Date post: | 13-Apr-2017 |
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Feed rateSpindle Speed
Radial cutting depthAxial cutting depth
…
CUTTING CONDITIONS
BACHELOR OF ENGINEERINGBACHELOR OF ENGINEERING
MANUFACTURING TECHNOLOGIESMANUFACTURING TECHNOLOGIES
CUTTING CONDITIONSCUTTING CONDITIONS
by Endika Gandarias
2by Endika Gandarias
Dr. ENDIKA GANDARIAS MINTEGI
Mechanical and Manufacturing department
Mondragon Unibertsitatea - www.mondragon.edu(Basque Country)
www.linkedin.com/in/endika-gandarias-mintegi-91174653
3
CONTENTS
BIBLIOGRAPHYCUTTING TOOLSCUTTING PARAMETERSCUTTING FLUIDSSELECTION OF CUTTING CONDITIONSGLOSSARY
by Endika Gandarias
4
BIBLIOGRAPHY
BIBLIOGRAPHY
by Endika Gandarias
5
The author would like to thank all the bibliographic references and videos that
have contributed to the elaboration of these presentations.
For bibliographic references, please refer to:
• http://www.slideshare.net/endika55/bibliography-71763364 (PDF file)
• http://www.slideshare.net/endika55/bibliography-71763366 (PPT file)
For videos, please refer to:
• www.symbaloo.com/mix/manufacturingtechnology
BIBLIOGRAPHY
by Endika Gandarias
6
CUTTING TOOLS
CUTTING TOOLS
by Endika Gandarias
7
CUTTING TOOLS
by Endika Gandarias
(HSS)
VIDEOVIDEO
8
CUTTING TOOLS
by Endika Gandarias
9
CUTTING TOOLS
by Endika Gandarias
Temperature [ºC]
Har
dnes
s [H
RC
]
1550
1400
1300
900
800
Ceramic
CBN
Carbide (Hard metal)
Diamond
HSS
ºC
10
Feed [mm/rev]
Cut
ting
spee
d [m
/min
]
50
CUTTING TOOLS
by Endika Gandarias
11
Solid tool Brazed insert Mechanically clamped insert
TOOL GEOMETRY
Turning
CUTTING TOOLS
by Endika Gandarias
VIDEO
12
CUTTING TOOLS
by Endika Gandarias
TOOL GEOMETRY
Turning RAKE FACE
Front Clearance (or end-relief) angle
Major (or side) cutting edge
Minor (or end) cutting edge
Front or back rake angleNose (or corner) radius
MAJOR CLEARANCE (FLANK OR RELIEF) FACE
Minor (or end) cutting edge angle
MINOR CLEARANCE (OR FLANK) FACE
Side rake angle
Major (or side or lead) cutting edge angle
Side clearance (or relief) angle
Major cutting edge angle
Minor cutting edge angle
RAKE FACE
CLEARANCEFACEClearance angle
Rake angle
Side clearance angle
Side rake angle
VIDEO
13
CUTTING TOOLS
by Endika Gandarias
TOOL GEOMETRY
Milling
Flat End Mill
Ball noseEnd Mill
Corner radius End Mill
END MILLING CUTTERS PERIPHERAL AND FACE MILLING CUTTERS
Shell End Mill
Side and Face cutter
Single and double angle cutter
14
TOOL GEOMETRY
CUTTING TOOLS
by Endika Gandarias
Drilling
Solid carbide drill
Chisel edgeMain cutting
edge
Rake face
Major flank faceMargin
Drill diameter
Web thicknessMajor
flank face
Majorcutting edge
Rake face
Point angleMinor cutting
edge
Helix angle
Point angle 140°
High Speed Steel (HSS)
Point angle 118°
VIDEO
15
TOOL INSERT
Main cutting edgedesign
Cheap-breaker macrogeometry
Geometry for small cutting depths (ap)
Rake angle 20°
Main facet 5°
Tip cutting edge design
Cheap-breaker macrogeometry
Cutting edge reinforcement of 0,25 mm
CUTTING TOOLS
by Endika Gandarias
VIDEO
Insert design
16
CUTTING TOOLS
by Endika Gandarias
Coated carbide tools
Ceramics
CBN (Cubic Boron Nitride)
Polycrystalline diamond
TOOL INSERT
Insert material types
Cermet
Non-coated carbide tools
17
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
VIDEO
POSITIVE
Rake angle
NEGATIVEIncreased tool insert resistance.Higher cutting forces.Shorter chip length.Clearance angle = 0º.Double side inserts.
Lower cutting forces.Longer chip length.Clearance angle > 0º.Used for internal machining.
Clearance angle
Clearance angle always > 0º.
18
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Lead angle / Entering angle
Entering angle
Lead angle
Side Rake angle
Same advantage discussed for rake angle, applies to side rake angle.
When rake angle is positive so is side rake angle, and vice versa.
19
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Nose radius and Nose angle Chipbreaker
Each insert has an appliation area.
