Mechanical Behavior Characterization of Helical Extension Springs Manufactured in Ecuador

The design and manufacturing of helical extension springs in Ecuador do not adhere to technical parameters that meet the requirements of the machinery in which they are employed. Several factors contribute to this issue. This study aims to characterize helical extension springs produced by various factories across the country by establishing characteristic curves. These curves will enable designers to estimate the mechanical behavior of springs produced on demand. We designed four springs, incorporating two spring rates (C) and two wire diameters ( \(d\) ). We selected eight made-to-order spring workshops located in different cities in Ecuador. We requested each workshop to manufacture three specimens of each model, resulting in a total of 96 springs. From the load-displacement curves obtained during testing, we estimated the stiffness coefficients and preload forces. Subsequently, we calculated the torsional stresses resulting from the preload and compared them with theoretical values. Our findings suggest that tension springs produced on demand in Ecuador, on average, exhibit stiffness constants close to the expected (theoretical) values based on the design. However, there is a considerable dispersion in these values, making it difficult to have confidence that randomly choosing a factory will yield springs meeting the desired specifications. Additionally, these workshops typically do not consider the initial load as a critical parameter in their manufacturing process. Consequently, the observed initial load appears to be an uncontrolled byproduct of the manufacturing process, rendering it impossible to rely on obtaining the required initial load for technical spring design.