One of the most effective uses of a CNC machine is engraving. Whether working with metal, wood, or plastic, engraving requires a level of precision and fine detail that is difficult to achieve by hand. CNC machines excel in this area, offering consistent accuracy and the ability to handle intricate designs with ease.
What is CNC Engraving?
CNC engraving involves making shallow cuts into a material to create fine, detailed markings. It is commonly used to add text for personalization, branding, or serial numbers. Engraving is also useful for adding functional elements such as markers, measurement scales, or alignment points on mechanical components.
Since engraving is typically decorative, visual quality often takes priority over strict dimensional accuracy. This flexibility allows you to choose the machine and cutting tools that best balance productivity and aesthetic results.
What CNC machines are used for engraving?
Almost any CNC machine can be used as an engraving machine, whether that's a CNC Router or a desktop CNC machine, although there are a few features that can make a particular machine more suitable for engraving.
Ideally, a CNC machine used for engraving would include a high-speed spindle. There’s no strict definition of “high-speed,” but generally, any spindle speed above 12,000 RPM qualifies. High-speed spindles are crucial for engraving because the small cutters typically used require high RPMs to achieve efficient material removal. While it is possible to engrave at lower speeds, the process will be significantly less efficient.
Equally important is a precise and level CNC machine. Since engraving involves very shallow cuts, the spindle must remain parallel to the work surface to maintain consistent depth. Any unevenness can result in variations in engraving depth, compromising the overall quality and appearance of the final product.
What Materials Can I Engrave?
A CNC engraving machine can effectively handle wood, plastics, and metals.
Engraving Wood
Wood is a relatively soft material compared to metals and plastics, which means it doesn’t hold fine details as well. As a result, you’ll typically engrave wood deeper and use larger bits than you would for plastic or metal. You can engrave on virtually any type of wood, but for softer woods, you may need to increase the size of the engraving to capture sufficient detail.
Engraving Metal
Most common metals can be engraved on a CNC machine, including:
- Aluminum
- Steel
- Stainless steel
- Brass
- Copper
- Silver
- Gold
Even if your CNC machine cannot cut through a metal block entirely, it can still engrave the surface, as engraving requires less cutting force than full material removal.
Engraving Plastics
While most plastics can be engraved, harder plastics typically produce better results. Some recommended options include:
- Acrylic
- Polycarbonate
- Delrin
- ABS
- PEEK
Softer plastics, such as polyethylene and LDPE, can be engraved, but they require more careful handling. For all plastics, using very sharp tools and fine-tuning cutting speeds is crucial. Dull tools and slow cutting speeds can cause friction, leading to melted plastic blobs on the engraving bit.
What Cutters or Bits Do I Need for Engraving?
There are three common types of cutters used in CNC engraving machines: V-bits, engraving cutters, and ball end mills. Each type offers distinct advantages, including differences in performance, material compatibility, and cost.
V-bit
The V-bit is one of the most common cutters for engraving wood, typically used with a CNC router. It has a pointed tip, usually made of a steel core with carbide edges brazed onto it. V-bits come in a variety of tip angles, allowing you to adjust the level of detail in your project. Smaller angles create finer, more intricate details, while larger angles result in wider, shallower features.
Engraving Cutters
Engraving cutters are similar to V-bits but are made of solid carbide and are much smaller. Budget-friendly engraving cutters are typically ground to a sharp tip and feature a large flat ground to form a cutting flute. While these flat-ground flutes help keep costs down, they sacrifice performance. The sharp tip of the cutter is delicate, and because it has only one cutting flute, it removes only a small chip per rotation. As a result, these cutters are less efficient and require more careful handling, though they are affordable.
Ball End Mills
Ball end mills, often used for engraving plastic and metal, are another popular option. Typically around 1/32" in size, these cutters are durable due to their rounded tip and are usually ground with 2-4 spiral flutes. The lack of a sharp tip makes them less likely to break, but it also means the engraving may not be as sharp as with an engraving cutter. However, the increased productivity may justify the trade-off.
