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Brazed Turning Tool Bits - Cutting Parameters, Carbide Grades and Application

APPLICATIONS OF TURNING TOOL BITS

DESIGNATIONS OF TURNING TOOL BITS ACCORDING TO ISO, PN, DIN, F, GOST

Tool bit type

ISO 243
ISO 514
(PN / M-58355)

PN / M-58352 DIN F GOST

NNZa_iso1

Straight tool bit

ISO 1 NNZa-b 4971 301 2100

NNZc_iso2

Bent tool bit

ISO 2 NNZc-d 4972 302 2102

NNBc_iso3

Side bent tool bit

ISO 3 NNBc-d 4978 303 2103

NNPd_iso4

Wide face tool bit

ISO 4 NNPd 4976 304 2120

NNBk_iso5

Offset face tool bit

ISO 5 NNBk-m 4977 305 2141

NNBe_iso6

Offest side tool bit

ISO 6 NNBe-f 4980 306 2103

NNPa_iso7

Parting-off tool bit

ISO 7 NNPa-c 4981 307 2130

NNWa_iso8

Internal straight tool bit

ISO 8

NNWa

NNUa

4973 308 2140

NNWb_iso9

Internal pointed tool bit

ISO 9

NNWb

NNUb

4974 309 2112

NNPe_iso10

Pointed straight tool bit

ISO 10 NNPe 4975 351 -

NNWc_iso11

Internal undercutting tool bit

ISO 11 NNWc 263 354 -

NNGc_iso12

External threading tool bit

ISO 12 NNGc-r 282 352 2660

NNGd_iso13

Internal threading tool bit

ISO 13 NNGd-s 283 353 2662

NNPy

NNPy_

Key-slot tool bit

- NNPy - - -

 

 CEMENTED CARBIDE GRADES - APPLICATIONS AND TECHNICAL INFORMATION

Cemented carbides are manufactured by cementing fine particles of carbide into a composite by a binder metal. Most commonly used materials in cemented carbides are:

  • tungsten carbide WC (basic component),
  • titanium carbide TiC,
  • tantalum carbide TaC,
  • niobium carbide NbC,
  • cobalt (binding material).

Cemented carbides, due to their structure, are classified as metal matrix composites, where carbide particles are bound together by metallic matrix. They constitute hard metal sinters of high-alloyed metals: WC, TiC, TaC, NbC, VC and metallic matrix (most commonly cobalt, less frequently used are nickel and iron). High hardness of these carbides (within the range of 1900 ? 2500 HV) determines wearing quality of the composite. Thier brittleness, however, limits significantly their application as materials subject to dynamic effects of external stress which occurs during machining. In order to utilize their assets and ensure acceptable malleability they are bound together through metallic phase. The following groups of cemented carbides may be distinguished according to their chemical composition: WC-Co with possible addition of TaC, NbC, VC: used mainly in tools for machining cast iron and non-metallic materials (2 ? 8% Co), rocks (10 ? 15% Co) and in tools for forming processes (20 ? 30% Co), WC-TiC-Co: used mainly in tools for machining steel, WC-TiC-TaC, NbC-Co: used mainly in tools for machining steel.

Types of carbide, application and designation:

PN-81/H-89500 standard divides carbide grades into three basic groups:

  • for machining (S, U, H grades),
  • for forming processes (G),
  • for mine drilling (B, G),
  • carbide grade designation consists of letters and numbers.

Initial letters of the designation suggest application of the carbide:

  • S - according to ISO: P (blue colour) - grades suitable for machining materials producing long chips (mainly steel, cast steel, malleable cast iron),
  • SM - used for milling steel,
  • U - according to ISO: M (yellow colour) - grades suitable for machining materials producing both long and short chips (stainless steel, heat-resistant alloys),
  • H - according to ISO: K (red colour) - used for machining materials producing short chips (mainly cast iron and aluminium alloys)

Numbers given in carbide's designation are conventional symbols. As the number increases, so does the malleability of carbide grade, while its wearing quality decreases.

Final letter of the designation points to:

  • S - grades containing tantalum and niobium carbides,
  • X - grades used mainly in milling of cast iron.

