cost efficiency, Think HSS
Transcript of cost efficiency, Think HSS
T h i n k c o s t e f f i c i e n c y , T h i n k H S S
SAWING
SAWING
BANDSAWING2 The basics of bandsawing
3 HSS and coatings
4 The bimetal concept
5 Tooth set
6 Tooth pitch and forms
7 Speeds and feeds
8 Blade break-in
9 Chips
10 Clamping of workpiece
11 Problem solving
CIRCULAR SAWING12 The basics of circular sawing
13 HSS and coatings
14 Tooth types
15 Tooth pitch
16 Speeds and feeds
17 Positioning of workpiece
18 Problem solving
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SU
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AR
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THE BASICS OF BANDSAWING2
A BANDSAW AROUNDTHE WORLD
French: une scie-ruban
German: eineBandsäge
Italian: una sega anastro
Spanish: una sierracinta
In bandsawing, a continuous bandsaw blade cuts inone direction with a uniform cutting action and evenlydistributed, low individual tooth load. Chips producedhave a constant thickness.
Bandsaws can be used for cut-off operation, straightsawing or contour sawing.
Three types of bandsawing machines are available:
• vertical, mainly used for contour sawing
• horizontal, for productive cut-off operations
• pendular machines.
HSS AND COATINGS
• Seldom used • Basic choice • For highperformance andlong tool life
• For nickel alloys,titanium alloys andhard steels
TOOL MAKER’S TIP
Use TiN coated bandsaws for longer
blade life andresistance to
abrasion
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HSS HSS-E8% cobalt
HSS-E-PM
THE BIMETAL CONCEPT4
Bimetal saw concept
In bimetal saws, a HSS wire is welded by electron beamor laser on a steel backing
Vocabulary
HSS wireRake angle
Tooth angle
Saw blade length
Tooth back face
Tooth rake face
Tooth heightGullet
Saw bladethickness
EB or laser welding
Bimetal bladeSteel backingSteel backing
TOOTH SET5
Raker set
• 3-tooth sequence, left,right, straight
• Reduces tooth load, forheavy cutting
• Uniform set angle
• Prefered for ferrousapplications
Wave set
• Progressive sine-waveoffset pattern with fine pitch
• Reduces tooth load
• Smoother in thin wallsections
• Also for high speed cuttingat reduced cutting depth
Alternate set
• 2-tooth sequence, left,right
• Prefered for non-ferrousmetals
Variable (multipitch) set
• One unset tooth (raker) ineach repeating pitchsequence
• Only the largest tooth ineach sequence is unset
• Appropriate for mostapplications
TOOTH PITCH AND FORMS
Tooth pitch
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Fixed pitch
• General purposeuse
• Good chip carryingcapacity
Fixed pitchpositive
• General purpose use
• Good chip carryingcapacity
Variable pitch
• Smooth cutting
• Reduces harmonicvibrations andnoise
• Good chip carryingcapacity
• Long blade life
Variable pitchpositive
• Smooth cutting
• Reduces harmonicvibrations andnoise
• Good chip carryingcapacity and easychip formation
• Good toothpenetration
• Long blade life
Hook positive
• Allows coarse pitchon narrow blades
• Easy chipformation
• Good chip carryingcapacity
• Use in cast ironand non-metallicapplications (wood,plastics,composites)
Pitch (P)
SPEEDS7Cutting speed in m/min
0 100
Special alloys
Heat resistant steels
Titanium alloys
Cast iron
Stainless steels
Valve steels
Tool steels
Aluminium bronzes
Spring steels
Carbon steels
Bearing steels
Case-hardening steels
Structural steels
Free machining steels
Bronzes
Copper
Brass
Thermoplastics
Aluminium Si >5%
Aluminium Si <5%
50 100 150 200 250 500300 350 400 450
Up to 2500Up to 1500
BLADE BREAK-IN
TOOL MAKER’S TIP
Break-in is necessaryfor long blade life
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New blade
• Razor-sharp tooth
With break-in
• Micro-fine radius
• Break-in is done by reducing thefeed rate/force control to achieve acutting rate approximately 20 to 50% of the normal cutting rate.