Groove type Obstruction type
Nose radius Nose angle
20
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert grade
VIDEO VIDEO VIDEO
VIDEO
21
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert fabrication
Raw material Crushed
Spray drying
Carbide powderReady to be pressed
CobaltTungsten carbide
Titanium
Tantalum Niobium
Powder fabrication VIDEO
22
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert fabrication
Pressing force20 - 50 t
Upper and lower die
Die and center pin
Pressing
23
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert fabrication Sintering
Sintering duration: 8 hours Temperature between 1200 - 2200 °C Inserts trays
Insert contraction (18% in all directions,
50% in volume)
24
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert fabrication Insert grinding
Higer and lower face Free profiling Profiling
Beveling, negative facet Peripheral
Bisel
Faceta neg.
25
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert fabrication Insert grinding
ER Treatment(Edge Roundness)
W/H proportion depends on the application
26
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert fabrication Chemical Vapor Deposition (CVD) coating
- Large coating thickness.- Mechanical wear resistance (TiCN).- Thermal & chemical resistance (Al2O3).
TiCN
Al2O3
Substrate
Inserts traysCVD oven
27
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert fabrication Physical vapor deposition (PVD) coatingPVD oven
TiN
Substrate
- Thin coating thickness.- Sharp cutting edge.- Good edge toughness.- Used in all monoblock rotating tools.- Can be used with soldered tips.
28
TOOL INSERT
CUTTING TOOLS
by Endika Gandarias
Insert fabrication Visual inspection, marking, packaging
Visual inspection
Marking
Distribution
Labelling
Packaging
29
CUTTING PARAMETERS
CUTTING PARAMETERS
by Endika Gandarias
30
SELECTION CRITERIA:
Make the highest profit considering the technical requirements.
OPERATIONS:– ROUGHING: It aims to remove as much as possible material from the workpiece for as
short as possible machining time. Quality of machining is of a minor concern.– FINISHING: The purpose is to achieve the technical requirements (i.e., dimensional,
surface and geometric tolerances). Quality is of major importance.
In order to make most profit the most relevant variables are:• Cutting time.• Cutting tool expenditure.
Machining parameters that most affect the above variables are:• Cutting speed (Vc)• Feed (fz, fn, F)• Radial and axial depth of cuts (ap, ae)
ROUGHING FINISHING
Vc
fn
fz
F
CUTTING PARAMETERS
by Endika Gandarias
31
DEFINITION: Relative linear speed at the contact point between tool and the workpiece.
Vc · 1000 N =
π · Dm
CUTTING PARAMETERS: TURNING
1. Cutting Speed (Vc)
by Endika Gandarias
N
Vc: Cutting speed (m/min)
N: Spindle speed (rpm)
Dm: machined diameter (mm)
VIDEO
VIDEO
VIDEO
VIDEO
32
CUTTING PARAMETERS: TURNING
1. Cutting Speed (Vc)
Given the following parameters calculate the spindle speed for each diameter:
Cutting speed Vc = 120 m/min
Diameter D1 = Ø 50 mm
Diameter D2 = Ø 80 mm
VC x 1000 x d
N =
N1
N2
by Endika Gandarias
33
F [mm/min]
DEFINITION: Relative movement between the workpiece and the tool.
fn [mm/rev]
IN TURNING
FEED PER REVOLUTION
(fn)
2. Feed
3. Cutting depth (ap)
FEED PER REVOLUTION
F = fn·N
CUTTING PARAMETERS: TURNING
FEED RATEor
FEED PER MINUTE
by Endika Gandarias
F
ap
ap
ap
34
MACHINE WORKPIECE MATERIAL TOOL MATERIAL OPERATION
Vc
(m/min)fn
(mm/rev)Ap
(mm)
TURNING MACHINE
STEEL
HIGH SPEED STEEL(HSS)
Turning and facing D 30 – 40A 40 - 50
D 0.1– 0.25 A 0.02/ 0.1
D 0.75-2A 0.2-0.8
Parting and grooving 10 – 15 0.02 – 0.1
Threading 10 Thread pitch According to formula
Drilling 18 Manual
Knurling 10
BoringD 20 – 30A 30 - 40
D 0.1– 0.25 A 0.02/ 0.1
D 0.75-2A 0.2-0.8
HARD METAL
Turning and facingD 80 – 100A 100 - 120
D 0.1– 0.25 A 0.02/ 0.1
D 0.75-2A 0.2-0.8
Parting and grooving 60 – 80 0.04 – 0.1
Threading 40 - 50 Thread pitch According to formula
Drilling 30 – 40 Manual
BoringD 70 – 90A 90 - 110
D 0.1– 0.25 A 0.02/ 0.1
D 0.75-2A 0.2-0.8
ALUMINIUM
HIGH SPEED STEEL(HSS)
Turning and facing D 40 – 60A 60 - 80
D 0.1– 0.25 A 0.02/ 0.1
D 0.75-2A 0.2-0.8
Parting and grooving 20 – 30 0.02 – 0.1
Threading 15 Thread pitch According to formula
Drilling 30 Manual
Knurling 20
BoringD 30 – 50A 50 - 70
D 0.1– 0.25 A 0.02/ 0.1
D 0.75-2A 0.2-0.8
HARD METAL
Turning and facingD 150 – 180A 180 – 200
D 0.1– 0.25 A 0.02/ 0.1
D 0.75-2A 0.2-0.8
Parting and grooving 80– 100 0.04 – 0.1
Threading 50 – 60 Thread pitch According to formula
Drilling 60 – 80 Manual
BoringD 140 – 170A 170 - 190
D 0.1– 0.25 A 0.02/ 0.1
D 0.75-2A 0.2-0.8
by Endika Gandarias
D: Roughing operationA: Finishing operation
CUTTING PARAMETERS: TURNINGO
RIE
NTA
TIV
E C
UTT
ING
TA
BLE
FO
R E
XE
RC
ISE
S
35
SURFACE ROUGHNESS:
Surface finish depends on:• Tool nose radius• Feed per revolution (fn)
WIPER INSERTS: Advantages:
Productivity
CUTTING PARAMETERS: TURNING
by Endika Gandarias
VIDEO
36
CUTTING PARAMETERS: TURNING
by Endika Gandarias
TOOL CENTRE HEIGHT
37
CUTTING PARAMETERS: TURNING
VIBRATION
_ +Vibration
by Endika Gandarias
RoundR
90ºS
80ºC
80ºW
60ºT
55ºD
35ºV_
+
Vibr
atio
n
ER: Edge RoundingGC: Ground coated insertsVB: Flank wear_
+
Stre
ngth
38
CUTTING PARAMETERS: TURNING
VIBRATION
They can reduce machining vibration in turning, milling or drilling.
