For machining small dimensions, various HSS, brazed tools and solid carbide endmills are used. Normally up to about 8.0 mm in diameter, all tools are solid, while larger diameter endmills are more and more made with indexable inserts. Small endmills are ground on the periphery,

on the rake face and on the frontal edge, either with square 90′ shapes with a corner radius or chamfer or with a full radius as on ballnose endmills. Rake angles are very positive to reduce forces and improve chip flow, while the possible clearance angle depends on the strength and diameter of the tool. Indexable inserts or endmills with brazed tips are produced with various geometries according to the material and conditions.

New endmills with larger diameters (≥8 mm) are equipped, for example, with helical cutting edge inserts, The frontal centerpoint is located in the center of rotation and the cutting edge moves upward, describing a full radius of the ballnose endmill. The rake angle is very positive, in order to guarantee a softer cut and easy chip flow. By using this unique helical shape, total cutting force values are reduced, the forces are lower during penetration into the material and the force gradients at entrance and exit are smaller.

Chipformer geometry is designed for the arc-shaped cutting edge used at varying cutting speeds and small to medium feeds. Smaller-size tools have a single cutting edge, and tools with more than 10 mm diameters have two ground edges for balancing and high surface quality.

The overall insert and tool design of small diameter tools can use positive or negative inserts. Positive inserts are normally weaker and reduce tool strength. The use of a negative insert configuration with a helical side cutting edge positioned above center provides the necessary relief angle. This unique insert design is clamped with a torx screw in the dovetail seat with sloped sidewalls in order to provide safe and secure holding. The cutter body design provides a larger cross section and a stronger cutter body with excellent performance even as an 8 or 10 mm diameter tool – and at higher cutting speeds.

For high-speed machining at higher cutting speeds and feeds, solid endmills are normally recommended. In some cases, screw-clamped or blade-type inserts also can be used. The inserts have a sloped-blade configuration with a unique clamping to insure safety at higher cutting speeds.

The horseshoe type insert is clamped against three points on the cutter body. The resiliency of the upper jaw and the self-clamping effect improve insert holding.
The upper jaw is lifted by rotating a screw, enabling the insertion and positioning of the sloped-blade insert into the seat. By rotating the screw in the opposite direction, the frontal part of the upper jaw is lowered, making contact and exerting clamping pressure on the insert. The larger size of the rear area of the insert acts to retain the insert in place, even at high cutting speeds.