When using a CNC oscillating knife cutter to process flexible materials like fabric, leather, foam, rubber, and cardboard, setting the right cutting speed directly determines the final product quality, scrap rate, and overall production efficiency.
Poor speed settings can cause blade breakage, waste of expensive materials, accelerated machine wear, and even customer complaints that harm your reputation.
Why Is It Important to Set the Cutting Speed of CNC Oscillating Knife Cutters Properly?
Cutting Speed Directly Affects Cutting Quality and Dimensional Accuracy
Unlike laser cutting that severs materials instantly, CNC oscillating knife cutting uses the blade
’s high-frequency back-and-forth vibration plus X/Y axis feeding movement to complete cutting.
Cutting Accuracy: If the X/Y axis movement speed is too fast—exceeding the tool’s cutting capacity—the blade will face huge lateral drag force. It won’t have time to cut the material effectively, leading to material dragging. This causes imperceptible micro-bending of the blade, resulting in: straight lines becoming curved, round holes turning elliptical, and smaller dimensions on the lower layer than the upper layer (taper phenomenon).
Material Deformation from Slow Speed: When the movement speed is too slow, the blade rubs against the material for a longer time, generating a lot of heat. This causes material deformation, and low-melting-point materials like foam or rubber may suffer from burnt edges, melting, or blade sticking.
Final Product Quality: Poor speed settings affect the flatness of material edges. Unreasonable speeds can lead to jagged edges, burrs, or scorching.
According to research in “CNC Interpolation and Motion Control” (Springer, 2022), in flexible material processing:
When the feeding speed does not match the tool’s vibration frequency, the incidence of cutting edge defects can increase by 25%–40%.
Optimal Cutting State: When the blade vibrates up and down once, the distance the machine moves forward is exactly equal to or slightly less than the effective cutting length of the blade edge.
Core Formula: Optimal cutting effect ≈ (Vibration frequency × Single cut amount) / Feeding speed
Three Key Factors Affecting the Speed of CNC Oscillating Knife Cutters
Material Characteristics (Hardness, Density, and Thickness)
Corrugated Paper/Honeycomb Board: Loose structure with low resistance. Usually, the speed can be set to the maximum (800-1500mm/s).
Rubber/Gaskets: High friction coefficient and resistance. The tool is tightly “clamped” by the material, generating extremely high lateral drag force. The speed should be significantly reduced (100-400mm/s) to prevent tool breakage.
Thickness Effect: Based on industry experience, for every 5mm increase in material thickness, it is recommended to reduce the cutting speed by 15%-20% to maintain tool perpendicularity and reduce deformation.
Tool Type and Edge Angle
Large-Angle Blades (e.g., 45°/60°): Wide blade body with good rigidity, capable of withstanding higher feeding speeds. Suitable for cutting hard materials.
Small-Angle Blades (e.g., 16°/26°): Slender and extremely sharp but fragile. If the speed is too fast, deflection is likely to occur at corners, leading to inconsistent upper and lower edge dimensions.
Complexity of the Cutting Pattern
Large Contours and Long Straight Lines: Can be set to a higher speed (e.g., 80%-90% of the machine’s maximum speed).
Dense Small Holes: When processing dense small holes, it is recommended to use a punching tool instead of a blade. Due to the blade’s width, it cannot complete small hole cutting.
How to Set the Cutting Speed for Different Materials?
Note: The following data is for reference only. Please conduct actual operation tests for final settings.
