Process-based cost modelling for gas induced semi-solid-processed below-knee prosthesis

Below-knee prosthesis is much needed in Thailand and the world over because it serves as a close substitute for a missing body part (e.g. a device to aid people with paraplegia). Production of these components by gas-induced semi-solid process is relatively new, and investors need to be assured of success before committing themselves into a venture. Most cost models, such as the activity-based model, have flexibility limitations, and hence more input-sensitive – the process-based cost model (PBCM) – is alternatively employed in analysing more simple work process, appropriate production volume and unit cost, and was utilised in this research. An array of production volumes (5000–100,000 sets) and a number of daily work shifts (1–3) were investigated. From detailed breakdowns, analysis results suggested an optimal annual production volume in the range of 10,000–40,000 sets employing any shifts per day. Below 10,000, unit cost escalates very sharply, and beyond 40,000 it decreases only marginally. Production for export purposes is feasible since the annual domestic requirement in Thailand is only a fraction of this volume. PBCM had also proven an effective tool in this case.