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CNC Mill Tool Loading & Unloading
CNC Mill Tool Loading & Unloading
To properly load a cutting tool into a CNC mill, the following steps should be taken:
Inspect the toolholder for any damage or debris. Clean and lubricate it if necessary.
Inspect the cutting tool for any damage or wear. Replace it if necessary.
Verify that the tool is securely clamped and has the proper stickout/clearances
Verify that the machine is in the proper mode and that the spindle is not rotating.
Unload any toolholders currently loaded in the spindle, or move to an open toolchanger position.
Load the new tool into the spindle, ensuring it is in the correct orientation (as needed)
Clear any former tool offsets, and enter the new tool's offset values on the control panel of the CNC Mill
Check/Verify the tool offsets are correct
Setting Tool Offsets Manually
Setting Tool Offsets Manually
Tool Offsets exist to let the CNC Machine know the cutting location of the Tool Tip (Tool Height Offset), as well as the cutting location of the tool’s edges (Tool Diameter/Radius Offset)
Without Tool Offsets, the machine does not know the length or diameter of the tools it uses to cut parts
Most of the time this results in the CNC machine alarming due to programmed movements exceeding the travel limits of the machine
In the worst-case scenarios, this can result in tool/part/fixture/machine crashes
Tool Offsets can be set anywhere on the machine, the location of which is called the “Tool Height Offset Reference Location” (THORL)
CRITICAL: All Tool Height Offsets must be set at the EXACT SAME THORL
Best practice is to pick a THORL that is consistent & unchanging from part-to-part, program-to-program, etc.
Raw (unmachined) surfaces are typically bad THORL’s, as they change once machined & are inconsistent part-to-part
When setting manual offsets, the most consistent & accessible location is often the top of the Machine table base
Rather than touch tool tips off at the top of the machine table, you touch-off on something sitting on top of the table, such as a
When using Tool Height Pre-setting Machines (Zoller, Haas, etc.), the THORL is located at Machine Z0.0
Tool Offset Setting Methods
Tool Offset Setting Methods
Tool height offsets are how a CNC machine knows where the tip of a tool is in relation to the machine z-axis home position. Today there are three predominant methods for setting tool length offsets.
Tool Setter Method
The "original" method.
Tools are measured outside or inside the machine by a separate device.
If tools are measured externally, tool length values most often are then entered into the machine manually.
If tools are measured by a device in the machine, the tool length values are entered in automatically.
Touch-off Method
The most commonly used method.
Based on measurements taken at the machine.
Some time loss during setup.
Basic procedure measures the distance the tip of the tool travels from the z-axis machine home to program z-axis zero position (Z0).
Distance is always negative
Master Tool Method
The most efficient method.
Based relative the measurement of the master tool.
Variation of the touch-off method with a specific procedure.
Value recorded as the tool length is the deviation from the master tool. This value may be positive or negative.
MET Shop Practice for Setting Tool and Work Offsets
MET Shop Practice for Setting Tool and Work Offsets
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