In precision electronics manufacturing, aerospace communication equipment, high-end medical devices, and new energy industries, EMI gaskets have become key sealing and components to ensure stable equipment operation.
There are many types of EMI gasket materials. Only flexible EMI gasket materials are suitable for a CNC oscillating knife gasket cutting machine. Metal gaskets with metal cladding or thickness over 0.3mm (such as beryllium copper reeds, full-grid metal gaskets) still require die cutting.
We recently received an email from a customer in the United States who works in the power industry. He needs to cut EMI gasket sheets of 305×305mm with a thickness of about 1mm. We provided him with a complete cutting solution from machine selection to high-quality cutting.
Why EMI Gasket Production Needs a Professional CNC Gasket Cutting Machine
EMI gaskets are different from ordinary industrial rubber. Their physical structure and application scenarios mean they have extremely strict requirements for processing, such as precision, edge quality, and material saving. A CNC gasket cutting machine can meet these requirements well.
What Is an EMI Gasket?
EMI(Electromagnetic Interference) gaskets are sealing materials used to seal gaps in electronic equipment enclosures. They not only provide the physical sealing functions of ordinary gaskets (waterproof, dustproof), but their core function is to form a continuous conductive circuit, block the leakage of high-frequency electromagnetic waves or the entry of external interference, and protect sensitive internal electronic components.
Main Application Industries of EMI Gaskets
EMI gaskets are mainly used to block electromagnetic interference and ensure stable operation of electronic equipment. They are widely used in industries with high requirements for signal purity.
Consumer electronics and 5G communications: Gaskets for internal shields of smartphones, flange seals for base station antennas.
Medical equipment: for MRI machines and control boxes of high-frequency surgical knives.
Aerospace and military: Radar systems, electromagnetic reinforcement for military rugged computers.
According to research reports from IPC and IEEE, as the operating frequency of electronic equipment continues to increase, electromagnetic interference is becoming more complex, and the demand for EMI materials and precision gaskets continues to grow.
Studies show that high-performance EMI materials play a key role in 5G communications, medical electronics, and aerospace equipment. Their efficiency usually needs to reach 60–100 dB to ensure stable system operation.
Source:
https://www.ipc.org
https://ieeexplore.ieee.org
This means that EMI gaskets are not just ordinary sealing materials, but precision functional components with very high cutting quality requirements.
Common Types of EMI Gasket Materials
Conductive elastomers: Silicone or Viton rubber evenly mixed with tiny metal conductive particles such as silver, copper, aluminum, and nickel.
Conductive foam: Polyurethane foam with conductive cloth on the surface.
Wire mesh over silicone: Silicone with fine Monel alloy or aluminum woven mesh embedded inside.
These materials share common characteristics:
- Thin
- Soft
- Easy to deform
- Conductive layer is easy to damage
- Sensitive to cutting pressure
According to Materials Today research, excessive mechanical pressure will damage the conductive layer of conductive foam and conductive rubber, affecting performance.
Source: https://www.materialstoday.com
Therefore, EMI gasket cutting cannot use high-temperature or high-pressure processing methods.
Why Are EMI Gasket Cutting Requirements Extremely Strict?
The function of EMI gaskets is not only physical sealing (dustproof and waterproof), but more importantly, to achieve electromagnetic conduction. If the gasket edge is carbonized or insulated due to heat or pressure during cutting, or the internal metal mesh is excessively pulled and falls off, the gasket will completely lose its electromagnetic effectiveness. This requires the cutting process to ensure “absolutely flat cut surfaces” and “zero material damage”.
In addition, according to Precision Engineering journal research, once the dimensional error of precision electronic gaskets exceeds 0.15mm, it may cause sealing failure or reduced performance.
Source: https://www.sciencedirect.com
This is why EMI gasket production must use a high-precision CNC gasket cutting machine.
Which EMI gasket Materials Are Suitable for a CNC Oscillating Knife Gasket Cutting Machine?
Fully suitable materials：1mm thick conductive silicone, full range of conductive foam, conductive cloth, silicone composite plates with ultra-fine metal mesh. A CNC oscillating knife can easily cut through these flexible substrates.
Unsuitable materials：Pure hard metal plates (such as pure copper plates thicker than 0.5mm, beryllium copper reeds), or heavy gaskets with very thick and hard steel wire skeletons inside. Such pure rigid or high-hardness metal materials will cause the carbide oscillating knife blade to chip instantly, and are more suitable for laser or punch processing.
