Bad Boy Mowers used an eight-piece steel weldment, fabricated internally, for its trailing arm on its Commercial Zero-Turn Mower. However, the fabricated weldment’s strength did not withstand impact testing. Impact tests showed that the welded axle would bend under extreme impact causing overall durability and assembly issues. Additionally, because of the many components of the weldment, the fit was never perfect, resulting in gaps. Due to the extensive manufacturing of the eight part numbers, production and management became difficult to manage and complete correctly. The company realized that by converting the weldment to a casting improved the overall quality, reduced warranty costs and improved assembly.
Tooling engineering at Waupaca Foundry led the design of the casting. As a proactive measure, assembly models were used to compare the 8-piece weldment to the single ductile iron casting prior to production. Additionally, Waupaca Foundry developed the casting models before moving forward with the project. Bad Boy Mowers recognized the improvements the casting would have on its operations and approved tooling to start on the project.
The VA/VE collaboration between Waupaca Foundry, Diamond Precision and its customer Bad Boy Mowers helped position its Renegade, Renegade Diesel and Rogue Commercial Zero Turn Mowers with new rear suspension as best on the market.
The rear suspension features a cast 3-link trailing arm—the first and only of its kind in the industry. Matched with front suspension arms, the result is a smoother ride, more consistent tire contact and increased hillside stability for the consumer.
By converting the 8-piece trailing arm to a single ductile iron casting part offered several benefits:
- Although weight increased slightly, the single ductile iron part strengthens the trailing arm and improves overall wheel stability.
- While the weldment trailing arm would bend and twist upon impact; whereas the casting performs under continuous, rigorous commercial use and has zero warranty claims.
- The single ductile iron casting is more efficient on production scheduling and also opened up laser and welding assets for other fabricated components at Bad Boy Mowers.
- The consistency and replication of the casting is more precise, therefore enhancing fit and function of the rear axle.
Through open communication, development and realization of the quality of ductile iron, this project eliminated Bad Boy Mowers’ current issues and exceeded their quality expectations. While a change in the makeup of a part may be intimidating, the conduciveness of the product design to one single part emphasizes the abilities iron castings have and the production complexities it can eliminate.