Cutting Tools Cutting Tool Properties Tool Materials Tool Life Lathe Cutting Tools Twist Drills Common Drill Bits Milling Cutters Cutting Fluids Essential Properties of Cutting Fluids

1. CUTTING TOOLS
AND
CUTTING FLUIDS

2. CONTENT
• Cutting Tools
• Cutting Tool Properties
• Tool Materials
• Tool Life
• Lathe Cutting Tools
• Twist Drills
• Common Drill Bits
• Milling Cutters
• Cutting Fluids
• Essential Properties of Cutting Fluids

3. CUTTING TOOLS
• One of most important components in
machining process
• Performance will determine efficiency of
operation
• Two basic types (excluding abrasives)
• Single point and multiple point
• Must have rake and clearance angles
ground or formed on them
• Success in metal cutting depends on
selection of the proper cutting tool
(material and geometry) for a given work
material

4. CUTTING TOOL PROPERTIES
• Hardness
• Cutting tool material must be 1 1/2 times harder than the material it is being used
to machine.
• Capable of maintaining a red hardness during machining operation
• Red hardness: ability of cutting tool to maintain sharp cutting edge
• Also referred to as hot hardness or hot strength.
• Wear Resistance
• Able to maintain sharpened edge throughout the cutting operation
• Same as abrasive resistance
• Shock Resistance
• Able to take the cutting loads and forces
• Shape and Configuration
• Must be available for use in different sizes and shapes.

5. TOOL MATERIALS
•Important properties
– Toughness - avoid fracture
– Hot hardness - resist abrasion
– Wear resistance - solubility
• Cutting tool materials
– Plain carbon and low alloy steels
– High-speed steels
– Cemented carbides, cermet and coated carbides
– Ceramics
– Synthetic diamond and CBN

6. TOOL MATERIALS
High-speed steels (HSSs)
• One of most important cutting tool materials
• Tungsten type (T-grade)– 12-20% of W
• Molybdenum type (M-grade)- 6% W and 5%
Mo
• Other elements: Tungsten and/or
Molybdenum, Chromium and Vanadium,
Carbon, Cobalt in some grades
• Can take heavy cuts, withstand shock and
maintain sharp cutting edge under red heat.
• Typical composition: Grade T1: 18% W, 4%
Cr, 1% V, and 0.9% C

7. CEMENTED CARBIDES
• Various types of cemented (sintered) carbides developed to suit different
materials and machining operations
• Operate at speeds ranging 150 to 1200 ft/min
• Can machine metals at speeds that cause cutting edge to become red hot
without loosing harness
• Advantages (Cemented Carbide, Cermet & Coated Carbides)
– High room and hot hardness
– Good wear resistance
– High thermal conductivity
– Lower in toughness that HSSs
• Grades
– Non steels grade – WC-Co
– Steel grades – add TiC and TaC due to the high solubility of WC into steels
resulting in extensive crater wear

8. • Plain Carbon and Low Alloy Steels
• Limited tool life. Therefore, not suited to mass production.
• Can be formed into complex shapes for small production runs.
• Suited to hand tools, and wood working.
• Carbon content about 0.9 to 1.35% with a hardness ABOUT 62
C Rockwell.
• Maximum cutting speeds about 26 ft/min.
• The hot hardness value is low. This is the major factor in tool
Ceramics
• Ceramics are essentially alumina
based high refractory
materials introduced specifically for high
speed machining
• These can withstand very high
temperature are chemically more stable
and have higher wear resistance.

9. • Diamond – the hardest material.
• Usually applied as coating (0.5 mm thick) on WC-
Co insert Diamond is the hardest of all the cutting
tool materials.
• Diamond has the following properties : extreme
hardness, low thermal expansion, high heat
conductivity, and a very low co‐efficient
Coated carbides
• Coated tools are becoming the norm in the metalworking industry because
coating, can consistently improve , tool life 200 or 300% or more.
• Coating thickness = 2.5 - 13 μm (0.0001 to 0.0005 in)
• Titanium-coated offer wear resistance at low speeds, ceramic coated for
higher speeds
• Best applied at high speeds where dynamic force and thermal shock are
minimal

10. TOOL LIFE
• Three modes of failure
– Premature Failure
• Fracture failure - Cutting force becomes excessive and/or dynamic, leading to
brittle fracture
• Thermal failure - Cutting temperature is too high for the tool material
– Gradual Wear
• Gradual failure
• Tool wear: Gradual failure
– Flank wear - flank (side of tool)
– Crater wear - top rake face
– Notch wear
– Nose radius wear

11. Flank wear
Crater wear

12. TOOL LIFE
•Tool life – the length of
cutting time that the tool
can be used
– Break-in period
– Steady-state wear region
– Failure region

13. TOOL GEOMETRY
•Single-point Cutting Tool geometry
– Back rake angle ( αb )
– Side rake angle ( αs )
– End relief angle (ERA)
– Side relief angle (SRA)
– Side cutting edge angle (SCEA)
– Nose radius (NR)
– End cutting edge angle(ECEA)

15. CUTTING EDGE FOR A SINGLE-POINT
TOOL

16. LATHE CUTTING TOOLS

17. TWIST DRILLS
The most common cutting tools for hole-making Usually
made of high speed steel

18. COUNTERSINK
BIT

20. MILLING CUTTERS
• Useful for production of
small parts.
• Types of form cutter
- concave
- convex
- gear tooth
• Important application -
gear-making, in which the
form milling cutter is
shaped to cut the slots
between adjacent gear
teeth
Form cutter

21. Face Milling Cutter
End Milling Cutter
• Looks like a drill bit but designed for primary
cutting with its peripheral teeth
• Applications:
– Face milling
– Profile milling and pocketing
– Cutting slots
– Engraving
– Surface contouring
– Die sinking

24. CUTTING FLUIDS
• Reduce friction and wear thus improving tool life and surface
finish of the workpiece.
• Cool the cutting zone, thus reducing workpiece temperature
and thermal distortion of the workpiece.
• Reduce forces and energy consumption.
• Flush away chips from the cutting zone, and thus chips rom
interfering with cutting process.
• Protect machined surface from environmental corrosion.

25. •Chemical formulation
– Cutting oils
– Emulsified oils
– Chemical fluids
• Application Methods
– Flooding
– Mist
– Manual
• Filtration
• Dry machining for Green Manufacturing

26. ESSENTIAL PROPERTIES OF CUTTING FLUIDS
• For cooling :
- High specific heat, thermal conductivity and film coefficient for heat transfer
- Spreading and wetting ability
• For lubrication :
- High lubricity without gumming and foaming
- Wetting and spreading
- High film boiling point
- Friction reduction at extreme pressure (EP) and temperature
• Other properties:
- Chemical stability, non-corrosive to the materials
- Less volatile and high flash point
- High resistance to bacterial growth
- Non toxic in both liquid and gaseous stage
- easily available and low cost

27. THANK
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