VIDEO
– Diameters starting from Ø > 10mm.– Maximum overhang value 14 × Ø.
by Endika Gandarias
Dampened toolUndampened tool
SSV technique may reduce or eliminate chatter. VIDEO
VIDEO
Dampened tools
Spindle Speed Variation (SSV)
39
DEFINITION: Relative linear speed at the contact point between tool and the workpiece.
CUTTING PARAMETERS: MILLING
1. Cutting Speed (Vc)
by Endika Gandarias
N
N
Vc · 1000 Vc: Cutting speed (m/min) N = N: Spindle speed (rpm)
π · Dc Dc: Tool diameter (mm)
VIDEO
40
Feed per tooth (fz): It defines the chip thickness, and so, the load that the tool is subjected to.
Feed per revolution (fn): It defines the tool displacement per tool revolution.
Feed rate or Feed per minute (F): It defines the tool movement speed.
fn = fz·z z tooth number (flute number)
F = fn·N = fz·z·N N spindle speed
DEFINITION: Relative movement between the workpiece and the tool.
IN MILLING
FEED PER TOOTH
(fz)
2. Feed
CUTTING PARAMETERS: MILLING
by Endika Gandarias
fn
F
VIDEO
41
As there are greater tooth breakage chances during tooth entry and exit, in facing operations the following tool size and positioning are recommended.
ap: axial depth of cut
ae : radial depth of cut
3. Cutting depth
Better size
Better positioning
CUTTING PARAMETERS: MILLING
by Endika Gandarias
VIDEO
42by Endika Gandarias
MACHINE WORKPIECE MATERIAL TOOL MATERIAL OPERATION
Vc
(m/min)fz
(mm/tooth*rev)Ap
(mm) Ae
(mm)
MILLING MACHINE
STEEL
HIGH SPEED STEEL(HSS)
Face milling D 20 - 25 A 25 - 30
0.05 – 0.10.01 – 0.05
D 1-2A 0.2-0.5
D (~2/3)ØA (~2/3)Ø
Side milling D 20 - 25 A 25 - 30
0.05 – 0.10.01 – 0.05
D (50%-80%)ØA (50%-80%)Ø
D (10%-25%)ØA (5%-10%)Ø
Other milling D 15 - 20 A 20 - 25
0.05 – 0.10.01 – 0.05
HARD METAL
Face milling D 80 - 100
A 100 – 1200.05 – 0.1
0.01 – 0.05D 1-2
A 0.2-0.5D (~2/3)ØA (~2/3)Ø
Side millingD 80 - 100
A 100 – 1200.05 – 0.1
0.01 – 0.05D (50%-80%)ØA (50%-80%)Ø
D (10%-25%)ØA (5%-10%)Ø
Other millingD 70 - 90
A 90 – 1000.05 – 0.1
0.01 – 0.05
ALUMINIUM
HIGH SPEED STEEL(HSS)
Face milling D 50 - 70 A 70 - 90
0.05 – 0.10.01 – 0.05
D 1-2A 0.2-0.5
D (~2/3)ØA (~2/3)Ø
Side milling D 50 - 70 A 70 - 90
0.05 – 0.10.01 – 0.05
D (50%-80%)ØA (50%-80%)Ø
D (10%-25%)ØA (5%-10%)Ø
Other milling D 40 - 60 A 60 - 70
0.05 – 0.10.01 – 0.05
HARD METAL
Face milling D120 - 150 A 150 – 180
0.05 – 0.10.01 – 0.05
D 1-2A 0.2-0.5
D (~2/3)ØA (~2/3)Ø
Side millingD120 - 150
A 150 – 1800.05 – 0.1
0.01 – 0.05D (50%-80%)ØA (50%-80%)Ø
D (10%-25%)ØA (5%-10%)Ø
Other millingD100 - 130
A 130 – 1500.05 – 0.1
0.01 – 0.05
Other milling: slot milling, t-shape milling, dovetail milling, form milling.D: Roughing operationA: Finishing operation
CUTTING PARAMETERS: MILLINGO
RIE
NTA
TIV
E C
UTT
ING
TA
BLE
FO
R E
XE
RC
ISE
S
43
DOWN MILLING or CLIMB CUTTINGDOWN MILLING or CLIMB CUTTINGSame cutter rotation and feedSame cutter rotation and feed
UP MILLING or CONVENTIONAL MILLINGUP MILLING or CONVENTIONAL MILLINGOpposite cutter rotation and feedOpposite cutter rotation and feed
The insert starts cutting with a large chip thickness:
It is more suitable.
