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International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 7, July 2017, pp. 1034–1051, Article ID: IJMET_08_07_112

Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=7

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

DESIGN OF FIXTURE FOR THE

MANUFACTURING OF COMPRESSOR ROTOR

BLADE IN AIRCRAFT ENGINE

M. Snigdha, C. Satya Sandeep, G. Swathi, Suresh. R, P. Hanuma

Assistant professor, Department of Aeronautical Engineering,

Institute of Aeronautical Engineering,

Dundigal, Hyderabad, India

Praveen. B

Assistant professor, Department of Aeronautical Engineering,

Marri Laxman Reddy Institute of Technology, Dundigal,

Hyderabad, India

ABSTRACT

Fixtures are work piece holding devices which support and hold the work piece

tightly during the manufacturing process. Compressor blades that might be stator or

rotor are parts which are very complicated with design. Even a slight diversion in the

design might decrease the compression efficiency. The current work includes design of

12 parts and their assembly into a final fixture used to hold the compressor blades while

machining. CATIA software was be used to accomplish the design process.

Key words: Fixtures, Compressor blades of aircraft engine, CATIA.

Cite this Article: M. Snigdha, C. Satya Sandeep, G. Swathi, Suresh. R, P. Hanuma and

Praveen. B, Design of Fixture for the Manufacturing of Compressor Rotor Blade in

Aircraft Engine, 8(7), 2017, pp. 1034–1051, 8(7),

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=7

1. INTRODUCTION

Compressors are one of the very important parts of gas turbine aircraft engines. Their main aim

is to provide compressed air to combustion chamber enable the efficient burning process. Apart

if this compressor supplies the bleed air into the different parts of the engine which is used for

the cooling purpose. We do have axial flow and centrifugal compressors with axial flow

compressors being more popular to be used in the aircraft engines. Design of the compressor

blades play a key role in deciding the quality of the compressor stage. The compressor

efficiency might be varied according to the amount of diversion of the blade design with the

optimal design point. It is very much important to manufacture a blades of compressor without

any noticeable flaws in output products design. It is not as simple as quoted above, the design

Design of Fixture For The Manufacturing of Compressor Rotor Blade In Aircraft Engine


of the compressor blades undergo nearly 200 steps of operation. Table 1 given below mentions

some of the important operations in the compressor blade design phase.

Table 1 List of the important operations in Compressor blade manufacturing process

OPERATION

S.NO NAME OF THE OPERATION

005 BILLET CHART

010 PREPARATION OF DOCUMENT

015 CNC MILLING (LATERAL SIDES & BASE OF ROOT)

020 CNC MILLING OF CONE (FACE OF ROUT}

025 BENCH WORK & WASHING

030 INTERMEDIATE INSPECTION

035 BENCH WORK S, ASSEMBLY WITH CERO BOND

040 CNC TURNING OF ROOT

045 DISMANTLING & BENCH WORK

050 BENCH WORK & ASSEMBLY WITH CERDBDND

055 CNC TURNING

060 DISMANTLING & BENCH WORK

065 INSPECTION & TRANSFER OF MELT

070 CNC MILLING OF PROFILE & EDGES

075 PARTING OFF

030 BENCH WORK

035 POLISHING OF PROFILE & EDGES,

090 VIBRD POLISHING OF PROFILE

095 POLISHING OF OBLIQUE RADIUS

100 MILLING (RECESS)

105 BENCH WORK

110 TIP TURNING IN A SET ON A DUMMY ROTOR

115 BENCH WORK & WASHING

120 INTERMEDIATE INSPECTION

125 PICKLING

130 INSPECTION

135 POLISHING OF EDGES

140 VIBRIO -POLISHING OF PROFILE

While all the above mentioned operations are performed, a very important agent which

holds the specimen without any movement in is a fixture. Fixtures play a key operational role

in holding the work pieces during the batch production. However, the advantage in use of

Fixtures are so great and so varied, that these devices have also naturally found their way into

the production of parts in limited quantities as well as into manufacturing processes outside of

the machine shop and even outside of the metal working industry.

