Power cut - machine tool energy efficiency

6 mins read

The improved energy efficiency of machine tools is captured in a new developing EU directive. Andrew Allcock explains what Europe's machine tool builders are thinking and doing in an effort to influence its content (see also online-only Green Production Supplement - link below)

Image, right: CECIMO director general Filip Geerts announces the Blue Competence Machine Tools initiative in February 2012 - see here

The European Union's Eco Design Directive "establishes a framework for the setting of ecodesign requirements for energy-related products" offered for sale in the EU. Machine tools were part of the directive's working plan for 2009-2011.

Already covered by the directive are electric motors, for example, which meant that, in the UK, minimum efficiency requirements (IE2) for electric motors came into force from 16 June 2011. Domestic appliances have also been subject to this directive, as well as its associated Energy Labelling Directive (energy efficiency ratings). The directive is in keeping with the EU's stated aim, as of March 2007, to reduce EU energy consumption by 20% by 2020.

Europe's machine tool association representative body CECIMO (The European Association of Machine Tool Industries) adopted German mechanical engineering association VDMA's Blue Competence model, launching at the European level its Blue Competence Machine Tools initiative last year, in February (described fully here).

A company that wants to participate in the initiative has to meet pre-defined sustainability criteria in its production and business practices, and so makes a public commitment to add value to the economy, environment and society. Such companies can subsequently highlight to their customers and to the public that they are an alliance member of the Blue Competence Machine Tools initiative.

This move follows, and complements, CECIMO's voluntary self-regulatory proposal (SRI) to the European Commission, which it prefers to imposed conditions via the directive, and which it kicked off in 2009 – "the self-regulation concept aims at respecting the potential of individual energy-efficiency measures and the freedom of innovation", CECIMO offers. The organisation's SRI approach is founded on functional modules – not a machine tool as a single entity, as in the case of a domestic appliance, for example.

To be acceptable to the European Commission, such voluntary agreements by industry have to achieve the same objectives as binding legislation (more quickly and at less expense), include staged and quantified objectives, and be open to new participants. CECIMO's SRI sets out to achieve this, of course. (Regardless of acceptance of CECIMO's SRI, any directive will still have provisions for non-CECIMO machine tool makers that, like the Machinery Safety Directive before it, will call for compliance against various criteria.)

ELECTRICITY SHOCKER

At the Blue Competence Machine Tools initiative launch, CECIMO director general Filip Geerts said that, according to a study, 96% of the environmental impact of a machine tool is in its use phase and that, within this, the consumption of electricity is the major factor. And, according to the EU Commission, industrial production accounted for 40% of total power consumption in 2007, of which 70% was used by electrical drive systems. So in-use energy consumption, from drives plus coolant pumps and standby power draw and so on, is the key focus for machine tools.

Image: The various consumers of electrical power in a metalcutting machining centre. Only 20% of the power consumption is directly related to the process; 80% is for auxiliary components – Eco Machine Tools report

A draft standard on machine tool eco-design has already been published – ISO/DIS 14955-1 Machine tools – Environmental evaluation of machine tools – Part 1: Design methodology for energy-efficient machine tools – and CECIMO says that it supports the efforts of the responsible committee, ISO TC 39 WG12. Standardisation underpins CECIMO's focus now on "the definition and the industrial validation of the environmental evaluation criteria for machine tools".

Says Dr Wilfred Schäfer, executive director of VDW, CECIMO's German member association: "The uptake of ecodesign measures in the industry, be it under regulation or self-regulation, will be possible only if standards are available in the marketplace. Standards are a pre-requisite to lend credibility to manufacturers producing energy-efficient products and prove energy performance to consumers."

STANDARDS DEVELOPMENT

The European Commission has also mandated European standardisation organisation CEN to develop standards in support of legislation and it also mandated a study via the Eco Machine Tools project (here), with CECIMO and ISO TC 39 WG12 feeding into this. The Eco Machine Tools report was published last year (here) and the European Commission has now set in motion an impact assessment study, undertaken by Bio Intelligence (here), which commenced in January of this year.

CECIMO says that the Eco Machine Tools study and its own investigations converge towards the conclusion that it is "an enormous challenge to set up standardised criteria for the evaluation of energy efficiency applicable to a large variety of products (machine tools), which at the same time can bear comparable results".

There is a large range of product types (around 400 categories and 2,000 models of machine tool) that exhibit divergent technical features, while this is complicated by the fact that product technical characteristics are determined by and customised to users' needs. Machine tool design parameters are affected by a complex interplay of factors, and this makes comparison of machine tools with different technical characteristics extremely difficult, it is said.

Because of this, CECIMO says that 'one size fits all' energy-efficiency measures may "become futile and ineffective".

