In the practical application of CNC oscillating knife cutters, besides cutting speed, cutting depth is also a key factor affecting cutting precision. Setting the cutting depth is one of the critical parameters that determine cutting quality, material waste, and equipment service life.
If the cutting depth is set too shallow, the material won’t be fully cut — there will be a layer left at the bottom. Tearing or breaking it manually later will result in frayed edges or even scrap, increasing the scrap rate. If set too deep, the sharp blade will damage the expensive breathable felt mat, not only increasing consumable costs but also causing vacuum adsorption leakage, which affects subsequent processing precision.
What Is “Cutting Depth”?
In the CNC control system, the Z-axis (vertical axis) coordinate determines the height of the blade tip.
Z = 0: Usually defined as the upper surface of the material (or the table surface, depending on the tool setting mode).
Z < 0: The tool moves downward to cut into the material.
For example, if the material thickness is 5mm, the theoretical cutting depth should be set to -5.0mm. But in reality, to ensure full cutting, we usually set it to -5.1mm or -5.2mm, allowing the blade tip to slightly touch the felt.
Why Is It Important to Correctly Set the Cutting Depth of CNC Oscillating Knife Cutting Machines?
Direct Relationship Between Cutting Depth and Cutting Quality
In oscillating knife cutting, the blade enters the material through high-frequency up-and-down vibration. Cutting depth not only determines “whether it’s cut through” but also affects the perpendicularity and smoothness of the cut edge.
Too shallow: Prone to uncut material at the bottom, frayed edges, and threading.
Too deep: Increases tool resistance, easily causing thin materials to wrinkle or deform near the cutting line.
Impact of Improper Cutting Depth on Equipment and Materials
Industry application experience shows that over-cutting beyond the necessary depth by 0.5 – 1mm significantly accelerates the wear of the table felt mat.
Maintenance statistics from some equipment manufacturers show that for machines with long-term over-deep cutting settings, the replacement cycle of the table felt mat is shortened by an average of 30% – 40%.
Equipment damage: Long-term over-deep cutting can scratch the aluminum table base. In severe cases, the blade tip may chip, and fragments may even fly into the vacuum pump and damage the impeller.
Material scrap: For multi-layer composite materials (such as carbon fiber prepreg), cutting through the bottom film will make the entire roll impossible to rewind, resulting in huge economic losses.
Why Are Oscillating Knives More Sensitive to Depth?
Unlike laser cutting (non-contact) or milling cutter cutting (rotary cutting), oscillating knives cut through reciprocating linear vibration with the blade in contact with the material. The blade tip vibrates up and down 0~18,000 times per minute. Even a Z-axis error of only 0.1mm will amplify the cutting precision error under high-frequency vibration. Therefore, the accuracy of the cutting depth setting directly determines whether the tool can fully cut through the material.
What Are the Key Factors Affecting the Cutting Depth of CNC Oscillating Knife Cutting Machines?
Material Thickness and Compression Characteristics
Nominal material thickness ≠ actual cutting thickness.
Materials such as foam, fabric, and non-woven fabric will compress significantly under vacuum adsorption, while leather and composite panels have lower compression rates. Studies show that the compression rate of high-elastic foam materials under vacuum adsorption can reach 10%–25% (Source: Journal of Materials Processing Technology).
Therefore, the cutting depth cannot simply equal the nominal material thickness; the cutting depth of the oscillating knife must be based on the thickness after adsorption. For relevant research, refer to: https://www.sciencedirect.com/science/article/pii/S0924013620305306
Differences in Tool Type and Blade Tip Structure
Blade length: If the length of the blade extending out of the collet is less than the material thickness, the Z-axis can’t cut through even when pressed to the bottom. Principle: Extension length ≈ material thickness + 3mm.
Blade tip angle: Acute-angle blades (such as 16°) have low cutting resistance and are easy to cut deep; obtuse-angle blades (such as 45°) have high resistance and may require more downward depth compensation.
Examples:
Standard straight blade: Suitable for medium-thickness materials
Long blade: Suitable for thick foam and multi-layer materials
Fine blade tip: Suitable for thin materials and high-precision cutting
If the effective tool length is insufficient, even if the depth parameter is set large, the material may not be cut through.
Table Flatness and Felt Wear
Uneven table: If the table is higher on the left and lower on the right, the same depth parameter will cause the left side to damage the table and the right side to not cut through.
Felt wear: Old felt is often concave in the middle and high around. This will result in the same Z-axis coordinate, with over-deep cutting around and incomplete cutting in the middle.
Impact of Vacuum Adsorption Strength on Cutting Depth
Insufficient vacuum adsorption will cause slight lifting of the material during cutting, thereby offsetting part of the cutting depth.
