Schilling Engineering

Stereolithography gives ERU Elektroinstallation the means to deliver in just eight months functioning prototypes for design review and testing by its customers. "Customers no longer talk to us about design drawings or timelines for their completion. Instead, we use models to communicate. 'Grasping' an idea is easier when you can 'touch' it." - Dr. Martin Schilling, Schilling + Partner Engineering

The Challenge
ERU Elektroinstallation RuNa GmbH, a manufacturer of electrical consumer products, had less than a year to design, test and ready for production a set of products consisting of 27 different parts. ERU's customer intended to pretest the product in accordance with European electrical and safety standards before building actual production tooling. The company also wanted the option of models to making last-minute changes to the product line right up to the start of production.

The product set consisted of universal and multi-circuit switches, two-way control and illuminated switches with and without child safety features, single- and dual-receptacles with and without side- and center-ground contact, and a combination of single-switch receptacles. The product variations would require 17 multi-sectional molds.

The Results
ERU Elektroinstallation RuNa Gmbll turned to the rapid-tooling and prototyping services of Schilling+Partner Engineering. Using stereolithography, Schilling designed and turned around prototypes of the 27 different components in two months. ERU, in turn, delivered the prototypes to its customer for design review and approval.

Two months after receiving customer approval, ERU and Schilling delivered 50 SLA built product sets for electrical and safety testing according to European industry standards.

While gearing up for production, Schilling, in order to reduce tool-making time, now used the tested-and-approved prototypes as master patterns for molding production tooling. Calculating the necessary mechanical and thermal properties, Schilling built tooling con-structed of epoxy resin reinforced with metal powder. This rapid-tooling approach allowed Schilling to cut tool-making times by 60% and costs by 90%. SLA rapid-tooling allows ERU to:

• Cut tool-making costs by 90%
• Dramatically reduce tool-making time by 60%
• Test and verify product designs before building production tools
• Use prototypes to reduce reliance on up-to-date engineering drawings

The Process
Managers at Schilling+Partner Engineering decided against conventional steel molds. Steel tooling would be impractical due to their expense, complexity of the required tooling and time constraints. Schilling engineers opted to apply rapid tooling methods, using stereolithography prototype parts as master patterns from which to mold epoxy-based production tooling.

Schilling engineers designed the 27 different surface-mounted parts using Pro/Engineer CAD software. ERU-approved CAD models were then downloaded to the SLA 250 machine at Schilling. In just two months after placing its order, the customer was provided SLA prototypes of the product set for design review.

Once approved, preproduction of additional prototypes began. In two months, the customer received 50 product sets for formal testing to VDE and KEMA electrical and safety standards. The products were industry approved before actual production had even begun.

Schilling designers now used the VDE- and KEMA-approved SLA prototypes as master patterns to build production tooling. Designers used Pro/MOLDESIGN software to calculate mechanical properties and shrinkage factors, as well as mold-parting lines and built production tooling of epoxy resin reinforced with metal powder from the SLA masters.

The rapid-tooling method delivered production tooling in 4 weeks at a cost of DM 16,000 ($11,000). Conventional tool-making methods using steel molds would have required 12 weeks at a cost of DM 160,000 ($110,000).

Rapid-tooling benefited both Schilling and ERU. SLA models were available to verify every aspect of product development, eliminated the need for engineering drawings, and cut tooling costs by 90% and delivery times by 60%.

The Tools

• Pro/Engineer software for 3-D CAD, version 12
• Pro/MOLDESIGN mold-making CAD software, version 12
• SLA 250 with Cibatool SL 5170 resin

Company Profile
ERU Elektroinstallation RuNa GmbH (ERU), Thuringia, Germany, is a manufacturer and marketer of electrical and electronic systems and components.

Schilling+Partner based in Sondershausen, Germany, provides rapid development services to translate ideas and concepts into designs. Its services include generating models and prototypes using stereolithography, designing tools, creating NC data and production of rapid tools and patterns.