Cycle time and chip load

Cycle time

After generating, the report gives the program’s estimated time, split into cutting, rapids and spindle start-up, with one line per operation. With several parts, each part’s time comes first, with its operations under it. With several tools, it also gives a time per file and the number of tool changes. Hovering an operation in the Browser shows its time, and so does the setup sheet.

• Feeds as programmed: the estimate uses the programmed feeds, and moves at the full feed from start to end.
• Real time is longer: a real machine slows down in corners and while accelerating. Take the estimate as a lower bound for jobs with many short moves.
• Rapids move at the machine’s max feed (Job settings > Machine). Without one, the estimate assumes 5 000 mm/min and says so: set the max feed for a better estimate.

chipload plan part.chipload prints the same, and --json gives it as numbers.

Chip load

For each operation, Chipload shows the chip load: how thick a chip each cutting edge takes, in mm per tooth:

chip load = feed / (spindle speed × flutes)

• Too thin and the tool rubs and heats up.
• Too thick and it may break.

The right value depends on the material, the tool and the machine, so Chipload shows the number and doesn’t judge it. As a rough guide:

• wood and plastics with 3–12 mm tools often take 0.05–0.25 mm per tooth;
• aluminium takes 0.02–0.08.

Check the tool maker’s figures.

Setting it up:

• Flutes and spindle speed: the tool needs both, on the tool (click it in the Browser) or in the tool library.
• Feed: a drill’s chip load uses its feed down; everything else uses the cutting feed.