Modelling of the life cycle of products with data acquisition features

Domestic appliances are long-lived and relatively expensive products that come under the new EC electrical waste recovery directive. In the UK, washing machines in particular tend to be unreliable; increasing the reuse of components could improve the economics of end-of-life operations. Trends in appliance design are towards more sophisticated control and networking; this makes adding functions to record data on the use of the machines feasible. The data would also have value for life cycle environmental assessment. This paper reports on the development of self-contained data acquisition units for washing machines based on a microcontroller and non-volatile memory. The data has applications in design, marketing and servicing as well as end-of-life. A batch of units have been manufactured and tested on limited field trials in washing machines. Ten parameters are continuously monitored, timed and/or recorded during appliance operation; error conditions are also logged for use during servicing. The data is then downloaded, either during servicing or at end-of-life; the dynamic data from use is combined with static data from manufacture. The information system which links all parties interested in the data is the key aspect of life cycle data acquisition. Two models are described which evaluate the economic benefits of adding such functions to products: a steady-state model as used by previous authors who were concerned with end-of-life product treatment and a more sophisticated transient model that accurately reflects the limited life of designs. Results show that in this case, more reusable components arise from servicing rather than from end-of-life recovery of parts. The cost savings from increased reuse are also estimated to be comparable to the additional cost of the system; greater savings could well arise from the use of the use data in marketing.