6-park&kwon-cutting tool for soft material

8/7/2019 6-Park&Kwon-Cutting Tool for Soft Material

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IAB meeting (10IAB meeting (10--1414--08)08) 11

DEVELOPMENT OF CUTTINGTOOLS FOR MACHINING SOFT

METALS

K.-H. Park and P. Kwon

Mechanical EngineeringMichigan State University

East Lansing, MI


INTRODUCTION

Machinablility of Soft Materials such as Aluminum &Copper Alloys, etc. Ductile and High Conductivity

Due to Ductility, BUE, long Chip and burr are Formed

High Thermal Expansion Deteriorate DimensionalTolerance

Aluminum Alloys Exhibit High Friction and StrongAdhesive Interaction with Tool Materials - BUEFormation (High Cutting Force, Poor Surface Finish and

Short Tool Life) Severe Abrasive Wear Cause Tool Failure in Silicon

Containing Aluminum Alloy Machining


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OBJECTIVES

After selecting a reference soft material

Select Candidate Coated/Solid Tools

Determine Optimal Cutting Edge Geometry(Sharpness)

Study of the Tool Wear Mechanism in VariousMachining Processes (Drilling or Milling etc.) WearMap

Machining Test Data of Available Coatings

A Better Cutting Tools & Coatings for SoftMaterial Machining


APPROACH

UNDERSTANDING OF CUTTING MECHANICSAND TOOL WEAR Tool Wear Evolution Test (Work Material types

(Microstructure), Cutting Conditions, Tool EdgeGeometry (Sharp tool), Lubrication System (Dry orMQL))

ALE FEM Simulation (Using Johnson CookConstitutive Model for a particular material)

Tool Wear Analysis (Adhesion, Abrasion, Diffusion,Chemical Reaction, etc.)

Wear Mechanism Map


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Pros and Cons with Aluminum

Cutting Temperature is relatively low.

Dissolution wear does not operate.

Abrasion and Adhesion wear are theimportant wear mechanisms.

Adhesion wear is not understood very well.

In Abrasion

Identification of abrasive phases Effect of Coherency of Inclusions.


Inclusions in a chosen Al Alloy

Casting Methods to control the nonmetallicinclusions

Settling under gravity field

Electromagnetic field

DC Electric and AC Electric field

Identification of Inclusions Peterson[1994], Eckert [1991] and Sigworth etal. [1989]


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Aluminum Alloys

A l loys Al Cu Fe Mg Mn Si1050 99.5 0.4 0.3

1100 99.0 0.6 0.3

2024 93.5 4.4 0.5 1.5 0.6 0.5

3004 96.5 0.3 0.7 1.0 1.2 0.3

4043 93.5 0.3 0.8 5.2

5050 96.9 0.2 0.7 1.4 0.1 0.4

6063 98.5 0.3 0.7 0.4

weight %

Intermetallics: Al6Mn, Al3Cr, Al3Ti and Al2Cu (during aging).

Others not included are Vanadium, Chromium, Titanium, Zinc.


WEAR MECHANISM ADHESION Size of loose particles due to adhesion (Rabinowicz, 1965)

E. Rabinowicz, Friction and Wear of Materials, Wiley, 1965, p. 161

Asperity Size


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Asperity Size

Size of loose particles due to adhesion

dloose = 60000 Wab / pa (plastic deformation)

dloose is the diameter of a loose particle created by

adhesion

Wab is the energy of adhesion = a + b abwhere ab is the interfacial energy between a and b

pa is the penetration hardness of material a

dloose = 6 E Wab / (2 y2) (elastic deformation) E is Youngs modulus of material a

is Poissons ratio of material a yis the yield stress of material a

Particles of smaller size do not come loose


Rabinowiczs formula for energy of adhesion Wab Wab = a + b ab C2 * (a + b), where

C2 is a compatibility coefficient based on solubility

is the surface energy

Formula for energy of adhesion Wab, table for C2 and compatibility figure taken from E. Rabinowicz, ASLETransactions, July 1971, 14(3):198-203 (Discussion pp. 203-205)

Calculation of W/p


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WEAR MECHANISM

Transformation of cobalts structureinto structure occurs at Temp300 ~ 422 -> Solubility ofaluminum in cobalt > cobaltaluminide (brittle and degradation)

ABRASION Silicon Containing Alloys (at low cutting speed) (2-BodyAbrasion Theory)

Built-Up Edge (BUE) - Prevent maintaining Sharp Cutting Edge

DIFFUSION Aluminum Diffuse into Tool Material (WC-Co) at BUE

Formed at High Cutting Speed

Due to High Temperature (Affinity)

Calatoru et al. 2008 (In Press)

Al-Co Diagram

Phase Transformation


WEAR MECHANISM ANALYSIS

Secondary Electron Microscopy (BSE, EDS) Stylus Profile Measurement Confocal Laser Scanning Microscopy Atomic Force Microscopy

Stylus Profiler Crater- Profiles

Tool Wear Evolution

0min

12min

18min

22min

Wavelet Transformation- Topography


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NIST - Machining Test-bed ? Tool

Workpiece

Chip

Custom Imaging

System

Tool Post

Dynamometer

Orthogonal Cutting

Force measurement

Temperature measurement

Tool wear ?

Cutting tools

Rake angle, flank relief angleetc.

Modified geometry Elastic recovery of workmaterials


Examples of Thermal Images

Tool

Chip

Schematic 100 m

TubeBody


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COATING MATERIALS

AVAILABLE COATINGS

- TiN and TiAlN

- Diamond CVD High Hardness (Castro et al. 2008)

- DLC Low Friction Coefficient (Low Affinity with Al) but Relatively

Low Abrasive Wear Resistance

- PCD High Abrasive Wear Resistance (Grain size and Roughness)

- TiAlCrYN PVD - (Luo et al. 2005)

- TiAlN/VN PVD - nanoscale multilayer (Havsepian et al. 2006)

Required Characteristics:Low Affinity, Low Friction Coefficient and High Hardness


MACHINING TESTS

Coating Materials Work Materials

Cutting Conditions Tool

Microstructures(Basavakumar et al. 2007)

Feed Rate (mm/rev)Cutting Speed (m/min)

Depth of Cut (DOC) (mm)

Lubricant System: Dry or MQL

Rake angle ()Clearance angel ()

Cutting edge Radius ()

Tool Material

Work Material


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ALE-FE Simulation

No Chip Separation Criterion No Arbitrary Contact Length

Coating Layer on top ofSubstrate Material

Temperature & Contact Pressure

{ }

++=

rm

rn

TT

TTCBA 1ln1

0

&

&

C)(25TemperaureRoom:Tre,temperatuMelting:T

))(1.0sratestrainReference:(rateStrain:

strainEquivalent:stress,Flow:

constantsMaterial:mandnC,B,A,

rm

1-

0

o

&&

Johnson Cook Constitutive Model


Wear Mechanism Map

Aluminium Alloys -Uncoated HSS Drilling

(Zhang et al. 2001)

Magnesium Alloys -Uncoated HSS Drilling

(Wang et al. 2008)


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Proposed Work 2008-9

Determine an ideal soft material with areliable constitutive model

Adhesion test with prospective cutting toolmaterials on MTS Oxidation or other surface layer?

Determine prospective cutting toolmaterials

Simulation on ABAQUS to determineCutting tool geometry


BUDGET

Labor: $30,000

Supply & Service: $10,000

Travel: $ 500

Total: $40,000

6-park&kwon-cutting tool for soft material

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