Some industrial test data shows that when the vacuum adsorption pressure drops by 20%, the cutting failure rate can increase by 15%–25%.
For relevant research, refer to: https://www.sciencedirect.com/science/article/pii/S0736584519300833
How to Set a Reasonable Cutting Depth for Different Materials?
Cutting Depth Setting for Leather and Artificial Leather
Leather materials have high density, strong toughness, uneven thickness, and low compression rates.
Generally recommended:
Cutting depth = measured thickness + 0.2–0.3mm. Leather fibers are hard to break, so the blade tip must slightly pierce the felt to ensure complete cutting.
Key Points for Controlling Cutting Depth of Foam, EVA, and Sponge Materials
These materials are air-permeable. Therefore, it is necessary to cover a layer of film on top and cooperate with a vacuum adsorption system to better fix them. After turning on adsorption, the material is easily compressed. So, you should measure the actual height with a ruler, or directly set the depth to “table surface coordinate 0.5mm”, and cooperate with a low cutting speed to avoid tool deviation.
Multi-Layer Cutting Depth Strategy for Fabrics and Composite Materials
In multi-layer cutting, the bottom layer is prone to displacement. Therefore, you can set the Z-axis origin on the table surface (instead of the material surface), set the cutting depth to 0 (i.e., just touching the table), and add 0.1mm over-cut depth.
You can also use multi-pass cutting, with a single cutting depth slightly less than the total thickness. Studies show that multi-layer step-by-step cutting can reduce the lateral force on the tool by 20%–30% and improve cut consistency (International Journal of Advanced Manufacturing Technology). Reference: https://link.springer.com/article/10.1007/s00170-020-06147-8
Core Differences in Cutting Depth Settings for Hard and Soft Materials
Hard materials (such as asbestos boards): Over-cut depth should not exceed 0.1mm; otherwise, the blade tip is easy to chip.
Soft materials (such as fabric): Over-cut depth can be relaxed to 0.5mm to ensure loose fibers are cut off.
How to Correctly Set the Cutting Depth of CNC Oscillating Knives (Step-by-Step Guide)
Step 1: Manual Tool Setting
1. Automatic tool setter: You can choose a machine equipped with an automatic tool setter. Click “Automatic Tool Setting”, and the tool head will slowly descend to find the red light left and right. When the blade tip touches the red light, it will automatically calibrate the set tool depth parameters to complete automatic tool setting.
2. A4 paper method (manual): If you want to save budget and not choose an automatic tool setter, you can use this tool setting method.
- Place a piece of A4 paper on the table felt surface.
- Manually control the Z-axis to descend in micro-steps while continuously pulling the A4 paper.
- When you feel the paper is slightly pressed by the blade tip, there is resistance when pulling, or the paper is cut, set this position as the Z-axis origin (Z=0).
Step 2: Software Configuration
In the control software (such as Ruida, Trocen, or ZhongRui), you need to enter two key values:
Material Thickness: Fill in truthfully, e.g., 3.0mm.
Over-cut / Offset: To offset minor table unevenness, you usually need to let the tool cut a little more.
Recommended value: 0.2mm 0.3mm.
Note: If cutting very hard materials (such as asbestos boards), the over-cut depth should not be too large; otherwise, the blade tip will chip when hitting the aluminum table.
Step 3: Test Cut
Test cut a 20mm x 20mm small square at the corner of the material. Then, check if the square can be easily removed and if there are slight scratches (which is normal) instead of deep cutting marks on the table felt.
How to Maintain Consistent Cutting Depth in Automatic Feeding Mode?
Impact of Feeding Tension Changes on Cutting Depth
The roll material will be stretched during feeding, resulting in reduced thickness. If the cutting depth is set in the relaxed state, the felt will be damaged.
How to Improve Depth Stability Through Parameter Compensation
Table height compensation: With the continuous development of technology, modern CNC oscillating knife cutting machines generally have a table height compensation function. After feeding, the machine will first scan the table flatness with a probe, and the Z-axis will automatically adjust the height according to the table undulation during cutting.
In CNC machining, Z-axis dynamic compensation technology based on surface topography measurement is crucial.
Studies show that through real-time monitoring and error compensation of the machining surface, the impact of table unevenness on machining depth can be significantly eliminated, and the depth error can be controlled at the micron level. For relevant research, refer to the paper “Surface topography measurement and compensation for CNC machining” on IEEE Xplore. Source: IEEE Xplore
Practical Setting Suggestions for Automatic Feeding Scenarios
In continuous production, it is recommended to perform depth calibration regularly. Since the annular felt is very expensive, it is recommended to control the over-cut depth within 0.1mm, especially after changing material batches.
