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:

  • Urethane casting
  • Investment Casting
  • Injection Molding
  • Thermoforming Patterns
  • Urethane Casting or RTV (Room temperature vulcanization) molding, often referred to as resin casting or silicon molding

Urethane casting is often used to fill the gap between prototyping 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 as it is an affordable solution for prototyping, functional testing, product demonstrations and short–run production. RTV molding offers lead times of three to seven days at well under the cost of machining or injection molding. The resulting firm but flexible mold can reproduce extremely complex geometries and intricate details with tight tolerances. Due to the cycle time, cost per piece and tool life, silicone molding is ideal for applications producing 1 to 50 parts.

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

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 jewellery, 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.

  • Injection Molding

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.