**4. Best practices and improvement opportunities**

Although energy efficiency improvements adopted along the last 20 years were seen to reduce energy requirements of machine-tools in approximately 50%, the basic guidelines for energy savings during process, such as the specification of most energy efficient components and guidelines for effective energy management during machine-tool processing are still not established. The examples given in the previous section support the two strategies generally proposed to improve energy efficiency: (1) the conversion of hydraulic to all electric systems and (2) the maximization of the rate at which the physical mechanism can perform the desired operation, i.e., the optimization of machine usage.

144 Metal Forming – Process, Tools, Design

equipment, the energy benefits were clear:

energy losses.

technology). Reference is 1 mm carbon steel sheet processing for 1 h.

on the SPE of the cutting process of thin sheets;

bein the same order to that of the control unit.

sub-systems apart from the Laser unit must be accurately specified.

**4. Best practices and improvement opportunities** 

**Figure 4.** Specific process energy (SPE) observed for the Laser cutting process, showing relative contribution of the main sub-systems per equipment type (FL: Fiber Laser technology; CO2: CO2-Laser

Regarding the individual contribution of each main sub-systems in CO2 equipment, the chiller unit of a 4.5 kW machine was seen to be responsible for more than 50% of the energy demand, contradicting the assumption that the Laser source dominates the total energy consumption of these machines (Devoldere et al, 2006). In what concerns to the FL




In resume, FL technology brings down the Laser and chiller energy needs, to the consumption level of standard control/motion units, or even exhaustion systems. In such a scenario of no predominant contributor, and targeting to maximize energy efficiency, all

Although energy efficiency improvements adopted along the last 20 years were seen to reduce energy requirements of machine-tools in approximately 50%, the basic guidelines for energy savings during process, such as the specification of most energy efficient It must be noted that awareness of the manufacturing end-user regarding the importance of energy management should be strongly enhanced. Although widely discussed in different areas, this is a topic that the manufacturing user tends to neglect, regarding each individual machine on his plant, particularly in what concerns technology, process and usage strategies. Independently on the many possible solutions targeting the automatic control of the machine-tool, the user's perception surely determines this optimization. Enabling the user to obtain detailed and real-time data about the energy consumption of the manufacturing process is essential to accomplish the optimization of the machine-tool environmental profile during the use stage, as the user must be actively involved in this process. It is on the side of the machine-tool manufacturer to preview and implement this. On the other hand, and apart from all criteria behind the selection of each individual subsystem on the machine, including its technology, it is on the manufacturer side to match the power demand profile of the main energy-consuming sub-systems integrated, in what concerns the power consumption of the sub-systems, as realised from the Laser cutting study followed.

However, as referred at start, the technology-related improvement potential of a manufacturing process towards benign metal forming must be sustained by an integrated perspective, mainly presenting energy-related technical solutions but notonly, as the contribution of the 3 types of resources listed above is affected, namely the assembly resources, the energy consumption during use and the other consumables related to machine operation, such as the influence of the hydraulic oil to the environmental impact of the bending process, as here demonstrated. Combining these perspectives, and in view of the discussed influence of the machine-tool technology on the environmental impact of the manufacturing process, special attention is here given to the assembled sub-systems of the machine-tool, and particularly to the materials incorporated on these, in which steel has traditionally been dominating. On the other hand, the change in steel pricing policy and current increasing steel cost are pressing overheads and margins at the machine-tools manufacturers and their components suppliers. As the need for alternative materials, less subjected to such market variations, becomes more evident, technical targets, process quality and environmental profile might be compromised. In addition, market has been specifically requiring performance increase, in the sense of higher stiffness, dimensional stability, ease of manufacturing, good dampening properties and high mass to avoid rigid body movements. Some examples of high potential actions enhancing benign metal forming currently being developed and adopted are pointed out in the next sub-sections.
