Design Improvement of Pumping Mechanisms in Daily Necessities for Efficient Recycling

This thesis concerns the design methodology that replaces metallic springs with plastic ones, which will improve the recycling rate of plastic products. Although metallic compression springs are inexpensive and widely used in daily necessities such as sprays and soap pumps, the recycling of the plastic products is highly limited because the non-plastic component is assembled in the products. This limitation should be solved because plastic waste becomes major issue especially in the ocean environment. In this thesis, we propose a design of a stable and effective structure for the plastic spring and perform theoretic analysis to confirm the possibility of practical use of the plastic springs. In addition, the spring models with various design parameters are also analyzed using the finite element method in computer aided design software to calculate spring constants and maximum stresses. The analysis results with various parameters are served as a guideline that can be used to design plastic springs with preferred elasticity. The selected 3D models are 3D-printed for prototyping and the spring constants are experimentally measured for validation of the proposed method.