Recent advances in modelling of metal machining processes

The cooling applications in machining operations play a very important role and many operations cannot be carried out efficiently without cooling. Application of a coolant in a cutting process can increase tool life and dimensional accuracy, decrease cutting temperatures, surface roughness and the amount of power consumed in a metal cutting process and thus improve the productivity. In this review, liquid nitrogen, as a cryogenic coolant, was investigated in detail in terms of application methods in material removal operations and its effects on cutting tool and workpiece material properties, cutting temperature, tool wear/life, surface roughness and dimensional deviation, friction and cutting forces. As a result, cryogenic cooling has been determined as one of the most favourable method for material cutting operations due to being capable of considerable improvement in tool life and surface finish through reduction in tool wear through control of machining temperature desirably at the cutting zone.

A review of cryogenic cooling in machining processes

Background Bone fracture treatment usually involves restoring of the fractured parts to their initial position and immobilizing them until the healing takes place. Drilling of bone is common to produce hole for screw insertion to fix the fractured parts for immobilization. Orthopaedic drilling during surgical process causes increase in the bone temperature and forces which can cause osteonecrosis reducing the stability and strength of the fixation. Methods A comprehensive review of all the relevant investigations carried on bone drilling is conducted. The experimental method used, results obtained and the conclusions made by the various researchers are described and compared. Result Review suggests that the further improvement in the area of bone drilling is possible. The systematic review identified several consequential factors (drilling parameters and drill specifications) affecting bone drilling on which there no general agreement among investigators or are not adequately evaluated. These factors are highlighted and use of more advanced methods of drilling is accentuated. The use of more precise experimental set up which resembles the actual situation and the development of automated bone drilling system to minimize human error is addressed. Conclusion In this review, an attempt has been made to systematically organize the research investigations conducted on bone drilling. Methods of treatment of bone fracture, studies on the determination of the threshold for thermal osteonecrosis, studies on the parameters influencing bone drilling and methods of the temperature measurement used are reviewed and the future work for the further improvement of bone drilling process is highlighted.

Drilling of bone: A comprehensive review.

Modelling metal cutting using modern ductile fracture mechanics: quantitative explanations for some longstanding problems

Flank wear of cutting tools is often selected as the tool life criterion because it determines the diametric accuracy of machining, its stability and reliability. This paper argues that the existing criteria of flank wear are insufficient for its proper characterization. Their existence is due to the lack of knowledge on the contact conditions at the tool flank–workpiece interface. Known attempts to evaluate the physical processes at this interface do not help to resolve this issue. This paper compares different characteristics of the evaluation of flank wear. The contact process at the mentioned interface is analyzed through the experimental assessment of the contact stresses, and the full validity of Makarow’s law is confirmed, i.e. minimum tool wear occurs at the optimum cutting speed. A new concept of tool resources is proposed and discussed. This resource is defined as the limiting amount of energy that can be transmitted through the cutting wedge until it fails.

/pdf/the-assessment-of-cutting-tool-wear-1fqyu7sly4.pdf

The assessment of cutting tool wear

INTRODUCTION Scope of the Subject Historical Development Types of Production References METAL CUTTING OPERATIONS Introduction Turning Boring Drilling Reaming Milling Planing and Shaping Broaching Tapping and Threading Grinding and Related Abrasive Processes Roller Burnishing Deburring Examples Problems References MACHINE TOOLS Introduction Production Machine Tools CNC Machine Tools and Cellular Manufacturing Systems Machine Tool Structures Slides and Guideways Axis Drives Spindles Coolant Systems Tool Changing Systems Examples References CUTTING TOOLS Introduction Cutting Tool Materials Tool Coatings Basic Types of Cutting Tools Turning Tools Boring Tools Milling Tools Drilling Tools Reamers Threading Tools Grinding Wheels Microsizing and Honing Tools Burnishing Tools Examples Problems References TOOLHOLDERS AND WORKHOLDERS Introduction Toolholding Systems Toolholder/Spindle Connections Cutting Tool Clamping Systems Balancing Requirements for Toolholders Fixtures Examples Problems References MECHANICS OF CUTTING Introduction Measurement of Cutting Forces and Chip Thickness Force Components Empirical Force Models Specific Cutting Power Chip Formation and Primary Plastic Deformation Tool-Chip Friction and Secondary Deformation Shear Plane and Slip Line Theories for Continuous Chip Formation Shear Plane Models for Oblique Cutting Shear Zone Models Minimum Work and Uniqueness Assumptions Finite Element Models Discontinuous Chip Formation Built-up Edge Formation Examples Problems References CUTTING TEMPERATURES Introduction Measurement of Cutting Temperatures Factors Affecting Cutting Temperatures Analytical Models for Steady-State Temperatures Finite Element and Other Numerical Models Temperatures in Interrupted Cutting Temperatures in Drilling Thermal Expansion Examples Problems References MACHINING PROCESS ANALYSIS Introduction Turning Boring Milling Drilling Force Equations and Baseline Data Process Simulation Examples Finite Element Analysis for Clamping, Fixturing, and Workpiece Distortion Applications Finite Element Application Examples Examples Problems References TOOL WEAR AND TOOL LIFE Introduction Types of Tool Wear Measurement of Tool Wear Tool Wear Mechanisms Tool Wear--Material Considerations Tool Life Testing Tool Life Equations Prediction of Tool Wear Rates Tool Fracture and Edge Chipping Drill Wear and Breakage Thermal Cracking and Tool Fracture in Milling Tool Wear Monitoring Examples Problems References SURFACE FINISH AND INTEGRITY Introduction Measurement of Surface Finish Surface Finish in Turning and Boring Surface Finish in Milling Surface Finish in Drilling and Reaming Surface Finish in Grinding Residual Stresses in Machined Surfaces White Layer Formation Surface Burn in Grinding Examples Problems References MACHINABILITY OF MATERIALS Introduction Machinability Criteria, Tests, and Indices Chip Control Burr Formation and Control Machinability of Engineering Materials References MACHINING DYNAMICS Introduction Vibration Analysis Methods Vibration of Discrete (Lumped Mass) Systems Types of Machine Tool Vibration Forced Vibration Self-Excited Vibrations (Chatter) Chatter Prediction Vibration Control Active Vibration Control Examples References MACHINING ECONOMICS AND OPTIMIZATION Introduction Role of a Computerized Optimization System Economic Considerations Optimization of Manufacturing Systems--Basic Factors Optimization of Machining Conditions Formulation of the Optimization Problem Optimization Techniques Numerical Examples Problems References CUTTING FLUIDS Introduction Types of Cutting Fluids Coolant Application Filtering Condition Monitoring and Waste Treatment Health and Safety Concerns Dry and Near-Dry Machining Methods Test Procedure for Cutting Fluid Evaluation References HIGH THROUGHPUT AND AGILE MACHINING Introduction High Throughput Machining Agile Machining Systems Tooling and Fixturing Materials Handling Systems References DESIGN FOR MACHINING Introduction Machining Costs General Design for Machining Rules Special Considerations for Specific Types of Equipment and Operations CAPP and DFM Programs Examples References INDEX

John S. Agapiou

Papers

Metal Cutting Theory and Practice

Metal-Cutting Operations

Minimum Quantity Lubrication

Machining Economics and Optimization

Tool Wear and Tool Life