Pressure-sensitive fasteners for active disassembly

Abstract

This paper presents a number of novel active fasteners developed to significantly lower disassembly costs during reconditioning, remanufacturing, and recycling of products. In the initial stage of the fastener development process, the applicability of distinct trigger signals for active disassembly (AD) is evaluated. Based on this evaluation, the high robustness of using a pressure increase or decrease as a nondestructive trigger for AD is demonstrated. Since previously proposed pressure-sensitive fasteners face considerable drawbacks upon implementation in electronic products due to the ongoing trend of miniaturization, a second generation of pressure-based active fasteners is developed. Evaluation of these fasteners by means of axiomatic design techniques and prototyping demonstrates that the presented snap-fits, which make use of a closed-cell elastomer foam, are most robust. Subsequently, the contraction forces that closed-celled foams can exert as a function of an increase in ambient air pressure are experimentally determined. Furthermore, the implementation of pressure-sensitive foam-based snap-fits in both a modem and a payment terminal is described. Results of these experiments demonstrate that the contraction force of a cross-linked metallocene polyethylene closed-cell foams can reach up to 6 N/cm 2 at an overpressure of 2 bar and that the foam-based snap-fits can be released at a pressure increase of 2 bar.

Ease of disassembly of products to support circular economy strategies

“…However, design for disassembly strategies as the one previously analysed should be carefully checked with manufacturing companies and designer in order to prove its feasibility for the considered product. Furthermore, eDiM can be used to identify other improvements, such as enhanced connector visibility, reduction in the number of components or the use of innovative fasteners, such as the ones proposed in ( Peeters et al, 2015a , Peeters et al, 2015b ). Concerning criteria for DfD, designers could set specific time thresholds for certain key components, especially those commonly replaced during the product use phase, repair and/or components that are likely valuable to be reused and/or remanufactured and/or components that should be extracted at EoL because they contain hazardous substances or critical raw materials.…”

Design, management and control of demanufacturing and remanufacturing systems

“…Another relevant enabling technology in this area is the development of reversible and detachable joints for active disassembly. In manual disassembly localizing fasteners typically accounts for one to two thirds of the disassembly time depending on the product category [53,210]. Visual localisation is also in conflict with the trend towards miniaturisation and the increasing aesthetics requirements for many categories of products.…”

“…Temperature Pressure [210] Impulse [212] Working principle a random variable. It mainly depends on static parameters (the kind of process, the number and geometry of tools, etc.…”