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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 9 5.2  12.2 62 13.5 3.5 8.7 1°25’43
    NO.2 17.78 14 6.3 18 75 16 5 13.5 1°25’50
    NO.3 23.825 19.1 7.9 24.1 94 20 5 18.5 1°26’16
    NO.4 31.267 25.2 11,9 31.6 117.5 24 6.5 24.5 1°29’15
    NO.5 44.399 36.5 15.9 44.7 149.5 29 6.5 35.7 1°30’26
    NO.6 63.348 52.4 19 63.8 210 40 8 51 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
    αx=Side clearance angle (alpha) 
    αxe=Effective side clearance angle 
    βx=Side wedge angle(beta) 
    γx=Front rake angle(gamma) 
    γxe=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 kmin 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 γf (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 γfis measured in place of the orthonagonal rake angle γo 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 bα
    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) 
    Check 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 12
    5/64 0.0781 1 5/65 12
    3/32 0.0938 1-1/4 3/32 12
    7/64 0.1094 1-1/2 7/64 12
    1/8 0.1250 1-5/8 2-3/4 12
    9/64 0.1406 1-3/4 2-7/8 12
    5/32 0.2188 2 3-1/8 12
    11/64 0.1719 2-1/8 3-1/4 12
    3/16 0.1875 2-5/16 3-1/2 12
    13/64 0.2031 2-7/16 3-5/8 12
    7/32 0.2188 2-1/2 3-3/4 12
    15/64 0.2344 2-5/8 3-3/7 12
    1/4 0.2500 2-3/4 4 12
    17/64 0.2656 2-7/8 4-1/8 12
    9/32 0.2812 2-15/16 4-1/4 12
    19/64 0.2969 3-1/16 4-3/8 12
    5/16 0.3125 3-3/16 4-1/2 6
    21/64 0.3281 3-5/16 4-5/8 6
    11/32 0.3438 3-7/16 4-3/4 6
    23/64  0.3594 3-1/2 4-7/8 6
    3/8 0.3750 3-5/8 5 6
    25/64 0.3906 3-3/4 5-1/8 6
    13/32 0.4062 3-7/8 5-1/4 6
    27/64 0.4219 3-15/16 5-3/8 6
    7/16 0.4375 4-1/16 5-1/2 6
    29/64 0.4531 4-3/16 5-5/8 6
    15/32 0.4688 4-5/16 5-3/4 6
    31/64 0.4844 4-3/8 5-7/8 6
    1/2 0.5000 4-1/2 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 22 6
    1 34 12
    1.5 40 18
    2 49 24
    2.5 57 30
    3 61 33
    3.5 70 39
    4 75 43
    4.5 80 47
    5 86 52
    5.5 93 57
    6 93 57
    6.5 101 63
    7 109 69
    7.5 109 69
    8 117 75
    8.5 117 75
    9 125 81
    9.5 125 81
    10 133 87
    10.5 133 87
    11 142 94
    11.5 142 94
    12 151 101
    12.5 151 101
    13 151 101
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