Milling, Laser and Plasma Cutting
Cut, shaped and polished metal signs carry a high-end caché and pay well, but not many signshops are equipped for this market. So, if you want to get into this niche and thereby find yourself needing to work with metals, what do you do? Hand tools only work with soft and very thin metals with the end results imprecise. If you need to fabricate signs from metal often, several technologies can make the job as easy as cutting vinyl with a plotter.
The first question you need to ask yourself is what materials you want to work with. Consider media thicknesses and how hard they are (e.g., steel vs. brass). Next you need to look at working sizes. Will a square foot do or will you need to handle something like 4 x 8-ft. sheets? Finally, analyze how precise you need the cuts – with extremely high tolerance required for parts and close-up viewing, or will your metal signs be viewed at a distance?
If you demand high-precision 3D parts for signs, then you will want to look at milling machines. Similar to CNC routers, these devices can add rotary attachments to mill cylindrical blanks. Desktop models can handle media up to 19 x 15 x 6 in. The machines mill wood, plastics, foams and nonferrous metals. You can make precise parts, molds and relief signs with these machines. The downside is speed. Do not expect to have an assembly line cranking out parts, although auto-tool changers do make it a set-and-forget process.
If you need to work with large sheets of material and virtually any type of metal, then you have a few choices. Typically the lowest-priced option is the plasma cutter, which uses a combination of compressed air and an inert gas to create a conductive, ionized gas that can cut metal. The key word here is metal. A plasma cutter does not cut other materials, so if you were thinking about using it as a general purpose machine, you’re out of luck. It does has some advantages, though. For one, it will cut virtually any metal, including reflective material that lasers may not be able to handle. Large and thick sheets of metal are also generally no problem. Plasma cutters run more slowly than lasers (800 in./sec. for entry-level machines), but that’s the tradeoff.
Finally, consider lasers, which come in a wide variety of shapes and power consumption, so you need to know what you’re looking for. First, you will encounter two different types of laser, CO₂and fiber. The CO₂can handle thicker material, offers more precision and in general, faster cutting speeds. However, fiber lasers are usually easier to maintain, will work better than CO₂on thin metals and handle reflective metal surfaces better. Higher-wattage lasers of either type will cut thicker material. The other big benefit of the laser cutter is that it can handle a wide variety of materials, including wood and plastics. You can also put these machines to work as engravers.
So, depending on your intended markets, the materials you plan to handle and whether or not you want to offer 3D parts for signs, your options are many.
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