The coordinate system of CNC machining center is divided into two types: machine tool coordinate system and machine coordinate system. The machine tool coordinate system is a coordinate system established by using the machine tool reference point as the coordinate origin, and the machine coordinate value is the important basis for judging the position of the tool. For the CNC machining center, because the workpiece origin is a "moving" point, only the mechanical coordinate value of the workpiece origin can be accurately applied to the CNC machining center processing, and the workpiece origin is accurately determined The mechanical coordinate value must be realized by tool setting.

The tool setting operation is divided into X, Y direction tool setting and Z direction tool setting. According to the different tool setting tools, the common tool setting methods are divided into the following types: trial cutting tool setting method; feeler gauge, standard mandrel tool setting method; using edge finder, eccentric rod and Z axis setter, etc. Tool setting method; top tool setting method; dial indicator tool setting method, etc.

1. Trial cutting method

(1) X, Y direction tool setting

①Place the workpiece on the worktable through the jig.

②Start the spindle to rotate at medium speed, move the table and spindle quickly, and move the tool to a certain safe distance near the left side of the workpiece, and then reduce the speed to move to the left side of the workpiece.

③When close to the workpiece, use the fine adjustment operation, so that the tool just touches the left surface of the workpiece, and record the X coordinate value displayed in the machine tool coordinate system at this time.

④Retract the tool in the positive Z direction, approach the right side of the workpiece in the same way, and record the X coordinate value displayed in the machine tool coordinate system at this time.

⑤According to this, the X coordinate value of the origin of the workpiece coordinate system in the machine tool coordinate system can be obtained.

(2) Z direction tool setting

Move the tool quickly over the workpiece. Start the medium-speed rotation of the spindle to make the tool move quickly to a position close to the upper surface of the workpiece with a certain safety distance, and then reduce the speed to move the end face of the tool close to the upper surface of the workpiece. Let the end face of the tool slowly approach the surface of the workpiece, so that the end face of the tool just touches the upper surface of the workpiece, and then raise the Z axis by 0.01mm, and record the Z value in the machine tool coordinate system at this time.

(3) Data storage

Input the measured X, Y and Z values into the storage address G54 of the machine tool workpiece coordinate system (generally use G54 ～ G59 codes to store the tool setting parameters).

（4） Starting to take effect

Enter the panel input mode (MDI), enter "G54", press the start key (in "automatic" mode), run G54 to make it effective.

(5) Inspection

Verify that the tool setting is correct, this step is very critical.