Rapid prototyping typically refers to a variety of subtractive and additive technologies that translate CAD data to three dimensional objects. Stereolithography has been a widely utilized RP process since the early 1980s.
Prototyping applications include:
Concept/Communication Models provide a 3 dimensional design representation that allows visual inspection and communication of an idea within a turnaround period as little as several hours or a few days. Concept models provide a hands–on communication tool that allows for the rapid refinement and iteration of designs.
UnionTech™ SL equipment provides excellent surface aesthetics. Exceptionally smooth sidewall quality minimizes layer line definition. Textures can be readily applied as part of the model build.
Form and Fit Prototypes provides practical confirmation of ergonomic factors, aesthetics,as well as how well the prototyped part integrates with other design elements. Multicomponent assemblies can be checked for fit and to ensure no interferences exist.
UnionTech™ SL equipment is compatible with one of the widest ranges of materials available for any AM process including, clear, colorless, pigmented, and ceramic filled materials.
Functional Prototypes, as the name implies, refers to evaluating a part under end use condition. This does not necessarily mean that a functional prototype will meet all the requirements of the end use design.
Typically a design can be evaluated for one or more critical performance parameters critical to the part design’s intended performance without needing to meet all the requirements of the final end-use. Examples include wind tunnel testing at a reduced scale to evaluate aerodynamics, impeller designs used to evaluate design elements that affect flow or mixing capabilities, and equipment housings for consumer goods in short term testing.
The evolution of stereolithography materials in recent years have allowed engineers to take advantage of the surface aesthetics, ease of finishing, and the ability to create parts ranging from micro to extremely large while obtaining end-use critical mechanical and physical properties.
Patterns and Tooling
While stereolithography is most often associated with prototyping, patterns and tooling account for a substantially higher percentage of overall SL material usage. The accuracy and precision of SL printing coupled with excellent surface aesthetics is ideal for creating patterns for various casting and molding processes including:
•Urethane casting ( also known as RTV molding)
Urethane casting is often used to fill the gap between prototype and production when part volume requirements or overall performance requirements exceed prototyping capability. SL is used as an efficient method of acquiring an accurate master pattern that is used to create a flexible RTV tool for casting. A specially formulated silicone rubber is poured and cured around the master pattern. The pattern is removed forming a core and cavity mold. Urethane casting capability is often a core competence of many AM service providers with SL capability.
UnionTech™ SL equipment is available in a range of sizes that can accommodate most master pattern needs. Photopolymers from multiple suppliers are well established for master pattern use and can be used on UnionTech SL equipment without restriction.
Investment casting of wax patterns in a ceramic shell to create forms for casting metal to create near net shapes is a historical and well established process. It is used to produce intricate small objects , like jewelry, as well as very large industrial parts. Stereolithography is used when tooling for wax patterns is not warranted due to volume or complexity to create an accurate hollow pattern.
UnionTech™ SL equipment utilizes a special software to create hollow, reinforced patterns that can withstand the ceramic pattern production process and still be efficiently removed via incineration without damaging the shell.
Use of SL for injection molding tooling has been an active area of development since the mid-90’s. The introduction of filled composite SL formulations in 2002 re-energized development efforts with heat deflection temperatures over 250° C and major increases in strength and stiffness.
As SL formulation advances have continued to improve ease of processing, interest in this approach continues to grow, especially when SL part manufacture and injection molding is an integrated operation.
The exceptionally smooth sidewalls produced by UnionTech™ SL coupled with the improved ease of finishing available from current filled composite SL formulations further enable this type of application for prototype, functional testing and bridge tooling.
Rapid Manufacturing is a generic term that can refer to using additive manufacturing to directly produce parts used in an end-use or indirectly using AM to create patterns and tooling.
Essentially all the processes described under patterns and tooling are applicable to rapidly producing end use parts: SL provides form while the material used in the final process provides properties needed in the final application.
•Direct Manufacture : SL has historically been relegated to prototype applications due to either mechanical properties or physical changes over time. As photopolymer formulations have advanced, the scope of applications for end use have advanced from art , dental guides and consumer articles to components used in manufacturing including material handling system components, jigs and fixtures. UnionTech™ equipment has been used for processing leading SL photopolymer formulations recognized globally for durability and versatility since 2003, creating a large information base that users can draw upon.
•Indirect Manufacture: Essentially all the processes described under patterns and tooling are applicable to rapidly producing end use parts: SL provides form while the material used in the final process provides properties needed in the final application.
Some of the more widely known applications are the creation of tooling for thermoforming dental aligners and metal clad parts used for a variety of applications benefiting from the structural and physical properties available from a structural metal/photopolymer combination.
Most AM technologies can be electroplated utilizing a copper-structural nickel coating , dramatically increasing mechanical properties including strength, stiffness, and impact resistance while imparting physical properties such as flame retardancy and EMI shielding.
The smooth, solid surfaces of SL parts have contributed to utilization in metal clad composites (hybrid compositions) for nearly 20 years.
Some AM service providers as well as photopolymer suppliers have commercialized the use of specific SL photopolymer/copper/nickel combinations to develop composite properties across a wide range of dynamic and static mechanical properties as well as various physical properties so that end users can utilize these composite properties to better optimize designs.