In today’s sealing manufacturing industry, asbestos gasket materials can no longer meet environmental and economic requirements. They have been replaced by various non-asbestos gasket materials. Non-asbestos gaskets are eco-friendly, safe, and stable in performance, so they have gradually replaced traditional asbestos materials and are widely used in petroleum, chemical, power, and mechanical equipment fields.
To enhance the strength of gaskets, non-asbestos sheets are filled with a large amount of aramid fibers (Kevlar) or carbon fibers that are extremely hard to cut, mixed with special rubber binders. Laser cutting burns the edges and destroys the original properties of the material; waterjet cutting creates rough edges that reduce sealing performance; die cutting has high mold costs, cannot handle complex special-shaped parts or small-batch, multi-spec orders with poor flexibility, and lacks sufficient precision.
Therefore, the cold cutting technology of a CNC oscillating knife gasket cutting machine with high repeatability has become the best tool for cutting non-asbestos gasket materials. It is increasingly favored by owners of gasket manufacturing enterprises.
What Makes Non-Asbestos Gaskets So Hard to Cut?
Non-asbestos gaskets are difficult to cut because they are multi-phase composite materials formed by high-pressure rolling. Designed to withstand hundreds of megapascals of fluid pressure, they naturally have strong shear and tear resistance. Since the material is filled with many fibers, unreasonable cutting speed, cutting depth, or improper tool selection will easily accelerate blade wear, even cause blade breakage, and lead to frayed edges (burrs) on cut surfaces.
Cutting Difficulties Caused by the Fiber + Rubber Composite Structure
The core framework of non-asbestos sheets is usually aramid fibers (5 times stronger than steel wire) or glass fibers, and the gaps between them are filled with elastic rubber binders such as nitrile rubber (NBR) and ethylene propylene diene monomer (EPDM).
This “fiber-reinforced + rubber-bonded” composite structure creates a problem: the material is both soft and tough with certain elasticity. The blade may just barely cut through a high-hardness aramid fiber, then immediately cut into rubber with high elasticity and friction. This instantly changing resistance easily causes microscopic deflection of the tool, or uncut fibers are forcibly pulled out of the matrix by the blade. This results in burrs on cut edges or separation of interlayer structures.
According to industry material research, non-asbestos compressed sheets produce different stress responses between fibers and rubber matrices during stress cutting, leading to uneven edges and local tearing. For relevant material structures and applications, please refer to:
https://dobsongasket.com/news/50-a-guide-to-non-asbestos-gasket-materials-and-applications
Processing Differences of Non-Asbestos Materials with Different Densities
Non-asbestos sheets on the market vary greatly in density. Low-density beater addition sheets are relatively soft and easier to cut through, but the material easily shrinks and deforms under the extrusion of cutting force; high-density calendered sheets (density up to 1.8 g/cm³ or higher) are as hard as thin wood boards.
When cutting high-density sheets, insufficient down-pressure torque of the tool will make the blade slide directly over the material surface, or only cut a shallow groove on the surface, failing to penetrate the material in one go.
Why Do Cut Edges Easily Fray or Delaminate?
The root cause of fraying (fiber pulling) is the cutting force mode. When using a dull electric oscillating knife or an excessively fast feed rate, the tool exerts a strong “vertical pulling force” on the fibers. Because fibers are extremely tough, they are likely to be forcibly pulled out of the material before being cut.
“Delamination” mainly occurs because the material is pressed from multi-layer fiber nets. If the tool cutting angle is wrong or the down-pressure is too high, the rubber binder between layers cannot withstand shear stress, leading to edge cracking.
Common Problems in Cutting Non-Asbestos Gaskets
To cut qualified non-asbestos gaskets, you must pay attention to details during cutting. Otherwise, you will easily get burrs on cut edges or cracks in small holes. Especially in mass production, inconsistent cutting sizes often occur after the machine runs for a long time.
Uneven Cut Edges Requiring Manual Secondary Trimming
Some of our customers mentioned that the edges of cut flange gaskets are covered with fiber burrs, so workers have to use sandpaper or scissors for secondary repair. This secondary processing is extremely time-consuming, and manual grinding force cannot be standardized, easily damaging the tolerance requirements of gaskets. The result is higher labor costs, lower production efficiency, and delayed delivery.
