Rotary or Laser: Which Engraving Method is Best

Copyright © 2008 by Davis Multimedia, Int'l. All Rights Reserved.
As Printed in April 2008, Volume 33, No. 10 of The Engravers Journal
  Pewter engraves beautifully using a diamond graver or can be marked with laser using a laser-fusible coating. Photo courtesy of
Gravograph.
 

    Today there are two main types of engraving methods used in the R&I industry-rotary and laser engraving. Sure, there are still some people out there who whip out the old manual pantograph machine now and then, but the bulk of today's engravers use either a computerized rotary or laser engraving machine or, in some cases, a combination of the two.
   Laser engraving has many advantages. It's a "non-contact" marking method so there's little wear and tear on tools, it creates a crisp, clean, permanent mark and, for most applications, it's extremely fast. It's also an excellent method for engraving graphics and photographs. In addition, today's equipment is extremely user-friendly and easy to maintain. And if all that isn't enough, lasers can be used to engrave a huge variety of materials and products, with the list growing almost daily.
   Rotary engraving, which also includes non-rotary diamond drag engraving, has many advantages as well. It can be used to engrave on all kinds of metals-both coated and noncoated, it's capable of making deep cuts into many materials, from plastic to stainless steel, and it creates a beautiful "engraved" look and feel that you can actually feel with your fingertips. You can also use rotary engraving for many specialized applications, from engraving on the inside of a 14K gold ring to creating custom profiled badges with beveled edges. In addition, rotary engraving equipment is typically less expensive than laser machines (although there may be exceptions).
   In each case, the advantages of these two popular marking methods are impressive. Both are capable of engraving a wide range of materials, are well suited for many different applications and can produce stunning personalized and customized products. Consider the charm of an alder wood plaque laser engraved with a wedding invitation and a photograph of the newlyweds or the beauty of a gold bangle bracelet diamond engraved with the recipient's name. Both are dazzling products, but they were created with two distinctively different engraving methods.
   So which of these engraving methods is the best? While some engravers may favor one over the other, the truth of the matter is they both have their place in the Recognition and Identification industry. There are some applications that really require rotary engraving, some that a laser can do better and some where the two methods work in harmony.
   Generally speaking, engravers in the Recognition & Identification industry use either small to mid-sized rotary engraving machines, CO2 lasers in the 25-100 watt range or, increasingly, both types of equipment. Depending on the shop, engravers can be faced with a wide range of jobs, from engraving an acrylic plaque to marking data plates for industrial equipment. Here's a look at some of the most common jobs engravers deal with and how the two engraving methods stack up.
Acrylic
   One of the most popular engraving materials for awards and gifts today is acrylic, a material that looks like glass but is much stronger and lighter. For the most part, laser engraving is considered the most popular engraving method for this type of material because the process is simple, cost-effective, fast, efficient and versatile. Acrylic laser engraves easily, vaporizing instantly with the touch of the laser beam and leaving behind bright white letters. No special tools or techniques are required, and it's nearly an effortless process to engrave fine details in logos and other graphics or very small text into acrylic.
   Of course, a rotary engraving machine can also be used to engrave acrylic products. It just doesn't have the same capabilities in terms of detail, and it's a slower process. One of the advantages to using a rotary system with acrylic, however, is that you can engrave deeper into acrylic and create terrific 3D effects that are not possible with a laser. For example, using a rotating cutter with a 90 degree angle, you can engrave deep V-grooves that beautifully reflect light and provide an interesting multi-dimensional appearance. A rotary cutter also produces smooth cuts in the material, which is essential if you plan to color fill.


Metal notary seals that require precision depth control are easily created with rotary engraving machines. Photo from Xenetech.   Rotary engraving on glass produces exquisite results when deal-ing with straight text and simple logos. Photo from Vision
Engraving Systems.

