If you’re considering a CNC machining project in Kansas City, MO, one of the most common questions is: How deep can a CNC cut?
Whether you’re a manufacturer, designer, or hobbyist, understanding CNC cutting depth limits is crucial for achieving the best results in your parts and prototypes. Let’s break down the factors that determine cutting depth, the practical limits, and how to optimize your CNC projects for precision and efficiency.
What Determines CNC Cutting Depth?
Several key factors influence how deeply a CNC machine can cut:
- Z-Axis Travel: This is the maximum vertical movement of the machine’s spindle and cutting tool. Most CNC routers and mills have a Z-axis travel ranging from a few inches to more than a foot. The Z-axis sets the absolute maximum depth you can reach, but it’s not the only consideration.
- Cutting Tool Length and Geometry: The length of your end mill or router bit is a major factor. While longer tools can reach deeper, they’re more prone to deflection and vibration. This can impact both cut quality and tool life.
- Material Properties: Harder materials like steel require shallower cuts to avoid excessive tool wear or breakage, while softer materials like wood or plastic can often be cut deeper per pass.
- Machine Rigidity and Power: More robust machines with higher spindle power can handle deeper cuts, especially in tougher materials.
- Chip Evacuation and Cooling: Deeper cuts generate more heat and chips. Effective chip removal and cooling are essential to prevent tool damage and ensure a clean cut.
CNC Cutting Depth Limits: Rules of Thumb
While every project is unique, there are some general guidelines for CNC cutting depth limits:
- Single Pass Depth: For most CNC routers, a typical maximum depth per pass is about 1 inch, but this can vary based on tool diameter, material, and machine power.
- Total Cutting Depth: The Z-axis travel and the length of your cutting tool limit your total achievable depth. Many CNC machines can cut between 1 and 7 inches deep, but only if the tool and setup allow it.
- Tool Diameter to Depth Ratio: A common rule is not to cut deeper than 3-4 times the diameter of your cutting tool in a single pass. For example, with an 8mm bit, a safe maximum depth per pass is around 24-32mm. However, tools with longer flutes can cut deeper, provided you use multiple shallow passes to avoid tool deflection and chatter.
Practical Considerations for Deep CNC Cuts
- Multiple Passes: Incremental passes are best for deep cuts because they reduce tool stress, improve surface finish, and minimize the risk of tool breakage.
- Tool Selection: Choose tools with longer flutes for deep cavities, but be aware that longer tools are more flexible and can vibrate. Reduced shank cutters and custom tools are available for extra-deep cuts, but can be costly.
- Machine Setup: Ensure your machine’s Z-axis clearance and tool length are compatible. If your tool is too long for the machine’s Z-axis, it won’t fit or operate safely.
- Material Removal Rate: Deeper cuts remove more material quickly but increase cutting forces and heat. Balance depth, feed rate, and spindle speed for optimal results.
CNC Cutting Depth Limits by Process
| Machining Process | Typical Depth per Pass | Total Possible Depth |
| Milling | 0.5 – 10 mm | Up to Z-axis travel |
| Routing (Wood) | Up to 1 inch (25mm) | 1 – 7 inches |
| Turning | 0.5 – 3 mm | Up to part diameter |
| Drilling | Bit length | Bit length |
Note that these are only general ranges. Always consult your machine and tool manufacturer’s guidelines for specific limits.
Tips for Maximizing CNC Cutting Depth
For the best cuts at the depth you need, make sure to:
- Use the shortest tool possible for the specific job to reduce deflection.
- Make multiple shallow passes for deep cuts.
- Ensure proper chip evacuation and cooling.
- Match the tool geometry to the material and depth required.
- Regularly inspect tools for wear, especially when making deep cuts.
So, to answer the question, “How deep can a CNC cut?” The answer depends on your machine’s Z-axis travel, the length and diameter of your cutting tool, the material, and your setup.
While some CNC machines can cut several inches deep, the best results come from understanding CNC cutting depth limits and using the right strategies for your project. For expert CNC machining in Kansas City, MO, our team is ready to help you achieve precision and efficiency no matter how deep your next cut needs to be.
CNC Machine Shop—Brown Industries
Ready to discuss your next CNC project? Contact us today to learn more about our capabilities, how deep can a CNC cut, and how Brown Industries can help you push the limits of CNC cutting depth.
Ensuring high-quality end products is at the heart of everything we do at Brown Industries. We combine advanced technology, skilled craftsmanship, rigorous quality control, and a commitment to continuous improvement to deliver products that meet the highest standards of excellence. We offer CNC Milling and other machine shop services to make the necessary parts when and exactly as needed. For more information or to discuss your project needs, don’t hesitate to get in touch with us at (816) 231-2454.