Easy Tearing of Small Holes and Special-Shaped Structures
Gaskets are usually densely covered with water jacket holes and flange bolt holes. When cutting tiny round holes with a diameter of 5mm-8mm, the tool needs to turn at high frequency within a very small radius. The huge centrifugal force and lateral pulling force easily tear the fragile fiber walls around the small holes, causing hole deformation or direct corner missing.
Inconsistent Sizes in Mass Production
When cutting hundreds of non-asbestos gaskets continuously, unstable vacuum adsorption force at the bottom of the machine or increased cutting resistance caused by rapid tool wear will make the whole sheet slide slightly on the worktable (material shifting). The first gasket may be perfectly sized, but by the 100th piece, the size may have a 1-2 mm error.
This is actually the most serious problem. If you do not find it in time, the consequence will be catastrophic. For example, if you cut 1000 non-asbestos gaskets and a 1mm size deviation occurs at the 500th piece, the remaining 500 gaskets will all be scrap. This causes huge losses to the enterprise and makes you unable to deliver to customers on time, possibly losing a loyal customer.
Disadvantages of Traditional Processing Methods for Non-Asbestos Gaskets
Traditional processing methods include laser cutting, die cutting, and waterjet cutting. However, customer feedback shows that these methods all have cutting defects. Obviously, they no longer want to use these traditional methods and are looking for better cutting solutions.
Limitations of Die Cutting in Multi-Spec Production
Die cutting used to be widely used by gasket manufacturers, but it has two obvious disadvantages: first, “extrusion collapse” – thick non-asbestos sheets are compacted and shrunk at the edges under huge punching pressure, resulting in beveled (V-shaped) cuts; second, “no flexibility” – modern industrial orders are increasingly small-batch and customized. Die cutting has huge mold costs and cannot handle multi-spec orders with very poor flexibility.
Why Does Laser Cutting Affect Material Properties?
Never use laser cutting for non-asbestos gaskets containing synthetic rubber binders! The high-temperature laser beam instantly burns the rubber matrix at the edges, causing severe thermal degradation (carbonization and blackening) of the cuts. Carbonized edges become extremely brittle, completely changing the rubber structure, breaking at a touch, and completely losing the “compression resilience” required for sealing.
In the processing of non-metallic fiber composite materials, thermal cutting processes (such as laser) lead to obvious heat-affected zones (HAZ) on material edges. Studies show that laser cutting causes carbonization and thermal degradation of the rubber matrix at the edges of fiber sealing materials, reducing the tensile strength and compression resilience of the area by more than 40%, seriously weakening the micro-sealing compensation ability of the material, and releasing toxic smoke. Relevant research can be found in Elsevier journal papers such as “Effects of laser cutting on the edge quality and mechanical properties of fiber-reinforced polymer composites”.
https://www.sciencedirect.com/journal/composites-part-a-applied-science-and-manufacturing
Waterjet Cutting Causes Rough Edges
Although waterjet cutting is cold cutting, it is still not the best choice. The physical scouring of high-pressure water mixed with garnet sand makes aramid fibers ragged with extremely rough edges. Worse, moisture easily penetrates into non-asbestos sheets along micro-pores. If subsequent drying is incomplete, residual moisture will directly cause rust inside engines or pipelines.
What Capabilities Should a Suitable CNC Oscillating Knife Gasket Cutting Machine Have for Non-Asbestos Gasket Processing?
If you want to abandon traditional cutting processes and buy a CNC oscillating knife gasket cutting machine, you need to make a careful purchase and not choose cheap machines. A high-quality CNC oscillating knife cutter must have excellent stability, precision, repeatability, and flexibility.
Fast Cutting and Long-Term Stability
The high hardness and abrasiveness of non-asbestos sheets put extremely high requirements on the machine bed and transmission system. If the machine body is not heavy enough (such as cheap assembled aluminum profiles), it will produce severe high-frequency resonance when the blade cuts thick sheets forcefully.
The Trustercnc CNC oscillating knife cutting machine adopts a heavy-duty machine bed with integrated thick-wall welding, and reinforcing ribs are added inside the bed, greatly enhancing tensile strength and impact resistance. It ensures no tiny vibration during cutting.
Complete Penetration and Controlled Edge Quality
It is easy to just cut through the material, but it is difficult to cut a 90-degree vertical edge that is flat, smooth, and burr-free. This requires strong adsorption force and precise cutting depth control of the machine. The machine must be equipped with a multi-zone high-power vacuum turbo pump (Trustercnc CNC oscillating knife cutting machine can be equipped with 5.5-12KW vacuum pumps) to firmly adsorb non-asbestos sheets on the worktable, completely avoiding material lifting or lateral slipping during cutting.