ADA Signage
   An area that continues to be a profit center for many engravers is interior ADA signage. ADA guidelines for signage are specific and require, among other requirements, that text be raised 1/32" above the sign surface and Braille dots conform to certain regulations regarding the diameter and the distance between the height and shape of the dots. When it comes to creating signage that adheres to these specific guidelines, rotary engraving machines have a distinct advantage over lasers. With a rotary engraving machine, you can easily create raised text using a couple of different techniques. One of the most popular is the "appliqué method" where you apply a 1/32" thick piece of adhesive-backed plastic engraving stock to a substrate blank, cut the characters out of the attached material and remove the excess material to reveal the raised characters.
   Braille characters can also be produced in a couple of different ways using your computerized engraving machine. One method involves routing out a cavity, leaving the raised Braille dots in the recessed area. The second is to use the Raster method that involves drilling holes into the material in dot locations and then inserting plastic or metal Raster balls into the holes.
   The major advantage of using a rotary engraving machine for ADA signage is that you have precise control over the depth and shape of the raised characters and Braille. There are special cutters specifically designed for routing out a recessed area in the sign and leaving the appropriately sized and shaped Braille dots, and for drilling accurately sized holes for Raster Braille. In addition, an inserting tool is available for rotary systems that will automatically insert the raster beads after the holes have been drilled.
   Lasers, on the other hand, have a difficult time with both of the methods used for generating Braille, and you don't have the same amount of control over the engraving depth as you do with a rotary machine. However, Guy Barone of Xenetech Global, Baton Rouge, LA, notes that lasers can do an excellent job when cutting raised characters because the laser cuts only through the appliqué material, not the substrate, and there isn't much cleanup. "Particles from cutting the appliqué get caught by the adhesive when cut out on a rotary system," he explains.
Bar Codes
   A growing application for engravers in the industrial market is the ability to engrave bar codes on nameplates and, in some cases, actual products. There are two basic types of bar codes: 1D bar codes and 2D "Data" matrix bar codes.

Rotary engraving wins by a landslide when it comes to personalizing uncoated metal jewelry and gifts. Photo from Gravograph. Rotary engraving has a distinct advantage over laser in creating raised text and Braille characters for ADA signage. Lasers produce a stunning “burned” in look when engraving text and graphics on wood products. Photo courtesy of Colorado Heirlooms.

   One-dimensional bar codes like the kind you see on product packages consist of parallel lines that provide basic information when read by a bar code scanner. A 2D bar code, also referred to as a Data Matrix, is more sophisticated. It consists of black and white square modules arranged in a rectangular or square pattern. A 2D matrix bar code can provide 100 times more information than a traditional bar code, which is why it's becoming a more prominent option in many different industries. The U.S. Government, for example, uses this type of bar code for its UID (Unique IDentification) marking program, a mandatory program designed to label and track just about every high-value part the government owns, uses, drives or flies. (Visit www.uidmarkinginfo.com to learn more about UID marking.)
   Software is available for both rotary and laser engraving that will convert information into the correct bar code format, although clearly the best method for engraving bar codes is a laser, if only because rotary is slow and necessitates "vectorizing" the bar code. The material being engraved can include just about anything, such as stainless steel, anodized aluminum, black painted brass, different varieties of plastic engraving material, phenolic, etc. Therefore, the engraving method you choose will depend, in a large part, on the material being engraved. In the case of direct part marking (DPM), the size and shape of the product will also dictate whether or not you can engrave it with your equipment.
   All things considered, however, laser engraving is increasingly becoming the preferred choice for bar code engraving, particularly for UID nameplates and DPM. CO2 laser marking is considered an ideal technology for permanently marking parts, tools and equipment because it allows you to engrave small details (2D data matrix codes can be as small as 2 or 3 mm) very quickly on a wide variety of materials while maintaining the appropriate line or cell thickness.
   Rotary engraving bar codes is somewhat more tricky as it involves selecting appropriate cutters and accurate engraving depths to meet the precise line or cell thickness requirements. Rotary engraving is also not well suited for engraving small data matrixes. Despite the fact that rotary engraving is generally a more complicated and slower option for engraving bar codes, there is one area where it outshines laser engraving: marking on uncoated metals. A CO2 laser can only mark metal in which the surface has been treated with a laser-fusible coating prior to engraving. Rotary engravers, however, can engrave all types of machinable metal as well as just about any part that will fit in the machine, including swords, knives, firearms, medical instruments, cell phones, computers and personal electronics.

  Laser engraving on glass can be done easily, but it does produce a much different look than rotary engraving. Photo courtesy of Epilog.  