Without break-in
• Premature tooth breakage
CHIPS9
Very fine or pulverized chips
• Increase the feed rate
• Or lower band speed
Thick, heavy or blue-coloredchips
• Decrease the feed rate
Loosely rolled chips
• Ideal cutting conditions
CLAMPING OF WORKPIECE10
Methods of clamping workpieces
Positioning of blade and workpiece
Right
Wrong
Select sawswith large teeth
Select sawswith small teeth
Select sawswith small teeth
PROBLEM SOLVING11
Reduce feed and increase speed. Use finer tooth pitch. Increase coolant flow. Check workpiece clamping.
Solutions
Reduce feed. Check coolant flow. Adjust blade tension and guides. Check for tooth set damage.
Inaccurate cut
Increase band tension. Increase speed. Reduce feed. Check for blade wear or chips.
Increase coolant flow. Reduce speed. Use coarser tooth pitch.
Blade stalling inwork
Chip welding
Use coarser tooth pitch. Increase feed or decrease speed. Check coolant flow.
Premature bladewear
Check blade fixture. Increase feed. Check blade break-in. Check coolant flow and type.
Premature dullingof teeth
Check speed and feed. Adjust saw guides. Check chip brush.Teeth fracture
Use finer tooth pitch and finer blade. Reduce blade tension and feed. Check coolant. Adjust speed.
Blade breakage
Problem
Tooth strippingand chipping
THE BASICS OF CIRCULAR SAWING
A CIRCULAR SAWAROUND THE WORLD
French: une sciecirculaire
German: eineKreisäge
Italian: una segacircolare
Spanish: una sierracircular
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• Circular saws are used for high performance cuttingof all forms of ferrous and non-ferrous metals: billets,tube, profile, bar, rounds, etc…
• Circular saws are available as:
- solid saws
- with HSS segments riveted onto a steel body,useful when large saw diameter is required.
HSS MATERIALS AND COATINGS13
• Basic choice
HSS et HSS-E
• For hard steels, stainless steelsand cast iron
• For materials with low thermalconductivity
• For dry cutting• For higher cutting speeds (+60%)
• Multi-purpose • For steels, tubes and
profiles• For higher cutting
speeds (up to 50%higher)
TiNGold
• Low friction coatingspreventing gumminess andbuilt-up edges
• For copper alloys, bronze,brass and aluminium
• For higher cutting speeds(up to 70% higher)
• For abrasive materials• For hard steels, titanium
alloys and stainlesssteels
• For higher cutting speeds(up to 90% higher)
TiCNGrey-violet
TiAlN Black-violet
CrN Metal
HSS-E
• For longer tool life• For difficult-to-machine
alloys
TOOTH TYPES
BW or ACME
Generally used for cutting thin walledsteel tubes (3- and 4 mm pitch)
C or Heller forms
Generally used for cutting flatsections or thick walled tubes(greater than 4 mm pitch)
BC or Chipbreaker
For cutting thin walled tubes andsmall profiles.
Improves the quality of the cut
Improves performance
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TOOTH PITCH
Pitch choice for plain section Pitch choice for tubes and profiles
For tubes and profiles, make sure that at least two teethare in contact with the workpiece.
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Pitch (mm)
3
4
5
6
7
8
10
12
14
Materialthickness (mm)
3-5
5-10
10-15
15-30
20-35
25-40
30-50
35-60
40-80
SPEEDS AND FEEDS16
Material
Steels 35-50 kg/mm2
Steels 50-65 kg/mm2
Steels 70-85 kg/mm2
Hardened steels
Austenitic stainless steels
Martensitic stainless steels
Cold rolled profiles
Tubes with thin walls
Tubes with thick walls
Girders
Grey cast iron
Aluminium
Copper
Brass
Bronze
Titanium alloys
Hard plastics
Cutting speed(m/min)
28-35
20-28
15-22
12-18
5-12
7-10
25-40
40-80
30-50
19-30
12-25
900-1500
80-400
400-600
40-120
10-15
900-1500
Feed(mm/min)
70-160
60-120
40-100
25-50
30-45
20-35
80-130
80-150
70-130
70-130
80-110
1200-1400
400-600
800-1000
400-800
80-160
1200-1400
POSITIONING OF WORKPIECE17
PROBLEM SOLVING18
Problem
Premature wear
Causes
Pitch too large Excessive cutting speedWrong feedCooling inadapted Wrong positioning of the workpiece
Wrong pitchExcessive feed Poor cooling
Teared-off teeth
Seizing-up due to poor sharpening Excessive feed Clamping problem
Saw breakage