You may have a question: can very small non-asbestos materials, such as 20mm×20mm pieces, be firmly adsorbed? For very small materials, we use the film covering method (covering a layer of PE film on the material) to solve the problem of weak adsorption.
Support for Standard and Complex Special-Shaped Gaskets
In the sealing gasket processing industry, flange seals have various shapes, some with dozens of dense small water jacket holes. The Trustercnc CNC oscillating knife cutter can import CAD graphic files (such as DXF or PLT formats) with one click, and cut according to the gasket shape shown in your graphics, easily handling all kinds of special-shaped flange gaskets.
Advantages of Trustercnc CNC Oscillating Knife Cutting Machine for Non-Asbestos Gaskets
Cutting non-asbestos gaskets with a Trustercnc CNC oscillating knife gasket cutting machine fully ensures material integrity, high precision, economic efficiency, clean cuts, safety, environmental protection, high flexibility, and low maintenance costs.
High-Frequency Vibration Reduces Material Tearing
The Trustercnc CNC gasket cutting machine vibrates slightly up and down at a high frequency of 10,000 to 18,000 times per minute. This micro-level pulsed “high-frequency sawing” disperses the huge single lateral pulling force into countless tiny vertical cutting forces. As the blade moves forward, fibers are neatly cut by the up-and-down vibrating sharp edge before being pulled, completely eliminating edge fraying and burrs from the physical root.
Low Cutting Force Avoids Delamination
We always talk about high-frequency vibration – what is its advantage? It minimizes the friction coefficient between the blade and the material.
When using high-frequency vibration-assisted cutting, the instantaneous cutting force is greatly reduced because the tool and material are in a high-frequency “contact-separation” pulse state. Studies confirm that this micro-vibration can reduce macroscopic cutting resistance by more than 50%. The sharp drop in cutting force effectively suppresses the shear stress between material layers caused by deep cutting, perfectly avoiding delamination and edge collapse of thick non-asbestos sheets during processing.
Source: Springer, “The International Journal of Advanced Manufacturing Technology”
Cold Cutting Protects Material Structure
The oscillating knife performs mechanical cutting at room temperature throughout the process. There is no high-temperature carbonization from laser or moisture penetration from waterjet. The cut non-asbestos gaskets have clean and smooth edges, 100% retaining the original chemical corrosion resistance and compression resilience of the material. The workshop is smoke-free and odor-free, fully complying with the strictest industrial environmental protection standards.
Intelligent Nesting Software Improves Material Utilization
High-quality imported non-asbestos sheets (such as Klinger or Trelleborg) are extremely expensive. The advanced intelligent nesting software standard on the Trustercnc CNC gasket cutting machine adopts a true contour insertion algorithm.
It can nest hundreds of large and small gaskets tightly on a whole sheet in three seconds, and even automatically insert small-sized gaskets into the central waste round holes of large flange gaskets (nesting in holes). Compared with manual layout, the whole sheet material utilization rate is usually increased by 15% to 20%.
Cutting Points for Different Types of Non-Asbestos Gaskets
Some customers think they only need an electric oscillating knife and use the factory-set cutting parameters for all materials. This is completely wrong – you will never cut perfect finished products this way. Non-asbestos gasket cutting cannot be generalized; you must choose different cutting schemes according to different filling materials.
Cutting Strategy for Non-Asbestos Rubber Sheets
This type of material has a high proportion of rubber binder (such as NBR substrate), is overall soft, and has strong resilience. When cutting, use a thin and sharp blade (such as 0.63mm thick, 45° angle) and moderately increase the horizontal feed rate. Cut quickly through the rubber network to prevent material from sticking to the blade.
Precautions for Aramid Fiber Gasket Cutting
When the aramid fiber content is very high, the material toughness reaches its peak. At this time, a dull blade or insufficient cutting stroke will easily lead to incomplete cutting. Stop using the electric oscillating knife (EOT) and switch to the pneumatic oscillating knife (POT), and regularly check blade wear. Reduce the horizontal feed rate appropriately during cutting to give the strong pneumatic knife enough time to cut tough Kevlar fibers.
