"3Dprinting" is a monthly column authored by Terry Wohlers for Time-Compression Technologies
This column was published in the November/December 2005 issue. 



Factors to Consider When Choosing a 3D Printer
With shipments of 3D printers nearly doubling over the past year, interest in acquiring 3D printing technology has increased dramatically.

By Terry Wohlers

According to the Wohlers Report 2005, estimated sales of 3D printers by the leading manufacturers jumped from $37.4 million in 2003 to $74.6 million in 2004, an increase of 99.5 percent. Product development organizations are not only acquiring the technology at a faster clip, but are also putting it to greater use. The number of models and prototype parts produced last year grew to an estimated 6.05 million, up from 4.83 million in 2003.

The heightened buzz surrounding 3D printing technology has prompted many manufacturers to consider bringing this capability in-house. The potential benefits of 3D printers for compressing design cycles and improving product quality are fairly well known. They enable product developers to validate design concepts, solicit feedback, and pinpoint potential design problems early in the design cycle. However, there are important differences among 3D printers that can produce varying results, depending on the nature of your design process and specific modeling needs.

Do We Need a 3D Printer?
The first question a product development organization should ask itself is whether it needs a 3D printer. In other words, will bringing a machine in-house provide increased productivity, faster time-to-market, and cost savings over buying parts from a service provider?

This is an important consideration because many manufacturers with internal 3D printing capabilities discover that while physical parts are valuable for developing and communicating design concepts, they often do not meet all of an organization's modeling and prototyping needs. Many manufacturers with 3D printers actually use a combination of in-house and outsourced models in the process of developing and producing products.

In-house 3D printing is usually faster and more convenient because it can eliminate delays related to shipping and the administrative work associated with purchasing external services. Also, it provides manufacturers with the flexibility for managing and prioritizing their own model production queues.

Realizing the benefits of speed and convenience is a function of the volume of models you need. If you require only a couple of prototypes a month, using a service provider may be the best option. But if you need a much higher number of models, internal 3D printing offers the opportunity for productivity improvements, lower cost, and control. Also, companies find that by having a 3D printer nearby, they produce models that they otherwise would not purchase, and this often results in a better quality product.

Another factor to consider in determining whether to purchase a 3D printer is the sensitivity of the new design. Many industries are very careful with how they handle CAD data and concept models. While most service providers are honest and will maintain confidentiality, mistakes occur. Some manufacturers will go to great lengths to guard against having secret product information leak out inadvertently. In these cases, having a 3D printer in-house helps to reduce the likelihood of new designs landing in the wrong hands.

Criteria for Evaluating 3D Printers
The leading 3D printers use different materials and processes, each of which have distinct strengths and limitations. Your final determination will depend heavily on how your specific needs apply to the model quality, speed, cost, ease-of-use, and ease-of-finishing afforded by the different machines.

What are the questions that one should ask? First, how does your organization plan to use the machine? Will it be used as part of concept development to support product design? Do you anticipate needing to perform design validation through limited fit-and-function testing? Will the models be used as visual aids to support tooling development? Do you expect to use the models for presentation purposes or for soliciting market/customer feedback, where model aesthetics are more important?

Assessing model quality needs against your intended purpose is fairly straightforward. If you plan to use models for customer presentations, you may need full-color and labeling capabilities, as well as the fastest production possible, both of which are available from Z Corporation's Spectrum Z510 system. If you require part durability for rigorous handling and limited fit-and-function testing, the Stratasys Dimension system is a good option. It melts and extrudes ABS plastic, which results in strong parts directly out of the machine. If you require a good surface finish and ease of finishing, consider the InVision SR or InVision HR systems from 3D Systems. It prints and cures photopolymer using an inkjet print head and UV light.

The leading systems range in price from just under $25,000 to about $60,000 per unit. An annual maintenance agreement costs about $3,000 to $9,000 and vary by machine type. Materials range from about $1.50 to $2 per cubic inch of part (including infiltrant) for the materials from Z Corp. to $250 per kilogram for the ABS material for the Dimension machine.

Request a demonstration of the 3D printing process--from start to finished part--and get a detailed description of maintenance needs and procedures. By seeing the printer in operation, and actually trying it out for yourself, you will gain an improved understanding of the time and effort required to complete the process. Ask to test-drive the machine's control software so that you can see how difficult it is to send STL files to the 3D printer. Training can range from computer-based instruction to taking a class.

Ask the vendor what you need to do after the model is produced. Most 3D printers require the removal of support material and it can be one of the most important considerations due to potential labor costs and the mess it can create. Z Corp's powder-based systems involve powder, so be prepared to deal with dust. The InVision SR and HR machines use a support material that melts away with heat. It sounds straightforward, but removing the material from parts with fine holes and deep slots and cavities can be tricky. Likewise, removing the support material from Dimension parts can be a challenge, depending on the geometric features of the part. The Dimension BST requires manual removal, while the Dimension SST uses soluble support material and automates the process. Also, make sure you understand whether the various build, support, and cleaning materials are potentially hazardous and have special disposal requirements.

Materials can differ greatly in their finishing characteristics. For example, sanding, painting, and coating a model are usually far easier with a photopolymer than a hard material such as ABS. Full-color capabilities from Z Corp.'s machines enable you to avoid painting altogether, but don't expect the same kind of finish that you get from paint. Also, consider that parts from the Z Corp. process are not suitable for handling and shipping without infiltration of a material such as epoxy resin. This takes time for both infiltration and drying and can be messy.

By evaluating your specific design and modeling needs, you can determine whether the acquisition of a 3D printer is the right move for you. And once you have made that determination, thoroughly evaluate your needs against what is available. Be sure to ask about hidden costs or any extras that have not been discussed in any publications or presented by the vendor. Also, consider whether technical support and service is local or a considerable distance away. Asking lots of questions and doing your homework will help you meet your goals of reducing cost, improving product quality, and accelerating time-to-market.

Industry consultant, analyst and speaker Terry Wohlers is principal consultant and president of Wohlers Associates, Inc. (Fort Collins, CO). Visit wohlersassociates.com for more information.