Backlash elimination is necessary. Vibration tendency ↑.
Fc tend to pull the workpiece into the cutter.
Not recommended when using ceramic inserts (fragile).
The insert starts cutting at zero chip thickness:
Rubbing Friction ↑, Fc ↑, Machine power ↑
Temperature ↑, work-hardened surface, Ra
Fc tend to: lift the workpiece from the table, push the cutter and workpiece away from each other.
Tensile stresses ↑ when teeth exit, tool life
Mc
Ma
MILLING: Discontinuous cutting process
Ma
Mc
CUTTING PARAMETERS: MILLING
MILLING DIRECTION
by Endika Gandarias
VIDEO VIDEOVIDEO
44
CUTTING PARAMETERS: MILLING
HIGH SPEED MACHINING (HSM)
by Endika Gandarias
HSM: Feed faster than heat
propagation.
Traditional milling: time for heat propagation.
In comparison with traditional milling:
Spindle speed (N) ↑, feed rate (F) ↑ and axial cutting depth (ap) ↑.
Radial cutting depth (ae) ↓ and feed per tooth (fz) ↓.
F F
VIDEO
45
CHARACTERISTICS:More productive cutting process in small sized components.
Possible to be used with high-alloy tool steels up to 60-63 HRc (EDM process can be avoided).
Excellent surface roughness can be achieved (Ra ~ 0.2 µm).
Machining of very thin walls is also possible.
Typical applications: dies and moulds, difficult to machine materials,…
CUTTING PARAMETERS: MILLING
HIGH SPEED MACHINING (HSM)
by Endika Gandarias
Trochoidal milling(typical HSM technique)
Progressive cutting(constant stock)
Constant peripheral cutting speed (Vc)
46
CUTTING PARAMETERS: MILLING
HIGH SPEED MACHINING (HSM)
by Endika Gandarias
DISADVANTAGES:Higher maintenance costs: Faster wear of guide ways, ball screws and spindle bearings.
Specific process knowledge, programming equipment and interface for fast data transfer is needed.
It can be difficult to find and recruit advanced staff.
Human mistakes, hardware or software errors give big consequences. Emergency stop is practically unnecessary.
Good work and process planning necessary.
Safety precautions are necessary:
Machines with safety enclosing (bullet proof covers).
Avoid long overhangs on tools.
Do not use “heavy” tools and adapters.
Check tools, adapters and screws regularly for fatigue cracks.
Use only tools with posted maximum spindle speed.
Do not use solid tools of HSS.
47
CUTTING PARAMETERS: MILLING
by Endika Gandarias
MILLING STRATEGY
When using a ball nose end mill, tilting the cutter 10 to 15 degrees can improve tool life and chip formation and provide a better surface finish.
VIDEO
ROLL-IN TECHNIQUE
48
CUTTING PARAMETERS: MILLING
by Endika Gandarias
MILLING STRATEGY
49
CUTTING PARAMETERS: MILLING
by Endika Gandarias
MILLING STRATEGY
THIN WALLS
ae sould be minimized (20% Dc).
ap should not exceed 100% Dc
Big entry-exit radii should be programmed.
Sharp and positive cutting edges should be used.
WEAK FIXTURE
50
CENTER-LINE OF THE CUTTER OUTSIDE THE WORKPIECE
CENTER-LINE OF THE CUTTER IN LINE WITH THE WORKPIECE
CENTER-LINE OF THE CUTTER INSIDE THE WORKPIECE
CUTTING PARAMETERS: MILLING
hex = fz cutter hits, no shearing
MILLING STRATEGY
by Endika Gandarias
ae > 70% x Dc ae < 25% x Dc
hex < fz high productivity
CVD coating inserts recommended (better thermal protection)
hex < fz F ↑ to mantain productivity
PVD coating inserts recommended (sharper cutting edge)
Carbide handles the compressive stresses at the impact of entering well.
VIDEOVIDEOVIDEO
51
CENTER-LINE OF THE CUTTER OUTSIDE THE WORKPIECE
CENTER-LINE OF THE CUTTER IN LINE WITH THE WORKPIECE
CENTER-LINE OF THE CUTTER INSIDE THE WORKPIECE
Chip thickness is at its maximum
CUTTING PARAMETERS: MILLING
At exit, chip bends and generates tensile forces on the carbide increasing fracture possibilities.
VIDEOby Endika Gandarias
MILLING STRATEGY
52
CUTTING PARAMETERS: MILLING
• Best for shoulder face milling & where 90° form is required.• Low axial forces Thin walls, weak fixtured components,…
• Best for face milling & plunge milling.• Excellent for ramping operations.• Lower radial forces Lower vibration.• Chip thickness feed ↑ to keep productivity.
• Best for face milling & profiling operations.• Excellent ramping capabilities.• Strongest cutting edge with multiple indexes.• The chip load and entering angle vary with the depth of cut.
