rake angle on cutting tools

8/11/2019 Rake Angle on Cutting Tools

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Rake angle on cuttingtools

Presented by

Mr. Mahesh TodkarM. Tech. (Manufacturing Engineering)

National Institute of Technology, Warangal .


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ContentsIntroduction to Tool GeometrySignificance of Rake angleDefinitions of Rake angleRake angles on Various Cutting Tools

Conversion of Rake anglesRake angle in oblique cutting

Types of Rake angleSelection of Rake angles

Effects of Rake angle on Chip flowEffects of Rake angle on cutting forcesConclusionsReferences


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Introduction to Tool Geometry

Role of material andgeometry Tool Geometry affect:

Chip controlProductivity ofmachining

Tool lifeDirection and magnitudeof the cutting forces

Quality of machiningWhat is ToolGeometry?


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Significance of Rake angle

Shearing of work material and formation of chipEase of controlling chip flow direction

Cutting angle, angle of shear and Power

Cutting force direction and magnitude

Strength to tools

Cutting speeds & feeds


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Definitions of Rake angleDefinition: Angle of inclination of rake face fromreference plane.

Reference plane:

Systems of description of tool geometry:ASA

ORS

NRS


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Rake angle on Single point cutting tools

Rake angle on Single pointcutting tool:

ASA System:

Back rake angle ( y )Side rake angle ( x )

Designation of tool

geometry y , x , y , x , e, s , r (inch)


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ORS System:Orthogonal rake angle ( o)

Designation of tool geometry , o, o, o, 1 , , r (mm)


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NRS System:Normal rake angle ( n)

Designation of tool

geometry , n , n , n , 1 , , r (mm)


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Conversion of Rake angles

Purposes:Understandactual toolgeometryBenefits of

various systemsCommunication

Methods:AnalyticalGraphical

Transformationmatrix methodVector method


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Rake angle in Oblique cutting

Oblique cutting Vs Orthogonal cuttingChip flow deviation angle ( c )Effective Rake angle ( e)


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Rake angle on Double point cutting tools

Twist Drill:


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Rake angle on Multi-point cutting tools

Plain Milling Cutter:


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Rake angle on Multi-point cutting tools

Face Milling Cutter:


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Types of Rake angleRake angle may be

Positive Rake angleNegative Rake angleZero Rake angle


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Selection of Rake angleFactors to consider:

Hardness of work material

Type of cutting operation

Material and shape of the cutting tool

Strength of cutting edge


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Recommended Rake anglesWork Material Tool Material

HSS & CastAlloys

Cemented carbides

Brazed Throw away

Back Side Back Side Back Side

Mild Steel 8 10 0 6 -5 -5

Medium Carbon Steels 0 10 0 6 -5 -5Alloy Tool Steels 0 10 -5 -5 -5 -5

Stainless Steel 0 10 0 6 -5 -5

Cast Iron 5 5-10 0 8 -5 -5

Aluminium Alloy 20 15 0 15 0 5

Copper Alloy 5 10 0 8 0 5

Magnesium Alloy 20 15 0 15 0 5

Titanium Alloy 0 5 0 6 -5 -5

All angles are in Degrees


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Effects of Rake angle on Chip FlowChip reduction coefficient () depends on

Tool rake angle,

Chip-tool interaction, mainly friction,

For Orthogonal cutting

= ( )

Chip thickness ratio, r = 1

2

=1


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Effects of Rake angle on Cutting ForcesCutting forces affected by

Cutting speed,Cutting tool material,

Tool geometry,Depth of cut, etc.

Main Cutting force (F c)F c = A c * k s

k s = k s11 h -zk vk k tk a

Where,

k = 1.5

100

Cutting Power, P c = F c * V


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ConclusionRake angle is most significant in tool geometry.

Choice to use any system to describe Rake angle.

Proper selection of Rake angle enhances the overall machiningprocess and its economy.

Carbide inserts with negative Rake angle facilitate high cuttingspeeds & feeds.

Rake angle is important geometric parameter to be consideredin cutting tools and carbide insert manufacturing industries.


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References[1] M. C. Shaw, Metal Cutting Principles, Oxford University Press, London.

[2] A. Bhattacharyya, Metal Cutting: Theory and Practice, Central press, Calcutta, 1984.[3] P. C. Sharma, Production Engineering, S. Chand & Company Ltd., New Delhi, 2006.

[4] E. Abele, M. Fujara, Simulation-based twist drill design and geometry optimization,Manufacturing Technology 59 (2010) 145 150.

[5] H. Saglam, S. Yaldiz, F. Unsacar, The effect of tool geometry and cutting speed onmain cutting force and tool tip temperature, Materials and Design 28 (2007) 101 111.

[6] H. Saglam, F. Unsacar, S. Yaldiz, Investigation of the effect of rake angle andapproaching angle on main cutting force and tool tip temperature, International Journalof Machine Tools & Manufacture 46 (2006) 132 141.

[7] M. Gunay, E. Aslan, Experimental investigation of the effect of cutting tool rake angleon main cutting force, Journal of Materials Processing Technology 166 (2005) 44 49.

[8] M. Gunay , E. Aslan, Investigation of the effect of rake angle on main cutting force,International Journal of Machine Tools & Manufacture 44 (2004) 953 959.

[9] R. Komanduri, M. Lee, L.M. Raff, The significance of normal rake in obliquemachining, International Journal of Machine Tools & Manufacture 44 (2004) 1115 1124.

[10] I. A. Kattan, K. R. Currie, Developing New Trends of Cutting Tool Geometry, Journal of Materials Processing Technology 61 (1996) 231-237.


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rake angle on cutting tools

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