Packaging Materials
| Material | Thickness (mm) | Recommended Speed (mm/s) | Vibration Frequency | Tips |
| Corrugated Paper (3-5 layers) | 3 – 7 | 800 – 1200 | High | Pay attention to creasing depth |
| Honeycomb Board | 10 – 20 | 400 – 700 | Med | Too fast speed may tear the surface paper |
| Gray Board Paper | 1 – 3 | 500 – 900 | High | A sharp blade is required; otherwise, edges will fray |
Advertising and Foam Materials
| Material | Thickness (mm) | Recommended Speed (mm/s) | Vibration Frequency | Tips |
| KT Board / PVC Foam | 3 – 5 | 600 – 1000 | Med | Too high frequency will melt the foam core |
| EPE Pearl Cotton | 20 – 50 | 200 – 500 | High | Use a long-edge blade to prevent material rebound and blade jamming |
| PP Hollow Board | 3 – 5 | 600 – 900 | Med | Resistance differs between along-grain and cross-grain cutting; take the median value |
Industrial Flexible Materials
| Material | Thickness (mm) | Recommended Speed (mm/s) | Vibration Frequency | Tips |
| Asbestos / Non-Asbestos Board | 1 – 3 | 100 – 300 | Low | Prone to blade breakage; better to use a slower speed |
| Silicone / Rubber Board | 3 – 5 | 150 – 400 | Med | It is recommended to apply a small amount of grease for lubrication |
| Genuine Leather / Composite Fabric | 1 – 2 | 300 – 600 | High | Enable strong vacuum adsorption to prevent displacement |
| Carbon Fiber Prepreg | 0.2 – 0.5 | 500 – 800 | High | Focus on cutting fibers; extremely high frequency is required |
The following demonstrates how to install, import graphics, and configure various cutting parameters using a round knife as an example.
Problems Caused by Too Fast or Too Slow Cutting Speed
Common Issues with Too Fast Cutting Speed
Frayed Edges and Threading: The blade cannot cut fibers in time, and the machine drags the material forcefully. For fabric or composite material cutting, this leaves uncut thread ends on the edges. We once had a Japanese customer who needed to cut composite leather with a foam interlayer. The fast cutting speed caused rough and burred edges, which were perfectly solved by reducing the speed.
Pulling, Deformation, and Dimensional Deviation: The huge lateral force generated by the tool during rapid movement can overcome the vacuum adsorption force, causing micro-displacement of the material on the table. If the final size is 2mm smaller than expected, this is usually the reason.
Overcut at Corners and Contour Deviation: According to Newton’s laws, the faster the speed, the greater the inertia. When passing a 90-degree right angle at high speed, the servo motor is difficult to brake instantly. The tool head cannot lift immediately, leading to overcut (the tool head rushes beyond the set path) or irregular rounded corners due to path correction.
According to processing statistics from the Society of Manufacturing Engineers (SME):
In CNC cutting of flexible materials, when exceeding the reasonable feeding speed by 20%, the probability of dimensional deviation increases significantly, especially for small-sized parts.
Problems Caused by Too Slow Cutting Speed
Low Cutting Efficiency: Slow cutting speed reduces machine productivity and increases unit costs.
Material Heating and Blade Sticking: High-frequency friction of the oscillating knife generates heat. If moving too slowly, heat accumulates at one point, causing foam melting, EVA sticking to the blade, or even burnt leather edges.
Reduced Edge Quality: This is particularly obvious for soft materials. Excessively slow speed causes the blade to rub repeatedly at the same position, easily fraying the cut edge instead of cutting it cleanly, resulting in unclean cuts and frayed edges.
Which Parameters Need to Be Adjusted Together with Cutting Speed?
Matching Relationship Between Cutting Speed and Vibration Frequency
The higher the feeding speed, the fewer vibrations per unit length. Therefore, if the cutting speed is increased without increasing the tool’s vibration frequency, the tool will “fail to cut through or cut cleanly.” In actual operation, if the speed is increased, the vibration frequency should be increased accordingly.
For example, if the speed is increased from 300mm/s to 600mm/s, check if the vibration frequency has been set to the maximum (usually via a potentiometer knob or software setting). If the frequency cannot keep up with the speed, blade breakage may occur. If the speed is reduced, the frequency can be appropriately lowered to reduce friction.
Relationship Between Cutting Speed, Tool Type, and Angle
Small-Angle Blades (16°-26°): Sharp with low resistance but fragile, suitable for cutting soft materials. Allow higher cutting speeds; not recommended for hard materials such as hard leather and rubber.