: Cutting edge angle affects the cutting force direction and the chip thickness. ENTERING ANGLE (Kr)
VIDEO VIDEO VIDEO VIDEO
_ +Chip thickness _+
Length of contact
by Endika Gandarias
90º 45º 10º VIDEO
53
CUTTING PARAMETERS: MILLING
The pitch is the distance between the effective cutting edges. Different pitches:
Differential pitch: A very effective way to minimize vibration tendencies.
PITCH (u)
_ +Productivity
Machine power consumption
by Endika Gandarias
Vibration
VIDEO
54
TOOL HOLDER ALIGNMENT RECOMMENDATIONS:
Finishing
CUTTING PARAMETERS: MILLING
by Endika Gandarias
< 0.006 mm
Roughing
Tool overhang (A) and total length (B) should be minimized.
Attention to the max. allowable torque. It depends on the tool holder type and tool diameter.
55
Surface finish, i.e. Surface Roughness, is mainly determined by the distance between the contiguous toolpaths, tool radius and surface slope.
How to calculate the axial (ap) and radial (ae) cutting depths to achieve a certain theoretical roughness?
In this type of milling; Ra Rmax/4
ae = Radial depth of cutap = Axial depth of cutRmax = Rz = Max. roughnessRhta = Tool radius = Surface slope
Rmax ae ap
Rhta
CUTTING PARAMETERS: MILLING
SURFACE ROUGHNESS:
by Endika Gandarias
56
In ball end mills, cutting happens at points with different diameters. Thus, as the whole tool rotates at the same spindle speed, the cutting speed varies along the ball end.
Effective radius in ascending toolpaths Effective radius in descending toolpaths
EFFECTIVE TOOL RADIUS
CUTTING PARAMETERS: MILLING
by Endika Gandarias
57
CUTTING PARAMETERS: DRILLING
1. Cutting Speed (Vc)
DEFINITION: Relative linear speed at the contact point between tool and the workpiece.
by Endika Gandarias
vc
N Vc · 1000 Vc: Cutting speed (m/min)
N = N: Spindle speed (rpm)
π · Dc Dc: Tool diameter (mm)
N
VIDEOVIDEO
58
2. Feed
DEFINITION: Relative movement between the workpiece and the tool.
IN DRILLING
FEED PER REVOLUTION
(fn)
3. Cutting depth (ap)
F [mm/min]
FEED RATEor
FEED PER MINUTE F = fn·N
CUTTING PARAMETERS: DRILLING
by Endika Gandarias
ap
VIDEO
59
DRILL ALIGNMENT RECOMMENDATIONS:
by Endika Gandarias
CUTTING PARAMETERS: DRILLING
0.02 mm 0.02 mm
Rotary drill Stationary drill
BA
Feed force
Better B than A tool position (lower torque).
Tool alignment method.
VIDEOVIDEO
60
fn ⅓ fn ⅓fn ⅓fn
A B C D
ENTRY AT NON-PLANAR SURFACES:
by Endika Gandarias
CUTTING PARAMETERS: DRILLING
MACHINE WORKPIECE MATERIAL TOOL MATERIAL OPERATION
Vc
(m/min)fn
(mm/rev)
DRILLING MACHINE
STEELHIGH SPEED STEEL
(HSS)
Spot drilling 18 0.04 – 0.1Drilling 18 0.04 – 0.1Counterboring 9 Countersinking 9
ALUMINIUMHIGH SPEED STEEL
(HSS)
Spot drilling 30 – 40 0.04 – 0.1Drilling 30 – 40 0.04 – 0.1Counterboring 15 – 20 Countersinking 15 – 20
OR
IEN
TATI
VE
CU
TTIN
G T
AB
LE
FOR
EX
ER
CIS
ES
61
Excellent Acceptable
Start chip
Chip jamming
The start chip from entry into the workpiece is always long and does not create any problems.
Chip jamming can cause radial movement of the drill and affect hole quality, drill life and reliability, or drill/insert breakages.
A hole affected by chip jamming. A hole with good chip evacuation.
CHIP CONTROL
The chip formation is acceptable when chips can be evacuated from the drill without disturbance.
The best way to identify this is to listen during drilling: A consistent sound = chip evacuation is good. An interrupted sound indicates chip jamming.
CUTTING PARAMETERS: DRILLING
by Endika Gandarias
VIDEO
62
PECK DRILLING
CUTTING PARAMETERS: DRILLING
by Endika Gandarias
Peck drilling may be necessary if chip evacuation is difficult due to a deep hole or the use of external lubricant.
VIDEO
63
CUTTING PARAMETERS
VARIABLE UNIT DESCRIPTION HOW TO CALCULATE? TURNING MILLING DRILLING
Vc m/min Cutting speed TABLES
N rpm or rev/min Spindle speed N=(Vc*1000)/(π*Ø)
fz mm/tooth*rev Feed per tooth TABLES
fn mm/rev Feed per revolution
TABLES
fn = fz * z
F mm/min Feed rate or feed per minute
F = fn * N
Ap mm Axial cutting depth
TABLES
Tool radius
Ae mm Radial cutting depth TABLES
Parameter introduced into the machine.
Parameter NOT introduced into the machine.
by Endika Gandarias
SUMMARY TABLE
64
CUTTING FLUIDS
CUTTING FLUIDS
by Endika Gandarias
65
Cutting fluid is any liquid or gas that is applied to the chip or cutting tool to improve cutting performance.
