Does ISCAR provide tools for Y-axis turning?

Yes, ISCAR provides these tools.

What is the advantage of natural diamond as a tool material when compared to synthetic polycrystalline diamond (PCD)?

The monocrystalline structure of natural diamond provides a perfect cutting-edge contour without any junction points. This feature provides a substantial advantage to ensure ultra-high, really "mirror" surface finish required in some applications such as machining crucial parts of optical equipment. In contrast, a PCD cutting edge is formed by various crystals. This produces appropriate junctions on the edge, consequently every junction produces its own trace on a machined surface.

Ball-end tool

A ball-nose tool.

Cobalt steel

In the past this definition related mainly to AISI M35 high speed steel (HSS) but now is commonly used for designating HSS containing cobalt.

Coupon

A test sample.

Rapid steel

An obsolete name for high-speed steel (HSS).

Segment mills, circle-segment mills

A general name of profile milling cutters with large-radius cutting edges such as barrel-, lens- and ovel-shape endmills.