chapters 11-13 - indiana university bloomingtonmet33800/4_chapter_23/chapter_23.… · ·...
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MET 33800 Manufacturing Processes
Chapter 23
Drilling and Hole‐Making Processes
Materials Processing
Chapters 15-17
Chapters 30-33
Chapters 20-27
Chapters 11-13
Chapter 22 ‐ 2
Hole‐Making Processes
Chapter 23 ‐ 3
2
Hole‐Making ProcessSteps required to produce a hole that is:
Sized accurately
Geometrically accurate.
Located correctly.
Chapter 23 ‐ 4
Drilling Process1. Small hole formed by the web (Chisel edge).
2. Chips formed by the rotating cutting edges (lips).
3. Drill guided by margins that contact wall of hole.
4. Chips removed from hole by screw action of helical flutes.
Chapter 23 ‐ 5
Margin
Drilling Process
Chapter 23 ‐ 6
3
Drilling is a complex process:
Two cutting edges.
Cutting tool is relatively flexible.
Cutting action inside workpiece.
Chip removal must be along tool.
Chip removal impedes cutting fluid.
High levels of friction chip formation, chip motion on tool, and tool on work.
Drilling Process
Chapter 23 ‐ 7
Cutting Parameters
Spindle Speed (Ns)
D = drill diameter
V = cutting speed
12 VN = S D
Chapter 23 ‐ 8
Feed (fr) ipr = Amount of material removed per revolution.
Feed (fm) ipm = fr x NS
Depth of Cut (t) = fr / 2
Cutting Parameters
Chapter 23 ‐ 9
4
Cutting Time (Tm)
P Pm
L + A + A L + A + AT = =
f N fr s m
Allowance (A) ≈ D/2 (text)
Length (L) = depth of effective diameter
P
oP
A = Allowance for drill point
D Drill Included AngleA = Tan 90 -
2 2
Cutting Parameters
Chapter 23 ‐ 10
AP = 0.3 x D (118° Drill Point)
AP
Cutting Parameters
Chapter 23 ‐ 11
L
Material Removal Rate (MRR)
D = drill diameter (inch)
NS = spindle speed (RPM)
V = cutting speed (sfpm)
2
r S DMRR = f N 3 D V fr4
Cutting Parameters
Chapter 23 ‐ 12
5
Example Problem
Material: ASTM A296 Grade CA‐15 Stainless Steel 300 BHN
Hole: 5/8 inch diameter x 2.0 deep
Data from Reference Handbook:
V = 50 fpm
fr = 0.0075 ipr
Chapter 23 ‐ 13
Example Problem ‐ Solution
Chapter 23 ‐ 14
Example Problem ‐ Solution
Chapter 23 ‐ 15
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Example Problem ‐ Solution
Chapter 23 ‐ 16
Example Problem
Material: ASTM A296 Grade CA‐15 Stainless Steel 300 BHN
Hole: 5/8 inch diameter x 2.0 deep
Data from Reference Handbook:
V = 50 fpm
Fr = 0.0075 ipr
Chapter 23 ‐ 17
Example Problem ‐ Solution
Chapter 23 ‐ 18
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Example Problem ‐ Solution
Chapter 23 ‐ 19
Drill Nomenclature1. Body:
a. Flutes Spiral or helical grooves.
b. Lands Area separating flutes.
c. Margin Area of land to support and guide drill.
d. Web Backbone between flutes. Relatively thin or narrow.
e. Heel Area of flute opposite side of land from margin.
Chapter 23 ‐ 20
Chapter 23 ‐ 21
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Drill Web
Backbone between flutes. Relatively thin or narrow.
Chapter 23 ‐ 22
Drill Nomenclature1. Body (continued):
f. Helix Angle Angle of flute to centerline.
24 Standard
30 used for deep holes and high feed rates.
0 ‐ 20 used for soft materials (plastic, copper).
0 used for thin sheets or soft materials.
Chapter 23 ‐ 23
Helix Angle VariationsType N – standard helix for steel and cast iron.
Type H – slow helix for brass and similar materials.
Type W – quick helix for aluminum and similar materials.
Chapter 23 ‐ 24
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Length Variations
Chapter 23 ‐ 25
Drill Nomenclature2. Point Cutting edges.
a. Cone Angle Included point angle.
Standard 118 90‐118 used soft materials
118‐135 used for hard materials.
< 90º used for drilling plastics.
Chapter 23 ‐ 26
Drill Nomenclature2. Point (continued)
b. Back Rake Angle determined by chisel
edge, relief angle and helix angle.
c. Chisel Edge Formed by web and cone angle. Tendency to ‘walk’ due to chisel edge.
Split Point (crankshaft) thinned web to reduce cutting force and improve centering.
Chapter 23 ‐ 27
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Drill Nomenclature
Chisel edge: negative rake angle / high thrust force required.
Cutting edge: positive rake angle / lower thrust force required.
