GlossaryKind of term: Manufacturing termMachining direction
What is the machining direction?
The machining direction is the direction from which the tool works a feature, stated in the part's own axes, such as +Z or −X.
The machining direction is the direction of the tool axis relative to the part when a feature is machined: +Z is from above, −X from the left in the front view. It is stated in the coordinate system of the part or model, not that of the machine. On a 3-axis machine the tool axis is fixed along the machine's Z, and the part is clamped so that the required side faces the spindle. Features that share a direction can, in principle, be machined in one setup.
What does the machining direction depend on?
The directions a part needs follow from its features: a hole takes the direction of its axis, a face that of its normal, a pocket that of its floor. Walls parallel to the tool axis are cut with the flank of the cutter from the same direction. Whether a direction can be reached in one setup depends on the machine: a 3-axis machine reaches one direction per setup without extra equipment, a fourth axis covers the directions around one axis, a 5-axis machine the directions within its tilt range that the workholding or table does not block. An angle head or angled workholding adds directions.
How does the machining direction work in practice?
Grouping features by direction gives a first estimate of the number of setups, not a final count. Tool access, tool length and the tolerances between features can call for more setups, and a 5-axis machine or a fourth axis can mean fewer. On a 3-axis machine, a feature at an angle can take an extra setup with angled workholding or an angle head, or it moves to a machine with rotary axes. The cheapest option varies with quantity, hourly rates and the workholding to hand.
What is the machining direction often confused with?
The machining direction is not the setup: the setup is the state in which the part is held, the direction is where the tool comes from. On a 3-axis machine without extra equipment one direction coincides with one setup; on a 5-axis, one setup can cover several directions. It also differs from the work origin, which is a point; a direction is an axis with a sense.
Frequently asked questions
Why write +Z instead of simply ‘from the top’?
Because +Z is tied to the part's coordinate system and does not change when the part is clamped differently. ‘From the top’ depends on how the part lies. With an axis, everyone who works on the part means the same side.
How many directions does a part have?
As many as its features need. A simple prismatic part often has one to six, a part with angled holes more. Whether each direction costs a setup of its own varies with the machine, extra equipment and the tolerances between features.