Machine kinematics

For CNC machines, a machine definition includes information about its kinematics, which describes how the physical CNC machine moves when running NC code. Understanding kinematics is important for ensuring accurate simulations and generating reliable NC code.

The kinematics tree

A kinematics tree provides a hierarchical view of the machine’s components and their relationships. The specific items and their order in the kinematics tree vary depending on the CNC machine type.

machine defintion dialog

Items that can be found in a kinematics tree:

Note: A machine definition must contain a head or turret, and a table or spindle.

Different CNC machine types

Milling machines typically have a head and a table. The head is equipped with a spindle that holds and rotates a cutting tool used for milling operations, and the table holds the workpiece.

Lathes typically have a turret to hold stationary tools used for turning operations, and a main spindle, and possibly a sub spindle, to hold and rotate the workpiece.

Turn-mill machines are lathes but with the capability of performing milling operations. They typically have a turret to hold stationary tools used for turning operations, and a main spindle, and possibly a sub spindle, to hold and rotate the workpiece. In turn-mill machines, the turret can be equipped with live tooling, allowing it to hold a rotating cutting tool used for milling operations.

Mill-turn machines are milling machines but with the capability of performing turning operations. Similar to milling machines, mill-turn machines typically have a head and a table. However, the head can hold a stationary tool used for turning operations, and the table can rotate to hold and spin the workpiece.

Examples of kinematics tree hierarchies

To help illustrate the concept of machine kinematics, below are some examples of kinematics tree hierarchies for different types of CNC machine:

3-axis milling machine

3-axis machine

In this example:

5-axis head-head milling machine

5-axis head-head machine

In this example:

Because all rotations are completed by the machining head, the machine's configuration is known as head-head.

5-axis table-table milling machine

5-axis table-table machine

In this example:

Because all rotations are completed by the table, the machine's configuration is known as a table-table.

Multi-axis turn-mill machine (dual-spindle lathe with live tooling)

multi-axis turn-mill machine

In this example:

Collision checking

You can choose which pairs of items of a machine are included or excluded from collision checks when simulating with a machine model. Collision checking against many items can slow the verification process during simulation. If you exclude pairs of items from the checks, collisions with those pairs are not reported.