In actual cutting applications, most of the customers we work with purchase a CNC oscillating knife cutting machine mainly for cutting fabric and leather, and some also use it for cutting cardboard, gaskets and foam. In fact, a CNC oscillating knife cutter can cut a wide variety of materials and has a broad range of applications. It is not only for cutting flexible materials, but also many semi-rigid materials.
In addition, for materials that are not suitable for laser cutting (such as materials that produce harmful gases during thermal cutting), choosing a CNC oscillating knife cutting machine is the best decision. This article lists some semi-rigid materials that can be safely cut with a CNC oscillating knife cutter, helping you make the right choice when purchasing a machine based on your materials.
A CNC Oscillating Knife Cutting Machine Is Not Just for Cutting Flexible Materials
Most customers think a CNC oscillating knife cutter can only cut fabric, leather, foam and cardboard. In actual consultations, many customers initially assume that a CNC oscillating knife cutting machine is only for soft materials and cannot cut slightly harder ones.
This perception mainly stems from the early industry applications focusing on the textile, advertising and packaging fields. With market development, many new industries and materials have emerged, and some emerging semi-rigid materials can still be cut with a CNC oscillating knife.
Semi-Rigid Materials Are Misunderstood as “Must Be Cut with a Milling Cutter or Laser”
In traditional perception, many semi-rigid materials are either milled slowly with a CNC milling cutter or cut with a laser, but one has to accept edge burning, deformation or odor issues. This judgment usually overlooks the material’s toughness and cutting mechanism.
For example:
Milling cutter: Cutting thin sheets (e.g., 1mm PP board) requires extremely strong vacuum adsorption; otherwise, the material will rotate with the cutter. It also generates a lot of dust and debris, requiring secondary cleaning.
Laser: Cutting rubber and PVC produces toxic black smoke (chlorine gas, sulfides), and the edges carbonize and turn black, affecting sealing performance.
What Really Limits Application Is Not the Equipment, But the Understanding of Materials
Hardness ≠ Cannot be cut with a CNC oscillating knife
Unlike laser or high-speed milling, an oscillating knife achieves local fracture and shearing of materials through high-frequency vertical vibration, rather than material removal via high-temperature melting or high cutting force. This means:
The material will not have edge burning, deformation or toxic gas release due to heat
It is more friendly to layered, composite or semi-rigid materials
Cutting can be completed while maintaining the material’s original physical properties
This has been repeatedly verified in multiple CNC machining studies.
For example, Springer’s research on non-traditional cutting methods points out that low heat input processing methods are more conducive to maintaining the structural integrity of polymers and composite materials (see references at the end of the article).
Why Is a CNC Oscillating Knife Cutting Machine More Suitable for Cutting Semi-Rigid Materials?
Advantages of a CNC Oscillating Knife Cutter for Cutting Semi-Rigid Materials
Cold Cutting: No heat-affected zone, edges do not blacken or harden, material properties remain unchanged, and the original physical and chemical properties of the material are preserved (critical for seals).
Dust-free: Suitable for the electronics, medical and food industries with extremely high cleanliness requirements.
No cutting force: Compared with the lateral rotational force of a milling cutter, the oscillating knife has minimal cutting resistance. It can not only cut small parts but also does not require “tabs” for fixation, making edge chipping and tearing less likely.
High safety: Multiple safety protection mechanisms, safer than laser cutting.
No secondary processing required: The cut is smooth and can be directly sewn or assembled.
Suitable for small batches and customization: No mold opening required.
Which “Semi-Rigid Engineering Plastics” Can Also Be Cut with a CNC Oscillating Knife Cutter?
Practical Cutting Advantages of Engineering Plastics Such as Modified Polypropylene (PP), Polyvinyl Chloride (PVC) and ABS
Characteristics: Acid and alkali resistant, light weight, excellent toughness, higher hardness than ordinary PP, and not easy to break.
Applications: Acid and alkali resistant liners for chemical equipment, automotive door panel interior parts, blister packaging pallets, industrial partitions.
Pain points: Laser cutting PP causes edge melting, glue flow and threading, with hard lumps on the edges that affect subsequent assembly; milling has low efficiency and many burrs.
Solution: Pneumatic Oscillating Knife (POT) + large-angle blades (45°-60°).
Oscillating knife advantages: Smooth and flat cut, no molten burrs, no manual chamfering required.