Chapter 23 ‐ 28
Drill Nomenclature3. Shank
a. Straight Shank
b. Taper Shank Tang for drill removal with drift and drive under heavy loads.
c. Bit Shank Non‐powered hand drills.
Chapter 23 ‐ 29
Drill Types
Subland
3-Flute Core
Straight Shank Twist
High-Helix Angle Twist
Taper Shank Twist
Bit Shank Twist
Straight Flute
Chapter 23 ‐ 30
11
Drill Types
Chapter 23 ‐ 31
Drill Types
Chapter 23 ‐ 32
Drill Types
Chapter 23 ‐ 33
12
Drill Types
Chapter 23 ‐ 34
Drill Types
Chapter 23 ‐ 35
Drill Types
Pivot Microdrill – very small diameter holes.
Spade Drill – with and without coolant holes.
Chapter 23 ‐ 36
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Deep hole drills are designed to drill to depths from 3x diameter to 12x diameter.
Most designs incorporate a parabolic flute for chip clearance and heavy web for rigidity.
Drill Types – Deep Hole
Chapter 23 ‐ 37
Drill Types – Insert Drills
Chapter 23 ‐ 38
Drill Types – Insert Drills
Chapter 23 ‐ 39
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Drill Types – Gundrill
Chapter 23 ‐ 40
Drill Types – Gundrill
Chapter 23 ‐ 41
Drill Types – Hole Saw
Chapter 23 ‐ 42
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Drill Types – Self‐Advancing
Chapter 23 ‐ 43
Drill Type – BTA
BTA (Boring Trepanning Association) – Deep hole drills.
Horizontal Deep‐Hole Drilling Machine
Chapter 23 ‐ 44
Drill Type Selection
Chapter 23 ‐ 45
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Drill Type Selection
Chapter 23 ‐ 46
Drill Size Series
Millimeter series: starting 0.015 mm in 0.01 to 0.50 mm increments.
Number series: #80 (0.0135) to #1 (0.228).
Letter series: A (0.234) to Z (0.413).
Fractional series: 1/64 to 4.
Chapter 23 ‐ 47
Drill Size Series
Chapter 23 ‐ 48
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Other Hole‐Making Processes
Chapter 23 ‐ 49
Other Hole‐Making Processes1. Center Drilling Used to locate hole accurately.
a. Start (Center) Drill center cutting drill which is short and stiff.
b. Center Drill Countersink Combination 60angle for lathe centers.
Chapter 23 ‐ 50
2. Reaming Accurate sizing and improved surface finish.
a. Stock removal 0.005 ‐ 0.015"
b. 45 corner chamfer typical
c. Types: chucking, taper, adjustable
d. Speed = 2/3 x drill speed
e. Feed = up to 2 x drill feed
Other Hole‐Making Processes
Chapter 23 ‐ 51
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Reamers
Chapter 23 ‐ 52
Reamers
Straight Flute Chucking
Taper Chucking
Straight Flute Hand
ExpansionShell
Adjustable Insert Blade
Chapter 23 ‐ 53
Straight Flute Rose
3. Counterboring Enlarge existing hole with flat bottom. Tools typically incorporate pilot for concentricity.
4. Spotfacing Machine rough surface. Tools may or may not be piloted.
5. Countersinking Enlarge existing hole with beveled section. Bevel self‐centering so pilot not required.
Other Hole‐Making Processes
Chapter 23 ‐ 54
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Counterbores
Chapter 23 ‐ 55
Toolholders1. Drill Chucks – for straight shank tools
2. Collet Holders – for straight shank tools.
3. Taper Shank Holders.
Chapter 23 ‐ 56
Cutting Fluids
Chapter 23 ‐ 57
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Machine Tools for Drilling1. Bench drill presses.
a. Plain
b. Sensitive
2. Upright drill presses.
a. Single spindle
b. Turret
c. CNC
Chapter 23 ‐ 58
CNC Drill Presses
Chapter 23 ‐ 59
Belt and Gear Drive
Chapter 23 ‐ 60
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Upright Turret Type
Chapter 23 ‐ 61
Machine Tools for Drilling
3. Radial drill presses.
a. Plain only vertical motion.
b. Semi‐universal spindle pivots on vertical plane.
c. Universal radial arm also rotates.
Chapter 23 ‐ 62
4. Gang drill presses.
5. Multi‐spindle drill presses.
6. Deep‐hole drill presses.
7. Transfer machines.
8. Gun Drills.
Machine Tools for Drilling
Chapter 23 ‐ 63
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Gang Type Drill Presses
Chapter 23 ‐ 64
Multiple Spindle Types
Chapter 23 ‐ 65
Multiple Spindle Drill Heads
Chapter 23 ‐ 66
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Multiple Spindle Drill Heads
Chapter 23 ‐ 67
Multiple Spindle Drill Heads
Chapter 23 ‐ 68
Deep Hole Type
Chapter 23 ‐ 69
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Gun Drill Type
Chapter 23 ‐ 70
The End – See Oncourse for Videos
Chapter 23 ‐ 71