Occasional Chair Development Case Study
In order to compliment his task seating line for Humanscale® with guest seating, Niels Diffrient designed the cantilever-frame stacking Diffrient Occasional™ Chair with the chair development help of designers and engineers here at Shea+Latone. The project started with Niels’ hand drawn sketches, which S+L translated into various CAD models. These CAD models were used for Class A surface evaluation, photo realistic renderings for design approval and functional prototypes for comfort and strength testing. The chair development was structured around multiple requirements; adherence to global ergonomic, strength and durability standards to allow world-wide sale of one configuration, a weight of under 22 lbs and adherence to a specific cost target while maintaining Neil Diffrient’s design intent.
Instead of the unsightly bend in the frame that most other cantilever chairs use, Niels’ design featured a unique welded joint that needed to be validated and tested for strength and durability from the onset of the project. Due to the stringent requirements of BIFMA and Humanscale’s quality team, we began testing the steel tube frame for strength immediately, relying on quick in-house fabrication of samples in order to do so.The ability to make and test physical samples allowed us to pair real world results with our FEA studies, which were then used to evaluate many different frame constructions without having to physically test each one. Using the combination of virtual analysis and real testing shortened the development cycle while also yielding more reliable results.
Once the design and BOM cost were approved and the engineering was validated through prototype testing and FEA, we prepared engineering-level CAD models for tooling and part inspection. Parts were optimally designed for various manufacturing processes including tube bending, die casting, injection molding and upholstery. Detailed drawings were prepared in accordance with the client’s documentation conventions and quality assurance needs. S+L validated first article parts from multiple vendors for the entire chair and tested the pilot run for full accordance to all regulatory and client requirements. By working directly with each vendor during tooling, we were able to ensure each part was economical, suitable in appearance and able to be produced efficiently. Throughout the development cycle, we produced prototypes that were indistinguishable from the production versions to support trade shows, photo shoots and various sales opportunities.
Shea+Latone’s contribution to the chair development process has extended into supporting initial production. We designed and fabricated assembly fixtures and custom machinery to make the chair production as efficient as possible. Potential design improvements are constantly explored through further design, development, engineering and prototyping services, and we continue to design and fabricate additional fixtures, assembly aides and tools in efforts to continuously improve production efficiency and adhere to high quality standards.