Case Study: Rigid Shaft Couplings

Design Brief

This coupling is required to provide torque from an engine to a variety of

propellers. There are three different sources which could provide the required

torque. All the specifications of the concepts fulfil the design constraints.

Department of Industrial and

Manufacturing Engineering University of

Malta

Case Study - Rigid Shaft Coupling 24 November 201208:46

10/12/2012 211/12/2012 2

Catalogue

Department of Industrial and

Manufacturing Engineering University of

Malta

Name: Shaft coupling A

Description: Rigid coupler with spline

Number of parts: 2 Bolt tightening torque (Nm): 6

Temperature Range (°C): -40 to 350 Material: Steel

Maximum speed (rpm): 800 Mass (kg): 0.761

Angular misalignment (°): 0.45 Axial misalignment (mm): 1.20

Nom. Torque (Nm): 12 Max. Torque (Nm): 19

Approximate cost (Euros): 23

Comments:

The rigid coupling has internal features

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Name: Shaft coupling B

Description: Rigid jaw shaft coupling

Number of parts: 5 Bolt tightening torque (Nm): 12

Temperature Range (°C): - 5 to 250 Material: Stainless Steel and Plastic

Maximum speed (rpm): 1000 Mass (kg): 0.602

Angular misalignment (°): 0.82 Axial misalignment (mm): 1.65

Nom. Torque (Nm): 2 Max. Torque (Nm): 4.1

Approximate cost (Euros): 16

Comments:

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Name: Shaft coupling C

Description: One piece rigid shaft coupling (keyed)

Number of parts: 5 Bolt tightening torque (Nm): 10

Temperature Range (°C): -20 to 555 Material: Stainless Steel

Maximum speed (rpm): 10000 Mass (kg): 0.894

Angular misalignment (°): 0.76 Axial misalignment (mm): 0.86

Nom. Torque (Nm): 12 Max. Torque (Nm): 20

Approximate cost (Euros): 29

Comments:

The shaft must have a key

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Name: Shaft coupling D

Description: One piece rigid shaft coupling (no-key)

Number of parts: 5 Bolt tightening torque (Nm): 10

Temperature Range (°C): -20 to 555 Material: Stainless Steel

Maximum speed (rpm): 12000 Mass (kg): 0.882

Angular misalignment (°): 0.70 Axial misalignment (mm): 0.81

Nom. Torque (Nm): 15 Max. Torque (Nm): 24

Approximate cost (Euros): 32

Comments:

11/12/2012 7

Name: Shaft coupling E

Description: Two Piece shaft coupling (keyed)

Number of parts: 10 Bolt tightening torque (Nm): 10

Temperature Range (°C): -20 to 555 Material: Stainless Steel

Maximum speed (rpm): 15000 Mass (kg): 0.963

Angular misalignment (°): 0.35 Axial misalignment (mm): 0.27

Nom. Torque (Nm): 18 Max. Torque (Nm): 31

Approximate cost (Euros): 43

Comments:

The shaft must be keyed

11/12/2012 8

Name: Shaft coupling F

Description: Two Piece shaft coupling (no key)

Number of parts: 10 Bolt tightening torque (Nm): 10

Temperature Range (°C): -20 to 555 Material: Stainless Steel

Maximum speed (rpm): 15000 Mass (kg): 0.963

Angular misalignment (°): 0.31 Axial misalignment (mm): 0.34

Nom. Torque (Nm): 16 Max. Torque (Nm): 28.5

Approximate cost (Euros): 38

Comments:

11/12/2012 9

Name: Shaft coupling G

Description: Keyed shaft coupling

Number of parts: 17 Bolt tightening torque (Nm): 15

Temperature Range (°C): -20 to 420 Material: Stainless Steel

Maximum speed (rpm): 11500 Mass (kg): 1.21

Angular misalignment (°): 0.04 Axial misalignment (mm): 0.21

Nom. Torque (Nm): 25 Max. Torque (Nm): 40

Approximate cost (Euros): 62

Comments:

Shaft needs to be keyed

11/12/2012 10

Name: Shaft coupling H

Description: Keyed shaft coupling with external spline

Number of parts: 4 Bolt tightening torque (Nm): 15

Temperature Range (°C): 15 to 80 Material: Plastic and steel

Maximum speed (rpm): 400 Mass (kg): 0.210

Angular misalignment (°): 0.98 Axial misalignment (mm): 0.82

Nom. Torque (Nm): 5 Max. Torque (Nm): 9

Approximate cost (Euros): 8

Comments:

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Meeting Notes

Department of Industrial and

Manufacturing Engineering University of

Malta

Spline is very difficult to machine - it is expensive in terms of resources.

Rigid Shaft Coupling A19 November 201219:34

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The plastic component has a very poor degradation resistance to sea and fresh waterIt has also a relatively low operating temperature.

Allen Keys (x2)

Rigid Shaft Coupling B19 November 201219:43

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Needs to be machined

Rigid Shaft Coupling C

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We had problems with this shaft due to degradation in sea water

Fasteners are easy to assemble

- additional cost

Has no key …easier to fabricate

4 Allen keys, our current assembly line can easily cope with 4 fasteners per interface

Rigid Shaft Coupling D19 November 201219:47

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Too many fasteners !

During the meeting the

out that we would need to

Open structure is easy to machine.

Yet on the other hand we

Rigid Shaft Coupling E19 November 201219:30

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need to machine the key

production engineers pointed

double the assembly lines.

No key = No machining

Rigid Shaft Coupling F19 November 201219:51

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Very complex assembly

Shaft Key Substantial material to be removed according to our

Rigid Shaft Coupling G19 November 201220:01

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production engineers

Problems with angular alignment

Only 2 Allen keys required

Rigid Shaft Coupling H19 November 201220:03

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People

Department of Industrial and

Manufacturing Engineering University of

Malta

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