Having purchased, outlasted, or excelled over all of its competitors, Stern Pinball, Inc is the only manufacturer of coin-operated pinball machines in the world. Housed in a single, 40,000 sq ft building in Melrose Park, IL, the company enjoys an exclusive market position, thanks in large part to a tradition of technological innovation. Today's pinball games are designed using sophisticated computer simulation software, including Algor's finite element analysis (FEA).
Stern's four mechanical engineers and numerous designers use 3D modeling tools to create many game parts in state-of-the-art pinball machines that include English, Spanish, French, Italian, and German voice and visual language response. Each new game takes about a year to design, and the designers challenge themselves with competition among design teams to develop innovative, exciting new games, such as its recent Grand Prix pinball machine.
Recently, the designers ran into problems with a mechanical assembly that was failing during use in one of the games. The part, known as the "drop-target assembly," consists of a plastic target that retracts beneath the playfield when struck by the solid metal pinball. The idea of the game element is to strike the target and then redirect the ball up the ramp to score points. In the new game, the drop target was placed, without backing, in front of the ramp. When struck by the ball at near-maximum speeds, the testers found a high incidence of breakage in the target.
Mechanical Event Simulation (MES) and Real-World Pinball
John Rotharmel, Stern project engineer, designs most of the games' unique elements. From his experience using FEA software, Rotharmel knew that Algor would be necessary for dynamic analysis of the moving target. He purchased a personal copy of Algor to evaluate the drop-target design and showed his design to Stern Pinball's president, Gary Stern.
Recognizing the value of Algor analysis, Stern asked Rotharmel to investigate the product more thoroughly. Convinced that Mechanical Event Simulation (MES) software was necessary, the company purchased Algor Professional MES, which combines large-scale motion and stress analysis and includes linear and nonlinear material models. The combination of motion and stress analysis considering full inertial effects allows engineers to see motion and its results, such as impact, buckling, and permanent deformation. Having never before used MES, Rotharmel was pleasantly surprised at how easy it was.
"It was simply a matter of knowing what parameters to use to set up the model, how to make sure you choose the right components for the assembly, how to test the proper criteria using comparative analysis, changing the ball velocity, and so forth." After experimenting, he quickly began to model and analyze the action of the ball against the target.
Around the same time, the company also purchased a high-speed video camera. Rotharmel recorded the action of the ball as it struck the drop target. Stern engineers then compared the high-speed video with the analysis results. After several iterations, Rotharmel realized that he had successfully modeled the event quite closely.
"The event in Algor and the real-world event were remarkably similar," said Rotharmel. The company was able to confirm that the drop target needed to be strengthened before use in one of its recent games.
Redesigning the Target
Using the analysis results, the part was entirely redesigned. In fact, the new target assembly barely resembles the previous part. The hardware was changed, and while made of the same material, the target itself was flattened and simplified. Using Algor, Stern engineers also cut the cost of designing and engineering the part.
"We are the only game in town, but we never want to be complacent about our product," said Rotharmel. "Algor helped us keep our commitment to quality, innovative, and robust games that challenge game users but won't break during use."