Large-Angle Blades (45°-60°): Large contact area with high resistance and strong rigidity, suitable for slow but stable cutting. It is recommended to reduce the speed; otherwise, the machine will be overloaded, affecting its service life.
Speed Must Be Controlled Separately for Corners and Small Graphics
In actual processing, the speed for straight-line cutting can be fast, but it must be slow at corners. Modern CNC control software (such as Ruida, Trocen) allows setting “small circle speed limit” or “corner acceleration.”
Recommendation: Limit the speed of round holes with a diameter greater than 10mm and less than 50mm to 30%-50% of the straight-line speed. This ensures the round holes are cut perfectly circular instead of polygonal. For round holes with a diameter less than 10mm, it is not recommended to use a tool; a punching tool is preferred.
Is There a Universal Method to Quickly Find the Right Cutting Speed?
Quickly Verify Speed Through Test Cuts
1. Square Test (50mm x 50mm):
- Set Initial Speed: A conservative value, such as 200 mm/s.
- Observe Corners: If the corners are clean and free of uncut threads, the frequency is sufficient.
- Speed-Up Test: Increase the speed by 100 mm/s each time until “overcut” (small tails) or “rounded corners” appear at the corners. The safe limit speed for the material is this speed minus 10%.
- Measure Sides: Check if the four sides are of equal length. If yes, the current speed is reasonable; if not, continue testing and adjusting.
2. Circle Test (20mm diameter):
- Observe Shape: If the cut shape is elliptical, first check the belt tightness, then reduce the speed. High-speed inertia can easily deform circles.
- Check Start and End Points: If the start and end points of the circle do not perfectly overlap (misalignment), the material has shifted during cutting. Reduce the speed or enhance adsorption force.
Establish Your Own Material Speed Parameter Library
It is recommended to create an “SOP Process Parameter Table” in the workshop, recording the following 5 items:
- Material type (e.g., 3mm gray board paper)
- Thickness
- Cutting speed (e.g., 800 mm/s)
- Vibration frequency (e.g., 10,000 RPM)
- Tool model (e.g., 16-degree blade)
By conducting speed tests to establish the parameter table, you can quickly look up the required cutting speed for each material and specification. Even if the operator changes, there is no need to repeat speed testing.
When Adjusting Speed Doesn’ t Work, It’ s Time to Upgrade or Maintain Your Machine System/Configuration
If you find that: No matter how much you reduce the speed, the accuracy cannot be improved; the same problems occur with different materials.
It means your machine system or configuration needs upgrading or maintenance:
- Insufficient Vacuum Adsorption: It is likely that the vacuum pump filter is clogged, the pipeline is leaking, or the felt is too old with poor air permeability.
- Tool Wear: A dull blade requires 3 times the cutting force of a new blade. Replacing it with a new blade may double the cutting speed.
- Increased Mechanical Clearance: Check if the gantry is loose, the belt is slack, or the clearance between the guide rails and racks has increased.
For information on machine maintenance and upkeep, also read: CNC Oscillating Knife Machine Maintenance Checklist
FAQs
Should the speed be fast or slow when cutting adhesive-backed materials (e.g., self-adhesive, adhesive-backed hook-and-loop fasteners)?
It is recommended to reduce the speed appropriately and use lubrication.
Reason for Speed Reduction: High-speed cutting generates heat, causing the adhesive to melt and stick to the blade (blade sticking), increasing resistance and even leading to blade breakage.
Solution: Reduce the speed to 200-300mm/s, use a tool holder with silicone oil atomization function, or regularly apply soapy water to the blade to reduce adhesive sticking.
Why do the same parameters work well in the morning but fail to cut through in the afternoon?
This situation is usually not due to speed parameters but tool wear or an uneven table.
Tool Wear: After the blade becomes dull, the required cutting force increases exponentially. The original cutting speed and vibration frequency can no longer cut through the material.
