SINUMERIK – Production with a focus on energy efficiency

CNC4you

With resources being scarce, "achieving more with less" is the order of the day. Legislators around the globe – especially in the European Union – are tough when it comes to sustainability. The extent to which companies are impacted can be seen in how contracts are awarded in the public domain. This is reflected in the fact that almost all large industrial corporations have made CO2 neutrality one of their top priorities.

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Climate-neutral supply chain by 2050

Siemens will significantly reduce its CO2 emissions. Actions speak louder than words, and this doesn't just apply to their own factories. The company is also scrutinizing sustainability in its own supply chains. "Annually, we purchase goods and services to the tune of 28 billion euros, and that's a strong lever," stated Siemens sustainability boss Jenny Bofinger-Schuster at the end of 2021. Siemens intends to reduce CO2 emissions in its supply chain by 20 percent by 2030 and be climate-neutral by 2050.

 

A central element to achieve this is green electricity for climate-friendly production. Complete independence from fossil fuels can probably only be achieved in the medium to long term due to the sharp increase in demand for e-mobility. Higher energy efficiency in production is therefore just as indispensable as it is effective for CO2 emissions. Car builder Daimler issued the following statement in its 2020 sustainability report: "It is important to us (for example) that production systems can be switched off during breaks and non-operational periods – and that they can also be operated efficiently under partial load conditions."

Sustainability with SINUMERIK

This places energy-intensive production with machine tools under particular scrutiny – in the production facilities of large companies and in downstream supply chains. Siemens Machine Tool Systems therefore places topmost emphasis on energy efficiency. Experience gained from using a wide range machine tools in their own factories – for instance, in the fabrication of servo and spindle motors – consequentially flows into feature specifications drawn up by product development. As a consequence, SINUMERIK CNC equipment packages, as well as Siemens CNC shopfloor management software, play a significant role when boosting energy efficiency and ensuring sustainable production using machine tools. 

Efficiency of almost 97 percent

The energy efficiency of machining processes can be measured. Energy usage in the main drive of the CNC equipment package is used to apply the machining force and to accelerate and move the various masses in the machine tool. Here, machine, tool and coolant manufacturers can play their role in making improvements. SINUMERIK equipment packages are optimized for maximum energy efficiency in the factory. This not only applies to energy costs. The transfer of heat into machines must also be avoided in order to guarantee high precision in the machining process. The SINAMICS S120 drive system has an efficiency of almost 97 percent at the rated load operating point. SIMOTICS spindle induction motors achieve up to 92 percent, while synchronous spindle and feed motors achieve an efficiency even up to 94 percent. It's tough to improve on these high values.

 

Surplus energy, for example when braking, is immediately reused in the machine. Energy is injected back into the line supply if the machine cannot use the surplus energy at that specific time. The result is that the reactive power of the complete machine can be fully compensated (cos phi = 1). This not only reduces the energy costs of the machine, but also reduces losses in the upstream line supply equipment.

Auxiliaries – the real energy guzzlers

According to a study carried out by the TU Darmstadt, over the complete lifecycle of a machine tool, the energy costs related to the actual machining process – the main drive of the CNC equipment package – only represent approximately 20% of the overall energy costs. Auxiliary equipment has a far higher energy consumption. Auxiliary drives for hydraulic systems, coolant pumps and chip conveyors represent 80 percent of the energy usage. Siemens also offers energy-efficient solutions in this domain: SIMOTICS low-voltage motors with an efficiency of up to approximately 97 percent and SINAMICS frequency converters, which can be used to efficiently control standard motors in the partial load range.

Shortest non-productive times

The base loads of auxiliaries during times where not a single chip falls have an especially negative impact. And specifically then when the machine is being set up or when it is non-operational. Reducing idle times – or even avoiding them in the first place – is one of the most important measures when it comes to reducing the energy consumption of a machine. SINUMERIK equipment packages as well as Siemens CNC shopfloor management software both provide intelligent solutions.

Intelligent standby as part of the solution

PCs and notebooks have already had this feature for a long time, and Siemens has now implemented it for machine tools – the hibernation mode: A machine that is not used during work breaks or in the unmanned late shift after the last job can be shut down. The same applies to auxiliary equipment. With SINUMERIK Ctrl+E, machine OEMs have a predefined application interface available with which the machine can be transitioned into the hibernation mode step-by-step. By pressing key combination Ctrl+E at the SINUMERIK control panel, operators can manually shut down energy guzzling auxiliaries and even measure the energy consumption. An energy measuring instrument in the control cabinet transfers the energy usage per workpiece and provides the basis for optimizing the energy of the complete machining process.

Speed saves energy

Setting up times for machining jobs have a significant impact, especially for universal machining centers used to machine small series and individual parts. The base loads of auxiliary equipment represent the large energy guzzlers. SINUMERIK Operate with its one touch philosophy to quickly set up machines shortens this process. In many cases, the CNC is programmed with the protective doors open, which is why it should always be performed in the job planning process. SinuTrain or Run MyVirtual Machine for SINUMERIK ONE plays a strong supporting role. Not only as programs can be generated offline at a system identical to the real machine, but also due to the shorter times when subsequently running-in programs at the machine.

Shortest clamping-to-clamping time

Especially for workpieces in series production, idle times quickly add up as a result of the machine automation: Tool and workpiece changes take up time. The result: Clamping-to-clamping times impact the energy costs. SINUMERIK with its integrated SIMATIC PLC is also optimally set up in this area. Based on this high-performance PLC teamed up with high-end CNC functions, such as synchronized actions and asynchronous subprograms, SINUMERIK CNC equipment plays a significant role in optimizing the energy efficiency of machines.

Increase in OEE key figures

Finally, the overall system efficiency of the shopfloor is the yardstick for the energy consumption of manufacturing. Here, too, Siemens CNC Shopfloor Management Software helps. Maximum transparency is ensured by Analyze MyPerformance /OEE Monitor. This software app determines meaningful key performance indicators (KPI) for manufacturing efficiency. Manufacturing is then optimized with Analyze MyPerformance /OEE Tuning. For this purpose, time periods can be compared and the effect of optimization measures can be recognized. Machine downtimes can be reduced, if not eliminated.


SINUMERIK CNC equipment packages and Siemens CNC Shopfloor Management are therefore an elementary contribution to the energy efficiency of machine tools. SINUMERIK is therefore not only a guarantee for maximum performance in the machine, but at the same time an important building block for the energy-efficient shopfloor, the shopfloor of tomorrow.

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