Semi-Rigid PVC (60 – 85 Shore A)
Characteristics: Waterproof, flame retardant, chemical corrosion resistant, heat sensitive.
Applications: Industrial protective curtains, advertising light box base plates, bathroom waterproof gaskets, industrial card slots, equipment protective plates.
Pain points: Laser cutting PVC releases highly toxic chlorine gas and damages flame retardant performance, corroding the machine’s optical path and harming the human body; milling cutter cutting is prone to chip winding.
Solution: Electric Oscillating Knife (EOT) + PTFE-coated blades (anti-adhesion).
Oscillating knife advantages: Cold cutting without edge burning, no toxic smoke or dust, neat cuts and stable edge quality.
ABS Thin Sheets (1 – 5mm)
Characteristics: Good rigidity, easy to process, high surface gloss, dimensional stability.
Applications: Prototyping of electronic product casings, electronic accessory bases, fixture bases, toy model components.
Pain points: High cost and long cycle for opening injection molds; milling thin sheets is prone to edge chipping.
Solution: High-frequency Oscillating Knife (EOT-25,000 rpm).
Oscillating knife advantages: Suitable for special-shaped parts and small-batch production, high efficiency, low cost and rapid prototyping. No mold opening required, cutting from a single piece, with precision up to ±0.1mm.
Ultra-High Molecular Weight Polyethylene (UHMWPE)
Characteristics: Super wear resistance, self-lubrication, impact resistance.
Applications: Conveyor belt guide rail liners, wear-resistant backing plates, chute liners, wear-resistant strips for food machinery.
Pain points: The material is extremely slippery and tough, ordinary knives cannot cut it, milling cutters are prone to slipping and burrs, and laser cutting has unstable edges.
Solution: High-power Pneumatic Oscillating Knife (POT) + serrated blades.
Oscillating knife advantages: Utilizes the “sawing” effect of serrated blades to overcome the high toughness of the material, with good cut perpendicularity, neat cuts, no burrs and unchanged material properties.
Nylon PA6 / PA66 (1 – 8 mm)
Characteristics: High strength, oil resistance, wear resistance, impact resistance, strong toughness.
Applications: Mechanical gaskets, gear bushings, textile machine accessories.
Pain points: Nylon is highly hygroscopic and hard during milling, leading to rapid tool wear and rough machined surfaces; thermal cutting is prone to deformation.
Solution: Pneumatic Oscillating Knife (POT). Reduce cutting speed (30-50mm/s) is required.
Oscillating knife advantages: Burr-free cuts, no subsequent grinding required, dimensional stability, and preservation of nylon’s high-strength characteristics.
Polyoxymethylene (POM) (1 – 6 mm)
Characteristics: Known as “Saigang”, high hardness and good rigidity.
Applications: Precision small gears, sliders, fasteners.
Pain points: Excessively high hardness makes ordinary blades prone to chipping; milling is prone to microcracks.
Solution: Pneumatic Oscillating Knife (POT). Only for thin sheets below 3mm; a milling cutter is recommended for thicker ones.
Oscillating knife advantages: Suitable for processing ultra-small precision parts, no part deformation or flying out due to excessive cutting force.
Cutting of Semi-Rigid Rubber and Elastomer Materials
Nitrile Butadiene Rubber (NBR) Semi-Rigid Sheets
Characteristics: Excellent oil resistance, temperature resistance.
Applications: Automotive oil seal gaskets, hydraulic system gaskets.
Pain points: High hardness makes it difficult to ensure roundness with manual cutting; laser cutting causes edge carbonization and failure. Ordinary knives are prone to sticking, and edges stretch and deform.
Solution: High-frequency electric oscillating knife. Blade lubrication is required, and appropriately increase the cutting frequency.
Oscillating knife advantages: Smooth cuts, precise roundness, no damage to the rubber’s molecular structure, guaranteed sealing performance, no knife sticking or edge pulling, and good dimensional consistency.
Chloroprene Rubber (CR)
Characteristics: Aging resistance, flame retardant.
Applications: Outdoor cabinet sealing strips, wetsuit materials, protective pads, anti-slip plates, door and window seals.
Pain points: The material itself is flame retardant, laser cutting is ineffective or produces thick smoke, die cutting cost is high, and processing of special-shaped parts is difficult.
Solution: Oscillating knife.
Oscillating knife advantages: Cold cutting, no smoke or odor, neat edges without charring, and preserved elasticity.
