As the drive for energy efficiency increases, auto manufacturers are scrutinising every shopfloor process
The automotive manufacturing industry is a massive user of energy. The US industry alone consumes 800 trillion Btus per year, according to estimates by the US Department of Energy (DOE). In its ‘Energy Use Benchmarking in the Automotive Supply Chain Case Study’, the DOE stated that 12% of automotive manufacturing energy is consumed by OEMs during assembly, while 88% of energy consumption occurs in the supply chain. Developing more energy-efficient processes is therefore vitally important as energy costs continue to rise.
“Conserving energy through more efficient processes, technologies, and products is the fastest way to lower energy use in automotive manufacturing in the near term," said the DOE. "While many manufacturing facilities today are modernised and relatively efficient, significant opportunities remain to reduce energy demand via innovation and R&D.”
It is well understood that energy is lost during the manufacturing process through waste heat and rejected parts that need reprocessing, but looking closely at the key stages of automotive production reveals a number of areas where energy efficiency can be improved. One good example is materials and component processing. Welding, for instance, can be enhanced to reduce energy consumption and improve production volumes.
Systems are now available to collect and analyse data on actual energy consumption and therefore how manufacturing processes can be improved to deliver savings. For example, CNC machines from Bosch Rexroth include monitoring software that gives visibility on energy usage, and this data also feeds into smart design applications that can influence how production processes are evolved.
Enser continues: “The semiconductor production fabrication facilities are high-energy consumers. Companies in this industry invested in new equipment, consolidated facilities and implemented an annual energy audit together with a monitoring and reduction programme. They commit to annual goals as an industry and make plans to continuously reduce energy consumption to achieve those goals.”
What is clear to all automotive manufacturers is that their facilities have to radically alter if they are to become significantly more energy efficient. A number of technologies are developing to deliver the ‘smart’ factory that can understand the current workflow and modify its manufacturing processes to achieve big energy savings.
The paintshop is responsible for the highest emissions of volatile organic compounds (VOC) and CO2, and for consuming 50% of the energy used in a typical automotive plant. The paintshop has therefore been the focus of much attention when energy efficiency and production are considered in combination.
Some of the most advanced paintshop facilities today have been developed by Dürr. The company has an ‘Eco+Paintshop’ initiative whereby all systems and products are “combined in a holistic, sustainable concept which consistently focuses on efficiency in all sections of the painting process”. A spokesperson for Dürr explains the benefits of its EcoDryScrubber equipment: “This technology, which makes air re-circulation in the paint booth possible, reduces the annual energy consumption of a fully automated paintshop by up to 16m kWh. At the same time, the CO2 emissions are reduced by up to 5,200 tons.”
EcoDryScrubber, which features in more than 70 painting lines worldwide, reduces the energy consumption in the paint booth by up to 60% and uses limestone powder to separate the overspray; contrary to conventional wet separation systems, no paint sludge is produced. When the limestone powder reaches a defined degree of saturation, it is replaced automatically and can be re-used in cement mills. This level of system and process integration is being adopted right across the automotive manufacturing industry.
Dürr’s holistic approach has been expanded to include Eco+Speed and EcoSmart AC. The former is based on the understanding that for high levels of energy efficiency, production must be integrated to include sub-systems, with the latter controlling air intake and circulation. Furthermore, ‘energy on demand’ is possible to control the fresh and exhaust air volumes dependent on the number of car bodies in the oven. The result is a process-optimised airflow and thus reduced energy consumption during break times or fluctuations in capacity utilisation.
Process innovation
In a recent report into sustainability, the UK’s Society of Motor Manufacturers and Traders (SMMT) outlined how one vehicle-maker is tackling the growing need for processes to be much more energy efficient. In 2013, Toyota identified the reuse of waste machining coolant from aluminium swarf as a means of reducing environmental impact. The OEM therefore implemented an extra filtration system to recover and return waste coolant directly to the engine block and head machining lines.
According to the SMMT: “As a result, the coolant consumption was reduced by 38%, lowering the coolant make-up water by 5.5% and the wastewater treatment volume by 11%.” Toyota also achieved a cost reduction in raw materials and processing costs of 15%. “The maintenance team’s achievement and other similar initiatives are being recognised by Toyota’s eco-kaizen awards and showcased to peers and company directors,” said the SMMT.
This is just one example of where a company has identified a clear energy drain and developed a new process to combat it. Understanding the part that energy plays in each primary and sub-process is critical for all of today’s automotive manufacturers, not only to attain long-term production efficiency but to remain competitive. With global production continuing to increase, developing these energy-efficient systems is a commercial imperative no manufacturer can ignore.
Mike Lomax, head of project management at Bosch Rexroth, says: “End users must understand that the lowest headline price for a machine may not be the most cost-effective solution in the long term. The energy needed to produce each component may be higher with one OEM than another. This cannot simply be calculated by looking at the installed power of the machine in kW, multiplied by the running time and divided by the production rate, as small changes to the process may dramatically reduce energy use per component.”
