What Materials Can CNC Machines Cut? And How To Choose The Right One

Choosing the right CNC machine for a given material is crucial for efficiency, safety, and quality results. Each machine type – CNC routers, CNC knife cutters, and CNC plasma cutters – has strengths and limitations with different materials. 

Using an ill-suited machine can lead to poor edge quality, damaged tools, or even safety hazards. By understanding which materials cut best on which machine, buyers and production managers can optimise performance and achieve clean finishes while avoiding costly mistakes. 

The following guide clarifies what materials each CNC machine can (and cannot) cut, and how to select tooling and parameters for the best outcome.

Material Compatibility Overview

To support quick decision-making, Table 1 below lists common materials and which CNC machine(s) can cut them, along with typical cutting methods, recommended tooling, and key considerations for each material.

Wood and Wood-Based Materials

Why routers are ideal for wood

Wood is one of the most commonly routed materials, including hardwoods, softwoods, plywood, MDF, and other composites. CNC routers excel at cutting wood because they provide high-speed spindle power and multi-axis control to carve and profile efficiently. Wood’s relatively low hardness means a router can quickly remove material and create smooth edges. 

Appropriate tooling is important – for example, using up-cut or down-cut spiral bits to minimise tear-out and burning. An up-cut bit clears chips upward, useful for deep cuts, whereas a down-cut bit presses the wood fibres down, protecting the top surface finish (ideal for plywood laminates). 

For laminated boards (like veneered plywood or MDF with melamine), compression bits (which combine up- and down-cut spirals) are often used to get clean edges on both faces. CNC routers also allow varied cutting strategies such as profiling (cutting shapes out), pocketing (hollowing recesses), and even 3D relief carving in wood.

Choosing the right tooling

When cutting wood, operators should adjust spindle speeds and feed rates to the specific timber. Softer woods (pine, cedar) cut easily at higher feed rates, while dense hardwoods may require slower passes to avoid overheating or bit deflection. Proper chip load prevents burning – if a router lingers or spins too fast without moving, wood can scorch. 

Dust extraction is another key consideration: milling wood generates lots of fine dust and chips, so a vacuum or dust shoe attachment is used to maintain visibility and safety. 

Wood is not suitable for CNC plasma or knife cutting. A plasma cutter’s flame would simply set wood on fire, and a knife blade cannot slice through thick or rigid wood. Thus, CNC routers remain the primary choice for virtually all wood-cutting applications, from furniture components and cabinetry to wooden signage and decorative carvings.

Browse our CNC Routers

Wood cutting applications and key considerations

Common applications for CNC routers cutting wood:

• Cabinetry and joinery
• Furniture components
• Architectural panels and decorative features
• Custom woodwork and signage
  

Why wood is CNC-friendly:

• Readily available in both sheet and block form
• Easy to machine compared to metals or composites
• Suitable for both beginners and professional workshops
• Can produce smooth, high-quality edges with minimal sanding when properly set up

READ: The 35 Types of CNC Machining Processes – A Quick Guide

Plastics (Acrylics, Polycarbonate, and More)

Plastics encompass a wide range of polymers, each with unique cutting behaviour. Rigid sheet plastics like acrylic (PMMA), polycarbonate, ABS, and PVC are commonly cut on CNC routers. These materials are softer than metals and machine nicely with sharp carbide tools, but they have a tendency to melt or chip if handled incorrectly. Using the right bit and settings is critical: typically a single-flute or two-flute O-flute end mill is recommended for plastics. This bit geometry helps eject plastic chips quickly to avoid heat buildup. High spindle speeds (e.g. 15,000–20,000 RPM) combined with a moderate feed rate ensure the cutter moves fast enough to throw out chips rather than rub and melt the plastic. 

Additionally, air blast or mist coolant is often used to keep the cut zone cool, especially for materials like acrylic which can soften and fuse to the bit if overheated. By maintaining a constant feed and adequate cooling, CNC routers can produce polished, flame-smooth edges on acrylic and other thermoplastics straight off the machine.

