Visualizing Chip Load
In woodworking, a properly adjusted hand plane produces a consistent, balanced wood shaving. Similarly, a properly calculated chip load allows a CNC cutter to remove material efficiently while maximizing tool life and cut quality.
Extremely thin shavings indicate excessive friction and heat, which can lead to premature tool wear and poor surface finish. Conversely, overly thick shavings require excessive cutting force and may contribute to part movement, poor edge quality, or tool breakage.
The goal is to produce a consistent chip that allows the cutter to operate efficiently without generating excessive heat or stress.
Too Thin → Excessive Heat & Premature Tool Wear
Ideal Chip Formation → Maximum Efficiency, Extended Tool Life, and Superior Surface Finish.
Too Thick → Excessive Cutting Forces & Increased Tool Stress
Extremely thin shavings indicate excessive friction and heat, which can lead to premature tool wear and poor surface finish. Conversely, overly thick shavings require excessive cutting force and may contribute to part movement, poor edge quality, or tool breakage.
The goal is to produce a consistent chip that allows the cutter to operate efficiently without generating excessive heat or stress.
Too Thin → Excessive Heat & Premature Tool Wear
Ideal Chip Formation → Maximum Efficiency, Extended Tool Life, and Superior Surface Finish.
Too Thick → Excessive Cutting Forces & Increased Tool Stress
In simplest terms the equation to calculate Chip Load is Feed Rate in inches or millimeters divided by Number of Flutes multiplied by RPM illustrated by the equation above.
Feed Rate, spindle RPM, and the number of flutes are directly related. Increasing or decreasing one variable will affect chip load. However, adjusting multiple variables together can maintain the same chip load while changing machine performance
Like a See Saw, the goal of your CNC cutting strategy should be finding the perfect "balance" to your materials and surface finish. Adjusting the feed and or the RPM without the consideration of the counter effect is the reason most struggle with bit breakage and poor tool performance. Below is our downloadable help guide for materials in Wood and Plastic for chip loads.
Feed Rate, spindle RPM, and the number of flutes are directly related. Increasing or decreasing one variable will affect chip load. However, adjusting multiple variables together can maintain the same chip load while changing machine performance
Like a See Saw, the goal of your CNC cutting strategy should be finding the perfect "balance" to your materials and surface finish. Adjusting the feed and or the RPM without the consideration of the counter effect is the reason most struggle with bit breakage and poor tool performance. Below is our downloadable help guide for materials in Wood and Plastic for chip loads.
The more aggressive chip loads require the machine to exert more force on the material to cut it, and lighter chip loads require less force. The ideal chip load is a balance between tooling, machine power, and desired surface finish. It's important to note Chip load is directly correlated to tool wear. There’s an entire science to this, which is beyond the scope of this write-up. However, there’s a sweet spot for tool life longevity. A perfect balance!
The larger the chip, the more material the machine is removing at a time. The common oversight by CNC operators is that by increasing or decreasing one of the values above will not effect cutting performance without consequence. Because RPM and feed rate both affect chip load equally, you should keep in mind, changing only one of the values will have negative effects on your milling results and tool life, including good surface finishes and possible movement of parts.
If you’re experiencing lines, scalloping, or other short tool life issues it might be time to look at the strategy employed by your team of operators. The inventor of the strategy usually adjusts the chip load to give a “decent” result and the shortest reasonable milling times. There are usually gains to be made in quality and tool life if you’re willing to create standards for your machine and your processes.
The larger the chip, the more material the machine is removing at a time. The common oversight by CNC operators is that by increasing or decreasing one of the values above will not effect cutting performance without consequence. Because RPM and feed rate both affect chip load equally, you should keep in mind, changing only one of the values will have negative effects on your milling results and tool life, including good surface finishes and possible movement of parts.
If you’re experiencing lines, scalloping, or other short tool life issues it might be time to look at the strategy employed by your team of operators. The inventor of the strategy usually adjusts the chip load to give a “decent” result and the shortest reasonable milling times. There are usually gains to be made in quality and tool life if you’re willing to create standards for your machine and your processes.
- Be careful of speed or RPM adjustments on your machine
Chip Load in Perfect Balance
Understanding the Chip Load Calculator
Input |
Description |
Chip Load |
Material removed by each tooth |
Feed Rate |
Machine Travel Speed while Cutting |
RPM (Revolutions per Minute) |
Rotation Spindle Speed of the cutting Tool |
Flutes |
# of Cutting Edges or Teeth |
Click for: CNC CHIP Load Calculator
Video of Chip Load Explained-"LMT Onsrud"
CNC Chip Load Calculator
Feed rate & speed reference for solid carbide router bits — CNC-Tool.com
Input parameters
Feed rate by material thickness
Adjust feed rate based on cut depth. Thicker material = slower feed; thinner = faster.
Enter your current machine settings