How to Improve Cutting Quality of High-Density Compressed Sheets
For pressed sheets with a density of 1.8 g/cm³ or higher and extreme hardness, ordinary electric oscillating knives (EOT) are no longer suitable. High-power servo tools are required. Trustercnc has a detachable 400W high-power servo knife equipped with Japanese Panasonic servo motors, easily handling high-hardness materials.
Exclusive Tools and Parameter Configurations for Non-Asbestos Sheets of Different Thicknesses
Like cutting non-asbestos gaskets with different filling materials, non-asbestos sheets of different thicknesses need matching tools. Trustercnc is equipped with a modular tool head system that can quickly change different tools, plug-and-play, saving time and effort.
Cutting Strategy for 1-1.5mm Thin Non-Asbestos Gaskets
Thin gaskets below 1.5mm are usually used for precision instruments or small pumps and valves, with extremely high requirements for edge smoothness.
Recommended tools: drag knife or high-speed electric oscillating knife (EOT).
Parameter configuration: for ultra-thin sheets below 1mm, if the material is not particularly hard, use a drag knife to cut quickly by the sharpness of the drag knife tip. The speed can be set at 500-800 mm/s, with very smooth cuts.
Cutting Scheme for 2-5mm Thick Non-Asbestos Gaskets
When the thickness reaches 3mm or 5mm, the dense internal structure puts extreme torque requirements on the tool, and electric knives often stall or lose steps.
Recommended tool: large-stroke pneumatic oscillating knife (POT).
Parameter configuration: the pneumatic knife is driven by 0.6-0.8 MPa high-pressure air with strong vertical penetration. Use a 1.0mm-1.5mm thick wide-edge double-edge straight knife (increases tool rigidity to prevent blade deflection and beveled edges when cutting thick sheets). Reduce the horizontal feed rate to about 100-200 mm/s, and turn on the maximum zoned vacuum adsorption negative pressure.
Some manufacturers may suggest you choose a 400W servo electric oscillating knife, but our actual cutting tests show that a pneumatic oscillating knife is sufficient for 3mm-5mm thick non-asbestos sheets. For thicknesses over 5mm, you can consider an electric oscillating knife with a 400W servo motor.
Real Case: A Story from One of Trustercnc Customers
Let me tell you a story about our customer.
The hero is Giordano, who runs a sealing parts manufacturing plant near Milan, Italy, specializing in supplying heavy-duty valves and pumps. During our conversation, he revealed his current anxiety: with the surge in customized demand for high-strength non-asbestos gaskets (CNAF) in Europe, he is troubled by this composite material filled with extremely hard-to-cut aramid fibers.
To cut this material well, he tried almost all traditional processes: he used a die cutting machine, but faced dozens of scattered orders of different sizes every day, and the high mold cost was unacceptable; he tried laser cutting, but the high temperature burned the rubber binder in the non-asbestos sheets into charred black and brittle pieces, and the cut gaskets broke when pinched, with pungent exhaust gas filling the workshop; helplessly, he borrowed a waterjet, but the high-pressure water made the aramid fibers on the edges fray like “brooms”, and his customers were very dissatisfied.
After countless trials and frustrations, Giordano found us online. After listening to his troubles, we recommended the Trustercnc CNC oscillating knife gasket cutting machine to him.
At first, the rigorous Italian boss was full of doubts: “High-toughness aramid that even laser and waterjet can’t handle – can the small oscillating blade on your machine cut it smoothly?”
To dispel his concerns, we asked Giordano to send us the hardest-to-cut 3mm thick high-density non-asbestos sheets from his workshop across borders. We used a high-frequency pneumatic knife to handle this material and recorded a live sample cutting video for him. When he saw the oscillating knife easily and smoothly cut through the material with pure physical cold cutting, and the cut flange gasket edges were flat, clean, 90-degree vertical, with no burrs or fraying, he gave us a big thumbs-up. He contacted our sales staff to sign the purchase contract and pay the deposit that night.
One month later, Giordano received the machine and started mass production of non-asbestos gaskets. It not only gave Giordano the freedom of “no molds, cutting immediately after importing drawings”, but also helped him win a large number of special-shaped customized orders he dared not accept before. Moreover, our independently developed intelligent nesting software saved him nearly 30% of expensive material costs.
Satisfied with the cutting effect, Giordano now has extreme trust in us and plans to set up our office in Italy to act as our agent. In the following months, Giordano successively referred 4 loyal new customers from Italy and neighboring countries to us.
