In “turn-and-burn“ operation, a part is rotated to a certain angle, burned or wire-EDMd, then rotated and burned again. This process continues until the part is complete. I recently created a complex 3D “sculpture“ of a hand holding a cube to show such capabilities on a Charmilles 240cc equipped with a 6th axis indexer. The process works like this: I first clamp a chunk of raw material in the chuck of the B-axis, indexed at 0°. I then run a program that tells the machine to cut the hand's side profile. After this operation, the indexer turns the semi-finished hand 90° and the wire cuts the top profile, completing the hand.

Using the same indexing technique, I cut the 2 × 2 × 2-in. cube, but this time with a square OD program. I then made a start hole with an EDM drill-machine through two faces of the cube. The Charmilles 240cc threads wire into the hole and cuts a portion of the cube's inside cavity. The indexer then turns the part and the machine cuts the rest of the cavity.

Increasing the flexibility of “turn and burn“ is what we call “turn-while-burn“ B-axis operation, an upgrade option that turns parts mounted on a rotary, servo-controlled B-axis. This means the servo speed of the indexer motor rotating goes faster or slower during machining, usually with feedback from (and relative to) the XY-axes' cutting speed, which lets users create complex, “twisted“ or helix parts.