TECHNOLOGY

Main Technical Conditions Of Twist Drill

Drill diameter
The values indicated in the relevant dimensional standards apply in respect of the diameter of Twist Drills.
Test point: On the lands at the corners,(see Fig.l)

Testing equipment: micrometer

Tapering of diameter
The diameter of twist drills usually reduces from the drill tip towards the shank in the area of the flutes.
Test values:The taper on diameter amounts to 0.02 to 0.08mm over a length of 100mm.
Test point: At the outside diameter on the land.
Testing equipment: micrometer and indicating measuring instruments.

Parallel shank
Tolerance for shank diameter f11,Tolerance for roundness and parallelism 0.02mm for the shank length.

Concentricity tolorance(Tr.)
The concentricity tolerance(Tr.) of the Twist Drill is calculated from the equation.
Tr=O.03+O.O11/d
In which I is the total length and d the diameter of the drill (all dimensions in mm)

Length
The tolerance of length for the total length corresponds for the degree of accuracy very coarse according to DIN 7168 part 1.The flute lengths given in the relevant dimensional stands are minimum dimensions.

Point angle
Test value:¦Ò=118¡ã;¦Ò135¡ã
Test point: At the cutting edges(See Fig.2)
Testing equipment: Universal bevel protractor indicating measuring instruments.

Materials and hardness

Materials
M2; M35i M42; F4341; 93410r4341;

Hardness
HSS HRC63-66
HSSCO HRC64-68
Test point: On outside diameter on the land or adjacent relieved land.
Test equipment: Hardness Tester.

Making

Twist drills with diameter 3mm and upwards shall be marked with:
Diameter
Material:(HSS;HSSCO;)
Name or mark of manufacturer.
Additional and/or differing marking by agreement.

Twist Drill with parallel shank

Twist Drill with taper shank

General dimensions of morse taper shanks
Morse Taper Shank A mm B mm C(h13) mm D mm E mm F(max.) mm G mm H(max.) mm ¦Á/2
No.1 12.065 9 5.2  12.2 62 13.5 3.5 8.7 1¡ã25¡¯43
NO.2 17.780 14 6.3 18.0 75 16 5 13.5 1¡ã25¡¯50
NO.3 23.825 19.1 7.9 24.1 94 20 5 18.5 1¡ã26¡¯16
NO.4 31.267 25.2 11,9 31.6 117.5 24 6.5 24.5 1¡ã29¡¯15
NO.5 44.399 36.5 15.9 44.7 149.5 29 6.5 35.7 1¡ã30¡¯26
NO.6 63.348 52.4 19 63.8 210 40 8 51 1¡ã29¡¯36

Cutting portion

¦Ò= Point angle (sigma)
¦× = Chisel edge angle(psi)
*)In the context of cutting technology, land width b is the body clearance land width which is to be by bfan see DIN 6581.

Angle at the cutting edges

The corner has been adopted as the observed edge point

¦Áx=Side clearance angle (alpha)
¦Áxe=Effective side clearance angle
¦Âx=Side wedge angle(beta)
¦Ãx=Front rake angle(gamma)
¦Ãxe=Working front rake angle
¦Ç=Resultant cutting speed angle(eta)

Clearance angle ¦Á,wedge angle ¦Â and rake angle¦Ãare measured in the tool orthogonal plane. For details, see DIN 6581, definitions of metal-cutting technology; geometry at the tool edge.

Web thickness K

Test values:The web thickness according to Fig.1 shall not be less than the minimum value kmin indicated in Fig.2.
Test point: At the point of the drill.
Testing equipment:Slide gauge with measuring points.

Margin width b¦Á

Test values: The land width as in Fig.3 shall lie within the limitting values indicated in Fig.4
Test point: 5mm behind the corner
Testing equipment: Slide gauge 

Angle on twist drills

(1)Side rake angle ¦Ãf (Helix angle)
Recommended test value: Recommended ranges depending on the tool types N,H and W according to DIN 1836 and the diameter of the drill included in Fig.5
Test point: At the corner, see Fig.6
Testing equipment: According to VDI Guideline 3331 Part1 ,Section Margin widthb¦Á
Note:The side rake angle ¦Ãfis measured in place of the orthonagonal rake angle ¦Ão found in the wedge measuring plane(see DIN 6581),as this changes along the cutting edge(becoming smaller towards the point of the drill)
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(2) Point angle ¦Ò
test value: Usual executin for tool types N and H:¦Ò =118¡ã,for tool type W:¦Ò =130¡ã
Test point: At the cutting, see Fig.7.
Testing equipment: According to VDI Guideline 3331 Part 1, Section Margin width b¦Á
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Resharpening Twist drills

(1) Drills are worn off irregularly.It should be sharpened prior to developing into excessive wear.
(2) Resharpening
¢ÙGrind the correct point angle to suit your application.(figure 8)
¢ÚCheck that both cutting lips have the same angle. On a 130¡ã point,each lip should be 65¡ã toward the axis.The point must be on center, i.e.,the chisel edge must produce cutting lips of equal length.(figure 8)
¢ÛGrind Primary relief and Secondary clearance,(figure 9)
¢ÜGrind web thinning.(figure 10)

Web Thinning

(1) Without thinning
Suitable for drill of general purpose.Thanks to thin web thickness, web thinning is not need.
This without web thinning type is applied to design of drills for mild steel, alloy steels, cast iron, stainless steel, titanium, inconel, etc. and conventional cutting conditons.

