Tolerance Allocation Considering Multiple Phases of the Product Life Cycle for Optimum Cost, Performance, and Sustainability Using the HEIM Framework

Abstract

Tolerance allocation is usually considered only at the stages when designers are designing the product and manufacturing/process engineers are forming a process flow for manufacturing the product. In this paper, the tolerances for a product are allocated considering the most crucial stages of manufacturing, quality, use, and reuse stages of a product life cycle. This approach helps to sustainably allocate the tolerances. A framework with an example of alternatives with attributes - cost, performance, and sustainability is discussed to achieve the intended tolerance allocation by considering multiple stages of the life cycle using the Hypothetical Equivalents and Inequivalents Method (HEIM). HEIM allocated the weightage to different parameters. In this case, HEIM is used to give weightage for different stages of the product life. This helps to allocate the tolerances with due importance to each stage. This is the main contribution of this paper as the application of HEIM for tolerance allocation is not found in the literature. Extending this framework to products like mobile phones, laptops, watches, etc. would help to avoid the redesigning of the product in the future for making it efficient in terms of cost, performance, and sustainability. Also, using this concept products can be reused with liberalized tolerances to obtain the same performance as new ones leading to cost savings and improving the sustainability of the product. The proposed methodology was used in the present work to estimate the tolerance for the least cost of manufacturing a product.