Hi-Res 3D :: Technical Library

Process Description & Overview - A brief description of the SLA machine, materials and how parts are fabricated.

SLA Process Video - A video that shows the SLA process, start to finish. Running time is 2 minutes and 52 seconds.

All SLA machines are not equal! - Pictures showing the differences of parts coming off new SLA machines (Viper and Viper PRO) in comparison to old SLA machines.

Why the Viper and Viper PRO build better parts than old SLA machines (250, 350, 500, 3500, 5000 & 7000) - Some technical details on why parts come off new SLA machines more dimensionally accurate and with better surface quality

Materials - Brief description of how SLA Materials work, what materials we offer and why we offer them.

Fine Feature Detail, Viper HR (Hi-Res) Mode - Descriptions of the Viper machine capability when running in HR mode with a .003" diameter beam and .002" z steps.

SLA Process Description & Overview

The SLA process, in fact any of the RP processes, begins by exporting your 3D CAD design from your CAD package in STL format. The STL file was originally created to work with the STereoLithography process and now the STL format has become the standard for all RP processes. All major CAD/CAM packages from Solidworks to Pro/Engineer include the ablity to directly export to an SLT file. The STL file contains your CAD design and the surface is made up of triangles. The smaller the triangles and the "cord height" the finer the detail on the surface of the part. There is an indirect relationship between # of triangles and files size in Mbytes. The greater the tesellation (# of triangles) the larger the file in Mbytes. We can help you export the appropriate file so that you get the best part.

The 3D design is then "sliced" in software and then built, layer by layer (or slice by slice) in the SLA machine. The laser that traces each layer emits UV energy and the material in the build chamber is a UV curable epoxy resin. The laser traces each layer and bonds successive layers to the previous layer.

The material used to build the part is a UV curable epoxy resin. The material is like a 2 part epoxy where the second part is energy from a UV light and in the case of SLA, the energy comes from a precision guided UV laser.

After the entire part is built, the part is removed from the machine and cleaned (with a soft bristle brush) in a material such as IPA to remove any excess resin. The part is then cured in a UV oven, basically a small tanning bed, and is ready for any secondary operation that is needed.

SLA Process Video

An SLA video that shows how STL files are prepared, how the machine builds the parts, how parts are removed from the build platform and cleaned in preparation for shipment. Running time is 2 minutes and 52 seconds.

Click "play" (you may need to click play button twice) and wait a few seconds (over high speed connection) for video to begin streaming:

All SLA Machines are not equal!

The following series of shots shows a 4" x 4" square that is .060" thick produced in SOMOS 11120. The square has Hi-Res 3D Incorporated in raised lettering. One part is built on an SLA Viper and the other is built on an SLA 5000. Both were built vertically in the build chamber in .004" layers and with a .010" nominal beam diameter.

As you can see, the Viper has created much smoother side walls and much clearer definition of the raised lettering.

The way most service bureaus (who do not have own Vipers) solve this problem is to use manual labor to finish the part so it is smooth. This process changes the dimensions from the original CAD data. You can also not sand around the fine detail like the raised lettering. Bottom line, Viper parts look better and are more accurate.

When you begin to see parts off a Viper or Viper PRO you will notice cleaner, crisper detail.

The following image shows the same 2 parts held up to a window. The part off the 5000 appears to be brighter due to the fact that is has more "layer lines" on the surface and is in fact acting like a prism would act, reflecting the light.

Why Viper and Viper PRO are better

Over the years there have been many advancements in Stereolithography machines. Most advancements have come in the software that runs the machines and the scanning mechanisms that controls the mirrors that guide the laser.

The reason that the Viper and Viper PRO produce better parts is that they both utilize the lastest software, scanning algorithms and scanning system harware. You will notice better accuracy, betters surface finish and the machines can also build faster.

Both machines also have the ability to build with a smaller laser beam. The Viper in HR mode is using ~.003" diameter beam. The Viper PRO does all outlines for each layer with ~.005" beam. This allows for building smaller details, just like using a smaller cutting tool while machining.

Part suppliers that do not have Vipers or Viper PRO's will tell you that the older machines make parts that are just as good. That is not the case. I have associates who have an SLA 250 with Hi Res Solid State upgrade and a Viper sitting side by side. They will attest that a Viper wins hands down when you compare accuracy and part quality. The older machines do not have the latest software and scanning mechanisms to do the same quality of work.

Materials

When the SLA process was first inveted, the materials were acrylic based. If you remember the "good old days" of SLA the materials were more brittle and not as accurate due to that fact that acrylics tend to warp in the process.

The majority of today's SLA resins are epoxy based. Acylics still are used, most widely in medical applications. Think of the epoxy resins as an epoxy that requires a specific amount of heat to "kick it over" and cure. In the case of SLA resins that heat is supplied in the form of UV energy delivery by a VERY PRECISE UV laser.

There are many materials for the SLA process that are available. 3D Systems and SOMOS are the main 2 manufacturers of material and each offers 10 or so materials that will run on the solid state lasers that are used in the Viper and Viper PRO.

This sheet shows all materials that will run in a Viper or Viper PRO. Viper/ViperPROMaterials

Materials range from general purpose resins that mimic well known plastics (ABS, Polypropelene, Polycarbonate, etc.) to specialty resins that handle high heat (greater than 500F) or are designed to mimic rubber like materials.

95% of the projects that are built in SLA require a good general purpose resin. We have 10+ SLA machines running general purpose resins. What this allows us to to is offer industry leading lead times. We feel that customers are most interested in saving a day or two in lead time and we are setting things up to be ablt to deliver!

If you have a need for a specialty material contact us at 978-463-0714 or info@hi-res3d.com and we can discuss your needs and get you the material that will work best for you project.

Viper HR (Hi-Res) Mode

When building in HR mode you will be able to replicate very fine details. Free standing vertical walls at .006" are buildable. In the image below, the holes and pins shown are .015" square. If you are doing work for medical prototyping or electrical connector prototyping a Viper in HR mode is an option that will produce beatiful parts right off the machine with virtually no need for finishing.