FINITE ELEMENT ANALYSIS USING DIFFERENT TOOL EDGE GEOMETRIES AND END RELIEF ANGLE FOR ORTHOGONAL MACHINING

PRESENTED BY:SANDEEP NAIR

CB.EN.P2MFG15018M. Tech , “MFG”

INTRODUCTIONStress analysis plays important role in structural

safety and stability of the system. estimation of stress and deformation helps in better

design and manufacture of products.Higher stress reduces the load carrying capacity of

the member along with source of crack generation. The machining is an important parameter in the

manufacturing process and is used for sizing and shaping the members for the required functionality.

Cutting tools are essential machine members for manufacturing process .

The Finite Element Method (FEM) is selected using the ABAQUS.

Six models of cutting tools will be selected having edge radii of (0.01, 0.05, 0.1, 0.15, 0.2 , and 0.25) mm.

Deformation processes produce the required shape, with the necessary mechanical properties, by plastic deformation in which the material is moved and its volume is conserved.

.The first one is the lecture delivered by F. W Taylor (1907) on “The art of cutting metals” in which up to twelve cutting variables that influenced the cutting speed selection were analyzed with a primary objective of “getting better and cheaper work out of machine shop”.

ORTHOGONAL & OBLIQUE METAL CUTTING

If the cutting face of the tool is at 90° to the direction of the tool travel the cutting action is called as orthogonal cutting.

If the cutting face of the tool is inclined at less than 90° to the path of the tool then the cutting action is called as oblique cutting.

METHODOLOGY

MATERIAL PROPERTIESTool Material : Analytical RigidWorkpiece Material : Aluminum( AL 2024-

T351)

WORKPIECE & TOOL DIMENSION:

RESULT & DISCUSSIONThe analysis has been carried out using Finite

element simulation using Abaqus. The problem has executed to find the stress

condition and strain formation during the machining operation.

The Strain and force forms the source for crack formation.

So the effect of nose radius on strain & force formation is done with different radius of edge.

VARIATION OF NOSE RADIUS VONMISES STRESS IN THE STRUCTURE (NOSE RADIUS = 0.01 MM)

The figure shows developed vonmises stress in the structure. Maximum von mises around 649.7Mpa. The stress increase shows problem is in plastic region as it is crossing the yield stress of the material .It can be observed from the figure that stresses are concentrated near the zone of machining.

STRAIN DEVELOPMENT IN THE PROBLEM (NOSE RADIUS = 0.01 MM)

The figure shows plastic strain development of 1.579. From the strain estimates one can estimate the type of chips formed during the machining operations. Also the plastic strain indicates the permanent deformation set up in the structure.

CONTACT PRESSURE GENERATION (NOSE RADIUS = 0.01 MM)

The figure shows contact pressure development in the problem. The contact pressure shows maximum value of 771Mpa as shown by red colour. Maximum contact pressure can be observed at the tip of the cutting tool. Contact pressure development can be observed in the orthogonal directions.

GRAPHICAL PLOTSTRESS ALONG DIFFERENT NOSE RADIUS

0 0.05 0.1 0.15 0.2 0.25 0.3570

580

590

600

610

620

630

640

650

660

NOSE RADIUS

STRE

SS

The Graph shows as the nose radius increase ,the vonmises stress acting is reduced which shows that the improved design of the problem.

PLASTIC STRAIN ALONG NOSE RADIUS

The Graph shows that strain estimation help to predict the types of chip flow during machining operation.

0 0.05 0.1 0.15 0.2 0.25 0.31.25

1.3

1.35

1.4

1.45

1.5

1.55

1.6

1.65

NOSE RADIUS

STRA

IN

Comparsion for nose radius and other parameters of machining

The results shows reduced developed von mises stress on the workpiece with the increase in the radius of the nose. Reduction in von mises stress shows improved design of the problem.

Contact pressure is also reducing from 649.7 to 598.4 Mpa. So reduced contact pressure, shows reduced load requirement for the cutting operation.

force shows increase values along with the increase in nose radius. This is also an important parameter for manufacturing process. Increase force indicates low life and low load carrying capacity for the cutting tool material.

Similarly the increased nose radius shows reduction in the plastic strain value. This helps in increase in the load carrying capacity of the member.

VARIATION OF END RELIEF ANGLE VONMISES STRESS ( RELIEF ANGLE : 5°)

CONTACT PRESSURE PLOT(RELIEF ANGLE : 5°)

PLASTIC STRAIN PLOT(RELIEF ANGLE : 5°)

PARAMETER COMPARISON WITH END RELIEF ANGLE

The table shows effect of end relief angle on structural parameter of stability using Finite element analysis.

With the increase in the relief angle, the stress values are reducing which is important parameter of stress condition.

Similarly contact pressure and plastic strain values are reducing. So with reference to the work piece, the increased relief angle improves the life of the work-piece.

But major parameters in the life of work piece are force and plastic strain. These are the sources of failures of members by initiating crack on the surface. So the design can be done in such a way as to reduce the plastic strain & force in the structure.

CONCLUSIONS

Initial analysis for change in nose radius shows, reduced values for vonmises stress(649.7-598.4Mpa), Force(158.2 – 557kn), contact pressure(771.3-596Mpa), Plastic strain (1.757-1.409) which are desirable features for cutting tool design.

This helps in protecting the crack generation on the work piece which will enhance load carrying capacity and higher fatigue life for the members.

Further analysis with end relief angle also shows similar trends for von mises, contact pressure and plastic strain. Reduction of values for Von mises(650.6-640Mpa), Force (140.9-160kn),Contact pressure(751-590Mpa), plastic strain (1.608-1.58) can be observed for end relief angle variation from 5 degrees to 20 degrees.

This is also a good trend for better life of the work piece where force and plastic strains are reducing.

FURTHER SCOPE Ls-Dyna simulation can be used for usage of

explicit algorithm to analyze flow boundary conditions with ALE techniques.

Thermal analysis can be done to find the thermal effect on the stress generation.

Topology optimization can be carried out better design of cutting tool

Lubrication effect can be analyzed. Composite material usage for cutting tool can be

carried out

REFERENCESStrenkowski, J.S., and Carrol III,J.T., “A finite element

model oforthogonal metal cutting”, Trans.Journal of Engineering forIndustry, Vol.107 No.4, pp.349-354, 1985.

T.TYAN, WE1 H. YANG “ANALYSIS OF ORTHOGONALMETALCUTTING PROCESSES”,International Journal For Numerical Methods in Engineering, Vol.34,365- 389,1992.

Ozel, T., “Modeling of hard partmachining: effect of insert edgepreparation in CBN cutting tools”,Journal of Materials Processing Technology, Vol.141, pp.284-293, 2003.

Altan, T., “Modeling of metalcutting using FEM”, (ERC/NSM),The Ohio State University,January 2003.

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