Cutting Tools for Machine Tools - Cost Reduction Opportunities

Topics in Chapter 4. Cutting Tools (Stephenson & Agapiou)

4.1 Introduction

4.2 Cutting-Tool Materials
4.2.1 Introduction
4.2.2 Material Properties
4.2.2.1 High-Speed Steel (HSS) and Related Materials
4.2.2.2 Sintered Tungsten Carbide (WC).
4.2.2.3 Cermets
4.2.2.4 Ceramics
4.2.2.5 Polycrystalline Tools
4.2.2.6 Polycrystalline Cubic Boron Nitride (PCBN)
4.2.2.7 Polycrystalline Diamond (PCD)

4.3 Tool Coatings
4.3.1 Coating Methods
4.3.2 Conventional Coating Materials
4.3.3 Diamond and CBN Coatings

4.4 Basic Types of Cutting Tools

4.5 Turning Tools
4.5.1 Indexable Inserts
4.5.2 Groove Geometry (Chip Breaker)..
4.5.3 Edge Preparations
4.5.4 Wiper Geometry
4.5.5 Insert Clamping Methods
4.5.6 Tool Angles
4.5.7 Thread Turning Tools
4.5.8 Grooving and Cutoff Tools
4.5.9 Form Tools

4.6 Boring Tools
4.6.1 Single Point Boring Tools
4.6.2 Multipoint Boring Tools

4.7 Milling Tools.....
4.7.1 Types of Milling Cutters
4.7.2 Cutter Design
4.7.3 Milling Inserts and Edge Clamping Methods

4.8 Drilling Tools
4.8.1 Twist Drill Structural Properties
4.8.2 Twist Drill Point Geometries
4.8.3 Spade and Indexable Drills
4.8.4 Subland and Step Drills
4.8.5 Multi-Tip (Deep Hole) Drills
4.8.6 Other Types of Drills
4.8.7 Chip Removal
4.8.8 Drill Life and Accuracy
4.8.9 Hole Deburring Tools

4.9 Reamers
4.9.1 Types of Reamers
4.9.2 Reamer Geometry

4.10 Threading Tools.
4.10.1 Taps
4.10.2 Thread Mills.

4.11 Grinding Wheels
4.11.1 Abrasives
4.11.2 Bonds
4.11.3 Wheel Grades and Grit Sizes
4.11.4 Operational Factors

4.12 Microsizing and Honing Tools
4.13 Burnishing Tools

Cutting Tool Materials

Ceramics - Ceramic Tools

Ceramic cutting tools can be divided into four categories

1. Alumina and Alumina mixed with zirconium oxide
2. Alumina-titanium carbide composites
3. Reaction-bonded silicon nitride (Si3N4, RB)

Si3N4 is the most appropriate ceramic tool material for machining cast iron at a speed up to 1200 m/min.

  4. Silicon carbide whisker-reinforced alumina, [SiCw-Al2O3]

Polycrystalline Diamond (PCD)

PCD, the hardest of all tool materials, exhibits excellent wear resistance, holds an extremely sharp
edge, generates little friction in the cut, provides high fracture strength, and has good thermal
conductivity. These properties contribute to PCD tooling’s long life in conventional and high speed machining of soft, nonferrous materials (aluminum, magnesium, copper, and brass alloys),
advanced composites and metal-matrix composites, superalloys, and nonmetallic materials. PCD is
particularly well suited for abrasive materials (i.e., drilling and reaming metal-matrix composites)
where it can provide significantly better tool life than carbide.

PCD is not usually recommended for ferrous materials due to the high solubility of diamond (carbon) in iron. However, they can be used to machine some of these materials under special conditions; for example, light milling cuts can be made in gray cast iron at speeds below 200 m/min.

PCD tooling requires a rigid machining system because PCD tools are very sensitive to vibration.

In mass production operations, the attainable tool life may be over 1 million parts (e.g., for
diamond-tipped drills or PCD milling cutters machining soft aluminum alloys). However,  tooling breaks due to vibration or rough handling might occur before wear becomes significant.

Grades of PCD  vary  between 1 and 100 μm.  Grades are grouped in several categories with average grain sizes of 1–4, 5–10, and 20–50 μm. The abrasive wear resistance, thermal conductivity, and impact resistance increase with increasing grain size, but finer grained tools produce smoother machined surface finishes. A coarse-grained PCD tool may provide 50% better abrasive wear resistance than a fine-grained tool, but produce a surface with 50% higher roughness. New laser-honing methods can reduce edge radii for coarse grained PCD and produce finer finishes with these grades. Because of their increased impact and abrasive wear resistance, coarse grades are preferred for milling and for machining high-silicon aluminum alloys and metal-matrix composites.

Multimodal PCD grades (made with bimodal, trimodal, or quadimodal distributions of PCD particles) provide the high abrasion resistance of coarse-grained unimodal grade with the high toughness and superior edge sharpness of medium-size grain tools. The PCD density increases with multiple particles sizes. Multimodal grades are less prone to chipping than unimodal grades.