Core Technical Difficulties in EMI gasket Cutting
Some EMI gasket materials contain metal mesh, so ordinary oscillating knives are difficult to cut. At this time, a 400W high-power servo tool or a high-power pneumatic knife is required. In addition, when cutting small-sized materials, how to fix the material well is another difficult problem. Let’s take the 305 × 305mm, 1mm thick EMI gasket material needed by our US customer as an example.
1mm thin materials are easy to deform
At a thickness of 1mm or even thinner, the material has very low mechanical strength, is extremely soft, and easily deforms. Whether it is a micro shield inside a mobile phone or a flange gasket for a radio frequency base station, its dimensional tolerance is usually strictly limited to ±0.05mm to ±0.1mm. Edge tearing and conductive layer damage are prone to occur during cutting, and any slight pulling force may cause deformation and scrap of the final product.
Studies show that tool pressure and vibration frequency have a significant impact on the deformation of flexible materials during cutting.
In CNC cutting technology research, optimizing cutting pressure and feed speed can significantly reduce material deformation and improve cutting quality.
Relevant research: Cutting force and deformation analysis in soft material CNC cutting
Source: https://www.sciencedirect.com
Difficult positioning of 305 × 305mm small sheets
Stability is the biggest problem when processing small sheets. The standard machine size on the market is generally 1600mm × 2500mm. A sheet as small as 305 × 305mm is too small to cover enough vacuum adsorption holes on the workbench. This will cause serious loss of adsorption negative pressure, and the small sheet is easy to slide on the table during cutting, resulting in full-page scrap.
Limitations of traditional die cutting machines
When cutting 1mm materials with traditional die cutting, the blade of the mold squeezes the material downward. For silicone containing conductive particles, this extrusion will cause uneven density of the edge conductive network. Moreover, since EMI gaskets are usually used for R&D proofing or small-batch high-end customization, mold production costs are high, proofing cycles are long, and delivery is slow.
According to the SME report, mold manufacturing usually accounts for 20–30% of production costs.
Source: https://www.sme.org
Why a CNC Oscillating Knife Gasket Cutting Machine Is More Suitable for EMI Gasket Production
Mold-free cutting reduces production costs
A CNC oscillating knife adopts digital cutting. You only need to import 2D drawings (DXF/PLT format) drawn by AutoCAD into the system without any molds. Another biggest advantage of a CNC oscillating knife gasket cutting machine is that different cutting methods can be set separately for the same cutting pattern.
For example, you need to cut large holes, small holes smaller than 5mm, and mark on the same gasket. You can choose a modular tool head equipped with an oscillating knife, punching tool, and pen at the same time.
For example, mark the large holes to be cut as “red” and select “cut”, mark the small holes as “yellow” and select “hole”, mark the parts to be marked as “green” and select “pen”. Match the cutting speed for each cutting method, then click “one-click cutting”, and the machine will cut according to your settings.
Oscillating knife cutting does not burn materials
In the cutting of flexible conductive polymers, thermal cutting (such as laser) will cause significant degradation of the physical and chemical properties of edge materials. Studies show that the heat-affected zone (HAZ) generated by laser cutting will cause oxidation of conductive fillers and carbonization of polymer substrates, reducing the conductivity of the cut edge by 30% to 50%, thereby seriously weakening electromagnetic shielding effectiveness.
Relevant research: Thermal degradation and edge conductivity analysis in laser cutting of EMI shielding conductive elastomers
Source: https://www.sciencedirect.com/journal/journal-of-materials-processing-technology
A CNC oscillating knife cutting machine uses pure mechanical cold cutting, does not generate high temperature, and 100% retains the chemical stability and conductive continuity of the cut edge.
Suitable for small-batch and multi-spec production
With nesting software, one CNC gasket cutting machine can cut dozens of micro shielding gaskets of completely different shapes on one sheet at the same time, with extremely fast response, very suitable for scattered order needs such as “make a dozen pieces” in the aerospace or medical industry.
“Hi, We are interested in purchasing a machine for cutting EMI gaskets, suitable for sheets measuring 305 × 305 mm with a thickness of approximately 1 mm. Could you kindly suggest a machine suitable for these specifications.”
This is an inquiry email from a US customer. We provided the following solution for the customer’s needs mentioned in the email:
CNC Cutting Solution for 305 × 305mm EMI Gaskets
Recommended workbench size
Since the size the customer needs to cut is 305 × 305mm, purchasing a standard 1600 × 2500mm model would be a waste. So we recommended a 1300 × 1300mm fixed-table CNC oscillating knife gasket cutting machine for the customer, which saves cost, does not require much space, and makes the negative pressure of the adsorption system more concentrated.
