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ResourcesBlogWhat is Rotary Engraving?
Rotary engraving on a crystal.  Image Credit: Monika Wisniewska/Shutterstock.com

What is Rotary Engraving?

Our guide to rotary engraving, equipment, and applications.

Xomety X
By Team Xometry
 7 min read
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Rotary engraving is the engraving method of rotating a cutting tool in a motorized spindle that moves through a substrate to create a groove at a specific depth and in the same geometry and width as the cutter tip. It is often used on flexible plastic stock to make name badges, key tags, architectural signage, and awards. It can also be used with brass, acrylic, and aluminum when deep cuts are required.

Rotary engraving can be performed using the least expensive pantographs to the most complex computerized engraving and routing systems. However, the principles are the same with each rotary engraving machine. In manual engraving, the worker lowers the cutter into the material's surface. Then, the worker “traces” the copy type or letter master and reproduces the image on the substrate. In computerized engraving, the z-axis is controlled mechanically by the systems stepper motors and the x and y-axis to form the characters.

The Rotary Engraving Process

Mechanical engraving was the standard until laser engraving was developed commercially. Rotary engraving involves physically removing material with a drill. The drill has a motorized spinning cutter that can engrave through the surface of almost any material.

The technique was initially done by hand, but now, in addition to manual engraving machines, software-assisted engraving machines can repeatedly produce this technique’s extraordinary detail and precision. In addition, it can deliver deeply etched, tamper-free characters and durable and aesthetic designs. Rotating carbide engraving is the most popular technique for engraving plastics and metal at depth. Rotating carbide-tipped cutters can spin to create greater depth and a wider tool path, two crucial characteristics when painting filling letters on materials.

Diamond drag engraving typically involves a non-rotating diamond-tipped bit that glides on the surface of the engraving material. This engraving style doesn’t create deep engraving cuts and often does not produce a very wide tool mark. Diamond drag engravers are typically applied to metal surfaces, create little dust, and operate faster. Some materials can be darkened with a marking compound to achieve a blackened engraving area. Diamond dragging is very popular with jewelry applications, industrial data tags, or serial plates.

Rotary Engraving Equipment and Engraving Cutters

Rotary or mechanical engraving predates the commercial development of laser engraving. The process involves physically removing material with an engraving drill. The drill has a motorized spinning cutter that can engrave through the surface of almost any material.

Rotary engraving was initially done by hand, but now there are software-assisted machines. With computerized machines, vector software designs the image and sends it to the machine, translating the vector data along X and Y axes to cut the design. A good software package allows rotary engravers to quickly and easily create text, graphics, and even photographs. Most engraving machine manufacturers provide their proprietary software, either as an option or bundled with their engraving accessories. In addition, some third-party software developers offer engraving-specific programs. These packages are custom-built to drive engraving machines, making communication between the software and the table exceptionally smooth.

A vacuum system is needed if engraving acrylic or a flexible plastic engraving stock. It keeps the engraving system clean and controls the depth of cut. If a vacuum system is not used, the depth of cut may change each time the cutter moves up and down. The reason for this variation is because the spindle nosecone may get plastic chips lodged between it and the material surface, causing the depth of cut to be uneven and the machine not to work correctly. The loose chips can also scratch the material's surface when caught between the nosecone and the material and dragged across the surface.

A burnishing cutter is a rotating cutter with a multi-faceted tip. These cutters are used with a burnishing adaptor, a spring-loaded mechanism that fits atop the cutter and lets it "float" across the material surface. Burnishing entails skimming away the top lacquered surface of the material and only a small bit of the base metal. Burnishing tools are wider and are available in various tip sizes as with traditional engraving cutters. One of the benefits of burnishing is that it is speedy while allowing very simple single-stroke fonts to be used while still getting a wide cut by using a wide-tipped cutter.

Rotary Engraving Applications

Rotary engraving can be used to engrave items in a wide range of different materials, including a variety of plastics, acrylic, glass, wood, ceramic, stone, and solid surface material. A diamond drag engraver can also work any type of machinable bare metal, including aluminum, brass, silver, gold, machinable grade stainless steel, titanium, and platinum. Rotary engraving is used to personalize metal products, including watches, identification bracelets, metal pens, die struck medals, 14K wedding rings, charms, bridal cake knives, brass or aluminum plates, etc. Diamond drag engraving will work on precious and semi-precious metals, stainless steel, brass, and pewter.

Other products that can be engraved include trophy plates, plaque plates, corporate gifts, and acrylic awards. While laser engraving works great for most award products, they are not always suitable for many traditional engravable gift items, such as engraving jewelry and metal products like tankards, flasks, compacts, and boxes. With ADA signage, rotary engraving holds the advantage because it's easier to create the required raised lettering and Braille dots. Rotary machines can create letter cutouts and then switch the cutter, drill Braille holes, and place the Raster Braille beads directly into the holes, which is something you really can't do with a laser.

A large market for engraving is the industrial sector. It is excellent for machine tags, legend plates, and permanent marking on fixtures and equipment. Rotary and laser engraving also produce different "looks." In many cases, customers want the look of a rotary engraver. This is because this process engraves into the material, instead of marking or burning it, producing noticeable depth, a characteristic that is often desirable for appearance and permanence. One of the desired attributes of engraving is its "look." Fonts that are ornate and stylized, can be used, and many manufacturers offer unique type fonts for initialing and monogramming, as well as decorative fonts such as scripts.

Rotary vs. Laser Engraving

The benefits of a rotary engraving job are that the marks won't fade, it works on virtually any material, and it can require only a single manufacturing operation. The disadvantages are that the corners will all have a slight curve equivalent to the bit's radius, fine lines must be cut slowly, large areas will often show a hatching pattern, and it requires coated or multi-layer material for the best contrast.

Laser engraving works by either ablating the surface away, vaporizing its top layers, or heating the surface to change the color. Its benefits are the sharp corners and fine lines created, the quick marking times, and the ability for large areas can be hatched without an obvious pattern. The disadvantages are that filling large areas can be less efficient than with the rotary process. The technique also requires a second operation after milling, increasing production time and cost, and there are some limitations to material size.

Review our guide to laser engraving to learn more about the process and how laser engraving differs from laser etching.

Summary

This guide provided a review of the basics of rotary engraving. Review our guide on the types of engraving to learn more about other engraving machines and techniques. More information about part marking is available in our ultimate guide to direct part marking.

Xometry can provide quotes for engraving services as part of our custom manufacturing on demand. Contact us to request a quote or to learn more about our capabilities.

Disclaimer:

The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.

Sources:

  1. A Basic Guide to Rotary Engraving - SignWarehouse Sign College
  2. Engraving Techniques: Laser vs. Rotary Engraving
  3. The Buzz About Rotary Engraving
Xomety X
Team Xometry
This article was written by various Xometry contributors. Xometry is a leading resource on manufacturing with CNC machining, sheet metal fabrication, 3D printing, injection molding, urethane casting, and more.