inventory or to discard the special tooling. The last decision is about preparing the AM method or not. The cost factors which are considered regarding the cost calculation are:
Production costs Downtime costs Preparation costs of the manufacturing methods Costs associated with inventory Salvage value of inventory
The model is validated by several experts in the field of AM working at Thales as well as experts from Thales’s partners. In addition, the model is verified by means of a discrete event simulation. During this simulation, the demand of parts is simulated and the corresponding costs are calculated. The average results of the simulation are approximately the same of the results of the model. Results Based on the result of the analysis of the model, it can be concluded that AM in combination with the use of inventory of parts, can decrease the life cycle cost of one-off parts. Two case studies of different parts, the protection cover and the sunshade, show the impact. The analysis of the protection cover results in cost savings between 16,07% (€67.000) and 17,06% (€72.000). It must be noted, a cost saving of €38.000 (8,42%) is a result of the use of inventory. So, only looking at AM results in a cost saving between €29.000 (7,65%) and €34.000 (8,64%). The analysis of the sunshade results in cost savings between7,14% (€5.500) and 9,55% (€8.000) over a period of 30 years in case we use AM during the after-sales phase. The cost savings of AM are a result of the use of AM, since no parts are put in inventory. The cost savings are dependent on the current way Thales deals with its special tooling. Is special tooling discarded in the optimal way, or does Thales apply their own discarding strategy. From the sensitivity analysis, four parameters turned out to be sensitive towards the outcome of the model. The most important parameter, is ‘the variable production costs of the AM method’, the other three are the life cycle length of the analysis, the demand rate of a single part per period, and the acquisition price of special tooling. In case the value of the variable production costs of the AM method becomes almost equal to the variable production costs in case of CM, AM will be used for the production of parts during the after-sales phase as well as for the production of parts within the initial phase. At that moment, AM will replace CM completely for that type of part. Regarding the protection cover, the variable production costs in case of CM have be declined after 6 years to the value of €5.678, where production will only take place by means of AM. This results in cost savings between 23,99% and 24,88%. Regarding the sunshade, the variable production costs in case of CM have be declined after 3 years to the value of €1.135, where production will only take place by means of AM. This results in cost savings between 16,88% and 19,50%. Regarding the other sensitive parameters, we can conclude that:
The use of AM results in higher cost savings if the life cycle length of the analysis increase The use of AM results in higher cost savings if the demand rate of a single part per period increase The use of AM results in higher cost savings if the acquisition price of special tooling increase ii Unclassified