Semi-Rigid Silicone (70 – 90 Shore A)
Characteristics: High temperature resistance, food-grade safety, good elasticity, insulation.
Applications: Coffee machine sealing rings, medical catheter fixators, electrical insulation pads.
Pain points: Prone to knife sticking, easy to stretch and cause cut deformation; extremely high cleanliness requirements.
Solution: Round Knife or oscillating knife. Soap water lubrication is required to prevent knife sticking.
Oscillating knife advantages: Complies with GMP clean production standards, no dust pollution, clean cuts and no edge curling.
FKM (Fluororubber), EPDM (Ethylene Propylene Diene Monomer)
Characteristics: Strong corrosion resistance (FKM), aging resistance (EPDM).
Applications: Chemical pump and valve seals, automotive wiper strips, photovoltaic gaskets, building seals.
Pain points: FKM is extremely expensive with high material costs; laser cutting produces corrosive gases.
Solution: Intelligent nesting software + oscillating knife.
Oscillating knife advantages: Maximize material utilization, no toxic smoke generation, protect the health of operators, reduce waste and improve yield.
Cutting of Insulating and Sealing Industrial Plates
Epoxy Board (FR-4) Thin Sheets (1 – 3 mm)
Characteristics: With epoxy resin as binder and glass fiber cloth as reinforcement, it has extremely high flame retardancy (UL94 V-0), good mechanical strength, dimensional stability and excellent electrical insulation performance, but high hardness and contains a lot of highly abrasive glass fibers.
Applications: PCB drilling backing plates, circuit board heat insulation sheets, insulation inserts for new energy battery packs, test fixture partitions, electrical insulation liners.
Pain points: Milling produces a large amount of ultra-fine glass fiber dust, which is extremely harmful to workers’ skin and respiratory tract and easily causes wear to equipment guide rails; laser cutting produces toxic smoke and black carbonized cuts, leading to reduced insulation performance, and the glass fiber structure causes rapid tool wear and high processing costs.
Solution: High-power Pneumatic Oscillating Knife (POT) + special tungsten steel serrated blades.
Oscillating knife advantages: Dust-free processing can be achieved. The oscillating knife cuts fibers through “shearing” rather than “grinding”, producing almost no dust, no need for expensive dust removal systems, and neat cuts without carbonization, no obvious edge burning or delamination, and preservation of the material’s high insulation and flame retardant properties.
Phenolic Resin Flexible Board (Substitute for Bakelite Board)
Characteristics: Temperature resistance, good mechanical strength.
Applications: Motor insulation pads, fixture partitions.
Pain points: Milling bakelite boards produces ultra-fine dust, which not only irritates workers’ skin but also pollutes the workshop environment; thermal cutting damages insulation performance.
Solution: Pneumatic Oscillating Knife (POT).
Oscillating knife advantages: Solves the dust problem, smooth cuts, no need to wear heavy dust masks, and unchanged insulation performance.
Semi-Rigid Mica Board & Aluminum Silicate Fiber Board
Characteristics: High temperature resistance, brittle, high dust generation.
Applications: Microwave oven mica sheets, industrial furnace heat insulation pads.
Pain points: The material is very brittle and breaks easily when touched; a lot of fiber splashes during cutting.
Solution: High-frequency oscillating knife.
Oscillating knife advantages: Suppresses dust. The cutting method of the oscillating knife will not lift fibers into the air like rotating tools, and avoids material chipping.
Polyimide (PI) Thin Sheets
Characteristics: A high-performance engineering material known as the “golden film”, with extremely high temperature resistance (-269℃ to 400℃), excellent insulation, radiation resistance and excellent flexibility.
Applications: FPC flexible circuit board reinforcement plates, aerospace heat insulation layers, microelectronic packaging, high-end motor insulation slot wedges.
Pain points: High stamping die cost, not suitable for small-batch prototyping; although laser cutting is fast, the edges inevitably have a heat-affected zone (HAZ) that causes carbonization, leading to brittle or discolored film and affecting the reliability of high-end electronic products.
Solution: High-frequency Electric Oscillating Knife (EOT) or Drag Knife.
Oscillating knife advantages: No thermal stress or charred edges on the cut, clean cutting edges, no damage to the heat resistance and insulation properties of PI materials, and can achieve complex special-shaped cutting and even kiss-cut.