Todd Montpas, automotive and tyre market development manager, Rockwell Automation comments: “When OEMs begin to develop their standard processes, energy is always one of the design criteria. They include various factors in their calculations including energy-efficient motors, data-centre power and energy usage. These are all part of the design process considerations now, and that increased awareness and monitoring is an improvement from ten years ago.”
The concepts and practical application of Industry 4.0 are also influencing the development of energy-efficient manufacturing processes, as Sanmina’s Enser explains: “Changes in production equipment are providing Industry 4.0 concepts, such as energy-saving features and M2M interfaces, allowing production engineers to design production processes which are much more flexible. This enables the management of machines in cluster groups to optimise energy efficiency. It also permits sub-sections of machines to be placed in standby mode, reordering of production schedules to optimise overall energy efficiency and complete production process redesign to take advantage of new equipment capabilities.”
He concludes: “Today, production process engineers focus not just on throughput, quality and repeatability but also on energy efficiency.”
Dynamic manufacturing
Cyber-physical systems (CPS) allow manufacturing processes to be optimised on a case-by-case basis across the entire value network. Moreover, rather than requiring a stoppage, systems can be continuously optimised during production in terms of their resource and energy consumption or reducing their emissions.
In the manufacturing environment, CPS comprises smart machines, storage systems and production facilities capable of autonomously exchanging information, triggering actions and controlling each other independently. This facilitates fundamental improvements to the industrial processes involved in manufacturing, engineering, material usage and supply chain and lifecycle management.
"Intelligent planning and automation software promises future savings of up to 50% by smoothing the movements of manufacturing robots in bodyshop and assembly.”
In its assessment of the role energy efficiency plays in the US automotive manufacturing industry, the DOE concluded: “Integrating energy efficiency into process and vehicle design is a priority. There are various ways that processes could be condensed or redesigned to remove inefficiencies. At the front end, when vehicles are designed, energy-efficiency considerations could be better integrated into design methods. Some design concepts that could be considered include consolidation of parts and components, design for re-use and recovery of parts and/or materials, the use of net shapes, and vehicles that require fewer process steps to manufacture."
So what of the future? Mary Burgoon, market development manager, sustainable production, power generation and energy management, Rockwell Automation predicts: “Over the next decade, price pressures will force companies to drive inefficiencies out of their activities in order to stay competitive. To remain competitive, nothing can be isolated anymore; a connected enterprise will be crucial for business growth.
“This type of environment can enable companies to correlate electricity, steam, water, etc and show the return on energy to produce profit – where things are most efficiently being made with the highest conversion. This connectivity makes collecting and monitoring data easier, and gives automotive companies a clearer look into their production process and ways to better manage energy use.”
The adoption of product lifecycle management (PLM) has reached a level of maturity that now delivers real benefits. From a production point of view, this detailed understanding of each production process and the part that energy plays enables the automotive manufacturing sector to constantly evolve its processes.
In fact, PLM is about to move to an entirely new level of integration and insight thanks to the Internet of Things (IoT) that will find its way into every machine process across the plant. Energy then becomes a component that can be managed with precise control. The ‘smart’ factories of the future will be fluid environments which change to meet demand and consequently efficiently manage their energy consumption.
Siemens UK & Ireland
Steve Barker (SB): The automotive sector has been extremely active in the pursuit of improved efficiency and productivity – looking systematically at new materials, manufacturing systems and processes. It also closely recognises the energy benefits of reduced wastage and scrappage and the analysis of the complete energy and carbon profile through the lifecycle of the products.
AMS: How have OEMs and tier suppliers developed their production systems to reduce energy use?
SB: This is seen especially around collaboration to develop and optimise new components and materials that require less energy to integrate into the final products. It needs to be encouraged by the manufacturers as there may be a tension between developing lower energy components if that compromises costs – even if the overall lifecycle benefit is to the advantage of the manufacturer.
AMS: Where do you think the next innovations will come in energy management and efficiency?
SB: There are still further opportunities to reduce energy consumption by the adoption of sophisticated energy analytical tools, which can identify improvement measures that otherwise go undiscovered. The further use of simulation software techniques can accelerate the development of improved energy-efficient processes and techniques, together with better exploitation of low-cost and effective control enhancements such as PROFIenergy.
AMS: How is the intelligent factory concept influencing the development of production processes?
SB: The intelligent factory provides the ideal platform for optimising energy performance with the potential to link intelligent analysis and control to provide the optimum energy efficiency whilst maximising productivity. Eighty per cent of energy savings come from ‘control’, so using the available intelligence to influence the control strategies for both the manufacturing and infrastructure facilities is essential to maximise energy performance.
There is still room for improvement in the integration of energy management into the overall manufacturing strategy. Key is the correct level of transparency of all energy consumption across the entire facility. This then enables the necessary analytical techniques, which can adapt to different manufacturing processes and conditions. There may be some remaining opportunities to focus on the wider infrastructure – lighting, compressed air, HVAC systems, hydraulics, building management, heat recovery etc.”