Choosing between routers and knife cutters for thick vs flexible plastics

Plastic comes in varying hardness and thickness. For thick-cast acrylic or polycarbonate sheets (say 10 mm or more), multiple shallow passes are advisable to avoid stressing or melting the material. Conversely, very thin or flexible plastics (such as thin styrene sheets or polypropylene film) can be challenging to rout because they may vibrate or buckle under a spinning tool. 

This is where CNC knife cutters come in. A drag knife or oscillating knife can cleanly slice flexible plastics like vinyl, polyester film, or thin foam board that a router might damage. For example, adhesive sign vinyl – a common plastic film – is ideally cut with a tangential or drag knife for precision. The knife swivels to follow curves, producing crisp results without burring or melting. In fact, many CNC router systems offer optional drag-knife attachments for tackling vinyl or thin plastic jobs that don’t warrant a spinning cutter.

Avoiding common pitfalls: burring, melting and workholding in plastic cutting

When routing plastics, it’s important to consider the material’s tendency to burr or chip. Acrylic is brittle and can chip at the edges if the feed rate is too high; polycarbonate is tougher but more prone to melting. A useful practice is to leave a thin skin at the bottom of plastic sheets (i.e. not cut fully through in the first pass) and then perform a finish pass to release the parts – this supports the plastic and yields cleaner edges. 

Workholding is another consideration: plastics often come with protective film on one or both sides; it’s wise to leave the film on to prevent surface scratches, but be mindful that it doesn’t wrap around the router bit. Clamping or vacuum hold-down should be firm, as plastics expand slightly with heat and can wobble if not secured. 

Plastic cutting applications and best-fit CNC machines

Plastics are found in almost every industry — from signage and display to protective equipment and electronics. Typical applications include:

• Signage and branding – acrylic letters, logos, lightboxes
• POS and retail – product displays, cases, countertop fixtures
• Enclosures and guards – polycarbonate covers, machine guards
• Electronics and prototyping – ABS panels, housings, 3D mock-ups
• Graphics and packaging – vinyl decals, film overlays, foam-core backing

How CNC routers are used:

• Carving and contouring polycarbonate or acrylic
• Drilling and profiling ABS panels
• Achieving polished or near-transparent edges in cast acrylic (using single-flute bits and proper feeds/speeds)
• Browse our CNC Routers

How CNC knife cutters are used:

• Cutting adhesive vinyl graphics and signage overlays
• Trimming polycarbonate films or protective labels
• Shaping thin foam-core boards for packaging and displays
• Browse our CNC knife cutting machines

Metals (Aluminium, Steel, etc.)

Metals present a stark contrast to wood or plastic in terms of hardness and cutting requirements. CNC routers can handle certain metals, primarily softer non-ferrous metals, while CNC plasma cutters are generally preferred for steel and other harder metals. The key is to align the metal’s properties with the machine’s capabilities.

Non-ferrous metals (Aluminium, Brass, Copper)

Many CNC routers (especially industrial or high-rigidity models) are capable of cutting aluminium and similar soft metals. Aluminium is popular in CNC routing because it’s relatively soft for a metal, but it still requires careful settings. When routing aluminium, one should use sharp carbide end mills (often 1 or 2 flutes) and run at lower spindle RPMs than for wood or plastic – usually in the few thousands RPM range, paired with a steady feed rate to maintain a good chip load. Unlike wood, taking too light of a pass on aluminium can be counterproductive: it may cause rubbing instead of cutting, generating heat. Instead, a proper depth of cut and feed will produce chips that carry heat away. 

