Gear Cutting Tools

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Solid carbide hobs Introduction Carbide hobs permit cutting speeds into the high-speed cutting (HSC) range, and significantly higher than those possible with high-speed steel hobs. The development of suitably rated hobbing machines enables the advantages of solid carbide cutters to be exploited in practical use. The combination of high-speed cutting (HSC) and dry machining presents substantial potential for rationalization. Modern solid carbide hobs boast the following characteristics: ■ High cutting speeds ■ Short machining times ■ Long tool life ■ High suitability for dry machining ■ Re-coating not required for P carbides ■ Lower gear generation costs (according to the machining task) 26
Carbide types and coatings The carbide types generally used are those of the main machining groups K and P. The types present advantages and disadvantages according to their material composition (alloying elements and components) and their grain size. Whereas K carbides, owing to the tendency of chips to bond to the uncoated substrate, can only be employed fully coated, P carbides can also be employed in uncoated form. There is therefore no need for the cutting face to be re-coated following regrinding. This reduces the maintenance costs for P carbide hobs considerably. In addition, P carbides are less sensitive to temperature, and the strong progressive increase in wear which takes effect from a flank wear of approximately 0.2 mm onwards is considerably lower. The substrate reacts more favourably. By contrast, fine-grain carbides have as yet only been developed for the K types. Fine-grain carbides permit very high hardness values and consequently a high resistance to wear, combined with excellent toughness. Consequently, fully coated K substrates generally permit higher tool life qualities when compared with hobs manufactured from P carbides, which lose their cutting face coatings at the first regrind at the latest. P carbide hobs must therefore be changed more frequently. TiN, manufactured by means of PVD, continues to be the main substance employed for the hard material layer of hobs. TiN possesses excellent chemical resistance to the hot steel chips. In addition to its hardness of 2200 HV, its relatively high toughness makes it particularly attractive for hobs. The logistics aspect represents a decisive advantage. TiN is the coating which, owing to its low pressure characteristics, can be re-coated more easily. This is essential following grinding of the cutting face of hobs with a K type substrate. Newly developed coatings such as TiCN and (TiAIN) can attain longer tool life travel for a given application, but have yet to be accepted by the market, particularly with regard to the re-coating aspect. Advantages: Disadvantages: ● Re-coating not necessary following regrinding ● Low maintenance costs (regrinding only) ● Shorter tool life in the reground condition, therefore: ● More frequent tool changes required ● Shorter maintenance times, consequently: ● Fewer tools in circulation (lower capital investment) ● Lower progressive rise in wear when the coating is penetrated, consequently: ● Lower risk of built-up edges Use of coated solid carbide hobs with P type substrate Maintenance process: regrinding (flank coated, cutting face uncoated) Advantages: Disadvantages: ● Generally longer tool life, therefore: ● Less frequent tool changing ● Fine-grain grades possible, therefore: ● Greater toughness and greater hardness ● Cannot be employed uncoated, i.e. removal of the coating and re-coating is required, therefore: ● Higher maintenance costs ● Longer maintenance times, therefore: ● More tools in circulation (greater capital investment) ● Strongly progressive increase in wear following penetration of the coating, consequently: ● Greater risk of built-up edges Use of coated solid carbide hobs with K type substrate Maintenance process: removal of coating - regrinding - re-coating (flank and cutting face coated) 27
Page 1: Gear Cutting Tools • Hobbing •
Page 4 and 5: Important information Product range
Page 6 and 7: FETTE - a brief introduction Ecolog
Page 9 and 10: Hobs for spur gears, straight- or h
Page 11 and 12: Notes to the descriptions and size
Page 13 and 14: Solid-type hobs for spur and helica
Page 15 and 16: Solid-type hobs for spur and helica
Page 17 and 18: Hobs For economical production on m
