In the world of woodworking and material processing, CNC machines p lay a key role and are the best solution for precision and efficiency. Router machines, in particular, are key tools that allow materials such as wood, metal, plastic, aluminum, and more to be shaped and worked with a high degree of precision. 

However, one of the most critical aspects of using these machines is managing the feed rate and number of rotations (RPM) of the router bits, which can greatly affect the final result of the work. In this article, we will explore the importance of router bits feed rate for CNC machines and share valuable advice from experts in the field.

Please note that the Sistemi company has been in this industry for more than 30 years, and our Brand Klein Tools are 100% made in Italy.

Why is Feed Rate Important?

Feed rate represents the speed that the tool moves through the material during the routing operation. This parameter is crucial because it directly affects the quality of the work and the life of the cutter itself. An incorrect feed rate can lead to various problems, including:

1. Overheating or breakage of the cutter: A feed rate that is too high can cause the tool breaking, or a higher speed than the maximum RPM can overheat and ruin the tool because of the enormous friction that is produced during machining. These mistakes can quickly ruin the cutter, which needs to be replaced. This can greatly increase operating costs due to frequent tool replacement.

2. Rough Surface or Poor Cutting Quality: If the feed rate is not properly calculated including: material to be worked, machinery and router bits used, the final result of the work will inevitably be compromised. The surface of the worked panel may be too rough in this case or irregular.

3. Low Productivity: On the other hand, a feed rate that is too low may result in slow and inefficient production, with additional costs due to extended working time.

4. Risk of Damaging the CNC Machine: An excessively high feed rate could jeopardize the stability of the CNC machine itself, causing extensive and costly damage with disruptions in production.

Advice from the Experts: Calculating the cutting speed of the router bit

Getting the best result while avoiding mistakes when working with CNC machines is possible!

There are a few key points you need to follow and a few 'rules' to observe. These valuable tips come directly from industry experts who have worked for years in this sector. You will have understood that it is essential to determine the feed rate by always considering an appropriate number of rotations (RPM) for the router bit, CNC machine and type of machining. Let's see some more tips from the experts:

Consider the Material: The feed rate must be adapted to the type of material to be worked on. Different materials require different feed speeds. The harder and tougher the material, the lower the feed speed. Wood, for example, can tolerate higher speeds than metal.

Pay attention to the correct clamping of the tool on the machine: There are European standards to be observed on the correct clamping of the cutter on the collet, EN847-1 for example outlines the safety requirements for milling tools and circular saw blades for woodworking. This standard specifies the minimum clamping length of the tool below which one cannot work. All Klein router bits have a special mark for correct clamping - see image. It is recommended to stay as close as possible to the cutting edge because the cutter is subject to bending.

Consider the Router Bit Diameter: The router bit diameter affects the ideal feed rate. As well as the design of the router itself, our range of spiral cutters have different helix types and sizes. Each Klein router bit is designed for a specific machining operation and ideal for different types of materials. Discover our TOP of the range - KleinDIA DLC anti-friction coated routers

Tool presetting: Do you want to increase the efficiency of your CNC machine? Setting the router before mounting it is the right way to do it. Also called axis zeroing, measuring tool dimensions is essential for the following reasons: 

- Accurate tool measurements to the mm or micron: radius, diameter, length

- No manual errors or distractions

- Analysis and detection of any damage in the cutting edge or router body, integrity check.

- Pre-mounting optimisation

Sistemi collaborates with m. conti, a manufacturer of measuring instruments with decades of experience in the field. Don't underestimate the importance of properly setting routers before assembly and checking them afterwards to get accurate data on their integrity. Visit the section dedicated to Presetters and Calipers.

Test and try: Remember that there is no precise, universal formula for finding the perfect feed rate, so testing and trying things out is useful to understand the best way of working. We recommend that you carry out tests from time to time on samples of material without putting maximum stress on the machine and router and evaluate the recommendations in this article to determine the feed rate.

Note these questions before starting the work:

- Is the router bit in good condition? We recommend replacing the tool with a new one after several sharpenings. A router bit that is worn out or has been sharpened many times cannot work at its best. Always check the condition and sharpness of the tool.

- Are the collet chuck and spring collet clean? Have they been mounted correctly? Every Klein router bit has the "K" symbol marked on the shank to indicate the ideal point for clamping. (see image)

- Have I looked carefully at the manufacturer's CNC machine manual?

- Is the machine properly secured and has it been properly maintained?

Listen to the Sound: The CNC machinery must not vibrate or move abnormally. An irregular sound is a warning bell indicating some kind of malfunction or anomaly. A regular, balanced sound indicates a correct feed rate.

Consult the Manufacturer's Recommendations: The manufacturer's manual is the first 'guide' to consider when in doubt. There can be valuable advice on determining the feed rate. We are aware that this information is often not 100% accurate, which is why we recommended testing in the point above.

All our Collet Chucks are marked indicating "MAX RPM", if you exceed the maximum RPM, we cannot guarantee the same performance as the optimum speed. Please note: this indication does NOT refer to the recommended RPM, the recommended RPM is a result of the type of work, router, machine and other factors that must be taken into consideration for every work.

The main parameters for a router operation are:

- Feed rate, in mm per minute (or metres per minute)

- Rotation speed in revolutions per minute (RPM) - Rotations per minute

- Depth of a single pass, in mm

Tip: If you increase the rotation speed, you will also increase the feed rate. The same applies if you decrease it.

What speed should cnc routers rotate at: RPM and feed rate

In our catalogue we recommend the optimum feed rate, see for example page 7.50, 7.51, 7.56

X-axis: Cutting depth in mm

Y-axis: Feed rate in metres per minute

Dx1 = Diameter (20 or 12 mm in this case, see table with colours) multiplied by 1.

Dx1.5 = Diameter multiplied by 1.5 (same calculation for all other entries Dx2 ...)

As can be seen, as the router diameter increases, the feed speed decreases.

The Cutting Depth: This parameter affects the feed speed. A greater depth usually requires a lower speed to avoid overheating and damaging the router.

Monitoring Temperature: We know this is not commonly used even though it should be standard. However, the use of infrared thermometers or other technologies to monitor the temperature of the router and material can help prevent overheating and other damage.

Conclusion: what is the ideal feed rate for router bits?

The feed rate of router bits in CNC machines is an essential parameter for high quality results during machining and is closely related to RPM.

The correct balance between adequate feed rate, material to be machined and all the considerations in this article will help you achieve the best results while avoiding expensive mistakes.

Once again, we advise: Test, yes, but with all precautions and adjustments and then carefully monitor the work you get, the data and according to that find the right result for your CNC and your job. The ability to adapt the feed rate to the needs of a specific project is what distinguishes professionals, good CNC work is precise, clean and efficient. These machines are built for that, you just have to work to achieve a great result!

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