Table Factors: If debris was removed from the felt or a new pad was replaced in the morning, changes in adsorption force can also affect cutting results. It is recommended to slightly reduce the speed by 10% in the afternoon or replace the blade.
To pursue output and improve production efficiency, can I always run the machine at the maximum speed limit (e.g., 1500mm/s)?
Not recommended.
Impact on Equipment Life: Long-term full-load operation accelerates the wear of drive belts, motor bearings, and guide rails. Without proper maintenance, the machine’s service life will be greatly shortened.
Stability: Based on our test experience and customer feedback, it is generally recommended to keep the working speed at around 80% of the machine’s design limit speed. This ensures high output while leaving a mechanical buffer margin to extend equipment life.
How to judge if the “vibration frequency” is too low or the “movement speed” is too fast? Is there a difference in their performance?
Yes, there is a difference, which can be judged by sound and cut edges.
Too Low Vibration Frequency: The cut edge will have obvious jaggedness, and the machine will make a dull “dragging sound” (thumping) during cutting.
Too Fast Movement Speed: The cut edge may be smooth, but the dimensions will be smaller (because the material is pulled), or severe overcut and tailing will occur at corners.
Is the slower the cutting speed of a CNC oscillating knife cutter, the more accurate it is?
Not necessarily. Excessively slow cutting speed causes prolonged friction between the blade and the material, generating heat that leads to foam melting, EVA blade sticking, or burnt leather edges. A reasonable speed should match the vibration frequency and material characteristics, not just blindly reducing the speed.
How should the cutting speed be adjusted when the material thickness changes?
Based on extensive industry experience, for every 5mm increase in material thickness, it is recommended to reduce the cutting speed by approximately 15%–20% to reduce lateral tool force, maintain tool perpendicularity, and avoid taper phenomenon or inclined cuts.
Does cutting speed affect tool service life?
Yes. Excessively fast cutting speed significantly increases the lateral drag force on the tool, easily causing micro-bending, chipping, or even breakage of the blade. Excessively slow speed leads to rapid dulling of the blade edge due to prolonged friction. Industry application data shows that operating within a reasonable speed range can extend the average tool life by 30%–50% while maintaining more stable cutting quality.
Does cutting speed affect the overall service life of the CNC oscillating knife cutter?
Yes. Long-term operation at an unreasonable high speed keeps the servo motor, belt, and guide rails under high load for a long time, accelerating mechanical wear. Excessively slow speed may cause frequent start-stop of the motor, increasing the burden on the control system. A reasonable cutting speed helps reduce the long-term maintenance cost of the entire machine.
Does cutting speed affect subsequent processes (e.g., sewing, bonding)?
Yes. Unreasonable cutting speed is likely to cause rough, uneven edges, threading, or scorching. These defects will be amplified during subsequent sewing or bonding, leading to thread breakage, poor adhesion, or even rework. Therefore, setting the cutting speed properly not only affects the current process but also directly impacts the quality of subsequent processes.
Why do I need to readjust the cutting speed for different batches of the same material?
Even for the same material, different batches may have differences in density, moisture content, coating, or fiber structure. These changes directly affect cutting resistance and material rebound characteristics. Therefore, it is recommended to conduct a small sample test cut each time the material batch is changed, instead of fully adopting the old speed parameters.
Do ambient temperature and humidity affect cutting speed settings?
Yes. In a high-temperature environment, materials like foam and rubber are more likely to soften, reducing cutting resistance but also making them more prone to blade sticking. In a high-humidity environment, the moisture content of cardboard and fabric increases, increasing cutting resistance. In actual production, environmental changes may require a 5%–10% fine-tuning of the cutting speed.
Why does machine noise and vibration increase significantly during high-speed cutting?
High-speed cutting amplifies tiny gaps and imbalances in the mechanical system, such as uneven belt tension, loose tool holder, or insufficient guide rail lubrication. These problems are not obvious at low speeds but are amplified during high-speed operation, affecting both cutting quality and shortening equipment life.