A measure that improves the energy efficiency in a machine tool may generate a contrary result when applied to a machine tool of the same type, but which features different technical characteristics and applications.

If they are not chosen carefully, measures for improving energy efficiency may have a negative impact on the performance of some machines, the organisation says.

Explains Jiri Vrhel, technical manager at SST, CECIMO's Czech member association, and expert to the CECIMO energy efficiency working group (CEEWG): "CECIMO's investigations have shown that only selective measures tailored to individual cases and taking into account individual conditions can lead to real improvements in energy efficiency. The common view of the CEEWG is that deciding whether or not a solution is suitable for a given application should be left to the discretion of the machine designer."

The difficulty is amply underlined by Heidenhain in the online-only Green Production Supplement (here). It highlights that, in the case of regenerative power supplies, the benefit, or otherwise, could vary from job to job,depending on the number of toolchanges.

So, even if a machine is tailored for a particular application at the outset, subsequent applications tackled over the life of the machine tool may be very different to this. That being the case, the benefit or otherwise of any measure taken to, theoretically, improve energy efficiency will vary over time.

Indeed, the Fraunhofer Institute, which conducted a 2010 preparatory study for the European Commission, concluded that "ecodesign solutions have to consider conditions of application" and "any option has to be assessed carefully for the intended application."

But the Eco Machine Tools report highlights that there are no big wins to be had. "The assessment of the various technical eco-design measures is based on a survey among machinery and component manufacturers, and complemented by research on technical options. The assessment unveils that there is a multitude of options, each with a small energy savings potential in the range of 1%, but it can be anticipated that a combination of several options could lead to significant total savings." And it adds that, for metalcutting machining centres, "total energy savings potentials at the point of Least Life Cycle Costs are in the range of 3-5%".

Considering three scenarios following a change occurring in 2014, energy savings for all machine tools considered (not only metalcutting) versus a do-nothing, business-as-usual case are put at between 5 and 9% in 2025, depending on the directive's chosen approach. Individual cases could be above and below this, the study offers, since the so-called 'base case' machines modelled in nine machine tool groups are not representative of all.

And the Eco Machine Tools report concludes: "Given the typically long lifetime of the machinery considered, any implemented measure is projected to yield significant overall savings results only over the mid to long term."

FEBRUARY 2014 REPORT

Returning to the present day and the Bio Intelligence impact assessment is expected to be available in February of next year, with the adoption of the directive likely to follow some 18 months, or so, later. However, in the autumn of this year, CECIMO says that there will be a consultation forum, organised by the European Commission, at which a draft report will be discussed, with further CECIMO SRI discussion also possibly on the agenda.

A looming problem highlighted by CECIMO is that the development of standards to underpin any regulatory or self-regulatory approach will lag the adoption of a directive – "When the implementing measures or a voluntary agreement becomes effective, the standards may not be ready."

As to any energy labelling, as per washing machines etc: "The machine tool industry does not support labelling, due to its complexity," the organisation offers.

In the meantime, the Blue Competence Machine Tools initiative moves on, with eight CECIMO national associations and 54 companies across Europe, but mostly from Germany, having jumped on board – the UK's Manufacturing Technologies Association (MTA) being one of those associations.

CECIMO has adopted a document template for use by member companies to highlight their energy-saving/eco-friendly efforts and technologies, although most are currently in the German language. These will be translated and made available at the organisation's Blue Competence webite (here) as they become available, but there are many machine tool companies already highlighting their energy-efficiency credentials, as the online-only supplement reveals.

How interested machine tool end users are is a moot point, however. As the Eco Machine Tools report offers: "Recent survey results show that 'energy efficiency' – despite some outstanding initiatives – is not very important in the marketing of the machine tool manufacturers [so not perceived important to end users]. The important facts are price, cutting speed and innovative equipment." Although it does add that, in the automotive industry, the Total Cost of Ownership approach is considered, however.

Image: How interested are end users in the energy efficiency message? Not much, as gauged by the marketing message priorities of machine tool suppliers

Of course, while we are talking EU-wide in this article, the price of energy, specifically electricity, varies greatly from country to country. The lowest industrial price is €0.06326/kWh, in Bulgaria, with the highest found in Cyprus, €0.16953, or 2.7 times as expensive. In the UK, the price is €0.09895 – ranking 12th out of 27 countries. So economic benefits will similarly vary.

But at this year's EMO exhibition in September (16-21 Hanover), there will be a Blue Competence booth that will see alliance members present their sustainability solutions.

[] The online-only supplement, Green Production, includes news, energy efficiency examples, a machine tool energy consumption analysis and an explanation of the benefits of MQL. Click here

First published in Machinery, May 2013