 

Application group according to ISO Cemented carbide grade Chemical composition
[%]
Average grain size
[?m]
Density [g/cm3] Cross-breaking strength
[MPa]
Hardness HV
WC Total content
TiC+TaC+NbC
Co
P P10

S10

S10S

78

56

16

35

6

9

2-3

2-3

11,3

10,1

1400

1500

1600

1600

P20

S20

S20S

78

58

14

31,5

8

10,5

2-3

2-4

11,6

10,6

1600

1700

1500

1550

P25 SM25 69,5 21 9,5 1-2 12,6 200 1550
P30

S30

S30S

87

78,5

5

13,5

8

8

2-3

2-3

13,4

12,4

1700

1800

1450

1500

P35 S35S 78 12 10 2-3 13,2 2300 1400
P40 S40S 79 7 14 2-3 13,0 2400 1200
M M10 U10S 84,8 9,7 5,5 1-2 13,2 1700 1600
K K05 H3 94 - 6 1-2 14,8 1100 1650
K10

H10

H10S

94

91

-

4,5

6

4,5

1-2

1-2

14,8

14,9

1800

1700

1600

1650

K20

H20

H20S

94

92

-

2,5

6

5,5

2

1-2

14,8

14,9

1900

1800

1450

1550

K30 H30 91 - 9 2 14,6 2000 1380
  - G10 94 - 6 3 14,9 2000 1400

Carbide properties depend on their chemical composition, e.g. amount of tungsten, titanium, tantalum and niobium carbides, material which binds cobalt, as well as grain size of the particles and production methods.

Cemented carbides:

  • have high hardness (depending on the chemical composition of approx. 90HRC),
  • have high wearing quality,
  • maintain machining properties in temperature up to approx. 1000 °C,
  • are sensitive to temperature changes during machining (eg. intermittent machining),
  • are sensitive to impact loading, impact value of carbides is 2-3 times lower than that of hardened steel,
  • their cross-breaking strength is lower than compressive strength.

 

Application of cemented carbides used in machining (accoring to ISO 513):

Application group according to ISO
Cemented carbide grades
Main application
Machined material Type of machining
P P10

S10

S10S

steel, cast steel

turning, boring, milling and tracer turning; both medium and high precision, high cutting speed with good rigidity of the machine - workpiece - tool setup; intermittent machining with negative rake angles

P20

S20

S20S

steel, cast steel, malleable cast iron

turning, boring, milling and tracer turning; coarse, medium and high precision, medium cutting speed with medium rigidity of the machine - workpiece - tool setup; continuous and intermittent machining

P25 SM25 steel, cast steel

milling and turning with large changes in temperature, e.g.: roughing during tracer turning, medium cutting speed

P30

S30

S30S

steel, cast steel with impurities

turning, chipping, coarse and medium precision chiselling, low cutting speed with low rigidity of the machine - workpiece - tool setup

P35 S35S steel, cast steel with impurities and sand accumulation

turning, chipping, coarse and medium precision chiselling, medium and low cutting speed with low rigidity of the machine - workpiece - tool setup; machining in unfavourable sand accumulation conditions

P40 S40S steel, cast steel with contraction cavity and sand accumulation

turning, chipping, chiselling, low cutting speed, large chips; machining in unfavourable conditions: sand accumulation, hardness differences, machining with intermittent chip, machine vibrations; automatic turning, chipping of steel prone to creating build-up (low-endurance steel, stainless and heat-resistant steel)

M M10 U10S

steel, cast steel, manganese steel, stainless steel, heat-resistant steel, creep-resisting steel, grey cast iron (plain and low-alloy), non-ferrous metals

turning, medium cutting speed, small and medium chips; medium and high precision turning, milling of steel and cast iron; turning of hardened steel and steel prone to cold working

K K05 H3

very hard cast iron, hardened steel, aluminium alloys with high content of silicon, plastics, fibre, ceramics, electrode carbon

high precision turning and drilling, finish milling of electrode carbon, scraping is not recommended