It is a special tool used for locating and firmly holding a workspace in the proper position

during a manufacturing operation. As a general rule it is provided with devices for supporting

and clamping the work piece. It is fixed to the machine bed by clamping in such a position that

the work in the correct relationship to the machine tool elements. These are the devices, which

accelerate the production particularly with 100% interchangeable parts. The origin of fixtures

can be traced back to the Swiss watch and Clock industry from which after proving their

usefulness they spread throughout the metal working industry. Inside a machine shop, Jigs and

Fixtures are used for the following operations: Drilling, Boring, Broaching, Grinding, Honing,

Lapping, Milling, Planning, Profiling, Reaming, Sawing, Shaping, Slotting, Spot facing,

Tapping and Turning. Outside the machine shop, fixtures may be applied to advantage for:

M. Snigdha, C. Satya Sandeep, G. Swathi, Suresh. R, P. Hanuma and Praveen. B


Assembly, Brazing, Heat treating, Inspecting, Riveting, Soldering, Testing and welding. The

main purpose of the fixtures are clearly mentioned below.

1. The main purpose of the fixture is to locate the work quickly and accurately, Support it properly

and hold it securely, thereby ensuring that all parts. Produced in the fixture will come out alike

within the specified limits, in this Way accuracy and interchangeability of the parts are provided.

2. It also reduces working time in the various phases of the operation, in the setup and clamping

the work in the adjustment of the cutting tool to the required dimensions, during the cutting

operation itself by allowing heavier feeds due to more efficient work support.

3. It serves to simplify otherwise complicated operations so that cheaper and relatively unskilled

labor may be employed to perform operations previously reserved for skilled machines.

4. By maintaining or even improving the interchangeability of the parts, a jig or fixture contributes

to a considerable reduction in the cost of assembly, maintenance and the subsequent the

potential of standard machines and the quality of the parts produced.

5. One important goal is used to design a fixture in such a way as to make it Foolproof, and there

by contribute to added safety for the operator as well for the work.

Design of fixtures for complicated parts like compressor and turbine blades is very much

important to avoid flaws in production of those parts. Many developments in design of fixtures

for complicated parts have been into picture since 1980s. In the year 1994, Peter.W.M along

with his team mates took a patent for Fixtures and methods for machining rotors, in which they

came out with an efficient method and apparatus including a rotor mountable fixture for guiding

a cutting tool powered by hand held air motor to machine a gas turbine engine rotor without

removing the rotors from the mounting of the engines. [1]

James L. Tangler provided a historical perspective of the evolution of rotor and blade design

during the last 20 years. He observed that the evolution is a balanced integration of economic,

aerodynamic, structural dynamic, noise, and aesthetic considerations, which are known to be

machine type and size dependent. The design of a modern rotor includes choices of blade

number, airfoils, chord and twist distributions, and materials. The justification for each of these

choices often includes conflicting considerations that need to be prioritized. For example, thin

airfoils are desirable for their high lift-to-drag ratios and are roughness tolerant, whereas thick

airfoils sacrifice some of these qualities to achieve the greater blade stiffness required for large

machines. The pros and cons of these considerations are explored to better understand the

current state of rotor and blade design. Some obvious blade design trends resulting from

increased rotor size include lower blade solidity, increased airfoil thickness, and maximum lift

coefficient, along with incremental increases in tip speed. Limits that govern these trends need

to be understood in order to achieve a minimum cost-of-energy design. [2]

C.Radha Madhavi and team had designed a machining fixture for turbine rotor blade. Their

fixture Design consisted of High product rate, low manufacturing operation cost. Their work

contained with study of input data from customers like Part drawing and Assembly drawing.