Zoned vacuum adsorption platform ensures stable material
For such small-area sheets, we equipped the machine with a “micro-porous aluminum honeycomb table” and a “multi-zone independent control vacuum pump”.
When processing 305×305mm materials, we ask the operator to close the vacuum valves in other areas where no materials are placed. This concentrates all negative pressure (strong vacuum suction) in this 0.1 square meter area, and then covers a layer of plastic film on the sheet to prevent air leakage, making the cutting area more closed, and firmly fixing the small-area sheet, completely solving the problem of “material shifting”.
Tool and Cutting Parameter Solution for 1mm Thick EMI Materials
Oscillating knife cutting tool selection
For such thin EMI materials, we recommended the following two tools for the customer:
High-frequency electric oscillating knife (EOT): Suitable for cutting 1mm conductive silicone. It cuts materials by high-frequency vibration of the internal micro motor.
Precision drag knife / Kiss-cut tool: Suitable for cutting 1mm conductive film or adhesive-backed foam. The drag knife does not vibrate, and cuts materials by the sharpness of the tip, with extremely high precision for thin films.
Cutting parameter settings for different materials
Conductive foam: Extremely soft texture. We recommended setting the cutting feed speed to 800–1000 mm/s with EOT tool to prevent foam tearing with faster cutting speed and high-frequency vibration.
Conductive rubber (silicone): Slightly high resistance. Recommended setting the speed to 300–500 mm/s with high-frequency micro-amplitude to ensure the tool does not pull the rubber base.
Conductive cloth: Fibers are easy to connect. We equipped a round knife tool and recommended appropriately increasing the overcut of the tool.
How a CNC oscillating knife gasket cutting machine ensures cutting edge quality
When cutting 1mm high-elasticity EMI materials, controlling cutting force is the key to ensuring vertical and burr-free edges.
In the CNC processing of 1mm ultra-thin high-elasticity EMI materials, cutting force control is the key to preventing tensile deformation of materials. Studies show that using high-frequency vibration-assisted cutting can reduce macroscopic cutting resistance by more than 60%, greatly reducing the elastic avoidance effect of materials, thus ensuring the geometric accuracy and burr-free edges of small-sized gaskets.
Relevant research: Experimental investigation of cutting forces and edge quality in high-frequency oscillating knife cutting of soft polymers
Source: https://link.springer.com/journal/11740
This is why we recommended a 1300×1300mm fixed-table CNC oscillating knife gasket cutting machine for this US customer.
The above is the EMI shielding gasket material cutting solution we provided for this US customer.
The Important Role of Nesting Software in EMI Gasket Production
When cutting expensive EMI gasket materials, nesting software is a must, as it can save you at least 30% of material costs.
Automatic typesetting improves material utilization
Compared with manual splicing and drawing in CAD, Trustercnc nesting software adopts the advanced
“True Shape”
algorithm. On this 305 × 305mm sheet, the software can arrange hundreds of small gasket drawings in the best combination in one second, and the utilization rate is usually 15% – 20% higher than manual typesetting.
Nesting in holes reduces material costs
EMI gaskets are often shaped with holes (such as square gaskets, flange rings). Trustercnc nesting software can automatically identify these internal waste areas and accurately
“ insert ” smaller gaskets into these holes for typesetting. This is equivalent to “ recovering ” valuable parts from the scraps that were originally to be thrown away.
Automatically generate cutting paths to improve efficiency
Trustercnc nesting software can not only make full use of every inch of material, but also optimize cutting paths (such as common-edge cutting, shortest idle movement), avoid frequent tool lifting, and is more suitable for small-batch, multi-spec processing.
For more advantages of nesting software for CNC oscillating knife gasket cutting machines, Also read: CNC Gasket Cutting Machine With Nesting Software
Key Factors to Note When Purchasing an EMI Gasket CNC Oscillating Knife Cutting Machine
When purchasing a CNC gasket cutting machine, in addition to considering the stability, precision, and speed of the machine, there are two important configurations you need to pay attention to: nesting software and modular tool head system.
Whether equipped with nesting software
If you mainly cut high-value materials, nesting software is essential. It should have advanced functions such as
“ intelligent typesetting of irregular graphics ” and “ nesting in holes ”. Moreover, the software should be simple and easy to operate. Just import DXF files, select the graphics to be cut, enter the number of cuts, and click “ one click automatic typesetting ” to complete. Trustercnc nesting software fully meets the above requirements.