Lubrication or mist coolant is highly recommended to prevent chips from welding to the cutter. Common practice is to use a light oil mist or specialised aluminum cutting fluid. Chip evacuation (via compressed air blast) is also important; if chips recirculate, they can get rewelded to the workpiece or cutter, ruining the finish. CNC routers cutting aluminium often make multiple passes to penetrate thick material, and the final pass can be a light finishing cut to smooth the edge. Workholding must be very secure (usually metal blanks are clamped or fixtured on the router table) to avoid any movement due to cutting forces. Even within the realm of “soft” metals, feed rates are much slower than for wood – cutting aluminium might be done at a few hundred millimetres per minute feed, versus several thousand mm/min in plywood, depending on the machine and bit.

Despite these precautions, using a router for metal is limited by machine rigidity and spindle power. Hobby-class CNC routers, for example, may handle thin aluminium sheets or PCB engraving, but not thick plate. If pushed beyond its capability (e.g. attempting stainless steel on a light router), the machine can be damaged or produce unusable parts. Steel and other hard metals generally require different technology – that’s where CNC plasma cutting comes in.

Ferrous metals (Steel, Stainless Steel)

CNC plasma cutters are the tool of choice for cutting steels that a router cannot handle. A plasma cutter uses an electrically conductive gas (plasma arc) to melt and blast through metal, enabling it to cut steel of various thicknesses. Plasma cutting is strictly a 2D process – it produces flat profiles from sheet or plate stock. The advantage is that plasma is extremely quick for rough cutting of metal: it can slice through mild steel, stainless steel, or aluminium of substantial thickness, given a powerful enough plasma source. For instance, a 40 Amp CNC plasma may cut up to ~6 mm thick steel, while a 100 Amp system can cut 25 mm or more, with cut speed decreasing as thickness increases. The cut quality from plasma is typically good for fabrication (holes, brackets, frames), though not as fine as laser cutting; edges will have some roughness and a heat-affected zone. On carbon steel, the cut edge gets a thin layer of oxidisation; on stainless, it may show a coloured heat tint. These can be ground or brushed off if needed.

Browse our range of CNC laser cutters here.

Plasma cutter setup

selecting the right nozzle and amperage for the metal thickness, and setting the correct standoff height and cutting speed. Too slow a cut or too low power will result in excessive dross (re-solidified metal on the edge) that needs cleanup. Plasma cutting also produces intense light, noise, and metal fumes – for example, cutting galvanised or zinc-coated steel releases toxic zinc fumes, so those materials are approached with caution (often avoided or thoroughly ventilated). 

Safety is paramount: operators use eye and ear protection and ensure there are no combustible materials nearby (the sparks can fly and cause fire if, say, wood dust or flammable vapours are present). Unlike routers, plasma cutters cannot easily do fine detail or holes smaller than a certain diameter (usually about the thickness of the plate as a rule of thumb), due to the kerf width of the plasma arc. Nevertheless, for most heavy fabrication tasks, plasma is an economical and fast way to cut steel parts that would be impractical to mill on a router.

Metals require matching with the proper CNC method. Use CNC routers for softer metals and precision milling of aluminium or brass parts – for instance, aluminium aerospace components, custom enclosures, or brass plaques can be router-cut with great accuracy.

Turn to CNC plasma for ferrous metals and thicker plate where precision edges are less critical than cutting through the material in good time – such as making steel brackets, frames, base plates, or artistic metal signs. By doing so, manufacturers ensure both the machine and material are used to their fullest potential without undue wear or risk. (For extremely hard or thick metals beyond plasma capabilities, waterjet cutting or CNC milling centers would be considered, but those are outside the scope of this comparison.)

Foams and Soft Materials

Foams are lightweight, porous materials used in packaging, signage, insulation, and modeling. They come in various forms – from rigid structural foams to soft sponges – and CNC machines can cut many of them very effectively. Both CNC routers and CNC knife cutters are commonly used for foams, depending on the foam type and desired outcome.

Rigid Foams (Polyurethane, Polystyrene, etc.)

High-density urethane (HDU) foam, expanded polystyrene (EPS foam board), and similar rigid foams are often cut on CNC routers. These foams can be block-carved to create 3D shapes (for instance, signs or prototypes that will be coated later). A CNC router handles foam with ease because of the foam’s low density – large depths of cut and fast feed rates are possible. In fact, one must be careful not to apply too much speed, which can tear the foam or cause chatter. 

