Product development of a grass discharge

This report includes a bachelor thesis project that has been carried out by Harald Johansson and Simon Wedegård, the project extended over the spring semester 2022 at Jönköping University. The work has been carried out for Cramer Tools and is also a final part of the authors’ education in Bachelor Science - Mechanical engineering with product development and design. Cramer Tools manufactures battery-powered products for landscaping for both professionals and amateurs. Cramer Tools handheld lawnmowers has three different ejections functions for treating the mowed grass, one of which is the side ejection that is located on the right side of the mower and is a function in need of developed. Therefore, Cramer Tools wishes to develop a new side ejection that fulfils the same function as the existing ejection but can be applied on the mower’s rear ejection that is usually used for the collection bag. By removing the side ejection, Cramer Tools can make a closed cover on its existing lawnmowers, which improves the grass flow and makes the mower being able to eject more grass. The goal of this project was to develop a working prototype with high functionality and an ease of use that can be introduced to Cramer Tools product range. The thesis has been carried out through an iterative product development process where the various theories and methods are described to explain the working method. What a final prototype should achieve to meet requirements and wishes is defined in the work that forms the basis for the result. To answer the thesis questions, the project work has used relevant theories for product development and applied methodology that is suitable for continuous testing and validation of development. The tests consisted of both virtual tests of the mower’s airflow generated during use and real tests that validated the developed prototypes. Since the work is carried out during the winter and spring season, grass was only available for the final testing and thus a secondary testing method was created during the project to be able to validate the development. The work results in a final prototype that Cramer Tools is very pleased with, both the performance of the grass ejection and the ease of use of the prototype with a reliable and easy-to-handle mount. Cramer Tools can further develop and take part of the work that will hopefully be useful and introduced in their product range.