Danyang Futai Tools Co.,Ltd.

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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:σ=118°;σ135°

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

α/2

No.1

12.065

5.2

12.2

13.5

3.5

8.7

1°25’43

NO.2

17.78

6.3

13.5

1°25’50

NO.3

23.825

19.1

7.9

24.1

18.5

1°26’16

NO.4

31.267

25.2

11,9

31.6

117.5

6.5

24.5

1°29’15

NO.5

44.399

36.5

15.9

44.7

149.5

6.5

35.7

1°30’26

NO.6

63.348

52.4

63.8

210

1°29’36

Cutting portion

σ= Point angle (sigma)

ψ = 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

α_x=Side clearance angle (alpha)

α_xe=Effective side clearance angle

β_x=Side wedge angle(beta)

γ_x=Front rake angle(gamma)

γ_xe=Working front rake angle

η=Resultant cutting speed angle(eta)

Clearance angle α,wedge angle β and rake angleγare 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 k_min indicated in Fig.2.

Test point: At the point of the drill.

Testing equipment:Slide gauge with measuring points.

Margin width bα

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 γ_f (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 widthbα

Note:The side rake angle γ_fis measured in place of the orthonagonal rake angle γ_o found in the wedge measuring

plane(see DIN 6581),as this changes along the cutting edge(becoming smaller towards the point of the drill)

(2) Point angle σ

test value: Usual executin for tool types N and H:σ =118°,for tool type W:σ =130°

Test point: At the cutting, see Fig.7.

Testing equipment: According to VDI Guideline 3331 Part 1, Section Margin width b_α

Resharpening Twist drills

(1) Drills are worn off irregularly.It should be sharpened prior to developing into excessive wear.

(2) Resharpening

①Grind the correct point angle to suit your application.(figure 8)

②Check that both cutting lips have the same angle. On a 130° point,each lip should be 65° toward the axis.

The point must be on center, i.e.,the chisel edge must produce cutting lips of equal length.(figure 8)

③Grind Primary relief and Secondary clearance,(figure 9)

④Grind 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

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

Length

Reduced torque levels

Jobber

Reduced chip congestion

Screw Machine

Deep Hole drills are offered in a length, material and finish for your application

Taper

Refer to the Technical Data (pgs. 14-15) for oPerating parameters.

Extra Length

Construction Comparison

Deep Hole Drills

Finish

Material

135° split point

Surface Treated

HSS

Increased flute area allows more room for chip evacuation

Bright

HSS

Reduced margin width reduces heat generation

TiN Coated

HSS

Wider land provides increased strength and rigidity

BRONZE

COBALT

Performs best in alloyed　steels

TIIALN

COBALT

Standard Parabolic Drills

135°　split point

Standard parabolic flute area

Standard margin

Narrow land

Performs best in mild steels

135° Split-Point, Heavy-Duty, TiN-Coated

Size

Decimal Equivalent

Flute Length

Overall Length

Env. Qty.

1/16

0.0625

7/8

1/16

5/64

0.0781

5/65

3/32

0.0938

1-1/4

3/32

7/64

0.1094

1-1/2

7/64

1/8

0.1250

1-5/8

2-3/4

9/64

0.1406

1-3/4

2-7/8

5/32

0.2188

3-1/8

11/64

0.1719

2-1/8

3-1/4

3/16

0.1875

2-5/16

3-1/2

13/64

0.2031

2-7/16

3-5/8

7/32

0.2188

2-1/2

3-3/4

15/64

0.2344

2-5/8

3-3/7

1/4

0.2500

2-3/4

17/64

0.2656

2-7/8

4-1/8

9/32

0.2812

2-15/16

4-1/4

19/64

0.2969

3-1/16

4-3/8

5/16

0.3125

3-3/16

4-1/2

21/64

0.3281

3-5/16

4-5/8

11/32

0.3438

3-7/16

4-3/4

23/64

0.3594

3-1/2

4-7/8

3/8

0.3750

3-5/8

25/64

0.3906

3-3/4

5-1/8

13/32

0.4062

3-7/8

5-1/4

27/64

0.4219

3-15/16

5-3/8

7/16

0.4375

4-1/16

5-1/2

29/64

0.4531

4-3/16

5-5/8

15/32

0.4688

4-5/16

5-3/4

31/64

0.4844

4-3/8

5-7/8

1/2

0.5000

4-1/2

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

1.5

2.5

3.5

4.5

5.5

6.5

101

109

7.5

109

117

8.5

117

125

9.5

125

133

10.5

133

142

11.5

142

151

101

12.5

151

101

151

101