Using an end mill or special foam-cutting bit (usually a long, straight-flute or spiral bit with aggressive chip removal geometry) allows for deep plunges. For example, cutting a 100 mm thick EPS foam panel into lettering can be done in a single pass with an extra-long bit. The downside of routing foam is the mess: it produces a lot of static-charged dust or small beads (in the case of EPS) that cling to everything. Good dust extraction or even a mist of anti-static spray can help manage this. 

The finish on routed foam is generally good – edges tend to be a bit fuzzy on softer foams, but sharp tools minimize this. One can also make multiple finishing passes for a smoother cut if needed.

Soft and Flexible Foams

For very flexible or spongy foams (like packing foam, EPE foam, EVA foam, foam rubber sheets), a CNC oscillating knife cutter is usually the better choice. These digital cutters use a reciprocating blade that saws through the foam without dragging. If one tried to cut a soft foam sheet with a spinning router bit, the foam might just rip or compress without cutting cleanly. An oscillating knife cleanly slices through by rapidly moving up and down. 

Industrial knife cutting tables are used to cut custom foam inserts for packaging – for example, a CNC knife machine can precisely cut slots and cavities in polyethylene foam to cradle products. Even comparatively hard closed-cell foams (like EVA gym mat material) can be knife-cut if the machine is equipped with a sufficiently strong oscillating blade. The thickness is limited by the blade length and stiffness; foams up to around 50 mm thick are commonly cut with oscillating knives in industry, but beyond that, multiple passes or flipping the material might be required.

One particular foam product, foamcore board (paper-faced foam used for displays and models), illustrates the division of labour: it can be cut on a router, but the paper facing will tear and the foam may melt from friction; instead, a knife (preferably oscillating) gives a crisp cut without delamination. Similarly, soft foam sheets (like memory foam or sponge) would bunch up under a router bit, whereas a knife slices them smoothly. To ensure quality, these soft materials must be fixtured securely on the table – often a vacuum bed is used, or the foam may be lightly glued to a sacrificial board during cutting, to prevent any shifting when the knife blade oscillates through.

READ: How Can CNC Machining Increase Production Efficiency?

Foam cutting applications and machine selection

Routers excel at cutting rigid foams and modelling materials, particularly for 3D applications:

• HDU foam signs – popular in the signage industry for its wood-like cutting properties without grain tear-out
• Prototypes and moulds – especially in automotive and aerospace (e.g. clay or foam vehicle forms, positive plugs for fibreglass layups)
• Sculptural forms – routers can handle large block material with deep passes and complex toolpaths
  

What CNC knife cutters are used for

Knife cutters are ideal for sheet-based, soft foams where distortion or compression is a risk:

• Custom foam inserts – tool trays, packaging, protective cases
• Furniture and upholstery – cutting foam batting and pattern templates
• Textiles and garment production – precision foam parts or interfacing materials

Browse our range of CNC knife cutters.

Composites (Carbon Fibre, Fibreglass, etc.)

What are composites and why are they challenging to cut?

Composite materials are engineered by combining different base materials to achieve specific properties – for instance, carbon fibre reinforced plastic (CFRP) and glass fibre reinforced plastic (fibreglass/GRP) are composites with high strength-to-weight ratios. These materials present unique challenges: they are often tough and abrasive, and can be hazardous to cut without precautions. CNC routers are typically used for cutting cured composite sheets or panels, while CNC knife cutters might be used for some pre-preg fabrics or uncured layers. Plasma cutting is not applicable since composites are not metal (plasma can’t effectively cut them, and would burn the resin).

Tooling and safety considerations when routing solid composite laminates

Cutting cured composites like carbon fibre or fibreglass requires the right bit selection due to their extreme abrasiveness.

