Detailed Explanation of the Tool Setting Method for end Mills on CNC Milling Machines

On a CNC milling machine, the tool setting of end mills is a crucial step to ensure processing accuracy and efficiency. The purpose of tool setting is to determine the relative position relationship between the workpiece coordinate system and the machine coordinate system, thereby ensuring that the tool can accurately process along the programmed path. The following are the commonly used tool setting methods and detailed steps for end mills on CNC milling machines:

First, trial cutting method tool setting (manual tool setting)

Principle: By having the tool directly contact the workpiece or the tool setting block, the coordinate values of the machine tool are recorded, and the origin position of the workpiece coordinate system is calculated.

Applicable scenarios: Single-piece and small-batch production, when the precision requirements are average.

1. Tool setting along the X and Y axes

Step:

Install the workpiece and fixture: Clamp the workpiece onto the workbench and ensure it is firmly clamped.

Select the tool setting reference: Usually, a certain corner or edge of the workpiece is used as the tool setting reference.

Manual tool movement: Use the handwheel or manual operation mode to gently move the end mill to the vicinity of the workpiece’s tool setting reference.

Trial cutting and knife setting:

Slowly move the tool along the X-axis to make it gently touch the surface of the workpiece (you can first sense the contact with a paper sheet and then feed slightly).

Record the current X-axis coordinate values of the machine tool (such as X1).

Using the same method, make a trial cut along the Y-axis direction and record the Y-axis coordinate values (such as Y1).

Calculate the origin of the workpiece coordinate system:

Suppose the origin of the workpiece coordinate system is at the lower left corner of the workpiece and the tool setting point is at the upper right corner of the workpiece, then the origin of the workpiece coordinate system X0 = X1 – the width of the workpiece, and Y0 = Y1 – the length of the workpiece.

If the tool setting point coincides with the origin of the workpiece coordinate system, then X0 = X1 and Y0 = Y1.

2. Z-axis tool setting

Step:

Select the tool setting reference: Usually, the upper surface of the workpiece or the upper surface of the tool setting block is used as the Z-axis tool setting reference.

Manual tool movement: Move the end mill above the tool setting reference.

Trial cutting and knife setting:

Slowly lower the tool so that it gently touches the tool setting reference surface.

Record the current Z-axis coordinate value of the machine tool (such as Z1).

Calculate the origin of the Z-axis workpiece coordinate system:

If the tool setting reference is the upper surface of the workpiece and the origin of the workpiece coordinate system is on the upper surface of the workpiece, then Z0 = Z1.

If the origin of the workpiece coordinate system is on the lower surface of the workpiece, then Z0 = Z1 – the thickness of the workpiece.

Second, edge finder tool setting (semi-automatic tool setting)

Principle: The edge position of the workpiece is measured by an edge finder, and the origin of the workpiece coordinate system is automatically calculated.

Applicable scenarios: When conducting batch production and improving tool setting efficiency.

1. Tool setting along the X and Y axes

Step:

Install the edge finder: Install the edge finder on the main shaft.

Manually or automatically move the edge finder: Move the edge finder to the vicinity of the workpiece tool setting reference.

Edge-finding measurement

Slowly move the edge finder along the X-axis direction. When the edge finder indicator light is on or the displayed value changes, record the current X-axis coordinate value of the machine tool (such as X1).

Using the same method, measure along the Y-axis direction and record the Y-axis coordinate values (such as Y1).

Calculate the origin of the workpiece coordinate system: Similar to the trial cutting method, it is calculated based on the relationship between the tool setting point and the origin of the workpiece coordinate system.

2. Z-axis tool setting

Step:

A Z-axis setter (such as an electronic tool setter) can be used instead of the trial cutting method to directly measure the height of the upper surface of the workpiece, record the Z-axis coordinate values, and calculate the origin of the workpiece coordinate system.

Third, tool setting with a tool setter (fully automatic tool setting)

Principle: The length and diameter of the cutting tool are automatically measured by a high-precision tool setter, and the workpiece coordinate system is automatically set.

Applicable scenarios: High-precision processing, automated production lines.

Step:

Install the tool setter: Install the tool setter on the machine tool’s worktable or at a fixed position.

Tool measurement

Install the end mill onto the spindle.

Start the tool setter and the tool will automatically move to the position measured by the tool setter.

The tool setter automatically measures the length and diameter of the tool and transmits the data to the machine tool control system.

Set the workpiece coordinate system:

Based on the data measured by the tool setter, the machine tool control system automatically calculates and sets the origin of the workpiece coordinate system.

Fourth, precautions for knife setting

Safety first

During the tool setting process, ensure that the tool and the workpiece do not collide.

When using the handwheel or manual operation mode, pay attention to the feed rate to avoid accidents caused by excessive speed.

Precision control

The tool setting accuracy directly affects the machining accuracy, and the tool setting error should be minimized as much as possible.

Multiple measurements can be taken and the average value can be obtained to improve the tool setting accuracy.

Tool and workpiece protection

When setting tools by the trial cutting method, avoid excessive cutting of the tool to prevent damage to the tool or the workpiece.

When using an edge finder or tool setter, ensure that the measured surface is clean and flat.

The relationship between the machine tool coordinate system and the workpiece coordinate system

Have a clear understanding of the conversion relationship between the machine coordinate system and the workpiece coordinate system.

After tool setting, tool compensation Settings should be carried out to ensure the correct processing path.

Fifth, Example of Tool Setting (Trial Cutting Method)

Suppose the workpiece is a rectangular prism with a length of 100mm, a width of 80mm, and a height of 20mm. The origin of the workpiece coordinate system is at the lower left corner of the workpiece, and the tool setting point is at the upper right corner of the workpiece.

Tool setting along the X and Y axes:

Make a test cut along the X-axis direction and record X1 = 150mm.

Make a test cut along the Y-axis direction and record Y1 = 130mm.

Calculate the origin of the workpiece coordinate system: X0 = X1 – Workpiece width = 150-80 = 70mm, Y0 = Y1 – Workpiece length = 130-100 = 30mm.

Z-axis tool setting

Test cut the upper surface of the workpiece and record Z1 = -5mm (assuming the origin of the machine coordinate system is 5mm above the worktable surface).

Calculate the origin of the Z-axis workpiece coordinate system: Z0 = Z1 = -5mm (since the origin of the workpiece coordinate system is on the upper surface of the workpiece).