Milling machines could consume less without their productivity being compromised

This Tecnalia researcher set out to design an eco-efficient, high-volume milling machine, but without compromising its productivity: “Normally, the aim of these designs is to make the machine as solid as possible. But that is not the case in my model, and this signifies a profound change in this area.” He has reduced mass in order to give priority to dynamism, and in this way has cut consumption by 20%. He submitted his thesis at the University of the Basque Country (UPV/EHU) under the title Metodología para la concepción de fresadoras de gran volúmen productivas y ecoeficientes (Methodology for the conception of eco-efficient, high-volume production milling machines). This innovative approach has also been applauded by the highest-impact journal in the sector (International Journal of Machine Tools and Manufacture).

Large-volume milling machines are about three or four metres high and 10-15 metres long. They are used to produce large-sized parts, like supports for railway carriages (‘boogies’), for example. Equipment of this type tends to be heavy and unwieldy, difficult to move, and that is why it consumes a large amount of energy in these tasks. That is what Zulaika’s research has focussed on. For example, if the machine has a column weighing five tonnes, he has set about making it lighter and leaving it at three or four tonnes: “If I reduce the weight of the machine’s components by 20%, the energy reduction is proportional.”

Productivity, the starting point

There have basically been two limits on these weight reduction tasks: the risk of weakening the components too much and having to maintain the same productivity. There lies the crux of the research, since Zulaika has created an innovative simulation model to establish and find out these limits in advance. It is innovative, because the aim is productivity, and all the rest is built up on the basis of this: “I have incorporated the dynamics of the machine and that of the process into an inclusive model. I decide what the aim is as regards productivity, and the model tells me what limits the milling machine has. It is as if a doctor were to diagnose the machine: we are told which components are too robust and which are too weak.”

What is more, this researcher has applied the simulation model he has created to a real milling machine, thus verifying its usefulness. Specifically, the model has enabled him to develop a new machine four metres high for a company in the sector. The results have exceeded expectations.

Firstly, Zulaika carried out a diagnosis of this new milling machine, and to do so, took as the starting point the level of productivity of the machine used previously at this company. Following the indications of the simulation model, he reduced the weight of the parts of the machine that were too robust and reinforced the weakened ones, thus achieving a 20% reduction in its mass. But he also added shock absorbers to cushion the jolts between the components when the milling machine is working. Thanks to this complementary measure, productivity has not only been maintained but also increased. “The aim in itself was to maintain productivity and to cut energy consumption; that is sufficient for any company. But in the end, when the two measures were combined, the results were better than expected,” explains the researcher. In comparison with the machine previously used at this company, productivity has increased 100% in the best tests. There they now work with the new optimised milling machine made possible by the simulation model.

About the author

Juan José Zulaika-Muniain (Zarautz, Basque Country, 1971) is a graduate in Industrial Engineering (University of Navarre) and a Doctor in Mechanical Engineering (UPV/EHU). He wrote up his PhD thesis under the supervision of Norberto López de Lacalle-Marcaide, Professor of Manufacturing at the UPV/EHU. The research was done at Tecnalia’s Industrial Systems Unit. Work was also done in collaboration with the company Nicolás Correa S.A. of Burgos (Spain). Zulaika currently works as a researcher at Tecnalia.