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Selection of Toolholder

1. Decide upon the rake angle to be used depending
upon the work material and condition of machine tool.

2. Select the suitable clamping system either LS, KS, LW or
LR.

3. Depending upon the operation, select the style of the
toolholder.

4. The shank size of the toolholder is dependent upon the
    tool post dimension of the machine tool. The maximum
    height of the toolholder as permitted by the tool post
    and centre height should be selected to ensure a rigid
    set up.

5. Assuming that the cross section of the shank is square
and overhang of shank is equal to its height. Shank
height of the toolholder

h =	6 x ps x d x f S	(keeping in veiw the strength of the toolholder)
h =	4 x Ps x d x f E x	(keeping in veiw the deflection of cutting edge)

    where:    h     = height of the shank (mm)
                  d     = depth of cut (mm)
                  f     = feed rate (mm/rev)
                  P_s = Specific cutting force (Kg/mm²)                              (250-350 Kg/mm² for steel and                             150-250 kg/mm² for cast iron)
                 S = Allowable bending stress on shank
                          (Kg/mm²) (3-6 Kg/mm²)
                  E = Modulus of longitudinal elasticity
                         (Kg/mm²) (21,000 Kg/mm² for steel
                         and 62,000 Kg/mm² for tungusten
                          carbide)
                 = Deflection of cutting edge
                         (about 0.02 mm)

6. The style of toolholder determines the shape of insert
and shank height determines the insert size

Shank height mm	Below 16	16	20	25	32	40	50
Insert	Below 16	16	20	25	32	40	50
	11.0	16.0	16.0	16.0	22.0	22.0	27.0
	9.52	12.7	12.7	12.7	19.05	19.05	25.4
	-	9.52	12.7	12.7	19.05	19.05	-

7. ISO Standard toolholders will have the following tolerances
over nominal size

    Cutting edge height h₁ = j_{s 14}
                                       = ą 0.08 mm for cartridges
    Shank height          h    = h₁₃
    Shank width          b = h₁₃
    Shank Length         l    = k₁₆
    Dimension              f = + 0.5 mm
                                      = ą 0.25 mm for neutral
                                          tool holders style D
                                      = - 0.08 mm for catridges

Qualified toolholders with a tol. of ą 0.05 mm on f and l_1' can
be supplied on request.

The dimensions f and l₁refer to the theoretical cutting
point as shown in figure, for inserts with corner radius as tabulated below :

I.C.D of insert in mm	Corner radius r for dim. f and l₁ in mm
6.35	0.4
9.52 and 12.7	0.8
15.88 and 19.05	1.2
25.4	2.4

When inserts with smaller or larger corner radii are
selected, the dimensions determined by the corner radius will change.

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