3D Printing FAQs
Rapid PSI takes the time to provide you with answers to some of your pressing questions involving additive manufacturing and 3D printing.
What are the different types of additive manufacturing?
Although used interchangeably, 3D printing is only one of the seven categories that fall under additive manufacturing. The other categories are:
- Material jetting uses droplets to form an object slowly
- Directed energy deposition slowly melts metals into predetermined shapes with lasers
- Material extrusion uses filaments to build an object layer by layer
- Sheet lamination shapes stacked laminated materials through cutting
- Vat photopolymerization cures liquid resin using directed energy
- Powder bed fusion melts powdered metals
Some of these processes are sometimes categorized under 3D printing as well.
What are the different 3D printing methods?
3D printing methods usually vary from the materials they use or the method by which they sculpt their designs. The most common 3D printing methods that we use at Rapid PSI are:
Fused deposition modeling (FDM)
3D printers that run on FDM Technology build parts layer-by-layer by heating thermoplastic material to a semi-liquid state and releasing it according to computer-controlled paths.
FDM uses two materials to execute a print job: modeling material, which constitutes the finished piece, and support material, which acts as scaffolding. Material filaments are fed from the 3D printer’s material bays to the print head, which moves in X and Y coordinates, depositing material to complete each layer before the base moves down the Z-axis and the next layer begins.
Once the 3D printer is done building, the user breaks the support material away or dissolves it in detergent and water, and the part is ready to use.
FDM is particularly effective for production runs, rapid tooling, and prototyping.
SLA is often considered the pioneer of the additive manufacturing processes, with the first production systems introduced in 1988. The SLA process utilizes a vat of liquid photopolymer resin cured by ultraviolet laser to solidify the pattern layer by layer to create or “print” a solid 3D model. Because of their accuracy and ability to reproduce fine details, stereolithography models are ideal for use as concept models, form and fit studies and master patterns for a variety of molding techniques. Options for finishing include color-matched painting, texturing and pad printing to give your model a “production quality” look and feel.
An Ultra Violet (UV) laser beam is directed by a computer-guided mirror onto the surface of the UV photopolymer resin. The model is built one layer at a time from supplied 3D CAD data.
The laser beam traces the boundaries and fills in a two-dimensional cross-section of the model, solidifying the resin wherever it touches. Each successive layer is applied by submersion of the build platform into the resin as the part gradually develops and the platform descends into the liquid resin.
Once the model is complete, the platform rises out of the vat and the excess resin is drained. The model is then removed from the platform, washed of excess resin, and then placed in a UV oven for final curing. After curing SLA parts are then ready for post-processing as required by the specific application.
SLA is widely used for prototyping, for representation models, as master patterns for urethane casting, and design verification before proceeding with hard tooling.
Selective laser sintering (SLS)
The printing process begins with your 3D CAD file which our machine mathematically slices into 2D cross-sections. Our machine then builds your three-dimensional parts by scanning those cross-sections and using a laser to selectively solidify heated plastic powder, fusing the powder particles together layer by layer according to the design until finished. Since parts are produced in a bed of powder, multiple parts can be produced at once.
SLS Is particularly useful for prototypes, functional models, detailed geometry, ECS ducting, production parts without tooling.
What does resolution mean in 3D printing?
3D printer resolutions are the level of quality to expect from a machine. Each printer can discharge layers of material, usually measured in microns, which are one-millionth of a meter. However, the micron-count of a 3D machine isn’t the only factor considered when measuring the resolution. 3D printers also take into account the dimensions, namely the X, Y, and Z axes.
What are the limitations of 3D printing?
Challenges of 3D printing include size limitations on designs imposed by the printer’s capacity, although larger devices are available. Materials suitable for additive manufacturing also lend their limitations to that of the finished design. If a brittle thermoplastic is used in the fabrication process, so too shall the end result. Luckily, at Rapid PSI we can work with a wide variety of equipment and materials to ensure that your end product meets or exceeds your expectations.