• Avoid: Standard high-speed steel (HSS) tooling – it will dull almost immediately
• Recommended:
  • Carbide bits for short-run jobs
  • Polycrystalline diamond (PCD) tooling for extended durability and production use
    

Even with the right tooling, expect accelerated wear — carbide bits may dull after just a few metres of cutting carbon fibre.

Dust and debris hazards:
Composites don’t produce chips – they produce fine, airborne fibres, which pose serious health and operational risks:

• Health risks: Dust is hazardous to breathe, similar to silica or asbestos
• Electrical risks: Carbon fibre dust is conductive and can short out electronics if not contained
  

Essential precautions:

• Use high-efficiency dust extraction systems
• Fit a vacuum shoe around the bit to capture debris at source
• Enclose the cutting area if possible
• Ensure all operators wear PPE, including respiratory protection

Optimising cut quality: feeds, speeds, and finishing techniques for composites

Machining parameters for composites are generally on the conservative side. High spindle speeds can overheat the resin matrix and cause delamination or burning, so a moderate speed paired with a steady feed rate works best. Shallow depth per pass is used for thick laminates to avoid fraying the edges. 

Often, down-cut router bits are chosen for composites to minimize the fraying on the top surface of a laminate, or special “compression” style composite bits that press the layers together as they cut. 

The finish edge on composites might not be as perfectly smooth as on metal or plastic – some fuzz or fibre breakout can occur – so additional sanding or sealing might be required if a perfect edge is needed. One trick for drilling or cutting composites is to use backing materials (sacrificial layers) to support the fibres and reduce splintering as the tool breaks through.

READ: The Ultimate Guide to Designing for CNC Routers: From Software to 3D Models

CNC knife cutters in composite layup and pre-preg preparation

While CNC routers handle the final cured composite parts, CNC knife cutters play a role earlier in the manufacturing process. In aerospace and auto industries, large flatbed cutters with rotary blades or specialty knives are used to cut shapes out of carbon fibre fabric or prepreg sheets (fibre cloth pre-impregnated with resin) before they are layered and cured. For instance, cutting a carbon fibre weave cloth is feasible with a very sharp rotary blade tool, which essentially presses and cuts the fibres without pulling. Drag knives would dull quickly on such materials, so wheel cutters or ultrasonic blades might be employed.

Real-world applications and routing considerations for composites

Composites are common in high-performance, weight-sensitive industries, including:

• Aerospace – structural components, ducts, panels
• Automotive – bodywork, brackets, interior panels
• Sporting goods – surfboards, bicycles, racquets
• Electronics – fibreglass circuit boards, housings
• Construction – phenolic panels, ACM cladding

How CNC routers are used with composites:

• Routers are well suited for:
• Trimming cured carbon fibre moulded parts
• Cutting precision openings in fibreglass sheets
• Profiling and slotting multilayer panels (e.g. phenolic board, ACM)

Other Materials (Rubber, Textiles, etc.)

If a material can be cut with a handheld utility knife, a CNC knife cutter (drag, oscillating or rotary) can likely cut it. Knife cutters are ideal for soft, flexible, and sheet-based materials.

Rubber and gasket materials:

• Use oscillating knives for clean, accurate cuts through rubber sheets, neoprene, foam rubber, cork and gasket materials.
• Thick or tough rubber (>10 mm) may require multiple passes or alternative methods like waterjet or die cutting.
• Effective material hold-down (via vacuum or adhesives) is essential to prevent slippage during cutting.
  

Textiles and leather:

• CNC knife cutters are standard for fabrics, technical textiles, and leather in sectors like apparel, upholstery and automotive.
• Use rotary blades or tangential knives for cloth; oscillating knives for tougher materials like leather.
• Vacuum beds and sacrificial layers help maintain material stability, especially for delicate or stretchy fabrics.
• Knife cutting avoids edge charring, unlike laser cutters – ideal for natural and synthetic textiles.
  

