A method of cutting metallic foams that eliminates the problem of smeared surfaces is provided. The method involves infiltration of the foam with another material to serve as a support structure to the foam when being cut. The method can be executed using softer polymeric materials such as waxes, which are then frozen for machining. These materials are subsequently heated and removed from the foam. In a similar manner, epoxy material can be used, which requires no freezing. In this method, the epoxy material is burnt from the foam upon completion of machining. The method allows for machining foams using conventional machining processes, rather than non traditional methods such as electrical discharge machining.

The present invention is concerned with twist drills for drilling of composite materials such as carbon fibre reinforced plastic (CFRP) and glass fibre reinforced plastic (GFRP). The present invention proposes that a twist drill (2) is provided with a variable helix having a defined start and finish helix angle, in combination with primary and secondary relief angles such that the drill (2) is adapted to minimise thrust force, particularly when used for drilling fibre-containing composite materials and especially for hand drilling. Start and finish helix angles of 50 and 10; 50 and 30; and 30 and 10 have been shown to provide excellent cutting performance and exit hole quality. A large secondary chisel edge angle (24) has also been found to contribute to excellent performance with composite materials, including stack machining.

In one embodiment, a holder includes a body part elongated from a first end part to a second end part along a rotation axis. The body part includes a first member, a second member, and a third member. The first member is located on a side of the first end part, and includes a pocket to receive a cutting insert. The second member is located closer to the second end part than the first member, and includes at least one cavity inside the second member. The third member is located closer to the second end part than the second member.

In one aspect, composite tool holders are described herein comprising advantageous structural arrangements of metal carbide and alloy components. Briefly, a composite tool holder comprises a metal carbide shank comprising a bore having an inner diameter and outer diameter. An alloy sleeve is positioned in the bore for engaging a tool, wherein the alloy sleeve is bonded to inner diameter surfaces of the bore via a crosslinked adhesive.

In one embodiment, a holder includes a body part elongated from a first end part to a second end part along a rotation axis. The body part includes a first member, a second member, and a third member. The first member is located on a side of the first end part, and includes a pocket to receive a cutting insert. The second member is located closer to the second end part than the first member, and includes at least one cavity inside the second member. The third member is located closer to the second end part than the second member.