Engman-Taylor now has access to all the processes explained below in the following blog. Engman-Taylor will work with you on any of your project needs and will find the best solution via 3D printing. Any questions on 3D printing please contact Jordan Nowak or call 855-382-6349.
SLA otherwise known as Stereolithography is one of the oldest ways of 3D printing. In fact this technology was developed by Charles Hull in 1986 where he patented this idea and founded the company 3D Systems Inc. SLA is the use of a vat of photopolymer resin and a UV light that cures the resin in specific areas, layer by layer, until the part is built up. In this blog I will be putting together useful information for using and printing with SLA technology. The following bullet points will be described.
- Benefits of SLA
- Post Processing and Finishes
Benefits of SLA
SLA technology has a wide range of photo-polymers that have a wide range of mechanical properties that mimic the typical plastics used like ABS and Poly carbonate. Using photo-polymers and a ultraviolet light for curing, SLA parts exhibit a very smooth surface finish that rival all other processes and are highly accurate up to 50 microns. Because of this accuracy parts can be printed with very small features. Printing with high definition, features can be as small as .01″. When printing with SLA, parts will be printed faster than FDM, however the time for post processing increases exponentially.
Manufacturers using this process will use this typically for prototypes that require water resistance, clearness, or exceptional surface finishes. SLA is great for printing large investment cast patterns, urethane casting patterns, and parts used for fit and form testing.
Not only do manufacturers use this process, but SLA is used heavily in the medical and architectural fields. Doctors can print out highly accurate anatomical models that are exact replicas of the patient’s hearts, organs, and bones using 3D scanning along with SLA printers.
SLA printers start out with beginner printers and then prices jump with the mid-level printers and production grade printers. The costs start around $2,000 and then jump to $100,000-$990,000. Maintenance on these machines include, doing monthly calibrations and making sure that the bin of resin is clean. Every once in a while the UV light may need replacements.
The beginner printers are going to have a very small build plate and are used by the average hobbyist that is looking to make nice looking figures and jewelry. The machines work in a way that the plate will start on top and will move upwards from the bin of resin while the UV laser cures each layer onto the existing hardened layer. This continues to happen until the part is built.
Form Labs have two quality beginner printers. Form +1 and the Form +2. Form Lab +1 starts out at $1,665. This printer has a bed size of 4.92″ x 4.92 x 6.5″, which is quite small in comparison to a typical build plate. This printer also has limited materials to work with, but does include an option of castable wax. The upgraded Form Lab +2 starts at $3,500 and has an increased bed size of 5.7″x 5.7″x 6.9″. This also has cartridges that contain the photo-polymers and it has a touch screen that isn’t included with the Form +1. Other printers that fall into this beginner category are listed below.
- XYZ Noble 1.0 $902
- 3D Systems Projet 1200 $4,900
- DWS Lab Xfab $5,000
Mid level printers typically have a slightly larger build plate and bin that can hold materials. There is one printer that has made a name for itself called the Carbon printer using CLIP technology. CLIP technology is basically stereolithography with a twist on it. It is the same as SLA in which the plate is placed within the bin of resin and moves upwards; however each layer is cured using a complicated exact mixture of light and oxygen. What this does is increase the speed of the print exponentially. On TED talks this printer could print a part that has about a 3 inch diameter in 10 minutes, which is unheard of. The downfall to this printer is that the build plate is very small (5.5″ X 3.1″ x 12.8″ ). Another two things to consider if wanting to get this printer is that it only uses materials designed by Carbon, and when buying the printer it is a rental agreement for 3 years, not an actual purchase. This costs minimum $120,000 and then there are additional purchase agreements that can be chosen that will increase the costs.
The production grade machines are made by 3D systems, which is only fitting because they had come up with this technology. 3D systems does this process a little differently though. The machines work in a way that the plate will start on top of the bin of resin and will move downwards into the bin of resin. Each layer the plate will move down (depending on the micron layer that has been chosen) and
the UV light will cure each layer. This continues to happen until the part is built. The machines are called the Projet 6000, Projet 7000, ProX800, and the ProX950. The build plate starts at 10 x 10 x 10 inches for the 6000 and increases to 59 x 30 x 22 inches for the 950. The Projet printers can only use the Visijet SL line of materials where as the ProX machines use the Accura line of materials. These machines are very expensive with the Pro X costing $990,000. These machines are meant for manufacturers that produce many prototypes that need a great surface finish, high accuracy, and larger sized parts.
SLA materials are materials that have been engineered to replicate typical plastics and work with UV curing. These materials will all have a great surface finish based on the way SLA works.
For most of the SLA machines each company has designed their own materials that work with their 3D printer. There are a couple brands out there that can be used for the other SLA machines. One of those main brands is Somos. The materials included in the Somos line are listed below.
- PerFORM Great for static testing in under-hood and wind tunnel applications
- ProtoGen 18420 Highly accurate and is humidity and temperature resistant
- WaterClear Ultra 10122 A colorless material suited for lenses and electronic covers
- WaterShed XC 11122 Produces highly detailed parts with great clarity and water-resistance
- NeXt Higher impact resistance than standard SL resins; Moisture resistance
- SC 1000P Custom formulation ideal for low cost investment casting patterns
- Element Antimony free formulation for investment casting patterns only
Carbon does make some great materials. Their mechanical properties mimic injected molded plastics and are tough, isotropic and machinable.
- RPU Rigid polyurethane tough abrasion resistant and stiff
- FPU Flexible polyurethane impact and abrasion resistance with moderate stiffness
- EPU Elastomeric Polyurethane Highly elastic resilient
- CP Cyanate Ester High temp resistance and stiff (Resist up to 220C)
- PR Prototype material general plastic
3D systems have developed many materials. I won’t go through all of them, but here is the link that will take you to their material page. They have developed a wide range of materials that are heat resistant, abrasion resistant, clear, castable, elastomeric, and snap fit-able.
Post-Processing and Finishing
After the part has been printed, there will most likely be some support that will need to be removed. This picture shows how the typical support structure will look like. To start with the plate should be agitated in a bucket of IPA and then let it soak for 10 minutes. Then take it out and move it to another rinse bucket with alcohol and let it sit for 20 minutes. After each time using the rinse buckets replace the solutions with new solutions to keep everything clean. Next most of the support you will be able to take your hand and it should just snap right off the part. There will be some leftover support that will be left on your part that look like bumps and may not be aesthetically pleasing. To remove these bumps you can take an exacto blade and pop them off or shave them off the actual part. To be able to see these better an easy way to bring out the definitions on a SLA part is to spray it with a primer. Lastly once all the bumps are gone take a sanding sponge (very light abrasive) and polish up the part. Removing support from holes will require a tweezers to pull it out. Sanding the inside of the holes may be difficult as well.
After the support is removed the part can be easily painted, textured, and plated. Most of these materials could also be machined afterwards if need be. Large parts can also be divided and printed separately then after can be assembled together with glue.
More information on our 3D Printing services.