Siemens Sinumerik 840D Operating Turning page 81

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Position of the machine zero point

All axis motions on a CNC-machine tool are referred to the right-hand car-

tesian coordinate system.

See also module B502 - "Geometry basics".

The entire path measuring system is initialized by approaching the refer-

ence point with all axes.

At the same time the control unit activates the coordinate system at the

machine zero point.

M Machine zero point

This fixed coordinate point (origin) is determined by the manufacturer and

cannot be altered by the operator.

It serves as a reference point for the machine coordinate system (MCS) of

the machine tool.

For reasons of design this machine zero point on turning machines is lo-

cated exactly on the rotational axis on the right hand planar face of the

spindle flange (see image above).

Hence this point cannot be reached during machining of the work piece.

However machine zero point cannot be ignored and it is this point which

serves as a reference to all other points in a working plan or work space

inside the machine.

A programmer either can use machine zero point to define a contour/path

else he can use a specific point instead of machine zero point as a refer-

ence to define a contour/path (see section 4 in this module).

840D/828D SINUMERIK Operate

Axis denominations:

Planar axis X

Longitudinal axis Z

Sinumerik 828d