“Non-Delaminating Cutting” Application in Composite and Lightweight Structural Plates
Flexible Aluminum-Plastic Panel (1 – 3 mm)
Characteristics: Aluminum skin + plastic core + aluminum skin, lightweight, waterproof, layered structure.
Applications: Advertising letter base plates, display stand panels, advertising interiors.
Pain points: Folding forming is required, milling grooving is easy to cut through the bottom aluminum, and laser is easy to damage the laminated film.
Solution: V-cut grooving knife.
Oscillating knife advantages: Precisely control the cutting depth, only cut through the upper aluminum skin and plastic core, and retain the bottom aluminum skin as a folding hinge to achieve a perfect folded angle.
High Hardness EVA Composite Board / Foam Composite (XPE / EPE)
Characteristics: Hard surface (with veneer), soft middle, cushioning, semi-rigid.
Applications: High-end tool box liners (e.g., drone boxes), sports protective gear.
Pain points: Laser will burn the flannelette or PU skin on the surface, leading to appearance damage and interlayer delamination.
Solution: Oscillating knife.
Oscillating knife advantages: Perfect layer protection, no delamination. Physical cutting without heating ensures the surface is intact, and the internal cut is vertical.
Glass Fiber Composite Flexible Board
Characteristics: Resin + glass fiber, extremely tough.
Applications: Drone fuselage skin, outdoor equipment accessories.
Pain points: Fibers are extremely difficult to cut and prone to threading; milling cutters wear out very quickly.
Solution: Serrated blades.
Oscillating knife advantages: Uses serrations to cut fibers, with neat cuts without threading and high efficiency.
Other Easily Overlooked Industrial Semi-Rigid Special Materials
Polyurethane (PU) Rigid Foam Board
Characteristics: Wear resistance, impact resistance, light weight.
Applications: Industrial caster liners, automotive bumper energy absorption blocks, wood-like carving materials, anti-collision pads.
Pain points: Large thickness (up to 50-100mm), ordinary knives cannot cut through, and cutting is prone to deformation.
Solution: Long-blade oscillating knife.
Oscillating knife advantages: Can perform large-depth profile cutting with good cut perpendicularity and dimensional stability.
Polycarbonate (PC) Thin Sheets (1 – 3mm)
Characteristics: Transparent, “bulletproof glass” material, impact resistance.
Applications: Membrane switch panels, instrument panel windows, special stationery, protective covers, electronic casings.
Pain points: Stamping causes stress whitening and even cracking on PC edges; laser cutting causes yellowing edges.
Solution: Oscillating knife.
Oscillating knife advantages: No stress whitening, retains the high transparency of the material, and no edge polishing required.
Wood Fiber Flexible Board / Thin MDF
Characteristics: Environmental protection, easy to process.
Applications: Cultural and creative puzzles, green furniture decorative parts, gaskets.
Pain points: Milling produces a lot of dust; laser cutting has blackened edges with a burnt smell.
Solution: Pneumatic Oscillating Knife (POT). Only for MDF below 3mm.
Oscillating knife advantages: No smoke or odor, low dust, suitable for indoor processing, compliant with export environmental standards, and natural cut color.
How to Judge if Your “Special Material” Is Suitable for CNC Oscillating Knife Cutting?
1. Whether the material mainly fractures with toughness rather than brittleness: For example, plastic, rubber and cardboard, where the material is squeezed open through the cut during cutting. Not suitable for brittle materials such as glass and ceramics, which are prone to fracture and chipping.
2. Whether it is necessary to maintain the original structure, coating or performance: If the material you want to cut is sensitive to heat, dust or delamination, choosing a CNC oscillating knife cutting machine is the best decision.
3. Hardness requirement: It is usually recommended that the material hardness is below Shore D 60. For materials exceeding this hardness (e.g., thick acrylic, aluminum plates), a milling cutter is required.
If you’d like to know what other materials CNC oscillating knife cutters can cut, also read：Materials You Can Cut With a CNC Oscillating Knife Machine
FAQs
Why do blades break easily when cutting semi-rigid plastics (e.g., ABS/PP) with an oscillating knife?
Reason: The feed rate is too fast or the oscillation frequency is too low, causing the lateral resistance on the blade to exceed the steel’s limit.
Solution: Reduce the cutting speed (it is recommended to test from 50mm/s) and use a thicker blade (e.g., change from 0.63mm to 1mm thickness).