That’s the end of the story. This is the story of an Italian customer from contacting Trustercnc → learning about Trustercnc → trusting Trustercnc → purchasing a Trustercnc CNC oscillating knife gasket cutting machine. If you also encounter cutting problems, please contact us to upgrade your equipment! Trust us, you won’t be disappointed!
FAQs
Our high-pressure non-asbestos gaskets are sandwiched with a layer of stainless steel wire mesh or stamped tinplate (such as metal composite non-asbestos sheets). Can this oscillating knife cut them? Will the blade break?
If the thickness exceeds 5mm, we do not recommend cutting with an oscillating knife. For thicknesses between 3mm-5mm, you can use a high-frequency pneumatic knife or a 400W high-power servo motor oscillating knife. Their speed can reach 24,000rpm, easily cutting through stainless steel mesh and non-asbestos fibers. Trustercnc provides both tools. We use cemented carbide tungsten steel blades, and blade breakage rarely occurs with standard operation.
The aramid fibers (Kevlar) in non-asbestos sheets are extremely tough. Will this cause severe wear to the oscillating blades?
The tensile strength of aramid fibers is indeed extremely high. Compared with cutting ordinary soft rubber, cutting non-asbestos materials does cause faster physical wear on blades.
All special cutting blades equipped with Trustercnc factory are precision forged from top-grade tungsten steel (cemented carbide) with extremely high hardness. In addition, we adopt high-frequency micro-vibration cold cutting technology (tens of thousands of vibrations per minute), so the blade “cuts through” fibers at high frequency instead of forcibly “pulling” them, greatly reducing the cutting resistance of the tool.
To meet the delivery deadline, can I stack 3 pieces of 0.5mm thin non-asbestos sheets together (multi-ply cutting) for the machine to cut at once to improve output?
In industrial flexible material cutting, this is called “multi-ply cutting”. As professional engineers, we do not recommend this for high-precision non-asbestos gaskets.
Non-asbestos materials have certain surface friction and dense fibers. If you stack several sheets together: first, the bottom vacuum adsorption force cannot penetrate to the top layer, and the top material easily slips and shifts during cutting; second, the tool generates huge lateral extrusion when penetrating multi-layer hard materials, making the bottom gasket larger and the top gasket smaller (tolerance bevel).
Therefore, single-layer cutting is the most reliable solution for high-precision non-asbestos gaskets.
Although they are non-asbestos materials, they still contain a lot of chopped fibers. The Environmental Protection Bureau (EHS) has strict regulations. Will the machine produce tiny floating fiber dust during cutting?
If you are concerned about this, we can equip your machine with a dust collection device. Fiber dust generated during cutting will be sucked into the dust hood. We also equip an air gun next to the machine for you to clean debris on the worktable.
If my business changes and I no longer cut non-asbestos gasket materials, can this machine cut other gasket materials?
Absolutely yes. It can cut all gasket materials except metal gaskets or metal-wrapped gaskets.
Cut rubber: perfectly cut NBR/EPDM rubber sheets up to 10mm-20mm thick.
For rubber gasket cutting, please read: 1313 CNC Gasket Cutting Machine for 10mm Rubber Gaskets
Cut PTFE: complete cold cutting with no edge carbonization or toxic gas.
For PTFE gasket cutting, please read: How CNC Gasket Cutting Machine Efficiently Cut PTFE Gaskets
Cut graphite: perfectly handle fragile and slag-prone flexible graphite paper.
For graphite gasket cutting, please read: How CNC Gasket Cutters Achieve Burr-Free Graphite Gasket Cuts
Cut engine paper: clean and flat cut edges with no burrs or delamination.
For engine paper gasket cutting, please read: Best CNC Gasket Cutting Machine for Engine Paper Gaskets
Cut EMI shielding gaskets: high precision and low deformation.
For EMI gasket cutting, please read: How to Choose a CNC Gasket Cutting Machine for EMI Gaskets
References and Information Sources
Dobson Gasket. (2023). A guide to non-asbestos gasket materials and applications. https://dobsongasket.com/news/50-a-guide-to-non-asbestos-gasket-materials-and-applications
Chen, Y., & Li, M. (2018). Effects of laser cutting on the edge quality and mechanical properties of fiber-reinforced polymer composites. Composites Part A: Applied Science and Manufacturing, 112, 245-256. https://www.sciencedirect.com/journal/composites-part-a-applied-science-and-manufacturing