Cutting fluids serve 4 principle functions:
1. To remove heat in cutting (=COOLING): The energy used in the cutting process is almost exclusively transformed into heat that goes to the workpiece, tool and chip. The effective cooling action depends on the method of application, type of fluid, fluid flow rate and pressure.
2. To lubricate the chip-tool interface (=LUBRICATION): It reduces friction forces and temperatures.
3. To wash away chips (=CHIP REMOVAL): This is only applicable to small and discontinuous chips.
4. To avoid part oxidation (=ANTI-CORROSION): The environment humidity in combination with the high temperatures (500-900ºC) obtained during machining may cause part oxidation. Thus, the cutting fluid must contain anti-corrosion additives.
Use of cutting fluids contributes to: Diminish tool wear (longer tool life). Produce workpieces of accurate sizes (reduce thermal expansion). Achieve proper surface quality of the workpiece. Support chip removal. Reduce thermal stress on machine tool.
CUTTING FLUIDS
by Endika Gandarias
66
CUTTING FLUIDS
- METHODS OF APPLICATION
LUBRICATION TYPE CONTENT USED
VOLUME CHARACTERISTICS
Wet machining (using coolant)
Manual application
10 to 100 l/min
Used for manual tapping. Cutting fluids are used as lubricants.
Flooding supply Lubricating system of machine tools need to be cleaned from time to time to eliminate microorganisms.
Coolant-fed tooling or internal cooling
Some tools (typically drills) are provided with axial holes so that cutting fluid can be pumped directly to the cutting edge. Coolant pressures up to 80 bars.
Coolant-fed tool holders
Special tool holders required for milling, turning or drilling operations. Coolant pressures up to 30 bars.
Reduced lubrication
Minimum quantity llubrication (MQL)
50 ml/h up to 1-2 l/h
Cutting fluid is deposited as drops or air-oil mix. Valid for not very demanding machining operations. It can be external or internal.
Without lubrication Dry machining without It shows economic and environmental benefits. Under
research.
Novel cooling methods are under research: high pressure cooling (> 70bar), criogenic cooling (N2, CO2),...
by Endika Gandarias
VIDEO
VIDEO
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CUTTING FLUIDS
Manual application Flooding supply Coolant-fed tooling Coolant-fed tool holder
by Endika Gandarias
Titanium alloys Nickel Stainless steel Hard steel ( 0.4 to 0.7 % C ) Copper Cast-iron Steel (More carbon more difficult) Aluminum Brass Bronze Zinc alloy-
Mac
hini
ng d
ifficu
lty +
Broaching Shaping Gear machining Drilling Reaming Sawing MillingTurning
- M
achi
ning
diff
iculty
+
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CUTTING FLUIDS
by Endika Gandarias
Cutting oils are based on mineral or fatty oil mixtures. Commonly used for heavy cutting operations.
Soluble oils is the most common (95% of the time), cheap and effective form of cutting fluid. Oil droplets suspended in water in a typical ratio water to oil 30:1. Emulsifying agents are also added to promote stability of emulsion, as well as anticorrosive additives.
Chemical fluids (synthetic) consists of chemical diluted in water. They may have harmful effects to the skin.
- TYPES OF CUTTING FLUIDLu
bric
atio
n
Refrigeration
Cutting oilsSoluble oilsChemical fluids WaterDry machining
Low speed applications (broaching, threading,…)
↓High friction
↓Maximum lubrication
High speed applications (turning, milling,…)
↓Low friction
↓Maximum refrigeration
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SELECTION OF CUTTING CONDITIONS
SELECTION OF CUTTING CONDITIONS
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SELECTION OF CUTTING CONDITIONS
Productivity is a combination of factors that really make a difference, such as:
• Increased cutting conditions = more parts per hour• Predictable tool life = machining security• Fewer tool changes = less down time• Fewer rejects = higher quality – more valuable end product• Product availability = less inventory• Technical training of employees = better understanding and less scrap
by Endika Gandarias
Important to identify the most relevant factors that influence the FINAL COST:
≈ 31%
≈ 27%
≈ 22%
≈ 3%
≈ 17%
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Important to identify the most relevant factors that influence MACHINE-TOOL UTILIZATION TIME:
SELECTION OF CUTTING CONDITIONS
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Machining efficiency suggests that good quality parts are produced at reasonable cost and at high production rate.
Most relevant cutting parameters that affect machining costs and productivity are:1. Depth of cut2. Feed3. Cutting speed
SELECTION OF CUTTING CONDITIONS
It is predetermined by workpiece geometry and final part shape.
In Roughing operations As large as possible (max. 6-10 mm). It depends on machine tool, cutting tool strength and other
factors.
In Finishing operations A single pass to achieve the final dimensions.
Finishing pass in a turning operationRoughing passes in a turning operation
1. Depth of Cut (ap, ae)
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SELECTION OF CUTTING CONDITIONS
In Roughing operations As large as possible (max. 0,5mm/rev). It depends on cutting forces and setup rigidity.
In Finishing operations Small to ensure good surface finish (~ 0,05-0,15 mm/rev).
Cutting at high cutting speed involves...
Reduction of tool life Increase of production costs as more cutting tools are needed.
Increase of productivity less time consumption.
Hence, optimal cutting speed range has to be calculated for:
Cutting speed for minimum cost per unit (Vmin). Cutting speed for maximum production rate (Vmax).