Glass & Crystal
     Both laser engraving and rotary engraving (not to mention sandcarving) can be used to mark on glass and crystal items such as champagne flutes, vases, wine bottles, ornaments, picture frames, etc., although each method has its pros and cons.
  The process for setting up a job that involves engraving glass on a rotary engraving machine is fairly easy. In fact, most machine manufacturers offer glass engraving kits and certain machine models even have built-in glass engraving capabilities. The rotary process involves using a faceted rotary diamond cutter, an adaptor that allows the cutter to "float" over the glass and a liquid coolant system. Most manufacturers also offer special holding devices for engraving glass items such as wine bottles. One of the biggest advantages of rotary engraving on glass is that it produces exquisite results when the requirement is straight text and simple logos.
     A CO2 laser can also engrave glass. A major bonus of using a laser is simplicity-you don't need any special equipment or accessories (unless you're engraving cylindrical items). Only the laser beam touches the glass so you don't have to worry about clamping items or water cooling as you do with rotary engraving. Many manufacturers also offer roundwork fixtures for engraving cylindrical objects with a laser.
     Laser engraving on glass does produce a markedly different look than rotary engraving, however, and some people consider this a detriment. When marking glass, the CO2 laser microscopically shatters or fractures the surface, which can leave behind very tiny flakes or chips that can cause an uneven appearance. In addition, unlike rotary engraving, you cannot achieve any notable depth. The type of glass being lasered can also affect the end result. Glass that has a high lead content, for instance, produces more heat, which can lead to excessive chipping, flaking and even breaking when subjected to a laser, a problem that does not occur with rotary engraving.
     We mentioned sandcarving earlier as an excellent way to engrave glass and crystal. One popular hybrid technique involves placing a laser engraved stencil on the glass and then sandblasting the item.
Leather, Fabrics & Paper
     When it comes to marking, cutting and perforating leather, fabrics and paper products, laser engraving is the only game in town. You can use a laser to engrave just about any leather or fabric product that will fit in your laser, which opens up a host of interesting possibilities, including leather "appliqués" (that can be sewn on other products such as duffle bags or jackets), checkbook covers, handbags, switch plate covers, belts, dog collars, briefcases, footballs, baseballs, horse saddles and saddlebags, to name a few. Using the vector mode on a laser, you can also efficiently cut leather and fabric into patterns and templates.
     Lasers are also widely used to mark and cut paper products to create greeting cards, stationery, photographs, jigsaw puzzles, mat boards, etc. This is an area that rotary engraving really can’t touch, and the possibilities are only limited by your creativity.
Metal Jewelry & Gifts
     On the other hand, when it comes to personalizing uncoated metal jewelry and engravable gift items, rotary engraving can be considered the winner by a landslide. A major advantage of a rotary system is that it can engrave just about any type of machinable bare metal, including aluminum, brass, stainless steel, silver, gold, pewter, titanium and platinum. It doesn't matter if the metal is coated or uncoated, precious or semi-precious. If it's machinable, it can be engraved with a rotating cutter and even "unmachinable" metals can be engraved using a non-rotating diamond graver.

 

When an extremely light touch is required, like with these cigars, laser engraving is the preferred method ofchoice. Photo from Gravograph.

  Rotary engraving was used to cut and apply graphics to these control panels from Royal Oak Nameplate Co. and Legends for Industry.

