Page 110 - Pafana

I. TOOLHOLDERS - technical information

rules of selection of toolholders, indexable inserts and parameters of machining

I. 1. At first you should select the toolholders:
- for roughing with insert clamped in „M” or „P-K” system
- for finishing with insert clamped in „S” system.

2. The shape of the insert should be selected according to the required clearance angle, and the workpiece
contour. With regard to strength, insert's durability and economic criteria, inserts with large tool included
angle and large radius of rounded corner should be selected, if possible.
3. For machining objects of low rigidity, toolholders of large tool cutting edge angle (Kr) and small
radius of rounded corner should be used.

4. Maximum possible machining depth (a ) should be selected, in order to reduce the required number
p
of processing passes, not exceeding: for „S” system: 0,25-0,5 of the cutting edge length, for „P”
system: 0,5, for „M”, „P-K” and „C” systems: 0,5-0,7.
5. Maximum feed value (f ) should not exceed the 2/3 value of radius of rounded corner. In order to
n
achieve lower roughness of machined surface, the feed value ought to be reduced.

6. While working with toolholders, you should remember about correct positioning and clamping the tool.
Clamping length should not be less than (3-4) x D (D -shank diameter). You should select the handle of
largest possible diameter and use the smallest possible tool's reach; not more than 4xD.
In case of the necessity of using boring tools of bigger reach, tools with handle made of sintered carbides
should be used, for which the maximum reach is (6-7) x D.
For clamping the boring tools with sintered carbide handle, toolholders PTA-… PAFANA should be used.
Clamping systems for inserts.

„S” SYSTEM - „zero” geometry of the seat -most toolholders for external turning, positive or negative
(internal turning) geometry of toolholders.

Indexable, single-sided inserts locked on the conical and arched hole with a screw with conical head.
„S” system is the most popular system for clamping the indexable inserts. It is characterised by simplicity,
high reliability and a very good repeatability of cutting edge position as well as the possibility of clamping
the inserts of very small dimensions.
The principal area of using the toolholders clamped in „S” system is finishing of external surfaces and hole
surfaces (especially holes of small diameters), but they are also used for roughing.

„P” SYSTEM - negative geometry of toolholders.

Negative indexable inserts (insert clearance angle 0°), triangle, square and diamond shaped, are locked
on the surface of the cylindrical hole with a pin, a wedge clamp and with a locking screw.
Toolholders with inserts clamped in the „P” system are used for roughing.
„P” system is characterised by easy insert replacement, no loose clamping elements. The simplicity of
construction results in worse repeatability of cutting edge position, than it was achieved in previous systems.

„P...-K” SYSTEM - negative geometry of toolholders.

Negative indexable inserts (insert clearance angle 0°) are locked with a clamp lever
on the surface of the cylindrical hole.
Toolholders with inserts clamped in the „P-K” system are the best choice for effective machining, both
medium and finishing, in cases when the highest rigidity and stability of clamping the insert is required,
as well as enabling the chip flow (no protruding clamping elements).
„P-K” system is characterised by fast and easy insert replacement, very high repeatability of cutting edge
position, no loose clamping elements, convenient replacement and clamping the insert; also in the “inverted”
position of the toolholder.

® info.tech.
108 103-119 tech.info.
тех.инфо.