K10

H10

H10S

cast iron with hardness of approx. 400HB, cast iron with selective hardening, malleable cast iron, austenic steel, aluminium and aluminium-silicon alloys, porcelain, stone, pressed paper, hard rubber, glass

turning, milling, drilling, counterboring, reaming, broaching; scraping

K20

H20

H20S

cast iron with hardness of approx. 220HB, copper and copper alloys, light alloys, plastics, wood

turning, milling, chipping, counterboring and reaming
K30 H30

cast iron with low hardness, non-ferrous metals and their alloys, plastics, wood

turning, chipping - roughing; possibility to use larger rake angles

  - G10 steel, cast iron, concrete, stone drilling

Coatings were intruduced in order to raise wearing quality of multiedged blades:

  • titanium carbide (TiC) - ensures high wearing quality and high adherence to foundation (which is the parent material of the blade),
  • titanium nitride (TiN) - protects edges against built-up and lowers friction factor between the edge and machined material (chip); it results in significantly lower machining force,
  • titanium nitride carbide (TiCN) - mainly used in intermittent machining as well as in heavy duty operations, e.g.: milling and threading,
  • aluminium oxide (AkOs) - gives the edge resistance to high temperatures.

Coated blades are not recommended for machining of aluminium, titanium, zinc, tin and nickel, and their alloys due to high affinity of carbides and titanium nitrides to those metals.

Note: Proper selection of cemented carbide grade depends on its chemical composition, structure, physical and mechanical properties, propeties and quality of the workpiece, machining conditions as well as dynamic properties of the machine.

RECOMMENDED MACHINING PROPERTIES FOR TURNING

Recommended speeds and feeds for turning steel and cast steel castings:

Material Tensile strength [MPa] S10 S20 S30 S35  
S10S S20S S30S S40S U10S
Feed [mm/rev]
0,6-0,05 1,2-0,1 2-0,2 3 2-0,2
finishing and roughing finishing finishing and roughing
Cutting speed V [m/min]
Carbon steel

500

500-600

600-700

700-800

800-1000

100-200-280

90-160-250

80-140-220

70-120-200

60-100-180

80-150-200

70-120-180

60-100-180

50-90-150

40-80-140

60-100-150

50-80-120

40-70-110

25-60-100

30-50-90

40-60

35-55

30-50

25-45

20-40

45-80-100

40-60-100

35-55-90

30-50-80

25-45-70

Alloy steel

500-700

700-850

850-1100

1100-1500

70-120-200

60-100-180

50-80-120

30-50-80

50-90-150

40-80-120

30-60-80

25-40-70

40-70-100

30-50-80

25-40-60

20-30-50

30-50

25-40

20-35

15-25

30-50-70

25-35-50

20-30-45

 

Cast iron castings

300-500

500-700

>700

70-100-150

60-90-120

40-60-90

60-80-120

45-70-90

30-50-70

40-60-90

30-40-60

20-30-50

25-45

20-35

15-25

35-70-110

30-60-90

20-50-70

Stainless steel

500-800 30-50-70 24-40-50 20-30-40 15-25 20-30-40

Recommended speeds and feeds for turning cast iron and non-ferrous metals:

Material Hardness HB H03 H10 H20  
  H10S H20S U10S
Cutting speed V [m/min]
finishing finishing and roughing finishing and roughing finishing and roughing

Cast iron, malleable cast iron (producing short chips), chill cast iron

<200

200-500

<500

>500

120-170

90-140

10-15

6-12

50-100-140

40-80-120

4-8-12

2-4-8

50-80-120

45-90-120

35-70-100

 

 

40-70-100

40-60-100

25-50-80

 

 

40-60-80

Copper and copper alloys

   

 

200-300-400

100-300-500

150-250-350

 

100-200-300

Aluminium and aluminium alloys

<80

80-120

>120

 

200-300-400

80-150-200

 

 

600-800-1500

300-600-1000

150-200-350

60-120-180

 

200-500-700

100-200-300

50-100-150

Plastic, hard rubber, porcelain, soft and hard stone

   

100-200-350

80-150-300

6-15-30

20-35-50

4-10-12

80-180-300

60-120-200

5-10-25

15-35-45

4-8-10

50-150-200

 

 

 

 

Manganese steel, hardened steel >500   4-20

10-25

4-20

 

4-20

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