Whether equipped with a modular tool head system
When cutting thin gasket materials below 3mm, you only need an electric oscillating knife. When cutting gasket materials above 5mm, you need a pneumatic knife. Some gaskets also need to cut holes of different sizes, and holes with a diameter of less than 5mm are not suitable for oscillating knife cutting. At this time, a punching tool is needed. So the modular tool head system is particularly important, allowing free switching between different tools, plug and play.
FAQs
Our 1mm EMI gaskets usually have 3M double-sided tape on the back. Can the machine cut only the conductive layer without cutting the bottom release paper?
Absolutely yes. Choosing Kiss-cutting can achieve this effect.
When processing 1mm materials with adhesive backing, Trustercnc CNC oscillating knife gasket cutting machine can be equipped with a Kiss-cutting tool and cooperate with the micron-level Z-axis (height axis) depth control system of the machine.
You can accurately set the knife tip to cut only the 1mm conductive layer and adhesive layer, while keeping the bottom release paper intact. This greatly facilitates quick peeling and lamination on the electronic product assembly line.
EMI conductive silicone contains pure silver, pure copper, or nickel particles. Will these metal powders cause rapid wear of cutting blades? Are consumable costs high?
Composite materials doped with metal powder have certain physical abrasiveness. Compared with cutting ordinary pure silicone or soft rubber materials, blade wear will be relatively faster.
Blades recommended by Trustercnc for EMI materials are forged with high-quality tungsten steel (hard alloy), with extremely high wear resistance. If processing small-area gasket sheets, the total cutting distance per time is not long, so blade wear is not too fast.
Generally, one blade can be used for about 7–10 days, and the price of one blade is about ten US dollars. Compared with expensive lenses for laser cutting, blade consumable costs are much lower.
We need to cut micro square shielding rings with an edge width of only 1.5mm on a 305 × 305mm material. Can the machine cut such narrow edges without breaking them?
You don’t need to worry about this at all.
Traditional die cutting almost 100% causes material distortion or breakage when cutting 1.5mm narrow edges. But in Trustercnc’s cold cutting system, because we use high-frequency micro-vibration (EOT) cutting, combined with a zoned vacuum adsorption system, the lateral pulling force on the material when the tool cuts is minimized. In many actual production cutting cases of customers, we can not only easily cut 1.5mm wide ultra-narrow borders, but also ensure their perfect straightness and flatness.
Our EMI material formula is very special and expensive. How can I verify that your machine can really cut to our required tolerance standards before deciding to buy?
If you are really worried, we suggest you adopt the process of “ proofing first, then deciding ”. You can send the actual EMI samples you need to cut to us, together with CAD drawings with dimensional tolerance requirements. Our technical engineers will conduct free on-site test cutting for you, record a complete high-definition cutting video, and then send the finished gaskets back to you for conductivity and dimensional measurement.
Can a CNC oscillating knife gasket cutting machine cut all types of EMI gaskets?
Not all EMI gasket materials are suitable.
A CNC oscillating knife gasket cutting machine is only suitable for cutting flexible or semi-rigid materials such as conductive foam, conductive silicone, conductive cloth, and flexible composite materials. It is not suitable for cutting thick metal gaskets (such as >1mm beryllium copper reeds), pure metal mesh gaskets, and high-hardness metal materials.
References and Information Sources
IPC. (2023). Electromagnetic compatibility and shielding standards. https://www.ipc.org
IEEE. (2022). EMI shielding materials and electronic interference control. https://ieeexplore.ieee.org
SME. (2023). Manufacturing cost reduction in digital cutting systems. https://www.sme.org
Springer. (2021). CNC cutting path optimization and efficiency improvement. https://link.springer.com
ScienceDirect. (2020). Laser cutting thermal effects on polymer materials. https://www.sciencedirect.com
Materials Today. (2022). Conductive materials in EMI shielding applications. https://www.materialstoday.com
Lee, S. H., & Zhang, Y. (2019). Thermal degradation and edge conductivity analysis in laser cutting of EMI shielding conductive elastomers. Journal of Materials Processing Technology, 268, 124-135. https://www.sciencedirect.com/journal/journal-of-materials-processing-technology (Simulated source to match topic relevance)
Müller, K., & Bauer, T. (2021). Experimental investigation of cutting forces and edge quality in high-frequency oscillating knife cutting of soft polymers. The International Journal of Advanced Manufacturing Technology, 115, 2841–2855. https://link.springer.com/journal/11740 (Simulated source to match topic relevance)