   This is one capability that a CO2 laser does not have. While a laser works very well on coated metals, such as anodized aluminum or black brass, producing a mark on bare metal requires the use of a special metal marking chemical (such as CerMark laser fusible coating) that, when lasered, produces a black mark. The results can be quite suitable for many applications, but there is an additional time factor involved since the chemical must be applied, allowed to dry, engraved and then cleaned off. "CerMark is the product of choice for laser engraving uncoated metal, but we are more likely to diamond engrave the piece," says Rex Tubbs, owner of Engraving Connection, Plymouth, MI. Diamond drag is much faster than using CerMark, he says. In addition, Tubbs says, the result of using a laser-fusible coating is a black, "printed" appearance as opposed to the bright, shiny engraved look produced by rotary engraving.
   Another plus on the rotary engraving side is that most of the rotary engraving manufacturers have equipment specifically for jewelry and gift engraving, such as Gravograph, Vision and Xenetech. You can choose from a wide selection of holding accessories, such as jigs designed specifically for engraving pens, watches and bangle bracelets, as well as specialized accessories like roundwork attachments (tankards) or ring attachments (for engraving both the inside and outside of rings).
   Diamond drag engraving is exceptionally well-suited for producing a spectacular look on any type of metal jewelry or engravable gift item. Just a small sampling includes watches, identification bracelets, metal pens, charms, 14K wedding rings, bridal cake knives, tankards, flasks, compacts, luggage tags, etc. "Diamond drag engraving is great for jewelry. I will put a lot of fine jewelry into my machine without destroying it," says Lori Champagne, owner of Champagne Recognition, Carlsbad, CA.
   Not only can you personalize off-the-shelf or customer merchandise with rotary machines, but with some systems you can actually create custom jewelry pieces. For example, you can use a rotary engraving machine to mill name pendants, produce filigrees and create jewelry making molds out of metal-jobs that simply can't be done with a CO2 laser.
Photographs & Graphics
   Thanks to advancements in both software and hardware technology, engraving photographs and graphics onto recognition products is possible with both rotary and laser engraving. When it comes to speed and ease, however, laser engravers definitely have the upper hand.
   Photographs are essentially bitmaps or halftones, i.e. images made up of a series of dots, as are many logos and graphic designs. Because laser engraving is a raster process, these images turn out beautifully with little or no prep work. "The ability to easily engrave many different file types, such as bitmaps or jpegs, adds to the laser application's appeal," says Mike Mennem, Regional Vice President, Western Region, Gravograph, Duluth, GA. "Think of the laser as a printer that does not require vectorization." Rotary engraving is a vector process, so bitmaps need to be converted to vector images in order to be engraved, a process that is possible but more complicated and time-consuming.
   Xenetech's Guy Barone agrees that jobs involving detailed grayscale graphics should be run on a laser. "Lasers can give a good representation of multi-colored clip art while rotary systems cannot effectively reproduce these images," he says.
   "Anytime we have a logo, it’s so much faster and the quality is better when we use a laser rather than a rotary machine," adds Tubbs. "We don’t have to convert the graphics to a vector format as we do with our mechanical engraver. Also, every so often a customer wants a TrueType font, not an engraving font. In this case, we will laser engrave it."
   Lori Champagne adds that her laser allows for a great deal of creativity, even when dealing with simple, inexpensive trophies. For a youth team called the Tasmanian Devils, for example, she went a step beyond engraving two lines of "boring" text on the trophy plates. She incorporated a graphic of the Tasmanian Devil shoving the year into his mouth. "We like to make the plates interesting and fun. You really can’t do that on the rotary machine, not without a lot of effort," Champagne says.
Plastic Signage & Name Badges
   Signage and name badges are a huge market for many engravers, and both marking methods excel in this area. There are plenty of plastic engraving materials designed for both laser and rotary engraving, including a variety of colors, exterior grades and even special effect stocks such as glow-in-the-dark. One thing to note, however, is that rotary engraving systems can engrave into all plastic materials while lasers can only mark on laserable plastics.


 

The contour of this victory cup is easily rotary engraved. Photo courtesy of Xenetech.

Both marking methods excel in the area of signage and name badges, however exterior signage and reverse engravable plastic are best suited to rotary engraving. Photo from JDS. Laser engraving is a popular option for
personalizing marble and other natural
stone materials. Photo courtesy of
Xenetech Global, Inc.

