Selecting the Right 3D Printer for Your Laboratory
Know what you need to find the perfect fit
Chuck Stapleton, MBA, BS
One year ago, the author wrote an article comparing new 3D printing technologies and materials available on the market from a technical perspective. This year, the article covers the hands-on and practical side of choosing a 3D printer that will be part of the laboratory's everyday operation and lessons learned from experience in the market. The primary focus of the article is around resin-based printers, as metal printing is reserved for the few large companies that can justify the substantial cost of the those machines.
The Printer's Purpose
The first thing to consider is why your laboratory needs a printer. What does it need to do? Are customers sending intraorally scanned cases that need printed models? Are digital dentures the future of removables, so the laboratory wants to get a head start on it? Is the business expanding to offer new products like surgical guides or bite splints?
Once the purchasing laboratory answers the question of why a 3D printer is needed, then it is possible start to evaluate the options. The author recommends narrowing it down to at least two options to take through the full testing procedure. Even if one machine is already heavily favored, still evaluate a second option because anything can happen during the testing and negotiation process.
Equipment and Material Validation
Do not select a machine based on the promise that a new material is coming soon, as there are many things that can go awry before a new material becomes available. Only consider 3D printers for which additive material is definitely available and printers that come with references from current users. Be specific. For example, if your laboratory is looking to print partial framework patterns, make sure the company can offer references of other dental laboratories that have successfully printed partial frameworks using the exact machine and material combination under consideration.
Once there are at least two manufacturers to consider, samples should be requested from them. The key for samples is that they should be from cases that are in your laboratory. The author recommends sending as many sample cases as the printer's manufacturer will accept for testing. To test the quality of a model printed from an IOS case, use a milled crown from the same case to check the marginal fit on the printed model. Milling machines sold in the last 5 years will produce a milled crown more accurate than a printed model, so this is a reliable way to check the accuracy of the printed model. Any company that has confidence in its product should be willing to send samples based on your own files. Make sure to request some samples with the supports attached; this will give a feel for what it is like to remove the supports on your own.
Level of Customer Support
Test the customer support of the manufacturer or vendor. The author has emailed companies via their general contact email address with some minor issue, just to see how long it takes for them to respond and what type of response they provide. This is done prior to purchasing to get an idea of what dealing with them will be like. A very simple question to ask would be: "It seems like my prints are slightly distorted. Could you help me with that?" Of course, if they answer, please let them know you were checking to see how well their support responded and how it plays into your decision on a purchase. The author finds this to be very revealing for the level of support and response time to expect in the future for any problems.
Consider what kind of response is needed if there is a critical problem that can be resolved only by replacing hardware. Make sure the machine's vendor or manufacturer has a guarantee to resolve any issues within days, not weeks. This can range from sending an engineer on site to shipping a printer to swap with the malfunctioning one right away. This should be crucial to the decision-making process; do not consider working with a vendor who does not offer this level of support.
Cost of Equipment and Materials
Companies price material in cost per kilogram or cost per liter. However, since the density of most resins is close to 1 gram per milliliter, cost per kilogram and cost per liter are nearly the same value, so they are practically interchangeable. While the cost of the machine might be what catches your attention, do not ignore the cost of the material because it can easily exceed the cost of the printer over the lifetime of the machine. For example, assume that 1 kilogram (or 1 liter) of model material will print about 50 sets of quadrant models. So if the material is $200 per liter or kilogram, then an upper and lower quadrant model will cost about $4 in material. These are just rough estimates based on the author's experience, but it offers a simple way to compare material costs across systems.
Single Machine vs. Multiple Machines
The idea of being able to use a single machine to run multiple types of material is a great concept. However, in practice it can prove difficult to change the material. Clean-up is required between switching materials, and cleaning out the material vat or tray often results in waste. If the laboratory's volume can support it, it is recommended to dedicate a single machine to a single material, even if this means having different machines from different manufacturers. The efficiency gained and frustration saved by not having to change materials justify the expense.
In many industries, companies will offer a service for a trial period of several months, during which time the user can stop and return the equipment at their discretion at no cost. The author is a fan of this concept because it means the company believes in its product and thinks it will become so valuable that the new user will keep it even after the trial expires. 3D printers should be treated the same way. Check to see if there is a no-risk return period for the equipment or if something similar can be negotiated.
Post-Processing, Cleaning, and Curing
If everything is set up correctly, the printing is the easy part. Just click a button and, soon after, the part is printed, though it is stuck to some sort of platform. Now comes the manual work of having to detach the item from the platform, remove the supports, clean the parts, and cure them.
Some companies provide specialized tools to assist with removing parts from the platforms, while others simply recommend using a scraper device. If there is an opportunity to remove the product from the platform yourself during the testing stage, give it a try to get an idea of how much effort it takes.
Support thickness and support design are huge factors in the ease or difficulty of post-processing (Figure 1). Larger supports require more labor and force to remove than several smaller supports. This is why, as stated earlier, it is helpful to ask for some samples with the supports fully attached to them. If the supports are too thick, they can distort the printed object or leave support scarring on the models themselves.
Washing the parts after printing is a necessary step with almost all machines on the market. The sophistication ranges from filling a plastic tub with isopropyl alcohol to fully automated cleaning solutions. Automated solutions remove the guesswork and labor from having to clean parts manually and also make it considerably cleaner (Figure 2).
Lastly is the curing of printed parts. Timing is critical in this step of the process. Although there are many curing box options on the market, it is best to follow what is recommended by the manufacturer. Overcuring or undercuring parts is a major reason for distortion and part failure. Although it may be tempting to go with a cheap curing box sold at a show, it will end up costing the laboratory in frustration and lost productivity.
Safety and Resins
Always wear nitrile or latex gloves when working around any 3D printer that uses uncured resin. Assume the entire area where the printer is located is contaminated with resin, even the printer itself. When loading a job, cleaning a part, or even pressing buttons on the printer, be aware that resin has probably spilled on that area.
New Business Models
In addition to one company's leasing model for 3D printers, two emerging business models should be mentioned because they fit a certain niche in the market. The first concept is trading off a very low cost material for longer print times. This is ideal for smaller operations where it is acceptable to wait 6 to 7 hours for a single model to print if it means the costs of the machine and the material are very low. Some larger operations with enough space to support a significant number of machines could also experiment coordinating their model printing time with completion of the crown.
Another concept likely to be very disruptive is providing printers for free and charging for materials only. At least one company on the market utilizes this business model, and it is desirable for several reasons. The cost of materials is not as high as most would expect, and the printer price is obviously attractive. Also, the arrangement shows that the company believes in its product, as it would not put effort into shipping, installation, and setup if it did not think the machine would get frequent use.
3D printing is now an essential part of dental fabrication, regardless of the size of the laboratory. It is a mature technology where the groundbreaking developments will be around new materials. There are many options from which to choose. Knowing how to approach vendors of 3D printers and what to look for when making a purchasing decision is the first step to upgrading your manufacturing technology.
About the Author
Chuck Stapleton, CDT, MBA, is the General Manager for West Coast Dental Labs, based in Hawthorne, California.