They performed fixture design beginning with part modeling, Machining and Analysis of

various parts in the fixture assembly using AutoCAD and Solid works, for analysis the used

COSMOS Software. [3]

S. J. Gallimore had worked on the design of axial flow compressor design, where he

outlined some of the basic principles and rules associated with the design of axial flow

compressors, principally for aero-engines, as well as the practical constraints that are inevitably

present. [4] Shailesh S.P have given a review on the design of the fixtures. He enhanced the

efficiency and reliability of the fixture design by the system and the result of the fixture design

has made more reasonable. He quoted that to reduce cycle time required for loading and

unloading of part, his approach is useful. He concluded that if modern CAE, CAD are used in

designing the systems then significant improvement can be assured and to fulfill the



multifunctional and high performance fixturing requirements optimum design approach can be

used to provide comprehensive analyses and determine an overall optimal design. [5]

2. DESIGN CHECK-LIST FOR FIXTURES

2.1. The Part Drawing

• Check the date and revision references on part blueprint and make sure that the print is the latest

edition and that it is up to date with respect to revisions.

• Make at least a cursory check of the part on the blueprint: make sure that all views and sections

are correctly oriented.

• Having ascertained the correct shape of the part, check all part outlines shown on fixture

drawings, particularly for correct orientation.

2.2. The Shop

• Make sure that there are no obstructions in the shop layout, or around the work station, as well

as along its access ways that will prevent or otherwise interfere to its station.

• Investigate whether the work station is equipped with the necessary services, such as

compressed air supply, if needed for activated the fixture.

• For heavy items (Fixture as well as part), a hoist should be available.

• Once the fixture is properly located, examine the shop layout around the work station to make

sure that it permits transportation and delivery of parts to the work station.

• The same consideration applies with respect to the loading of the part into the fixture.

Specifically, watch out for long pars projecting out of the fixture.

• For a work station that is part of a production line, the fixture, when installed, should be correctly

located and oriented with respect to the line.

2.3. The Machine Tool

• Be sure that the fixture will fit the machine tool for which it is intended. Check overall

dimension and the space within which the fixture is to be installed (the tooling area). Check

dimensions of machine table, and the dimensions, location, width, and accuracy of T-slots, and

compare with the locating blocks in the fixture base.

• The fixture must be fully supported and must not overhang the edge or end of the table.

• Investigate the condition of the machine tool to make sure that the accuracy is satisfactory for

the tolerances required in the operation.

• Make sure that the machine is strong and rigid enough to carry the weight of the fixture and

absorb shocks and vibrations from the operations.

• For rotating fixtures such as turning fixtures, make sure that it is balanced with part in place.

• Make sure that the breakage of part, tool, or fixture does not present a hazard to the machine

tool or the operator.

• The machine must be capable of performing the required table traverses and other motions with

the fixture, the cutter, and the part in place.

• Check the machine tool for the required speeds and feeds.



2.4. Cutter

• With respect to the maintenance of the cutters, it is required that they can be conveniently

removed for re-sharpening without disturbing the fixture.

• Check for operator safety

• Check for cutter and fixture safety: Make sure that there shouldn’t be any interference while

cutting operation with clamps locators or other fixture parts.

• Check for interference while loading and unloading of the part.

• The fixture should be designed for minimum cutter travel.

• Standard cutters should be used to the greatest extent.

2.5. The Part

• Check the part for such unusual features as overly heavy weight, imbalance, and long projecting

ends. Provide required support if the part is long.

• Check the effect of variations in the shape and dimensions of the part. Allow clearances in the

fixtures for the variations of the part (Castings, Forging).

2.6. Locating the Parts

• Check the part for the best possible surfaces or points for locating from the point of stability,

compatibility with the surfaces.

• For rough surfaces buttons are used and they should be hardened.

• Place locating points as widely as possible, particularly on rough surfaces use three locating

points. If fourth point is needed for stability, make it adjustable.

• Check previously machined surfaces for location. The tolerances must be fine enough for the

accuracy required in the subsequent operations.

• Locating elements are subjected to wear and they should be easily replaceable.