Why is the cut slanted (tapered) when cutting rubber sheets with an oscillating knife?
This situation may be caused by the elastic deformation of the rubber material. When the blade is pressed down, the rubber is compressed; it rebounds after being cut, resulting in a cut that is wide at the top and narrow at the bottom.
Solutions:
1. Film covering method: Cover a layer of film on the rubber and use the vacuum adsorption system to compact the rubber to reduce rebound.
2. Use PTFE-coated blades to reduce friction.
3. Spray a small amount of soap water to lubricate the blade before cutting.
How thick of rigid foam (e.g., thick EVA) can an oscillating knife cut?
The CNC oscillating knife cutting machine of TRUSTER CNC equipped with a pneumatic oscillating knife can cut EVA up to 120mm thick at maximum.
What to do if the blade wears out quickly when cutting glass fiber composite boards with an oscillating knife?
Glass fiber has high hardness and causes faster blade wear than other flexible materials. TRUSTER CNC uses tungsten steel (hard alloy) blades, which greatly extend the tool service life and are 5-10 times that of ordinary high-speed steel blades.
Can my machine with only an ordinary electric oscillating knife cut 3mm PP boards?
It is relatively strenuous to cut. Ordinary electric oscillating knives (EOT) are usually not equipped with high-power motors on the Z-axis. A high-power pneumatic oscillating knife (POT) is the best choice for cutting hard boards.
Is there dust when cutting insulation boards (e.g., FR-4) with an oscillating knife? Do I need to wear a mask?
There is almost no dust, but tiny particles are generated, unlike the swirling fine powder produced by milling cutters. Although dust is minimal, it is still recommended that operators wear light dust masks or turn on dust collection devices for health reasons.
Which semi-rigid materials are not suitable for cutting with a CNC oscillating knife cutter?
The following materials are generally not recommended:
Thick FR-4 boards with high glass fiber content (>3mm)
Pure brittle materials (e.g., ceramic boards, glass)
Materials that require molten or ablated edges
These materials are more suitable for laser cutting. If you have to cut them with a CNC oscillating knife cutting machine, you can also complete the cutting by matching a milling cutter on the modular tool head.
What to note when cutting FR-4 and PI thin sheets?
FR-4: It is recommended that the thickness is ≤3mm. Use a high-frequency oscillating knife and control the feed rate to avoid glass fiber fraying.
PI thin sheets: It is necessary to match sharp and thin-edge tools, focus on controlling material pressing (vacuum adsorption system with film covering) and rebound. Reasonable parameter settings can avoid delamination, burrs and dimensional drift.
What are the most common problems with failed cutting of semi-rigid materials?
The main reasons can be summarized as: wrong tool type selection, too fast feed rate, and insufficient material pressing leading to material warping.
Will cutting semi-rigid materials with a CNC oscillating knife accelerate tool wear?
Compared with flexible materials, semi-rigid materials do increase tool wear speed, but by selecting the right tools (e.g., high-power oscillating knife or high-power pneumatic oscillating knife) and controlling the feed rate, the tool life can be effectively extended and cutting stability maintained.
Is the material pressing system also important when cutting semi-rigid materials?
Yes. Insufficient pressing of semi-rigid materials is prone to warping, vibration offset or incomplete cutting. A stable material pressing system can significantly improve cutting precision and reduce burr problems. The CNC oscillating knife cutting machine of TRUSTER CNC is equipped with a high-power vacuum adsorption system of 5.5KW/7.5KW/9KW/12KW, which can firmly fix the material when combined with the material film covering method.
Can the edge quality of semi-rigid materials cut by a CNC oscillating knife meet the requirements of industrial assembly?
The materials cut by the CNC oscillating knife cutting machine of TRUSTER CNC have smooth and neat edges without the need for secondary processing. For applications such as seals, gaskets and insulation sheets, the cut products can be directly used for assembly.
References and Information Sources
Altintas, Y., et al. (2015). Accurate prediction of machining feedrate and cycle times considering interpolator dynamics. International Journal of Machine Tools and Manufacture. https://www.sciencedirect.com
Denkena, B., & Biermann, D. (2014). Cutting edge geometries. CIRP Annals. https://www.sciencedirect.com
IEEE Dielectrics and Electrical Insulation Society. (2020). Thermal effects on dielectric materials. https://ieeexplore.ieee.org
SpringerLink. Non-thermal cutting methods for polymer materials. https://link.springer.com
