There are new additive manufacturing techniques being developed all the time. Some are best for consumer applications and others for industrial environments, but not all of them are suited for rapid prototyping. Let’s take a look at the top 7 methods for 3D prototyping and their strengths and weaknesses so that you can decide what might be best for your next project.
Stereolithography was the first successful commercial 3D printing method. A bath of photosensitive liquid is solidified one layer at a time using a UV light controlled by a computer. These layers are derived from two-dimensional cross sections of the 3D CAD model and controlled with a software file format called .stl.
SLA printers often use an orange filter to screen out unwanted UV light.
This is noteworthy because, being the first, .stl has become the default computer language used by most modern 3D printers, regardless of the printing technology employed.
Stereolithography is best for prototypes and to make master patterns for vacuum casting. SLA is fast and inexpensive and the finished product is strong with a good surface finish. Supports may or may not be needed depending on the machine.
This is a form of powder bed fusion. Parts are formed on a build plate one layer at a time, using a laser to sinter the powder media. Because the support is surrounded on all sides be the powder medium, it is self-supporting and additional structures are not needed.
Excess powder being cleared away after SLS printing.
SLS can work for either plastic or metal prototypes. Like many other 3D printing processes, the great advantage here is that parts can be made with complex geometries like internal lattice structures that would be difficult or impossible to do any other way.
However, the surface finish is usually rough and may require secondary work to complete it, especially if it’s used as a master pattern for later casting. The strength is also not as good as SLA printed parts.
This is the kind of 3D plastic printing often found in desktop machines in a home or small shop. It uses a spool of plastic filament that is melted inside the barrel of a printing nozzle. This hot liquid resin is then laid down layer-by-layer, again controlled by an .stl cutting program.
FDM printers are commonly found in small shops and even in the home.
FDM printing is inexpensive, easy-to-use, and can accomodate different types and colors of plastic combined in a single build. It’s also safe enough that even children can use it in a classroom. FDM printed parts have poor resolution and finish quality compared to industrial techniques, and the parts are not very strong. However it can be ideal for making prototypes and models during the development stage.
Another form of powder bed fusion, SLM is an industrial process that requires carefully controlled conditions. Very fine metal powder of a uniform size and shape is fully welded onto a build plate using a high-powered laser inside of a sealed chamber. Common metal powders may include titanium, stainless steel, maraging steel and cobalt chrome.
These bike frame components were made with SLS prototyping technology.
SLM is the preferred technique for making sophisticated parts of the highest strength, durability and complexity and this is what we use at Star Rapid for our DMLM service.
The process can be expensive and must be controlled by a skilled engineer, but the results are ideal for the most demanding applications in aerospace, automotive, defense and medical parts
Each of these 3D printing techniques has trade-offs in terms of speed, cost, strength and available materials. Want to know more? Contact us today for a free quote and our technical specialists can give advice based on your schedule, design and budget.