2.7. Clamping

• Evaluate the part in terms of part weight and cutting forces.

• The part should be supported directly below the clamping points with solid metal in between,

and close to the point of cutting forces.

• The cutting force should be directed against the supporting points.

• The cutting and clamping forces shouldn’t act to distort the part.

• Make sure that the fixture and clamps have ample strength and rigidity to withstand all loads.

• Make sure that clamps can’t be loosened accidentally by centrifugal forces, shock, vibration,

and chatter.

• Consider the dimensional variation in the part while selecting the clamps.

• The clamp in any position (open or closed) should not interfere with any part of the machine.

• All forces from clamping must be retained inside the structure of the fixture.

• For CNC machines, investigate the use of power clamping i.e. pneumatic or hydraulic clamps.

• The clamps should be easy and quick to operate.



2.8. Loading & Unloading

• Provide sufficient clearance for the part in all positions during loading and unloading.

• Make locating pins as small as possible for easy loading & unloading.

• Make the loading progressive i.e. make one of the locating pins longer particularly the

cylindrical pin or primary locator.

• For heavy parts to be located in the previously drilled holes, use disappearing locating pins so

the part can slide over them into position.

• Provide handles for lifting of the fixtures.

• Provide fool proofing pins so that the part can’t be loaded incorrectly.

2.9. The Chips

• Establish the chip type that is produced when machining the part i.e. continuous or segmental.

• Crumbling chips require space to escape between surface of the part and the end of drill bushing;

stringy chips require bushing close to the surface to guide chips up through bushing.

• Cutters should have ample space in flutes to escape the chips.

• Avoid pockets in the fixtures that can collect the chips.

• Provide openings for chip cleaning.

• Lift surfaces of locators and supports above possible chip accumulations.

• Prevent chips from entangling in clamp lifting springs, rotating machine parts etc.

2.10. Cutting Fluid

• The cutting fluid must reach the edge of the cutter.

• Provide channels and guards to prevent cutting fluid from running waste, from being spilled on

the machine floor.

• Utilize the flow to wash chips away.

2.11. Safety

• Make general review of all manipulations and operations to be performed on the part to ensure

that they do not present any hazard.

• Check the fixture for visibility at all times that is loading, locating, clamping etc.

• Remove sharp edges, screws should not project out.

• Check motion of Hydraulic or pneumatic clamps.

• Provision should be made for power clamps if used in case of power failure.

• See that the operator is protected from flying chips and any splashing cutting fluid.

• Use the notes or Cautions on the fixture wherever required.

2.12. Miscellaneous

• The fixture cost should be optimum for high volume of production.

• Utilize to the max extent the standards parts.

• Check the manufacturing facilities for mfg. capability.



• Check for lubrication of all moving elements.

• Be certain that the replacement can be made without interference with other fixture elements.

• Provide aids for lifting such as eye bolts, lifting holes.

• Secure small loose parts against the loss in storage

• Provide identifications marks on the parts.

• When in storage, the fixture should be in balanced and stable position.

2.13. During the final checks

• Look once again for the following details:

• Strength, Rigidity, Simplicity, Safety, Operating conditions as well as accidental overloading.

3. DESIGN OF FIXTURE

The main purpose of the clamping is to securely hold the work piece against the locators

throughout the machining cycle. After clamping the work piece should keep in contact with the

locators so that the location is ensured. The clamping force should be sufficient for resisting the

machining force and other forces so that the work piece will not change its position and

vibration will not appear, but the clamping force should not be so great that the work piece

surfaces are damaged or work piece deformation is significant. The clamping operation should

be simple, time saving, safe, and easy for work piece loading and unloading, especially no

impact to the work piece, machine tool components, and cutting tools. Table 2 given below lists

out the parts designed to manufacture the required fixture.

