Design Innovation in Mexico

When I first met Mauro Monarris, President of Abastecedora Rimova S.A de C.V. located in Mexico City, Mexico, for the first time, I was immediately impressed with his high energy level and vibrant imagination.  His company, Rimova is the foremost educational toy manufacturer in Mexico. Rimova is noted for manufacturing and distributing innovative educational toys to Mexico’s schools. Its line of injection molded products boasts design innovation and originality. During our initial meeting Mauro expressed his desire to expand his product line to include a line of rotationally molded products ranging from interactive toys to children’s furniture. Our discussion quickly focused on developing a line of school furniture for children in the 3 to 6 year age group. In keeping with Rimova’s reputation for design innovation and creativity, Mauro wanted a design that was unique. He showed us some examples of rotationally molded children’s products which had features similar to those he wanted in his product line. Shortly after our meeting we began to develop design concepts for Rimova based on a very loose set of specifications.  Needless to say, we were very excited about the design freedom provided to us and the challenges that lay ahead.

Our initial concepts were a major departure from typical rotationally molded children’s furniture, which mimicked traditional adult tables and chairs. We kept our designs very loose and devoid of much detail to provide Rimova with innovative ideas for seating as well as play stations as shown in Figure 1.

We wanted to provide children with an aesthetically appealing design that they would crave without compromising our high design standards. Initial design concepts originated from sketches which explored playful 3D abstract forms. Very little thought was given to molding or function. Our objective was to capture an exciting gesture which would establish the foundation for an innovative design direction. After discussions with Mr. Monarris, we focused our attention on chair concepts. The selected design would later be used as the foundation for a companion table design. After evaluating each concept, Mauro expressed a desire to mold the chair in one piece, which influenced us to modify one of the concepts developed earlier, into a one piece part. The initial design was a three legged chair shown in Figure 2.

This design was later further developed with some consideration of molding, stability and ergonomics into a more stable 4 legged chair shown in Figure 3.

Upon closer examination Rimova directed us to include stacking as another requirement. This decision presented us with a major challenge and significant impact on the current design. We had to modify the current chair design to include stacking, while minimizing cost, maximizing stability, supporting 200 lbs and remaining compliant with rotational molding requirements. These specifications required extensive revisions to the overall geometry and presented complications in maintaining our initial concept. Exceptional artistic and technical expertise was required to ultimately create a design that satisfied all these requirements.  

The final design was developed after many hours of modifying the surfaces and overall part geometry to comply with the design requirements. Surfaces on the front legs which wrapped around the back of the chair had to be twisted avoid undercuts. The rear legs had to be modified to avoid undercuts yet also permit stacking. These complex surface features were checked for undercuts using computer draft checks as shown in Figure 4.

Another complex detail was the area between the seat and rear back support, which was detailed as a shut-off in line of draw for easy molding as shown in Figure 5.

Parting lines were carefully evaluated throughout the part to insure that the finished chair would comply with aesthetic, ergonomic and molding requirements as shown in Figure 6.

Modifying the design to include stacking was quite challenging. This added specification required us to stack one chair upon another in a CAD assembly. The geometry of the chair was first adjusted to permit stacking without interference. Later adjustments were made to the underside of the chair to include relief cuts to permit stacking. Careful consideration for rotational molding design parameters was continually included in the refinement process as shown in Figure 7.

This was especially true for double wall separations which were balanced between aesthetics and molding to eliminate any chance of bridging. It would have been virtually impossible to design a chair with this complexity without the aid of CAD because the top surface of the chair had to be perfectly matched to the under side of the chair to insure stacking. After the CAD modeling was completed, files were sent to the mold maker, Wheeler Boyce. The design intent and details were reviewed with Mr. Bud Boyce who approved the design for tooling. Parting lines and shut-off angles were reviewed to insure that the production parts would be consistently molded with the desired quality specified. An interesting point that was raised by Bud pertained to filling the mold. Since the parting line was so complicated, there was no cavity in the open mold to retain resin. The mold had to therefore be filled closed, requiring a fill port at some appropriate location. We decided to add a fill port in one of the legs, which required a certain minimum area for an opening. This important consideration had an impact on the design which required a recess at the base of the front legs and an adequate area to include a reasonably sized fill port.

After the final chair design was completed, a pattern was cut and verified by Rimova. Children, ranging in age from 3 to 6 were seated in the chair to confirm comfort, overall size and stability. Upon approval, the first mold was completed within 10 weeks and tested in the US at Atlanta Rotomolding before additional molds were fabricated. Initial parts were exceptionally good and additional molds were ordered shortly thereafter to create a multi-mold spider.

As the chair mold was being created, we were instructed to focus our attention on the companion table design. Mauro instructed us to consider tables which could accommodate a minimum of two children and a sloped easel writing surface. In response to these requirements, we submitted numerous concepts as shown in Figure 8.

Although the basic function of the last concept complied with Mauro’s product requirement it did not project a family resemblance to the chair. Additional modifications were subsequently made to the design which finally attained the desired family resemblance we desired. The early concept shown in Figure 9. captured many of the aesthetic characteristics we sought and was selected for further development.

Continued design development focused our attention on ergonomics which was an important consideration in establishing dimensions, proportions and overall size of the system. We verified clearances between the table legs and chair legs to insure that chairs could be easily tucked under the table. Establishing the height of the table surface and clearance between the underside of the table and child’s legs were also verified. Details between the lid and table base were carefully developed to integrate safety considerations with aesthetics. Light weight and avoidance of pinch points between the lid and table base insured adequate safety of the table without compromising appearance. Discussions pertaining to flatness and surface finish of the double walled table top were conducted with Wheeler Boyce. As we expected the table top was one of the most challenging parts to mold. Ultimately parts were molded flat and with the quality expected for a writing surface. This was only achieved with methodical process control and slight modification to the kiss-offs.

Similar to the chair, stacking considerations had to be included in the design of the table which required special cutouts underside to permit stacking without compromising aesthetics. Additionally fill ports were added to the base of the table legs to permit resin to be poured into the closed mold, as in the chair. A clever feature was added to the table to permit the lid hinge to be assembled as a concealed piece of hardware. This detail is best described in Figure 10.

Since its introduction in 2005, Rimova has been molding the tables and chairs around the clock seven days a week with multi-mold spiders for each. Their huge success with this first venture into rotational molding has encouraged them to expand their product line with new rotationally molded products in new market areas. The unique design for this system has been patented, affording then protection against pirated copies In addition, to patent protection, Rimova enjoys additional security in their intellectual property because of the difficulties in duplicating the complex design which is fully integrated with subtle technological challenges that cannot easily be overcome.