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SUMOMILL T290 is a family of milling tools with coolant holes that uses tangentially clamped
inserts with two cutting edges. The T290 inserts are available in 5 and 10 mm long cutting
edges. The inserts are the next evolution of the most popular HELIMILL inserts. As a result of
their tangential orientation in the pocket, the inserts allow tool design with larger core diameter,
providing a much stronger tool construction, which sustains a higher impact load and reduces the
risk of fracture to a minimum. When compared to the current HELIMILL and HELIPLUS tools of
similar sizes, the tools of the line feature high long-term strength and remarkable tool life, due to
the tangential orientation of the inserts in the pockets and higher tooth density.
The tools runs at higher feed speeds (table feeds), producing excellent surface finish and no
mismatch; and are suitable for plunging and rampdown applications. Their increased radial and
axial rake angles lead to a major reduction in cutting forces, improve tool stability and prolong life of
the cutting edge.
The T290 unique convex shaped insert enabled the development of small diameter cutting tools of
even 8 mm diameter.

Tangential or radial?
The question: what is more effective – tangential or radial clamping, often can lead the
user to hesitate when selecting the right cutting tool when there are both milling cutters with
laydown (radial) inserts and with inserts clamped tangentially. As in many practical cases,
the question has no strictly unambiguous answer. The academic studies of the question are
beyond the scope of the guide. Therefore, a brief review of advantages and disadvantages of each
clamping principle can be useful for the right choice. In general, the tangential configuration allows
increasing feed per tooth because the tangential component of a cutting force acts against an
insert with more rational orientation of its cross-section.
The well-designed tangential insert contributes to optimal loading of a clamping screw while
the resultant cutting force is transmitted directly to the cutter body. The tangential clamping
enables cutter design with larger core diameter than tools with radial inserts. It is much easier
to provide an indexable double-sided insert with helical cutting edges if a tangential configuration Milling Tools
is applied. And finally, the tangential clamping configuration also offers a higher insert density.
Typically, the milling cutters with tangentially clamped inserts run at high feed rates especially
when machining cast iron.
However, relative to milling tools with the laydown (radial) inserts, the cutters with the tangential
clamping normally have lesser ramping abilities, and their resources for shaping rake face and high
positive axial rake, which can significantly reduce cutting forces, are limited. Greater chip gullets in
case of the radial inserts go a long way towards better chip evacuation when milling materials such
as steel with high metal removal rate, particularly in machining deep cavities.
The latest ISCAR design provides the customers with the milling tools with tangential and radial
inserts for which in many cases the disadvantages related to tangential and radial clamping
correspondingly were overcome. For example, the H490 line with double-sided radial H490 AN…X
inserts, real workhorses, are intended for heavy milling operations with high feed per tooth;
and T290 line that is based on tangential T290 LN…T inserts is notable by excellent rampdown
performance. In either event the question of using the cutters with tangentially or radially clamping
inserts should be solved specifically. The ISCAR application specialists will be glad to advise
you the best choice.

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Die and Mold