Laser structuring has recently been applied to flat-topped PCD inserts to produce 3-D chipbreaking grooves and similar features, which have proven effective in ductile material applications
where chip control has traditionally been an issue.

PCD-tipped HSS or carbide rotary tools (e.g., reamers, end mills, drills, etc.) are available in
a limited range of geometries due to difficulties in grinding complex geometries, particularly on
small diameter tools. More complex geometries can be used on carbide rotary tools by sintering the
diamond into slots (veins) located at the point and/or along the flutes.

Issues to be resolved include identifying the optimal cutting edge geometry for the diamond
tip and the best method of pocketing the polycrystalline blank for strength and manufacturability.
The methods of brazing the polycrystalline/carbide substrate tip to the main tool body have been improving steadily, but one of the major failure modes is still the detachment of the polycrystalline tip or the wear and erosion of the braze joints intersecting the cutting edge. Wear and erosion of brazed joints is avoided when the diamond is sintered into veins within the carbide tool.

The point geometry, flute geometry, and web thickness have not been refined sufficiently to allow
use of polycrystalline brazed drills at penetration rates comparable to the feed rates attainable in
turning and milling. (Stephenson-agapiou)


BASIC TYPES OF CUTTING TOOLS
The six basic types of cutting tools are solid tools, welded or brazed tip tools, brazed head tools,
sintered tools, inserted blade tools, and indexable tools

https://www.productionmachining.com/search?q=PCD

Microsizing

Honing

Common honing tool designs: Single stone,  Multi-stone and Krossgrinding tool design

Brush honing

Burnishing Tools




Production Machining - Cutting Tool Case Studies

Systems Approach to Tooling

Advanced Turning Insert Selection - Mitsubishi Course
http://www.mitsubishicarbide.com/permanent/courses/75/index.html


17.1.2020
Pocketing with high speed router RAL 90

The RAL90 aluminium milling cutter is designed for extremely high metal removal rates. The extra robust cutter body with optimized insert seats sets the standard for a new level of process stability in high speed milling - ideal for heavy roughing to semi-finishing pocketing of aerospace frames in aluminium alloys.

In applications requiring even higher metal removal rates, the new RAL90 Super MRR milling cutter can reach extra high spindle rotation, e.g. up to 33000 RPM for DC 50 mm compared to 23500 RPM for RAL90. This means a 40% productivity increase.
Machining aluminium for lighter and better recyclable vehicles
https://www.sandvik.coromant.com/gb/News/technical_articles/pages/machining-aluminium-for-lighter-and-better-recyclable-vehicles.aspx

Options, Benefits and Applications of Machining with Ceramic Turning or Milling Inserts
26/06/2019
https://www.cutwel.co.uk/what-are-the-benefits-of-machining-with-ceramic-turning-or-milling-inserts

12.2.2019

Kennametal’s KBH10B and KBH20B grades are designed for hard turning. They are available in double-sided inserts for materials as hard as 65 HRC.  The inserts are  for “high-volume production of hardened gears, shafts, bearings, housings and other drivetrain components. A ceramic binder structure and TiN/TiAlN/TiN coating provide extreme wear resistance even at elevated cutting speeds.  A gold PVD coating makes it easier to identify when an insert needs indexing, while the numbered corners ensure that a machine operator does not inadvertently switch to a used edge. Edge preparation in a “trumpet-style” hone, is  for heavier and interrupted cuts. a
A light hone edge inserts are for continuous turning. Both inserts give extending tool life and generate surface finish values as low as 0.2 Ra.
https://www.mmsonline.com/products/pcbn-inserts-from-kennametal-make-hard-turning-more-cost-effective

2014-07-29 (Reg Ral 90)
An optimally designed, high-precision insert seat with seat numbering ensures a maximum runout accuracy of 20 microns axially and 15 microns radially, a feed rate of 0.3 mm/tooth and cutting depths of up to 14 mm.
https://www.sandvik.coromant.com/en-gb/news/press_releases/pages/ral90.aspx

Sandvik Coromant 2020 catalogues
https://www.sandvik.coromant.com/en-gb/downloads/pages/default.aspx


Optimization in Tool Engineering Using Geometric Programming
Don T. Phillips &Charles S. Beightler
Journal: A I I E Transactions
Volume 2, 1970 - Issue 4
Pages 355-360 | Published online: 09 Jul 2007
This paper explores the use of geometric programming to solve tool engineering problems. The primary objective is to relate the technical factors involved in the cutting process to the economics of a particular tooling operation, and from this relationship determine the optimum speed and feed resulting in minimum cost per machined piece. Solution techniques are presented for non-linear objective criteria, subject to both linear and non-linear constraints. Computational procedures are illustrated through the solution of two typical examples.

https://www.tandfonline.com/doi/abs/10.1080/05695557008974776?journalCode=uiie19


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Updated on 24 July 2020
 1 May 2020,  9 April 2020,
29 March 2020