Table 2 List of parts designed for the assembly of the fixture

Det. no. Nomenclature Quantity

1 Base plate 1 nos.

2 Non dovetail support 1 nos.

3 Dovetail fixed support 1 nos.

4 Dovetail adj. support 1 nos

5 Dovetail strap clamp 1 nos.

6 Non dovetail clamp 1 nos.

7 Tenon 2 nos.

8 Clamp support 1 nos.

9 Clamp rod 1 nos.

10 Thumb screw 1 nos

11 Hex.soc.hd.cap screw 4 nos.

12 lock nut 2 nos.

It is common practice fixtures used for high volume manufacturing processes which given

the growing importance of precision manufacturing in high-volume products (e.g. aerospace) it

has become important to provide fixture capable of providing micron/µradian accuracy and

repeatability between each piece part of equipment. Precision fixtures provide micron/µradian

repeatability irrespective of small inaccuracies in their geometry. Fixture accuracy is a

kinematics phenomenon and therefore dependent on inaccuracies in the construction and

assembly of the fixture. This means that tolerances on contacting elements and contact wear

errors will directly affect fixture With current manufacturing technology, it is difficult to ensure



tolerances better than ± 10 microns on placement, ± 10 microns on size and ± 10 µradians on

orientation. Likewise, the constant engaging and disengaging of fixture contacts makes it

difficult to limit the effects of wear on fixture accuracy to less than 5 microns.

FIXTURE PARTS

Figure 1 Design of the base plate



Figure 2 Design of the Non Dovetail Support



Figure 3 Design of Dovetail Fixed Support



Figure 4 Design of Dovetail Adjustable Support



Figure 5 Design of dovetail strap clamp



Figure 6 Non Dovetail Strap Clamp



Figure 7 Design of Tenon



Figure 8 Clamp Support



Figure 9 Thumb screw

Figure 10 Steel grade hexagon (c) head bolt

Figure 11 Steel grade a hexagon (a) head bolt

Figure 12 Steel grade (a) hexagon nut



Figure 13 Assembly of complete fixture

4. CONCLUSION

• A brief introduction of the use of fixtures in mass production was debated.

• Requirement of compressor blade holding fixtures was discussed.

• Step by step process in designing a fixture was deliberated about.



• 12 Parts have been designed using CATIA.

• The parts were assembled to create a compressor blade holding fixture.

5. FUTURE SCOPE

Analysis of the design to find out its validation at different workloads and conditions can be

performed.

REFERENCES

[1] Peter W.M, Stevenson, Amelia, Elbert Stonom, Fixture and methods for machining the

rotors, U.S Patent number 5,284,406, Feb 8th 1994.

[2] James L. Tangler, The Evolution of Rotor and Blade Design, Presented at the American

Wind Energy Association Wind Power 2000, Palm Springs, California, and April 30–May

4, 2000.

[3] C.Radha Madhavi, B.Ramu, K.Srinivasulu, and Design of machining fixture for turbine

rotor blade, IJRET: International Journal of Research in Engineering and Technology

eISSN: 2319-1163 | pISSN: 2321-7308.

[4] S. J. Gallimore, Axial flow compressor design, Proceedings of the Institution of Mechanical

Engineers, Part C: Journal of Mechanical Engineering Science 1999, DOI:

10.1243/0954406991522680.

[5] S Srujana, S Aashritha, V Sai Aashrith, G Koushik, Design Analysis And Life Estimation

of A First Stage Rotor Blade Using Nickel Based Super Alloy (CMSX4), Volume 4, Issue

5, September - October (2013), pp. 21-25, International Journal of Mechanical Engineering

and Technology.

[6] P. Yogesh, C. Arun, R. Arunkumar, S. Muruganantham and P. Abinesh, Elimination of

Rejection in Injector Manufacturing Process by using Hydraulic Fixture. International

Journal of Mechanical Engineering and Technology, 8(3), 2017, pp. 331–343.

[7] Shailesh S.Pachbhai, Laukik P.Raut, A Review on Design of Fixtures, International Journal

of Engineering Research and General Science 2(2), Feb-Mar 2014, ISSN 2091-2730.

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