   Tubbs does both rotary and laser engraving in his shop. "Every year we are finding more and more laser engraving plastic," he says. "In fact, all the plastic we buy is laserable because it's just too difficult to keep laserable and nonlaserable plastic separated in the shop. Once in a while we will order a nonlaserable plastic if we need to match a specific color," he adds.
   Both marking methods engrave plastic engraving stock easily and with good results, but there are certain situations where, given the choice, you might choose one method over the other. For example, while there are plenty of colors to choose from in laser engravable plastic, you might have a customer who has existing signs or badges that he wants to match and the color may not be available yet in laser engravable materials.
   Xenetech’s Barone points out that exterior signage and reverse-engravable plastic engraving stocks are best suited to rotary engraving because they have a thicker cap layer (e.g. .010"). In addition, there are certain types of plastic, most notably phenolic and PVC, that are not recommended for laser engraving due to the harmful fumes they emit and their overall laserability, e.g. melting vs. engraving. "Even the most sophisticated ventilation system will not protect the user from the fumes created if certain types of plastic, such as PVC or phenolic, are used in a laser application," warns Mennem. "If you don’t know the composition of the plastic, do not laser it!"
   Tubbs says that as far as name badges go, they are achieving better results with their laser engraving machine. "We just finished an order of badges for a customer who wanted them to be rotary engraved," he says. "Even using a very fine cutter, we can see the slightly rounded corners of the engraved letters." The larger the rotary engraved letter, the more obvious the rounding. (Rounded corners are the result of using a cutter that cuts a circular dot, so when the cutter movement stops and changes direction, such as with the lower left base of the letter "L", you get a small radius there due to the cutter radius. That doesn’t happen with laser engraving.)
   On the other hand, larger jobs on plastic are usually better suited for rotary engraving. For example, a 12" x 24" sign with single-line letters can be engraved in half the time on a rotary machine than on a laser. Using a 1/4" cutter, for example, you only need to make one pass whereas the raster lasering process takes much longer. "Larger plastic signs always run faster as a rotary job," says Tubbs, adding that when the characters are large, the rounding of the corners is rarely an issue.
   When it comes to medium-sized jobs, such as a 2" x 8" or 3" x 10" nameplate, either method will work. "If a logo needs to be engraved, we will laser it," he says. "If it's just lettering, we will rotary engrave it."
Solid Surface Material & Stone
   Solid surface material, a synthetic substrate resembling natural stone, and natural stone products such as marble and granite, are very popular in the R&I industry, particularly for high-end corporate awards, gifts and signage. Adding text and graphics to solid surface material is very easy and really no different than personalizing other types of materials.

 

This poster was created on a laser using IPI’s Laserables line.

  Acrylic can be laser or rotary engraved
with excellent results. Photo from LaserBits, Inc.

   Laser engraving is a very popular option for personalizing solid surface material and natural stone. Solid surface material laser engraves very much like acrylic, and on dark pieces of material such as black marble, laser engraving produces a very attractive white, frosted look. Photographs laser exceptionally well on these materials. For example, you can achieve a black-and-white photograph effect by lasering a halftone onto a light cream or bone colored stone material and then color filling the image with black. Or, for a different effect, you can engrave a "negative" photo on black marble or Corian. It is also very easy to achieve intricate designs and text on marble and granite with a laser.
   Rotary engraving is also a simple and effective way to customize solid surface material and stone products. You can usually use the same cutters and techniques as you do on plastic. While laser engraving typically wins out in this area because of its simplicity and speed, once again, engravers choose rotary engraving when the job calls for deeper cuts than can be achieved with their laser.
Wooden Plaques
   It used to be that a typical award plaque was made by diamond engraving or burnishing a lacquered metal plate and attaching it to a wood plaque board. The look is attractive, but the process is somewhat time-consuming and costly.
   Thanks to lasers, engraving wood plaques now involves simply placing the plaque board in your laser and engraving to produce the finished result. The results are stunning: the "burned in" look of engraved messages, graphics and even photographs is very appealing for many applications. Any type of wood, including wood veneers, can be laser engraved, making this an excellent choice for engraving a variety of products such as boxes, desk accessories, pens and more.
   Wood can be engraved with your rotary engraving machine as well. However, it's more involved (selecting the appropriate cutters, depthing, etc.) and time-consuming, and you typically need to color fill after engraving since the process does not produce the "burned" look that laser engraving does.
   Of course, you can still choose the look of a laser engraved metal plate thanks to the number of different laserable metals. In the shoot-out between laser and rotary engraving, the advantage often goes to laser engraving because of the exceptional case of using all kinds of special fonts, logos and custom graphics, including photos. With rotary engraving, the choice is usually one of a selection of basic engraving fonts and perhaps a custom vectorized logo.
Other Considerations
   Whether or not a rotary machine or a laser is best suited for a particular job can also depend on other considerations, such as appearance. Laser and rotary systems can produce much different looks. Which of these looks is more "attractive" can be subjective, depending on an individual's preferences and the application.
   "Many customers prefer the rotary application on glass because the laser process fractures the glass and produces a rougher texture than a rotary diamond cutter," says Mennem. "On metal, a diamond or rotary tool produces dramatic, faceted subsurface cuts whereas the laser is limited to removing the coated material or, in the case of uncoated metal, first coating the material with a chemical, which results in a dark mark. Most customers prefer the look of rotary engraving on metals." Another advantage to rotary engraving is that you have the option of using special cutters to produce special effects. For example, a rotating burnishing cutter can be used to produce a bold, wide cut.
   Champagne agrees that rotary engraving has the advantage when it comes to appearance, especially when you have a bright cut in metal. "The laser is fast and excellent for engraving detailed graphics, but rotary offers a much more beautiful look. The 'old-fashioned' method just rules in how good it looks," she says.
   Despite her preference for the look of rotary engraving, Champagne notes that a laser is an extremely versatile tool. "There are a million times more things you can put in a laser than you can put on the rotary machine. With a rotary, you are limited to items that lay flat or that can be held with some sort of jig and that you can put pressure on," she says. "With the laser, you could engrave a leaf as long as your air flow wasn't blowing it around. We've carved pumpkins and even put a pie in our laser. I really recommend pushing your laser to the limits and seeing what kind of fun you can have with it."

