**Author details**

148 Metal Forming – Process, Tools, Design

**5. Conclusion** 

**4.4. Selection of sub-systems technology and power matching** 

auxiliary main-systems against the main energy-source sub-system.

savings are maximized with the increase on system usage.

such as the energy per bending cycle proposed for bending.

use-phase of the machine-tool life-cycle.

As concluded from the study on Laser cutting, although the sub-systems dimensioning and energy-consumption could be individually optimized for a specific range according to the application conditions, these are quite technology dependent. Besides, considering that one same machine-tool model typically operates in very distinct operating modes, it is important to insure that all sub-systems are properly synchronized in each operating condition, and the respective power-consumption profiles should be matched. This is expected to contribute significantly for the reduction on the power demand and improved efficiency of

Besides the evidences coming from the laser case analysed, the impact of the motor power to the SPE values of the bending case also reflects some needs for improvement. Although the energy models presented are able to be tuned for different motor rated power levels integrated in press-brakes of different maximum bending capacity, this is indirectly associated to the maximum loading capacity of the machine. Obviously, in order to minimize power consumption, the motor rated power installed should be as low as possible, as made evident when comparing hydraulic systems (Table 1), where the lower motor rated power of the former resulted in over 49% energy savings when comparing a 110 t equipment with that of a 170 t equivalent. Moreover, in these hydraulic systems, where the stand-by consumption contributes significantly to the SPE, the motor power related energy

The environmental impact of a manufacturing process is strongly determined by the basic features associated to the characteristics of the machine-tool selected to execute the process. The analysis of the machine-tool assembly is supported by the inventory of all substances used as components' materials or production consumables. In addition, the analysis of a specific manufacturing process corresponds to the collection of all substances used during utilization of the machine. In a full LCA of the machine-tool, this would correspond to the

Machine-tool technology is the factor determining the assembly components type, amount and arrangement, and consequently the energy consumption profile of the machine, which rules the environmental performance of the manufacturing process. Modelling the energy consumption of a process firstly requires an adequate process categorization based on the technology of the main functional sub-systems. Other categorization criteria, such as the utilization mode, are also interesting, but more extensive work is needed to validate and reveal the most relevant sub-categories and associated environmental features. Attention should also be paid to the exergy reference unit used to define the specific process energy indicator. In the case of pure metal forming processes, which includes a set of chiplessshaping processes, some applying only discrete loads, typical units based on the amount of material removed are not appropriate. In such cases alternative units can be introduced, Marta Oliveira *INEGI – Instituto de Engenharia Mecânica e Gestão Industrial, Portugal* 
