This is a complete presentation on Manufacturing and FMS layout for Marine Gears which are Helical, Spiral Bevel and Conical Bevel. It includes manufacturing, heat treatment process, FMS and testing also.

1. A Presentation on:
HELICAL GEARS
CONICAL GEARS
SPIRAL BEVEL GEARS
Application- MARINE
Presented By:
SOMESH SAURABH BT13MEC081
SONU VERMA BT13MEC082
DEBA PRAKASH BT13MEC099

2. PHYSICAL AND MECHANICAL PROPERTIES OF SAE-8620 STEEL
COMPOSITION
Carbon Manganese Nickel Chromium Molybdenum
0.18-0.23 0.70-0.90 0.40-0.70 0.40-0.60 0.15-0.25
MECHANICAL PROPERTIES
NORMALIZED AT 915˚ C
Tensile
Strength
(MPa)
Yielding
Strength
(MPa)
Elongation/
50 mm
BHN
Hardness
(HB)
635 360 26.3 183
ANNEALED AT 870˚ C
Tensile
Strength
(MPa)
Yielding
Strength
(MPa)
Elongation/
50 mm
BHN
Hardness
(HB)
540 385 31.3 149

3. Since marine gears are high speed gears and also there are
chances of high shocks during operation so the gears surfaces
must be strong enough to withstand dynamic loading and wear
resistance. So, in order to get these properties we do Heat
Treatment that includes:
1.Pre-hardening process
Annealing- Improves machinability- Involves heating to
870C and then slowly cooled to 315C in a furnace.
Normalizing- Controlling dimensional variations during
hardening processes.
- Heating to 800C and then cooling in atmospheric air
to relieve residual stresses.
Heat Treatment

4. 2.Hardening Process
 Case Hardening- To produce hard, wear-resistant surface
layer on top of a ductile, shock-resistant core.
- Idea is to keep the core of gear teeth at a level of
30-40 HRC to avoid tooth breakage while
hardening at outer surface up to 50 HRC to
increase pitting resistance.
 Carburizing- A Time-proven process in which a carbon-rich
atmosphere surrounding the workload is used to
chemically react with the surface of the parts to
allow an adequate quantity of carbon to be
absorbed at surface and diffused into the
material.

5. SIZE AND WEIGHT OF GENERAL HELICAL GEARS USED IN MARINE
APPLICATIONS
Diameter
(mm)
Thrust (kN) Approximate
Weight
(metric
tonnes)
1000 245 2.5
2000 1000 17
•MARINE GEARS ARE MADE HAVING FACE WIDTH UPTO 1000 mm
• THEY ARE SUPPOSED TO TRANSMIT POWER UPTO 15 MW (20,000 HP)

6. MANUFACTURING PROCESSES INVOLVED
CASTING : Centrifugal casting is used for manufacturing these large gear blanks.
• In this method the mould is rotated about its central axis and there exists a
continuous pressure as metal is solidifying
• This method is predominantly used for radial symmetrical casting

7. GENERATION OF TEETH BY MACHINING ON CASTED BLANKS
HOBBING
•Hob teeth are shaped to match the
tooth space and are interrupted with
grooves to provide cutting surfaces. It
rotates about an axis normal to that of
the gear blank, cutting into the rotating
blank to generate the teeth.
•It is the most accurate of the roughing
processes since no repositioning of tool
or blank is required and tooth is cut by
multiple hob-teeth.
•Excellent surface finish is achieved.

8. FINISHING OPERATIONS
• Grinding : In grinding , a contoured
grinding wheel is run over machined
surface of the gear teeth using
computer control .
• Small amount of metal removal with
high surface finish is obtained

9. • Lapping : Lapping employs an abrasive-impregnated gear or gear-shaped tool that
is run against the gear to abrade the surface.
• In lapping the abrasive tool drives the gear to an accelerated and controlled run-in
to improve surface finish and the accuracy.
• The figure shows the lapping operation for spiral bevel gears in employed in
marine.

10. MACHINES AND MATERIAL HANDLING SYSTEM
Flat AGVs for heavy and large gears
Grinding Machine
Hobbing Machine

11.  Rate of Production= 15pc/day
 Number of Shifts= 2 shifts/day
 Time for one Shift= 8hrs
 Heat treatment processes are not included in the FMS Layout
but it will come after hobbing process.
 Part mix is assumed on the basis of the number of gears
present in a standard gearbox of marine engine.
Assumptions for
FMS

12. Number of Servers per Station
Station Description Number of Servers
1. Loading/Unloading 2
2. Hobbing 2
3. Grinding 2
4. Lapping 2
5. Inspection 1
Total number of Servers=9

13. Operations to be performed by FMS
Part Part Mix
(Pj)
Operation Descriptio
-n
Station Process
Time(min)
Frequency
A 1 Loading 1 10 1
(Helical 2 Hobbing 2 60 1
Gear) 0.6 3 Grinding 3 40 1
4 Lapping 4 30 1
5 Inspection 5 10 .5
6 Unloading 1 5 1
B 1 Loading 1 2 1
(Conical 2 Hobbing 2 20 1
Bevel 0.2 3 Grinding 3 15 1
Gear) 4 Lapping 4 10 1
5 Inspection 5 5 .3
6 Unloading 1 2 1

14. Contd...
Part Part Mix Operation Descriptio
-n
Station Process
Time(min)
Frequency
C 1 Loading 1 2 1
(Spiral 2 Hobbing 2 20 1
Bevel 0.2 3 Grinding 3 15 1
Gear) 4 Lapping 4 10 1
5 Inspection 5 5 .3
6 Unloading 1 2 1

15. Line-Sketch of FMS

16.  Work Load at each Station=Wli= ∑∑tijk.fijk.pj
 Bottleneck Station = max(Wli/Si)
 Rp* = (No. of servers on bottleneck station)/(Work load on
bottleneck station)
 Production Rate, Rp= Pj.Rp*
 Utilisation, Ui =(Wli/Si).Rp*
Formulae used for calculations

17. Calculations For Bottleneck Station
Stations Workload(WLi)
(min.)
No. of Servers(Si) Wli/Si
1 10.6 1 10.6
2 44 2 22
3 30 2 15
4 22 2 11
5 3.6 1 3.6
Maximum Value of Wli/Si= 22 (Station 2).
Station 2 (Hobbing Station) is Bottleneck Station.

18. Utilization of Each Station
Station Description Utilization
1. Loading/Unloading 47.7%
2. Hobbing 100%
3. Grinding 67.5%
4. Lapping 49.5%
5. Inspection 16.2%
Overall Utilization of Stations=62.2%

19.  Rp*= (No. of servers on bottleneck station)/(Work load on
bottleneck station)
 Rp*=2.72 pc/hr
 Production Rate for Part A (Helical Gear)=1.632 pc/hr
 Production Rate for Part B (Conical Bevel Gear)=.544 pc/hr
 Production Rate for Part C (Spiral Bevel Gear)=.544 pc/hr
Production Rates of each
Part

20. TESTING OF MANUFACTURED GEAR
PARKINSON’S GEAR TESTING METHOD
•The standard gear is mounted on a fixed spindle and the gear to
be tested is mounted on another spindle which can slide over a
carriage
•The dial indicator gives the deviation of teeth profile of gear
being tested

23.  A flexible manufacturing system (FMS) is a manufacturing
system in which there is some amount of flexibility that
allows the system to react in case of changes, whether
predicted or unpredicted.
 Most FMS consist of three main systems. The work
machines which are often automated CNC machines are
connected by a material handling system to optimize parts
flow and the central control computer which controls
material movements and machine flow.
FMS