(2) Type C thinning (DIN 1412 FORM C,SPLIT POINT)
Because Split point enables good centering
when drilling and breaks the chips,chip removals is easy.
Suitable for drill design in high hardened tough materials,i.e, heat treated steel, titanium alloy,     stainless steel, incoroy inconel, nimonic, etc.

(3) Type R thinning (HEI.ICAL THINNING)
Helical thinning ensure to frequent chip breaking and removal. The different direction force of cutting edges and helical thinning parts enables that chips curl, break and remove through the flutes. In addition helical thinning makes the chip room up to center, remove the chisel and enables good centering.

(4)Type A thinning (DIN1412 FORM A)
A type thinnings makes thin chisel, good chip removal and favorable centering.
This type is the easiest type to grind the thinning. In narrow web and wide fluted drills,keeping of the rigidity and smooth chip removal are possible.

(5) Type B thinning (DIN1412 FORM B)
In case of work materials with low cutting resistance and good chip removal,ie,cast iron,aluminium, plastic etc, B type thinning is suitable.
Especially when drills for high hardended steels are designed, this type is applied to decrease rake angle and avoid chipping of cutting lips. 

The Industry`s Most Verstile Deep Hole Drill
¡¡
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    The wide land parabolic design provides greater strength and rigidity while wllowing move flute area to accommodate chip flow.The stronger cross section allows to handle a wider variety of medium to heavy-duty applications. The benfits of the design include;
Improved coolant flow to point
Reduced machining time;less retooling and downtime
Closer hole tolerances
Reduced torque levels
Reduced chip congestion
Deep Hole drills are offered in a length, material and finish for your application
Refer to the Technical Data (pgs. 14-15) for oPerating parameters.

Construction Comparison

Deep Hole Drills
135¡ã split point
Increased flute area allows more room for chip evacuation
Reduced margin width reduces heat generation
Wider land provides increased strength and rigidity
Performs best in alloyed¡¡steels

Standard Parabolic Drills
135¡ã¡¡split point
Standard parabolic flute area
Standard margin
Narrow land
Performs best in mild steels

Length
Jobber
Screw Machine
Taper
Extra Length

¡¡
Finish Material
Surface Treated HSS
Bright HSS
TiN Coated HSS
BRONZE COBALT
TIIALN COBALT


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135¡ã Split-Point, Heavy-Duty, TiN-Coated

Size Decimal Equivalent Flute Length Overall Length Env. Qty.
1/16
5/64
3/32
7/64		 .0625
.0781
.0938
.1094		 7/8
1
1-1/4
1-1/2		 1/16
5/64
3/32
7/64		 12
12
12
12
1/8
9/64
5/32
11/64		 .1250
.1406
.2188
.1719		 1-5/8
1-3/4
2
2-1/8		 2-3/4
2-7/8
3-1/8
3-1/4
¡¡		 12
12
12
12
3/16
13/64
7/32
15/64		 .1875
.2031
.2188
.2344		 2-5/16
2-7/16
2-1/2
2-5/8
¡¡		 3-1/2
3-5/8
3-3/4
3-3/7
¡¡		 12
12
12
12
1/4
17/64
9/32
19/64		 .2500
.2656
.2812
.2969		 2-3/4
2-7/8
2-15/16
3-1/16		 4
4-1/8
4-1/4
4-3/8		 12
12
12
12
5/16
21/64
11/32
23/64
¡¡		 .3125
.3281
.3438
.3594		 3-3/16
3-5/16
3-7/16
3-1/2
¡¡		 4-1/2
4-5/8
4-3/4
4-7/8		 6
6
6
6
3-8
25/64
13/32
27/64		 .3750
.3906
.4062
.4219		 3-5/8
3-3/4
3-7/8
3-15/16		 5
5-1/8
5-1/4
5-3/8		 6
6
6
6
7/16
29/64
15/32
31/64
1/2		 .4375
.4531
.4688
.4844
.5000		 4-1/16
4-3/16
4-5/16
4-3/8
4-1/2		 5-1/2
5-5/8
5-3/4
5-7/8
6		 6
6
6
6
6

Material Application Chart

Finish Range of Application details
Black/Bronze Oxide Iron,Steel,Stainless Steel,Wood

135 Split-Point for quick penetration and reduced walking
Premium-grade M-7 industrial steel and super hard performance coating for longer, heat resistance and easier drilling
Unique flute design for superior material removal
Heavy-duty construction provides additional strength
Designed for enhanced performance in medium-and high-tensile strength alloy materials

Size Flute Length Overall Length
0.5
1
1.5
2		 22
34
40
49		 6
12
18
24
2.5
3
3.5
4		 57
61
70
75		 30
33
39
43
4.5
5
5.5
6
6.5		 80
86
93
93
101		 47
52
57
57
63
7
7.5
8
8.5
¡¡		 109
109
117
117		 69
69
75
75
9
9.5
10
10.5
11		 125
125
133
133
142		 81
81
87
87
94
11.5
12
12.5
13		 142
151
151
151		 94
101
101
101

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