3. Cutting Speed (Vc)
2. Feed (F, fn, fz)
by Endika Gandarias
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Production cost
Fixed costs
EconomicVc
Tooling cost
Cutting speed Vc
Cos
t per
par
t
Parts per hour
Vc for max. productivity
High efficiency range
Machinery costs
SELECTION OF CUTTING CONDITIONS
by Endika Gandarias
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SELECTION OF CUTTING CONDITIONS
- HOW TO CALCULATE THOSE VALUES?
Several limitations need to be considered:
1. MACHINE2. TOOL3. GEOMETRY4. MATERIAL
1. MACHINE: The machinery usually exists in the workshop, and it may be a limiting factor. Anyway, either an existing or a new machine is used, attention should be
paid to the following machine features:
General characteristics: number of axes, machine configuration type, general dimensions and weight,…
Axes: traversing range, power, accuracy, max. workpiece weight, max. acceleration and feed.
Workholder system: Forces, vibrations,… Spindle head: power, speed range, run-out, stiffness, clamping system,
automation possibilities, internal cooling.
Toolholder system: Run-out, torque,… Tool changer: chip to chip time, max. number of tools, tool length and diameter,… Cooling unit system: internal or external, MQL, HPC CNC controller: capabilities …by Endika Gandarias
76
SELECTION OF CUTTING CONDITIONS
2. TOOL: Tool wear will occur.
There are five main wear mechanisms which dominate in metal cutting:
1. Abrasion.2. Diffusion.3. Oxidation (corrosion).4. Fatigue (thermal).5. Adhesion.
These wear mechanisms combine to attack the cutting edge in various ways depending upon the tool material, cutting geometry, workpiece material and cutting data.
Flank wear is the most common type of wear (abrasion) and the preferred wear type, as it offers predictable and stable tool life.
by Endika Gandarias
VIDEO
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SELECTION OF CUTTING CONDITIONS
2. TOOL
by Endika Gandarias
In the case of pasty materials, layers / new
edges are formed.Adhesive
SiC inclusions of Fe foundry materials may
create cutting edge wear.Abrasive
Chemical reaction between tool carbides
and the machining part create wear.
Chemical
Temperature variations create cracks in the
cutting edge.Thermal
Mechanical efforts on the cutting edge create tool
failures.Mechanic
CauseWear descriptionSymbolLoad type
FA
FA = Filo de aportación
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SELECTION OF CUTTING CONDITIONS
1. Flank wear2. Crater wear3. Plastic deformation4. Notch wear5. Thermal cracks6. Mechanical fatigue cracks7. Chipping on edge8. Tool breakage9. Built-up edge (BUE)
TOOL WEAR TYPES
Inappropriate cutting conditions Inappropriate tool features Material properties Too low or high cutting
temperature …
by Endika Gandarias
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SELECTION OF CUTTING CONDITIONS
by Endika Gandarias
VIDEO
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SELECTION OF CUTTING CONDITIONS
Vc : Cutting speed [m/min]fn : Feed per revolution [mm/rev]ap : Cutting depth [mm]T : Tool life [min]a, b, n, C: Constants
by Endika Gandarias
VIDEO
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SELECTION OF CUTTING CONDITIONS
Vc
fn
ap
Workpiece material hardness
Toolmaterial
R: RoughingM: Medium machining
F: Finishing
by Endika Gandarias
INSERT GRADE
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SELECTION OF CUTTING CONDITIONS
WORKPIECE MATERIAL
INSERT GRADES
by Endika Gandarias
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Select geometry and grade depending on the type of the workpiece material and type of application.
SELECTION OF CUTTING CONDITIONS
by Endika Gandarias
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SELECTION OF CUTTING CONDITIONS
CUTTING DATA ON DISPENSERS
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TURNING INSERTS
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SELECTION OF CUTTING CONDITIONS
by Endika Gandarias
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SELECTION OF CUTTING CONDITIONS
When increasing the cutting speed (vc), feed rate (fn) should be decreased and vice versa.
