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How to chose a 3D Printer: What job shops need to know

Choosing a plastic 3D printer: questions, considerations, and other additive manufacturing concerns

man operating a 3d printer

Shops considering purchasing a 3D printer have many choices.

So you’ve decided to buy your shop a 3D printer for building plastic prototypes, jigs, fixtures, and other common tools of the trade. Or maybe you want to perform short-run production jobs.

Whatever your reason for getting into 3D printing, the first thing you need to decide is which kind of printer to buy.

If you have attended additive manufacturing (AM)-focused trade shows, read trade magazines, and launched internet searches about the subject, you know you have a quite a few printers from which to choose.

Today there are more than 100 companies selling 200 to 300 styles of 3D printers—and this is only plastic-type models. According to estimates, plastic accounts for 65 to 70 percent of the 3D printing market in the U.S.

3D Printer Price Points

Prices for resin 3D printers range from $400 to more than $200,000. (Metal printers, which is a topic for another day, cost anywhere from $100,000 to $2 million.)

Resin-based 3D printers can be subdivided into the following grades and price ranges:

- Hobbyist ($400 to $2,000).

- Prototyping and low-volume production ($2,000 to $5,000).

- Semiprofessional ($5,000 to $15,000).

- Professional ($15,000 and higher).

3D printing in action

Selecting a plastic 3D printer for a shop should be based on the types parts to be printed, the materials they will be made from, the volume of part runs, and personnel.

Shops generally should avoid the hobbyist grade. Although these printers have advanced greatly in the last few years and can produce parts from a variety of materials, they require a lot of oversight, and the number of acceptable parts they produce remains low.

Many small to medium-size shops benefit from a prototyping-grade 3D printer. If you want to dip your toe in the AM pond and experiment with 3D printing, this is the way to go.

Consider a $2,000 to $5,000 printer that accommodates a variety of materials and provides good surface finishes and good day-to-day reliability. When you’ve set up your new printer, experiment with multiple materials, including composites such as glass-filled nylon, fiberglass, and PEEK, to see how they perform in real-world applications. The relatively low cost of this type of printer will allow machinists, pattern makers, and other shop employees to experiment without breaking the bank.

Also, most of these printers are open source, allowing the use of cheaper materials. FFF (fused filament fabrication) printers—the generic name for Fused Deposition Modeling printers—are the most common type of prototyping machine. Another popular style is the SLA (stereolithography) printer, which imparts an excellent surface finish.

Semiprofessional-grade printers are an extension of the prototyping category and typically cost $5,000 to $15,000. If you have already qualified your parts with 3D printing through a service bureau or with an entry-level printer and are ready for short-run production jobs, you should invest in of these printers. They are reliable printers and typically can run unattended.

However, they also tend to be closed source, can only build parts from a few materials, and are difficult to experiment with.

If you intend to 3D-print high volumes of parts and require them to perform like injection-molded or machined parts, buy a professional-grade printer. But be aware that the technology is moving quickly in this space, and the printer you buy today might be a dinosaur in a few years.

Choosing a 3D Printer to Suit Your Needs

Which is the right plastic 3D printer for your shop? Answering the following questions will be a big step in helping you decide.

1. Are you planning to use your 3D printer for prototyping or short-run production? If you want to experiment with 3D printing for prototyping, you will need to consider surface finish and resolution. SLA printers provide very fine resolution, good details, and excellent surface finish.

The Formlabs Form 2, for example, puts down layers 0.001 to 0.012 inch thick and is equipped with a laser having a spot size of 0.0055 in. It can build parts from 20 different resins, allowing you to select a material that closely matches your prototyping needs.

3D printers in production

Ultimaker offers 3D printers for prototyping and short-run production.

For prototypes that only need to be verified just for form and fit, Ultimaker and MakerBot offer FFF printers that will suffice.

If you want a printer for short production runs, consider a semiprofessional printer. The Ultimaker S5, Stratasys UPrint and F120, and Markforged Mark 2 models are reliable, yield good surface finishes, and accommodate a range of materials for short-run production.

An additional advantage of the Mark 2 is that it can print parts from composite materials, which improve part strength.

2. Will you be printing with traditional plastic materials such as ABS, nylon, or HIPS, or do you plan to try experimental materials like PLA? Sometimes you may want to print a part just to have a feel for its design, iterate your design, and check basic features and fit.

FFF printers that print with traditional materials would not be the best choice.

An FFF printer that runs PLA, a material made from renewable sources, is suitable for such design iterations because it yields excellent surface finishes and geometries. It is much faster to print parts from PLA than from some other materials, and it costs 50 percent less. If you opt for a prototyping printer that prints PLA, you might consider something like the Ultimaker 3 or AirWolf EVO22.

3. What kind of strength is required for the parts you plan to 3D-print? Will they need to perform at a high level, like injection-molded parts? Will they be exposed to high temperatures? Will you be printing composites? If you need to print parts that will replace machined, injection-molded, composite-layup, or other traditionally manufactured parts, you will need to invest in a semiprofessional or professional 3D printer.

Stratasys’ F123 printers can print a vast array of materials, including ABS, PC, and TPU, and the company’s Fortus printers can print carbon-filled nylon. Markforged printers can build parts from glass and carbon-filled plastics.

4. How stringent will the surface-finish requirements of the parts be? How much time, money, and effort can you put toward final-finishing printed parts? Postprocessing is one of the most overlooked aspects of 3D printing. To obtain a surface finish suitable for display parts or a mirror-like finish, you might consider a high-end printer like an HP PolyJet. For prototyping or low-volume jobs where you can spend a few hours polishing parts, an FFF printer would be a good option.

SLA printers offer the best compromise between surface finish and part strength.

5. How long will you printer run? Four hours a day? Eight? 24? Choose a prototyping printer like the Form 2, Ultimaker 3, or MakerBot if you want to print four to eight hours daily. For lights-out production, select a semiprofessional- or professional-grade printer like a Stratasys UPrint, F120, or F240.

Hands assembling 3D printed parts

Being able to quickly and easily produce jigs, fixtures, and other tools is one reason shops buy 3D printers.

Related to run time is run speed. Generally speaking, the faster a 3D printer is the more it costs. Speed also helps in creating parts with higher infill density because the part will have less time to warp while being printed.

6. What kind of printer oversight are you OK with? Do you need the printer to run unattended? Prototyping printers typically require some oversight. SLA printers can run without a lot of supervision. But if you have a mid-level prototyping printer, such as an Ultimaker or MakerBot, you will to need to constantly monitor it. Semiprofessional and professional printers can run without a lot of supervision.

7. What size part will you 3D-print most frequently? Choose a printer with a work envelope that accommodates the middle 50 percent of your part-size range.

Very rarely will you print parts outside this range.

A typical printer has a work envelope of 6 by 6 by 6 in., and a semiprofessional printer often can accommodate parts up to 10 by 10 by 8 in. Most people will not need anything bigger than this.

Asking yourself questions about the types of plastic parts you expect to 3D-print is a good first step in the process of choosing the best machine for your shop. But, as with buying a car, you should “test-drive” various printers to see which one best meets your build, resolution, and finish requirements while fitting your budget.

About the Author

Kuldeep Agarwal

Co-director of the Minnesota Center for Additive Manufacturing Associate

507-389-6157

Kuldeep Agarwal is a Professor in the Department of Automotive and Manufacturing Engineering Technology, Minnesota State University, Mankato.