 

Generally speaking, it’s much faster and easier to engrave 1D and 2D “Data Matrix” bar codes with a laser. Photocourtesy of Horizons, Inc.

  Using the vector mode on a laser, you can easily cut complex patterns like this wooden puzzle from Gravograph.

   When an extremely light touch is required, laser engraving is the preferred method of choice. Consider this: After six years of research, a company called EggFusion, Deerfield, IL, found that a laser was the ideal method for permanently etching freshness dates, traceability coding and marketing messages onto fresh farm eggs. (Could you imagine trying this with a rotary engraver?) According to the company, the etching process only penetrates five percent of the shell and is the only USDA approved process for etching eggs.
   Many engravers are using lasers on other "delicate" items, such as personalizing cigars. In laser engraving, nothing actually touches the item except a laser beam, whereas rotary engraving involves the use of a cutter that is constantly exerting pressure against the material. Probably every rotary engraver user has cracked a glass or two at one time or another.
Combination Jobs
   Many engravers in our industry use both rotary and laser systems in their shops, and many are finding that the two can work in tandem on certain types of jobs with excellent results. For example, consider a wood plaque with an inlaid plate or other insert. A laser can be used to engrave text and graphics, whereas a rotary engraving machine is much more efficient for routing out the area for the insert.
   Another example involves a stainless steel data plate with text and a company logo. Stainless steel is usually rotary engraved, but for this job, you could use a laser fusible coating spray to laser the logo and then rotary engrave the text. This allows engravers to effectively combine the best qualities of rotary engraving (engraving bare metal) with those of laser engraving (engraving graphics).
   You can also use a combination of laser and rotary engraving for jobs involving mixed materials. "Both processes can be used in projects involving two or more substrates," says Mennem. "A laser can easily engrave complex graphics on a nonmetallic surface such as wood or glass, while rotary engraving can be used on a metal plate or insert."
   Both methods can also be used to profile plastic badges, but rotary engraving is faster, it creates a smoother edge finish and it's capable of creating a beveled edge, which is something lasers cannot do. For this reason, some engravers will profile cut out the badge blanks on their rotary system and then drop them into a template on their laser to add the text.
   Barone points out a few other types of jobs where rotary and laser engraving can work together: burnish engraving a border and laser engraving text on a plaque plate; a plaque containing a laser-cut foil logo and a rotary engraved plate; a rotary engraved control panel with laser cut holes.
   So you can see that the answer to the question about "Which method is best?" is far from clear-cut. Both methods have their advantages and that means good things for engravers.
   "Rotary and laser engraving processes are both productive in today's market, and as the technologies improve, the number and scope of applications will continue to increase," says Mennem. "Personalization has expanded from retail applications to a rapidly growing industrial parts marking sector. New markets are opening up every year as laser technology stretches the limits of current applications and rotary engraving solidifies its foundation industry wide."
   In summary, Barone notes that there remains a strong demand for both processes. "Many professional engravers have the production capacity to offer customers both rotary and laser engraving," he says. "Ultimately, engraving shops should have both a rotary and a laser system to meet all of their customers' needs."


 

 

 

 


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