Common Cutting Depth Setting Errors and Solutions
Reasons for Incomplete Cutting Even With Sufficient Depth Setting
Tool wear: A dull blade can’t cut fibers; it only crushes them. Replacing the blade is often more effective than adjusting the cutting depth.
Loose tool holder: The Z-axis descends, but the collet in the tool holder shrinks upward. Check the locking screws.
Insufficient vacuum: The vacuum adsorption strength is not enough, causing the material to move during cutting.
Hidden Problems of Unclean Cutting Despite Over-Deep Setting
Too soft table: If the felt becomes soft after long-term use, it will sink when the tool presses down. This results in deep cutting but insufficient reaction force to cut through the material. At this time, the felt needs to be replaced.
Too fast cutting speed: Setting the cutting speed too fast means the oscillating knife has insufficient effective cutting contacts with the material per unit time, which is prone to incomplete separation of the material bottom, local threading, or tearing.
From a mechanical perspective, the faster the cutting speed, the shorter the tool’s residence time in the material, and the vibration energy cannot be fully transmitted to the material bottom — this is more obvious in high-density or high-toughness materials (such as cutting leather and composite materials).
Industry application experience shows that when the cutting speed exceeds the recommended range for the material by more than 20%, even increasing the cutting depth cannot effectively improve cutting cleanliness; instead, it will accelerate tool wear.
For how to reasonably set the cutting speed of CNC oscillating knife cutters, also read: How to Set Cutting Speed for CNC Oscillating Knife Cutter
Mismatched tool and material: Different materials have different requirements for tool structure. If you use an oscillating knife with a too-short blade tip, insufficient rigidity, or unsuitable blade type, even if the cutting depth is set deep, the blade tip may slightly bend or deviate in the material, leading to incomplete cutting.
Examples:
Using a short straight blade to cut thick foam or multi-layer materials
Using an ordinary straight blade to cut high-toughness composite materials
Using a worn tool to cut high-density leather
In these cases, the problem is not improper depth setting, but insufficient effective cutting stroke or dullness of the tool. Therefore, when the depth is set correctly but the material still can’t be cut through, you should also consider whether the tool selection matches the material.
Troubleshooting Ideas for Inconsistent Cutting Depth
Uneven gantry: Check the levelness of both ends of the crossbeam.
Feeding system: In automatic feeding mode, if the feeding tension is unstable, the actual height of the material when entering the cutting area will change, directly leading to different performances of the same cutting depth parameter at different positions. This may result in complete cutting in the front section, incomplete cutting in the rear section, or different cutting effects in left and right areas.
Uneven adsorption: Insufficient adsorption in some areas will cause the material to slightly lift under the tool’s action, thereby offsetting the cutting depth. Both research and practical applications show that when insufficient adsorption causes the material to lift 0.2–0.3mm, it may result in the problem of “seemingly normal cutting depth but actual incomplete cutting”.
How to Extend the Service Life of the Table Felt While Ensuring Full Cutting?
Principle of Reasonable “Light Cutting” Setting
Slow plunge speed: Set a slow plunge speed to prevent the blade tip from impacting the felt.
Correct Blade Length Installation
Don’t extend the blade too long for convenience. For example, cutting 5mm material with a 20mm extended blade. This will cause the blade to deflect under high-frequency vibration, resulting in a wider top and narrower bottom cut. The correct approach is: Blade extension length ≈ material thickness + 3mm. This avoids blade chipping and improves cutting precision.
Effectively Use the “Table Compensation” Function
Level the table once a week, allowing the Z-axis to automatically adjust the cutting depth according to the table flatness during operation, ensuring that the cutting depth is accurate and consistent everywhere.
When Should the Table Felt Be Replaced?
When the table becomes pitted and uneven, and you have to set an over-cut depth of >1mm to cut through the material, it means the felt needs to be replaced. Continuing to use it will accelerate tool wear and damage the vacuum pump.
Reduce Long-Term Usage Costs Through Depth Management
For example, establish a “Tool-Material-Depth Comparison Table”. Record the optimal over-cut depth for each material to avoid blind test cuts that damage the table. Reasonable cutting depth settings can extend the felt service life by more than 20%.
Experience Summary and Optimization Suggestions for Cutting Depth Setting
Safe Depth Setting Strategy for Beginners
Tool setting: Set the Z-axis origin on the table surface (instead of the material surface).
Setting: Enter the material thickness in the software and set the over-cut depth to 0.
Test cut: If not fully cut, increase the cutting depth in 0.1mm increments.
