New Tool-life Relationships for Machining Processes Research Team:
Principal Investigator: Professor I. S. Jawahir Postdoctoral Researcher: K.C. Ee Graduate Students: Abhijit D. Kardekar Xiqun Wang
Objectives
• Develop a new methodology for characterizing tool-wear parameters in tool inserts for turning and milling operations through an experimental study of the effect of chip flow on tool-wear progression
Sponsors: Ford Motor Company
National Science Foundation Kentucky Science and Engineering Foundation
Influence of Cutting Conditions on Tool-life for Different Chip-grooves and Tool Coatings Tool-life Versus Cutting Speed(CNMG 432K) (f = 0.254 mm/rev, a = 2.54 mm and Work material = 1037M Steel)
• Establish the effects of cutting conditions, operation types, tool coatings and chip-groove configurations on tool-wear and tool-life • Develop new tool-life relationships for turning and milling (face and end milling) operations based on experimental work and a detailed analysis of machining parameters, cutting conditions, work and tool material properties and tool geometry
Measurable Tool-wear Parameters in a Grooved Tool for Turning VB BW BL KT SW SD N NL1 NW1 NL2 NW2
Tool-life Versus Feed (V = 274.32 m/min, a = 0.254 mm and Work material = 1037M Steel)
flank wear width of groove backwall wear length of groove backwall wear depth of groove backwall wear width of secondary face wear depth of secondary face wear nose wear notch wear length on main cutting edge notch wear width on main cutting edge notch wear length on secondary cutting edge notch wear width on secondary cutting edge
Tool-life Versus Depth of Cut (V = 274.32 m/min, a = 0.254 mm and Work material = 1037M Steel)
A New Tool-life Relationship For Turning with Grooved Tools New Tool-life Equation
V T = T RW g R V
Wc
1 n
Tool-life Equation
Where Where,
where
V = cutting speed D = cutter diameter = helix angle m 1/ n 5 fz = feed per tooth K1 D δ T = 1/ n 1/ n1 1/ n2 1/ n3 1/ n aa = axial depth of cut V f z a a ar z 4 ar = radial depth of cut z = number of teeth Face Milling K1, K2 = tool-life constants n1, n2, n3, n4, n5 and m = empirical constants m End Milling
where W is coating effect factor and W is chip-groove effect factor c
Validation of Current Tool-life Relationships for Milling Operations
g
km W g = n1 n 2 f a
k = bl l = engaged cutting edge length f = feed a = depth of cut m = machining operation effect factor (m = 1 for turning) n1, n2 and b = empirical constants
T=
V
1/ n
fz
K2 D 1/ n 1/ n a a 2 a r 3 z 1 / n4
1/ n1
SEM Observation of Flank, Face and Nose Wear of End Mill Tool Inserts
Tool-wear Patterns of Typical Grooved Tools for Turning
Work material = 4140 Steel, TiN Coated Carbide Tool Inserts (V = 400 m/min, f = 2 m/min and a = 4 mm) Tool-life (ISO standard: 0.8 mm localized flank wear) = 5 min. 54 sec.
Tool-wear Progression in Different Grooved Tool Inserts (V = 274 m/min, f = 0.25 mm/rev, a = 1.9 mm, tool coating: KC850)
ISO Standards for Tool-life in Milling Operations
Tool Deterioration Phenomena Flank wear (VB, uniform) Flank wear (VB, localized) Face wear (Crater depth, KT)
Criteria (mm) 0.5 0.8 0.1
Illustrations
Work material = 4140 Steel, TiN Coated Carbide Tool Inserts (V = 400 m/min, f = 1 m/min and a = 7 mm) Tool-life (ISO standard: 0.8 mm localized flank wear) = 9 min. 8 sec.
Future Research Direction • Develop a new methodology for characterizing tool-wear in end milling • Develop a complete tool-life model for milling, which incorporates the effects of tool material, tool coating, tool geometry and machining parameters • Extend the new tool-life relationships to drilling operations • Form a universal tool-life model for all turning, milling and drilling processes