Because the WALL-E from the movie has been around for a long time, his body had been weather worn and beat up by the work he does – compacting trash and stacking it neatly. Computer animation allowed animators to create the look and feel of a well-worn WALL-E, but transferring that same look and feel to a ‘real’ robot was another story.

Pixar utilized sophisticated computer graphics to create the digital representation of this fun-loving robot. This digital data was well suited for rapid and precise fabrication of all of the external covers that comprise WALL-E. Although, the covers could have been created in a number of ways, the Disney Imagineering team chose to have the parts created on an SLA rapid prototyping system (see sidebar on the SLA process)

The form, fit and overall appearance of the prototype SLA covers were validated with a working robot. The final covers for the traveling robot needed to be significantly tougher than the initial SLA covers. Advanced cast urethane covers were reproduced using a silicone tool created from the SLA masters. The cast urethane process has been accomplished a number of ways by a variety of companies. Although we don’t have information on which method was used for the job, here’s an explanation of what the process might look like.

General practices for secondary processing of the master might look similar to what some services do for their customers. Here’s one method that may be used: First prepare a master pattern — created using SLA, CNC, or PolyJet technology — that is worked to a desired surface finish. Then carefully position tape in specific areas to create joint or parting line to assist with cutting the pattern out of the mold.

After this step, a mold box is built to enclose the master pattern. The box size is minimized so that the poured Platinum-based Silicone material is not wasted. The master is elevated off the floor of the box to allow the Silicone to surround the master. The material is allowed enough time to cure and then the cured mold is cut into two halves and the master pattern removed.

A two-part polyurethane liquid is mixed and then poured (with a proprietary pressure differential) into the mold. The polyurethane filled mold is then placed into a proprietary pressure oven and the final cast polyurethane part is allowed to fully cure thus achieving maximum mechanical properties. Finally, the top half of the mold is removed and the final cast part is removed from the mold.

The stressing and rust texture for WALL-E was reproduced from the animated production using paint. “Exterior components – including the treads and details on the inside of the WALL-E camera eyes – were based on the movie data and placed ‘on-model’ to look as authentic as possible,” according to Akhil Madhani, Principal Technical Staff Director for Walt Disney Imagineering Research & Development.

“For motion, the tracks are driven using custom designed brushless DC servomotors, which operate through planetary gearheads,” Akhil said. The remaining motors are standard brushed motors using a variety of reduction mechanisms. All the mechanisms themselves were custom designed, including the tracks and treads. As with WALL-E’s panels, the tread texture was copied from the movie models.

Control software, as well as all the animation software, was written in-house at Disney and Pixar. This includes the system that allows the company to play Pixar-created animation on the physical robot in order to maintain its character.

Designing the ‘real’ WALL-E was, as many Disney projects, highly proprietary, allowing only for general information to be discussed. Akhil did say that “every part of the system, including electronics, was included in the CAD model.” His team used Pro/engineer CAD software for design.