Paper, card, and similar materials:

• Easily cut with drag knives or oscillating cutters. Common applications include labels, packaging, and custom boxes.
• Use vacuum hold-down or sticky mats to keep lightweight materials stable
• Routers can handle thick or dense paper products (e.g. MDF), but knife cutters are cleaner and dust-free for single-ply sheets.
• Tangential wheel cutters are available for tough fibrous sheets like Kevlar or glass cloth.
  

For these “other” flexible or soft materials, the CNC digital knife cutter is the hero. It enables automated, precise cutting where manual methods or other CNC machines fall short. 

Materials to avoid with each CNC machine

Every CNC machine type has its limits — materials it simply shouldn’t be used on, either for performance reasons or safety. Below is a breakdown of what not to cut with each machine type, and why.

CNC routers are not suitable for:

• Hardened steels and titanium – These materials are too hard for routers. Attempting to cut them will quickly wear out tooling and can damage the spindle or lead screws. These metals require CNC milling centres or specialised equipment.
• Glass, ceramics, and stone – Extremely hard and brittle. Cutting them requires water-cooled diamond tooling, typically used on waterjets or CNC bridge saws.
• Soft, fibrous materials – Fabrics, carpet or insulation can wrap around spinning bits, causing jams or safety hazards. Use a knife cutter or laser instead.
• Thin films or vinyl – Can technically be routed, but with poor quality and low efficiency. Knife cutters are far more suitable.
• Hazardous materials – Avoid cutting composites like fibreglass or carbon fibre without full dust extraction. Never cut anything containing asbestos.
  

Stick to woods, plastics, and softer metals. Avoid overly hard, brittle, soft, or hazardous materials unless you have the correct tooling, extraction and safety measures. Browse our range of CNC routers here.

CNC knife cutters – what not to cut

CNC knife cutters are excellent for flexible, sheet-based materials, but not for:

• Metals – Except very thin foil, knife blades will dull or snap on any metal. These materials lack the shear properties needed for knife cutting.
• Thick plastics or wood – Knives can’t cut through solid polycarbonate, acrylic blocks, or timber.
• Very dense or thick rubber – May deflect the blade rather than cut cleanly. Waterjet or high-power oscillating blades may be needed.
• Resin-hardened composites – Cured carbon fibre, fibreglass or layered laminates must be routed or waterjet-cut. Knives cannot handle their rigidity.
  

If you can’t cut it cleanly with a hand knife, you likely can’t cut it on a CNC knife. Stick to soft, sheet-based materials with paper- or cloth-like consistency. Browse our range of CNC routers here.

CNC plasma cutters – what not to cut

Plasma cutters are only for electrically conductive metals. Avoid:

• Non-metals – Wood, plastic, rubber, glass, or concrete will burn, melt or release toxic fumes under a plasma arc.
• Galvanised steel – Can be cut, but releases hazardous zinc fumes. Requires excellent ventilation.
• Thin foil – Plasma may blow away or warp lightweight metal sheets.
• Composite materials – Sandwich panels (e.g. metal-plastic-metal) will burn internally and cut unevenly.
• Flammable or explosive items – Never cut containers that have held flammable fluids, even if “empty”.
• Reactive metals – Magnesium and (in some conditions) titanium can combust when plasma-cut. Use specialist equipment if cutting is essential.
  

Plasma = metals only. Avoid coated, layered, highly flammable, or non-conductive materials. Browse our range of CNC routers here.

So…

Matching the material to the appropriate CNC cutter type is a critical step in production planning. By doing so, you ensure optimal results – clean cuts, efficient cycle times, and safe operation. Industrial customers should leverage this knowledge to make informed decisions or reach out to CNC specialists to discuss the best machine setups for their unique material portfolio. With the right machine and material pairing, your shop will achieve higher quality and productivity, and you’ll extend the lifespan of your tools. 

Feel free to contact our team for a detailed consultation on CNC machine selection and cutting parameters tailored to your materials – ensuring you get the most out of your CNC investment.

READ: A Comprehensive Commercial CNC Router Buying Guide