Efficiency-First Setting Method for Mass Production
Directly set the Z-axis origin on the table and the depth to -0.3mm (i.e., cutting 0.3mm into the table).
Ignore minor changes in material thickness to ensure 100% cutting through, reduce inspection time, and it is suitable for high-output scenarios where table wear is not sensitive.
Establish a material parameter table to form fixed adjustment parameters, and calibrate the machine regularly.
FAQs
How to achieve “Kiss Cut” without full cutting?
Kiss cutting is usually used for self-adhesive stickers, requiring only cutting through the surface layer without cutting the backing paper. A kiss-cut knife is needed.
Depth setting method:
1. Measure the backing paper thickness (usually about 0.1mm).
2. Set the cutting depth to: total material thickness 0.1mm.
3. Perform a test cut and fine-tune in 0.05mm increments until the sticker can be peeled off but the backing paper is intact.
Why is the material edge cut at an angle (tapered)?
Reasons:
Over-deep cutting causes the blade to bend under resistance inside the material.
The blade extends too long with insufficient rigidity.
Solution: Reduce the blade extension length (only 2-3mm thicker than the material) and appropriately lower the cutting speed.
Do I need to reset the depth after replacing the blade with a new one?
Yes, you must re-set the tool. Even for the same model blade, there may be minor errors (such as 0.5mm) in the extension length during installation. If you don’t re-set the tool, it may damage the table felt or fail to cut through.
How to set the depth of the Creasing Wheel? Is it the same as the oscillating knife?
No. Creasing does not require cutting through — only creating a mark, usually used in the corrugated carton or gift box industry. The creasing depth is usually set to 70%-80% of the material thickness. If set too deep (100%), it will burst the surface paper and cause the carton to break; if set too shallow, the creasing effect will be unclear, which is not conducive to folding the carton.
Can the cutting depth be universal for the same material with different thicknesses?
It is not recommended to be fully universal. Even for the same material, the compression rate under vacuum adsorption will change with different thicknesses. The thicker the material, the higher the probability of uneven compression. Therefore, the cutting depth should be adjusted with the change of material thickness.
Why is the cutting depth set in the software inconsistent with the actual cutting depth?
The software parameter is only an “instruction value”. The actual cutting depth is also affected by felt wear, material compression, vacuum adsorption, and Z-axis zero calibration. It is recommended to re-calibrate the Z-axis reference surface regularly, especially after replacing the felt.
Will frequent adjustment of cutting depth affect production efficiency?
In the short term, it will increase machine setup time, but in the long term, it can significantly reduce the rework rate and scrap rate. We recommend establishing a fixed depth setting parameter table for commonly used materials. Each time you cut, set the cutting depth directly according to the parameter table to reduce the time for repeated test cuts.
Does the cutting depth setting affect tool life?
Yes. Over-deep cutting causes long-term high friction between the tool and the felt, leading to rapid blade dulling. A reasonable depth setting can extend the tool service life and reduce replacement frequency.
What if the cutting depth effect is inconsistent when cutting the same file at different times?
You need to focus on checking the felt condition and vacuum adsorption system. With increased usage time, the felt elasticity will decrease, and the vacuum holes may be blocked by dust — these will change the actual cutting depth effect.
Do I need to adjust the cutting depth as the tool wears?
Yes. After the tool wears, the effective cutting length will shorten. Even if the cutting depth parameter remains unchanged, incomplete cutting may occur. Instead of continuously increasing the cutting depth, it is better to replace the tool with a new one in a timely manner.
What is the relationship between cutting depth and cutting precision?
Over-deep cutting increases the lateral force on the tool, which instead reduces path precision; over-shallow depth is prone to incomplete cutting. Only within a reasonable depth range can both cutting precision and quality remain stable.
Is there a universal method to quickly judge if the cutting depth is appropriate?
The simplest method is to observe the tool marks on the felt:
Shallow and continuous tool marks indicate the depth is basically appropriate.
Deep and blackened tool marks indicate over-deep cutting.
Almost no tool marks indicate insufficient cutting.
References and Information Sources
Kelekçi, E., & Kizir, S. (2020). Effects of cutting parameters on flexible material processing. International Journal of Advanced Manufacturing Technology, 108, 2345–2358.
https://link.springer.com/article/10.1007/s00170-020-06147-8
Li, X., et al. (2020). Influence of vacuum holding force on cutting accuracy. Journal of Materials Processing Technology, 282, 116685.
https://www.sciencedirect.com/science/article/pii/S0924013620305306
IEEE Xplore. (n.d.). Surface topography measurement and compensation for CNC machining. Retrieved from https://ieeexplore.ieee.org/