Cutting speed and feed data compensation for turning
by Endika Gandarias
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GLOSSARY
GLOSSARY
by Endika Gandarias
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GLOSSARY
by Endika Gandarias
ENGLISH SPANISH BASQUE
Alignment Alineación AlineazioAlloy Aleación AleazioAluminium casting Fundición de aluminio Aluminio burdinurtuaAxial cutting depth Profundidad de pasada axial Sakontze sakoneraBacklash Desajuste DesdoitzeBall nose end mill Fresa de punta esférica / punta de bola Boladun fresaBend Doblar TolestuBeveling Biselado AlakaketaBrass Latón LetoiaBrazed Soldado SoldatuaBreakdown Averiar MatxuratuBroaching Brochado BrotxaketaBronze Bronce BrontzeaBuilt-up edge Filo de aportación Aportazio ertzaCarbide Metal duro Metal gogorraCarbon steel Acero al carbono Karbono altzairuaCast-iron Fundición BurdinurtuCBN (Cubic Boron Nitride) Nitruro de Boro Cúbico Boro nitruro kubikoaCheap breaker Rompevirutas Txirbil hausleaChip Viruta TxirbilChip Viruta TxirbilChipping Astillado ZatiChisel edge Filo central Erdiko sorbatzClamp Abrazar LotuClearance face Cara de incidencia Eraso aurpegiaClimb cutting Concordancia KonkordantziaCoarse Basto BaldarCoat Recubrimiento Estaldura
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GLOSSARY
by Endika Gandarias
ENGLISH SPANISH BASQUE
Contiguous Contiguo AlbokoConventional milling Contraposición KontrajartzeCoolant Lubricante LubrifikatzaileCorner radius end mill Fresa tórica Fresa torikoaCrush Machacar BirrinduCutting edge Arista de corte Ebaketa ertz / SorbatzCutting speed Velocidad de corte Ebaketa abiaduraCutting tool Herramienta de corte Ebaketa erramintaDampened tool Herramienta antivibratoria Bibrazioen aurkako erramintaDie Molde MoldeDiminish Disminuir GutxituDispenser Dispensador KaxaDovetail Cola de milano MirubuztanDown milling Concordancia KonkordantziaDrilling Taladrado ZulaketaDrop Gota TantaEdge rounding Redondeo de arista Ertz biribiltzeEDM Electroerosión Elektro-higaduraEnclosing Cerramiento ItxituraEnd mill Fresa plana Fresa lauaEngagement Empañe LausotuaFatty Graso OliotsuFeed per revolution Avance por vuelta Aitzinamendua birakoFeed per tooth Avance por diente Aitzinamendua hortzekoFeed rate Avance por minuto Aitzinamendua minutukoFinish Acabado AkaberaFlank Flanco / Lateral AlboFlooding Inundación Gainezkatze
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GLOSSARY
by Endika Gandarias
ENGLISH SPANISH BASQUE
Friction Fricción MarruskaduraGauge Calibrar KalibratuGear Engrane EngranaiGrinding Rectificado ArtezketaHard metal Metal duro Metal gogorraHardening Endurecimiento GogortzeHardness Dureza GogortasunaHarmful Dañino KaltegarriHeat Calor BeroHeight Altura AltueraHigh Speed Machining Mecanizado a alta velocidad Abiadura azkarreko mekanizazioaHigh Speed Steel (HSS) Acero rápido Altzairu lasterraHit Golpear KolpeInsert Plaquita intercambiable Plakatxo trukagarriaJamming Atasco TrabatzeLabelling Etiquetado Etiketa jarriLoad Carga KargaMajor Mayor NagusiMargin Faja guia Faxa gidariaMarking Marcado MarkaketaMilling Fresado FresaketaMinor Menor TxikiNose radius Radio de punta Muturreko erradioaNotching Entallado HozkaketaOven Horno LabeOverhang Voladizo HegalkinOverhead Gastos generales Gastu orokorrakPackaging Empaquetado Paketeak egin
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GLOSSARY
by Endika Gandarias
ENGLISH SPANISH BASQUE
Pecking Picada ZiztadaPin Punzón PuntzoiPitch Paso NeurriPlunge Penetración BarneratzePowder Polvo HautsPower Potencia PotentziaPressing Prensado PrentsaketaProfiling Perfilado ProfilaketaRadial cutting depth Profundidad de pasada radial / ancho de pasada Iraganaldi zabaleraRadii Radios ErradioakRake Desprendimiento JaulkitzeReaming Escariado OtxabuketaReject Rechazo ErrefusRelief face Cara de desahogo Lasaitasun aurpegiaRevolution Vuelta BiraRoughing Desbaste ArbastaketaRubbing Bruñido TxartaketaSawing Serrado ZerraketaScrap Residuo HondakinSeat Asiento EserlekuShank Mango KirtenShape Forma Forma / ItxuraShaping Limado KarrakaketaSharp Afilado ZorrotzShearing Cizallamiento Ebakidura / ZizailaduraShell end mill Fresa hueca Kofadun fresaShift Relevo Txanda / ErrelebuShim Calza Altxagarri
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GLOSSARY
by Endika Gandarias
ENGLISH SPANISH BASQUE
Shoulder milling Escuadrado EskuairaketaSide Lateral / Secundario Albo/BigarrenSintering Sinterizado SinterizazioSkin Piel AzalSlope Pendiente MaldaSolid tool Herramienta enteriza Pieza bakarreko erramintaSpindle Cabezal BuruSpindle speed Velocidad de giro Biraketa abiaduraSpray drying Secado por pulverización Lainoztatze bidezko lehorketaStaff Personal LangilegoStiffness Rigidez ZurruntasunStrength Resistencia ErresistentziaStress Fatiga / Estrés EstresSubstrate Sustrato SubstratuSurface roughness Rugosidad superficial Gainazal zimurtasunaTapping Roscado con macho Ardatzarekin egindako hariztaketaThickness Espesor LodieraTilting Inclinación InklinazioTip Punta PuntaToolholder Portaherramientas Erraminta etxeaTorque Par MomentuToughness Tenacidad ZailtasunTray Bandeja ErretiluTrochoidal Trocoidal TrokoidalTurning Torneado TorneaketaUnleaded Sin plomo Berunik gabekoUp milling Contraposición KontrajartzeWash away Limpiar Garbitu
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GLOSSARY
by Endika Gandarias
ENGLISH SPANISH BASQUE
Weak Debil AhulWear Desgaste HigaduraWeb Alma ArimaWedge Cuña Kuña / FalkaWeight Peso PisuaWet Humedo BustiWorkpiece Pieza Pieza Workshop Taller Tailer