2023, Vishwas Mokashi
Backlash - Backlash is
the amount by which
the width of a tooth
space
exceeds the thickness
of engaging gear
tooth.
In general, backlash
in gears is
play/clearance
between mating
teeth.

13. Gear Manufacturing Processes:
Basics of Gears, 03/2023, Vishwas Mokashi
METHODS:
Broaching
Shaping
Milling
Plastic Injection Molding
Powder Metal Sintering
Forging
Casting
Hobbing
Hobbing:
Generally gears are produced by hobbing. Gear hobbing is
continuous indexing process in which both cutting tool(hob) and
workpiece rotates in a constant relationship , while the hob is being
feed into work. After one complete rotation of gear blank, the gear
blank is feed horizontally towards the hob to cut next tooth depth.
This process is repeated until the required depth is obtained.

14. Process Flow of Gear:
Basics of Gears, 03/2023, Vishwas Mokashi
Gears_-_How_its_Made.mp4

15. Gear Accuracy:
 Gear must work in transmitting rotation or power from one gear axis to
another, efficiently and quietly. To improve gear accuracy is to improve the
performance of a gear.
 Gear accuracy can be classified into three types;
1. Precision in involute tooth profile --- Profile deviation(error)
2. Precision in tooth face --- Lead deviation(error)
3. Precision in tooth positioning/ tooth trace ---
a) Precision in pitch – Single pitch variation and total cumulative pitch variation
b) Variation of position – Run out error
Basics of Gears, 03/2023, Vishwas Mokashi

16. Gear Metrology:
1. Size inspection:
a) Span measurement by span micrometer
b) Bore and keyway measurement by gauges
c) Symmetry, run out, face out and
parallelism measurement.
d) Worm gear tester - To measure tooth
contact and backlash.
Basics of Gears, 03/2023, Vishwas Mokashi
2. Composite inspection:
In this method the work gear is rolled in tight
double flank contact with master gear. No
backlash is provided. The roll tester allow
variation in the center distance during rolling.
This variation in center distance will yield a
‘tooth to tooth’ and a ‘ total composite ’
indication that can be read on simple dial
indicator or recorded graphically.

17. Gear Metrology: Lead and Profile Testing
Basics of Gears, 03/2023, Vishwas Mokashi
3. Lead and profile
testing
Lead and profile
testing is done on
L&P tester.
Internationally
accepted
prominently used
standards are DIN,
AGMA, JIS.

18. Terms in Lead and Profile Graph:
Basics of Gears, 03/2023, Vishwas Mokashi
Various characteristics identified for such
a classification are
called “Gear Errors”.
Main categories of such characteristics
are Tooth Profile /
Form Errors , Pitch Errors , Lead / Helix
Errors , Eccentricity
GEAR ACCURACY
Errors , Finish Errors , Cyclic errors,
Rolling errors etc.
We need to understand these to
implement and build
preventive measures in our manufacturing
process design ,
selection of equipment and tooling's,
selection of appropriate
measurement method etc. for achieving
appropriate class of gears.
Symbol Nomenclature Definition
fHα Profileangularerror
Distance between two nominal profilesthat intersect theaverage profile at startandend
points of theprofile range.
Fα TotalProfile error Distance between two nominal profilesenclosed within the profile testrange.
ffα Profile formerror
Distance between two involutesof the actual basecircle thatenclose the actual involute
profile within theprofileinspection range.
fHβ Lead angularerror
Distance between two nominal leads that intersectthe average lead at start and end points
of the lead inspection range.
Fβ Total lead error Distance between two nominal leadsenclosed within the leadtestrange.
ffβ Lead form error
Distance between two helical lines thatenclosethe actual lead enclose within the lead
inspection range.
fp Tooth to toothspacing
Fp Total cumulativepitch variation Difference betweenthe themost positive and the most negative valueforall teeth
Fr Radial runout
Radialposition difference of a probe contacting allteeth at measuring diameter(pitch
diameter).

19. Class of Accuracy Comparison:
Basics of Gears, 03/2023, Vishwas Mokashi
In DIN ( German
Standards) lower the class
higher the accuracy ,
where as in AGMA (
American Standards) lower
class represents lower
accuracy.
The allowable Errors in
equivalent class as
represented in the
comparative are not
exactly same but near
about. That means if
drawing specifies class of
accuracy as per AGMA we
need to follow allowable
errors as per AGMA and so
on.

20. L&P Report Header:
Basics of Gears, 03/2023, Vishwas Mokashi
General Info Gear data

21. Profile Error Chart:
Basics of Gears, 03/2023, Vishwas Mokashi

22. Profile Error Evaluation:
Basics of Gears, 03/2023, Vishwas Mokashi
Average
value
Nominal value as
per DIN 3962
Observed
class
Required
class

23. Basics of Gears, 03/2023, Vishwas Mokashi
THANKS !
vsm_97@rediffmail.com