Fixture Layout

8/10/2019 Fixture Layout

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Machining Fixture Layout


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1.0 Int rodu ct ion

Higher efficiency and lower production costs in terms of product

quality and productivity - development of automated manufacturing

systems.

Fixture - locate and constrain the workpiece during machining,

inspection and assembly.

Design and manufacturing of fixtures become costlier because of

tight tolerance and restrictions in the machining operations.

Design and fabrication of fixtures incur 10-20 % of the total cost

spent in the manufacturing system.


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Fixtures-To locate and constrain a workpiece during machining

operation, includes locators and clamps. In machining fixture layout, externally applied clamping force and

reactions exhibited in locator causes moment which in turn produces

deformation on machined workpiece. The moment is influenced not only

by the magnitude of clamping forces and reactions but also by the

positions of fixture elements.

Clamping and cutting forces can not be minimized beyond a extent.

Hence, the interrelationship between the position of fixture elements andworkpiece deformation is critical to ensure the accuracy of the

machining process.

1.0 Introduction (Contd.,)


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1.0 Introduction (Contd.,)

Conventionally, an appropriate position for fixture elements is determined

by relying on design experience or trial and error methods which are

proved to be expensive and time consuming.

No assurance of optimal or near optimal solutions. Further, these

practices are not flexible.

Numerical models like FEMs were used to replace the analytical models.

Many researchers have been used FEM for modeling and analysis fixture

workpiece interactions. Commercial finite element solver has also been

employed for FEM calculations. ANSYS software was used to calculate

the displacement of the workpiece at the time of machining.


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Author Year Objective Design criteria Tools used

Menassa

andDeVries

1991 To determine the

position of supports

The minimization of the

workpiece deflection atselected points as the

design criterion

FEA

Meyer

and Liou

1997 To synthesize fixtures

for dynamic machining

conditions

For the minimum

clamping forces and

locator forces is given

Linear

programming

technique

Li andMelkote

1999 To optimize layoutproblem

Minimizes workpiecelocation errors due to

localized elastic

deformation of the

workpiece.

Nonlinearprogramming

method

Roy and

Liao

1999 To plan for the best

supporting andclamping positions

--- Heuristic

method

Tao et al. 1999 Determining the optimal

clamping points and

clamping sequence

For arbitrarily shaped

workpieces

A geometrical

reasoning

methodology

1.0 Intro duct ion (Contd.,)


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Liao andHu 2000 Fixtureworkpiecesystem subject to time-

varying machining loads

fixture configurationanalysis based on a

dynamic model

Influence of clampingplacement is also

investigated

Li and

Melkote

2001 Combined fixture layout

and clamping force

optimization

--- Contact elasticity

modeling method

Amaral etal.

2004 Optimization analysis --- ANSYS

Tan et al. 2004 Modeling, analysis and

verification of optimal

fixturing configurations

--- By the methods of

force closure,

optimization and finite

element modeling

Kumar et

al.

1999 Designing a fixture --- Both GA and neural

networks

Marcelin 2001 Optimization of support

positions

--- GA



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Vallapuzhaet al.

2002 Fixture layoutoptimization

--- GA based optimizationmethod

Krishnakum

ar and

Melkote

2000 Fixture layout

optimization

Minimizes the

deformation of the

machined surface due

to clamping andmachining forces over

the entire tool path

GA

Necmettin

Kaya

2005 To find the

optimal locator

and clamp

positions in 2D

workpiece

Chip removal is taken

into account while tool

forces moving on the

workpiece

GA tool



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Vallapuzha

et al.

2002 Fixture layout

optimization

--- GA based optimization

method

Krishnakum

ar and

Melkote

2000 Fixture layout

optimization

Minimizes the

deformation of the

machined surface due

to clamping and

machining forces over

the entire tool path

GA

Necmettin

Kaya

2005 To find the

optimal locator

and clamp

positions in 2D

workpiece

Chip removal is taken

into account while tool

forces moving on the

workpiece

GA tool



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REFERENCES

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3. R.J. Menassa, and W.R. DeVries, Optimization methods applied to

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Industry, ASME Transactions, Vol. 113, Pp. 412418, 1991.4. S. Jayaram, B.S. El-Khasawneh, D.E. Beutel, and M.E. Merchant, A

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6. Rdrigo A. Marin and Placid M. Ferreira, Analysisof the influence of

fixture locator errors on the compliance of work part features togeometric tolerance specifications, J. Manuf. Sci. Eng., Vol.

125,No.3, 609 (8 pages),2003.

7. Necmettin Kaya, Machining fixture locating and clamping position

optimization using genetic algorithms, Computers in Industry, Vol. 57,

No.2, Pp.112-120, 2005.8. ANSYS 8.0, ANSYS Inc., 2003.

9. Wang, X. Chen, Q. Liu, and N. Gindy, Optimisation of machining

fixture layout under multi-constraints, International Journal of Machine

Tools & Manufacture, Vol. 46, Pp.12911300, 2006.

10. Xiaoyun Liao and G. Gary Wang, Simultaneous optimization of

fixture and joint positions for non-rigid sheet metal assembly, The

International Journal of Advanced Manufacturing Technology, Vol. 36(3-

4), Pp.386-394, 2006.

REFERENCES


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REFERENCES

11. S. Ratchev, K. Phuah, G. Lammel, and W. Huang, An experimental

investigation of fixture workpiece contact behaviour for the dynamic simulation of

complex fixtureworkpiece systems,Journal of Materials Processing Technology,Vol. 164165, Pp.15971606, 2005.

12. Shao-Gang Liu , Li Zheng , Zhi-Hai Zhang , Zhi-Zhong Li and Da-Cheng Liu,

Optimization of the number and positions of fixture locators in the peripheral

milling of a low-rigidity workpiece,Int J AdvManuf Technol., Vol. 33, Pp.668676,

2007.

13. D. Biermann, , Kersting and T. Surmann, A general approach to simulatingworkpiece vibrations during five-axis milling of turbine blades, CIRP Annals -

Manufacturing Technology, Vol. 59, Pp. 125128, 2010.

14. ShashaZeng , Xiaojin Wan, Wenlong Li , Zhouping Yin and YoulunXiong, A

novel approach to fixture design on suppressing machining vibration of flexible

workpiece,International Journal of Machine Tools & Manufacture, Vol. 58, Pp.29

43, 2012.15. G. Prabhaharan, K.P. Padmanaban, and R. Krishnakumar, Machining fixture

layout optimization using FEM and evolutionary techniques, Int J

AdvManufTechnol, Vol. 32, Pp. 10901103, 2007.


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REFERENCES

16. K.P. Padmanaban, K.P. Arulshri, and G. Prabhakaran, Machining

fixture layout design using ant colony algorithm based continuousoptimization method, Int J AdvManufTechnol, Vol. 33, Pp.668676,

2007.

17. KrishnakumarKulankara, SrinathSatyanarayanaand Shreyes N.

Melkote, Iterative fixture layout and clamping force optimization using

genetic algorithm, Journal of Manufacturing Science and Engineering,

Vol. 124, pp.119-125, 2002.

18. S. Ratchev, K. Phuah, and S. Liu, FEA-based methodology for the

prediction of partfixture behaviour and its applications, Journal of

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REFERENCES

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Fixture Layout

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