Seven common tool setting methods for CNC

1. Trial cutting and tool setting method

This method is simple and convenient, but it will leave cutting marks on the CNC workpiece surface and the tool setting accuracy is low. Taking the tool setting point (which coincides with the origin of the workpiece coordinate system) at the center of the workpiece surface as an example, the double-sided tool setting method is adopted.

Applicable environment: There is only one blank and the excess thickness or length and width of the blank needs to be removed.

Advantages: Fast.

2. Feeler gauge, standard mandrel, block gauge tool setting method

This method is similar to the trial cutting method, except that the spindle does not rotate during tool setting. A feeler gauge (or standard mandrel, block gauge) is added between the tool and the workpiece until the feeler gauge cannot be pulled freely. Note that the thickness of the feeler gauge should be subtracted when calculating the coordinates. Because the spindle does not need to rotate for cutting, this method will not leave marks on the workpiece surface, but the tool setting accuracy is not high enough.

3. Tool setting using tools such as edge finders, eccentric rods and z-axis setters

The operation steps are similar to the trial cutting method, except that the tool is replaced with an edge finder or eccentric rod. This is the most commonly used method, with high efficiency and guaranteed tool setting accuracy. Be careful when using the edge finder to allow the steel ball to slightly contact the workpiece. At the same time, the workpiece to be processed must be a good conductor and the positioning reference surface must have a good surface roughness. The z-axis setter is generally used for the transfer (indirect) tool setting method.

Applicable environment: when the accuracy is required not to exceed 0.02MM.

Advantages: High versatility.

4. Transfer (indirect) tool setting method

It often takes more than one tool to process a workpiece. The length of the second tool is different from the length of the first tool, so it needs to be re-zeroed. However, sometimes the zero point is machined away and cannot be directly restored, or damage to the machined surface is not allowed. In addition, some tools or occasions are not suitable for direct tool alignment. In this case, the indirect zeroing method can be used.

5. Top-notch tool setting

(1) Tool setting in x, y direction

① Install the workpiece on the machine tool table through the fixture and replace the center.

② Move the worktable and spindle quickly to move the center point above the workpiece, find the center point of the workpiece drawing line, and then reduce the speed to allow the center point to approach the center point.

③ Use fine-tuning operation to slowly move the center point of the workpiece drawing line until the tip of the center point is accurately aligned with the center point of the workpiece drawing line, and record the x and y coordinate values in the machine tool coordinate system at this time.

(2) Get the z-axis coordinate value

Remove the center, install the milling cutter, and use trial cutting, feeler gauge method and other tool setting methods to obtain the z-axis coordinate value.

6. Tool setting with dial indicator (or micrometer)

Applicable environment: When high precision is required or the edge finder cannot meet the requirements, it is used for tool setting of circular workpieces, such as centering of circles with a diameter less than 4MM.

Advantages: Accurate.

(1) Tool setting in x, y direction

Install the dial indicator mounting rod on the tool handle, or attach the dial indicator magnetic base to the spindle sleeve, move the workbench so that the spindle centerline (i.e., tool center) is approximately moved to the center of the workpiece, and adjust the length and angle of the telescopic rod on the magnetic base so that the dial indicator contact contacts the circumference of the workpiece (the pointer rotates about 0.1mm). Slowly rotate the spindle by hand to rotate the dial indicator contact along the circumference of the workpiece, observe the deviation of the dial indicator pointer, and slowly move the workbench axis. After repeated movements, the dial indicator pointer is basically in the same position when the spindle is rotated (when the dial head rotates one circle, the pointer's runout is within the allowable tool setting error, such as 0.02mm). At this time, the center of the spindle can be considered to be the origin of the axis.

(2) Get the z-axis coordinate value

Remove the dial indicator and install the milling cutter, and use other tool setting methods such as trial cutting method, feeler gauge method, etc. to obtain the z-axis coordinate value.