Page 19 and 20: Multiple-gash hobs 19
Page 21 and 22: In order to achieve a high tool lif
Page 23 and 24: Gear quality The gear quality is de
Page 25: Multiple-gash hobs Recommended stru
Page 29 and 30: High-speed cutting (HSC) The advant
Page 31 and 32: Size table for solid carbide hobs R
Page 33 and 34: These requirements are met perfectl
Page 35 and 36: Heavy duty roughing hobs (roughing
Page 37 and 38: The rough hobbing of gears form mod
Page 39 and 40: Roughing hobs with indexable carbid
Page 41 and 42: A special position among the above
Page 43 and 44: Pitch- and tooth trace deviations a
Page 45 and 46: Skiving hobs with brazed-on carbide
Page 47 and 48: Solid-type hobs for straight spur g
Page 49 and 50: Hobs for internal gears, with strai
Page 51: Solid-type hobs for internal gears
Page 54 and 55: Hobs for compressor rotors Rotors a
Page 56 and 57: Rotor hobs, for finishing for screw
Page 59 and 60: Hobs for sprockets, timing belt pul
Page 61 and 62: Hobs for sprockets for Gall’s cha
Page 63 and 64: Hobs for sprockets with involute fl
Page 65 and 66: Hobs for timing belt pulleys with i
Page 67 and 68: Hobs for spline shafts quality grad
Page 69 and 70: Hobs for p.t.o. shafts to DIN 9611
Page 71 and 72: Hobs for spline shafts with involut
Page 73: 73
Page 76 and 77:
Hobs for worm gears The specificati
Page 78 and 79:
Tangential method This method is su
Page 80 and 81:
Engagement area and bearing contact
Page 83 and 84:
Hobs for special profiles Hobs for
Page 85:
. Multi-start single-position fly-c
Page 88 and 89:
Worm thread milling cutters for mod
Page 90 and 91:
Worm milling cutters for roughing f
Page 92 and 93:
Rack milling cutters/worm milling c
Page 94 and 95:
High-precision rack tooth gang cutt
Page 97 and 98:
Gear milling cutters for spur gears
Page 99 and 100:
Involute gear cutters for spur gear
Page 101 and 102:
FETTE has considerable experience i
Page 103 and 104:
End mill type gear cutters (finishi
Page 105 and 106:
Gear roughing cutters with indexabl
Page 107:
Gear finishing cutter ■ With carb
Page 110 and 111:
Profile milling cutters for coarse-
Page 112 and 113:
Rotor profile cutters for screw com
Page 115 and 116:
Gear milling cutters for sprockets,
Page 117 and 118:
Form milling cutters for timing bel
Page 119 and 120:
Cat.-No. 2730 relief turned or reli
Page 121 and 122:
Gear chamfering cutters for chamfer
Page 123:
123
Page 126 and 127:
Comparison: module pitch - diametra
Page 128 and 129:
Tolerances for multiple start hobs
Page 130 and 131:
Hob inspection records The toleranc
Page 132 and 133:
The effect of cutter deviations and
Page 134 and 135:
Effect of the quality grades of the
Page 136 and 137:
Hob clamping Keyway Hob clamping Dr
Page 138 and 139:
Basic profiles for spur gears with
Page 140 and 141:
Basic hob profiles Defination of th
Page 142 and 143:
Basic hob profiles to DIN 58412 Sym
Page 144 and 145:
Profiles of current tooth systems a
Page 146 and 147:
Sprocket tooth system for roller- a
Page 148 and 149:
Spline shaft tooth system; basic cu
Page 150 and 151:
"Carbide" is a generic term for pow
Page 152 and 153:
The enormous increases in tool life
Page 154 and 155:
Total a - Initial edge wear b - mec
Page 156 and 157:
Cutting materials for hobs (See als
Page 158 and 159:
A further a table of recommended va
Page 160 and 161:
Number of starts of the hob With th
Page 162 and 163:
Tool cutting edge length A distinct
Page 164 and 165:
Tool cutting edge length (continued
Page 166 and 167:
Shift distance The chip cross-secti
Page 168 and 169:
Maintenance of hobs Introduction In
Page 170 and 171:
Requirements placed upon the cuttin
Page 172 and 173:
If the high or low points of the tw
Page 174 and 175:
Hobs with a slightly concave cuttin
Page 176 and 177:
Gash lead (item no. 11 DIN 3968) Th
Page 178 and 179:
When regrinding, ensure that the co
Page 180 and 181:
form circle diameter is less than t
Page 182 and 183:
Wear phenomena on the hob The cutti
Page 184 and 185:
Ziegler (2) demonstrated that the c
Page 186 and 187:
The effect of the cutting condition
Page 188 and 189:
the penetration line is important p
Page 190 and 191:
left-hand start machines a gear wit
Page 192 and 193:
Involute gear cutter with indexable
Page 194 and 195:
DIN number index DIN Page 138 30, 4
Page 196 and 197:
196
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Gear Cutting Tools

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