For custom metal fab shops, a reliable cutting machine is a must. And when your shop’s future is on the line, your success can ultimately ride on making the right investment in your machinery. In today’s blog, we’re going to be comparing 2 popular cutting machines for sheet metal: CNC routers, and CNC fiber laser cutting machines.
Form & Depth of Cut
A CNC router allows operators to carve into a material bit by bit, not unlike a CNC mill. Generally, this subtractive manufacturing method is used with materials like wood, foam, and polymers. With metal sheets, it’s much more common for a CNC router to be used to cut plain blanks with very few additional features, if any. If a design does call for depth-of-cut features on a metal part, a CNC milling machine is likely a more efficient tool for the job. In addition to cutting and carving, CNC routers can also be used to engrave a workpiece either for aesthetic purposes or for traceability.
The depth of cut on a fiber laser machine cannot be controlled the same way as on a router. Where a routing machine has controls in the X, Y, and Z axes (with the Z axis to a lesser extent than the others) a sheet laser cutting machine primarily moves in the X and Y axes. The Z axis position is only used to determine the laser’s focus, with many modern machines utilizing an auto focus feature. The laser either cuts all the way though the material, or just etches the surface when it’s used for engraving rather than cutting. If you’re planning on cutting blanks from sheets or plates of material, a fiber laser can cleanly and quickly cut through stainless steel plates up to 3” (or 7.26cm) thick. However, if you plan on adding features that don’t go all the way through the workpiece like blind holes, it may be better to explore other CNC options like routing or machining.
Want to see how a fiber laser handles your part? Contact Universal Tool & Engineering for a part sample made with one of our sheet fiber CNC laser cutting machines.
Securing The Workpiece
CNC sheet lasers don’t make any mechanical contact with the workpiece, so there is no need to secure the sheet in place for the cutting process. Typically, the sheet is simply placed on a metal grid or rack that is built into the laser cutting machine’s table to help dissipate heat away from the final piece. This makes setup for a given job relatively quick to complete.
CNC routers, on the other hand, can call for some creative fastening methods. Unlike laser cutting machines, the router’s end mill does make physical contact with the sheet, so there is a significant chance of movement; and unlike a mill, there’s no vise in which to secure the piece. When using a router, the sheet material is typically screwed into boards that are part of the router’s table for a temporary hold while the cut is made. Some operators utilize adhesives to keep a piece in place, but this involves waiting for the glue to cure before machining and can add hours to the process. Whichever fastening method you choose, securing a workpiece to use with a CNC router is much more involved and time-consuming compared to the laser cutting machine’s simple setup.
Cutting Speed & Part Quantity
CNC routers’ travel speed typically caps out at around 200”/min (508cm/min), depending on the machine at hand and the material being cut. For low volume operations and prototyping, this can be plenty fast. Routers can also produce multiple parts at once, with larger bed sizes providing more room for a larger quantity. These higher quantity jobs do take more time, especially when cutting sheet metal.
Fiber lasers, on the other hand, can cut thin sheets of metals like aluminum and steel at a top speed of over 4,000”/min (10,160cm/min)—20 times faster than a router’s top speed. With a comparable bed size, a sheet fiber laser has a router completely beat in terms of time. If high throughput is something you’re worried about, then a laser is the obvious choice.
Edge Finish
Depending on the material you’re working with and the machine you choose, the type of secondary finishing you’ll need to achieve a clean edge can vary greatly.
CNC routers are capable of producing clean edges with the right programming, though this often requires multiple passes. Whether working with metals or nonmetals, many operations will require a series of rough cuts and finishing cuts in order to achieve the desired edge quality.
When working with sheet metal, a CNC laser cutting machine can achieve a very clean edge in one pass. Laser cut parts rarely require secondary finishing.
Dimensional Accuracy
Because a CNC router can utilize such a variety of cutting tools, it’s difficult to say just how accurate its cuts can be. Other factors like feed rate and tool RPM can also influence how feasible it is to stay within a given tolerance. It may also be difficult to create features like sharp inner corners, depending on the diameter of the cutting tool that is selected for the job.
Fiber laser cutting machines are incredibly accurate across the board, with the laser’s positional accuracy falling in the range of ±0.03mm (or 0.001”). One thing that may need to be taken into account depending on your tolerances is kerf, or the diameter of the focused laser beam. The laser’s tool path may need to be adjusted to compensate for the size of the kerf.
Compatible Materials
CNC routing is often associated with nonmetals such as wood and composites, but industrial grade routers can also be used to cut through soft metals like aluminum, brass, and some grades of steel. If you’re primarily looking to work with these families of materials, a CNC router may be a way to go.
If you’d like to cut all of those materials and harder metals, a fiber laser machine is the clear winner. While both tools are compatible with a wide range of materials, a fiber laser cutter has the advantage in its ability to cut through stainless steel plates up to 3” (or 7.26cm) thick. A cut to that depth on a material of that hardness simply isn’t possible with a CNC router. Fiber laser cutters can also cut other hard metals like titanium and nickel alloys, making them an excellent choice for fabricating parts for high-demand applications. Fiber lasers also hold an advantage over CO₂ laser cutting machines, which struggle to cut highly reflective metals like aluminum and titanium.
It’s also important to consider how the material you intend to cut will interact with the machine, and how the material’s behavior can negatively impact safety. For example, some materials may be safe to cut with a laser, but could generate hazardous dust when cut with the mechanical process of a CNC router. Conversely, another material that may be safe to use on the router could generate noxious or toxic fumes when exposed to the high heat of a laser cutter. Understand your material and machinery well, and always take the necessary precautions to protect operator safety and health.
For more on materials, check out our blog on the Best and Worst Metals for Laser Cutting.
Operating Costs
While a CNC router may have a lower price tag than a CNC laser cutting machine, it’s important to remember that a router requires consumables like end mills and other cutting tools in order to function. CNC routers can often take many passes to cut through metal sheets and plates, and they typically do so without coolant—meaning that you’re going to burn through a lot of tools over the machine’s lifetime. Along with tooling costs, CNC routers also require regular machine maintenance. Generally the bigger the machine is, the more involved the maintenance process will be. This also increases with the addition of accessories like vacuum tables, which require a vacuum pump that will need to be regularly serviced.
While lasers have historically been associated with high operating costs, fiber laser cutters offer massive energy savings compared to CO₂ lasers. Combined with the fact that fiber CNC laser cutting machines operate with very little consumables at a much higher rate than routers can achieve, a sheet laser machine will provide a much faster ROI with much less downtime spent on things like maintenance and tool changeover.
Frequently Asked Questions
1. What’s the main difference between CNC laser cutting and CNC routing?
CNC laser cutting uses a focused laser beam to cut through metal sheets quickly and precisely, while CNC routing uses a physical cutting tool to carve material. Lasers are faster and more accurate, while routers are better suited for soft materials and detailed carving.
2. Can a CNC laser cutter create features like blind holes or engravings?
Laser cutters can engrave the surface of a material but cannot create true blind holes. The laser either cuts completely through or marks the surface. For deeper, partial-depth features, a CNC router or milling machine is a better choice.
3. Which machine provides better edge quality and accuracy?
CNC fiber laser cutters produce clean, burr-free edges in a single pass with positional accuracy around ±0.03 mm (0.001”). CNC routers often require multiple passes and may need secondary finishing to achieve similar edge quality.
4. Which option is more cost-effective in the long run?
While routers are cheaper upfront, they require consumables like cutting tools and more frequent maintenance. CNC fiber laser cutters have higher initial costs but lower operating expenses, faster production, and fewer consumables, leading to a quicker return on investment.