Churning out energy efficiency

It's all about performance, efficiency and speed that perfectly matches any given situation. Even Krones’ fastest filling and packaging machines will achieve top output only when the individual process steps are interlinked by fit-for-purpose conveyor technology. So conveyors are much more than just transport routes for cans and bottles. Rather, they serve to control a line’s entire logistics. By intelligently distributing, guiding and buffering containers, they assure a harmonised product flow between the individual machines. That means that SynCo, Krones’ own container conveyor system, is nothing less than the discreet guarantor for a smoothly running operation. 

Outstanding energy-efficiency  

What sets SynCo conveyors apart is their electrified drive featuring permanent magnet motors, whose energy rating of IE5 (in accordance with IEC/TS 60034-30-2) represents the highest standard for motor efficiency. So these motors are in a league of their own. A brief digression into the world of synchronous and asynchronous motors helps to better understand the background here. Hartmut Davidson, Head of Machine and Control Drives in Neutraubling, has a degree in electrotechnical engineering and can draw upon 40 years of experience in this field. He explains it all to us: “In an asynchronous motor, the outer rotary magnetic field and the magnetic field in the rotor run asynchronously: The rotor rotates, in other words: drives the three-phase motor. But in order to create this magnetic field in the rotor, energy is needed which is then not available as drive power. Nor can the motor ever reach its full rpm, since induction is conditional upon a differential between rotor and outer magnetic field.” 

In a three-phase synchronous motor, by contrast, the rotor contains permanent magnets which generate the requisite magnetic field so that it is not necessary to use energy for creating it. This type of motor, hence also known as permanent magnet motor (or PM motor for short), is therefore significantly more efficient and does not heat up so much as there is no slip. And Hartmut Davidson adds: “The fact that a PM motor cannot be directly connected to the mains but always needs a frequency converter does not limit its usability for Krones customers because all motors in Krones conveyors are frequency-controlled anyway.” 

Power consumption significantly below that of asynchronous motors 

Right in line with its self-imposed high sustainability standards, Krones wanted to exactly quantify the energy efficiency and low consumption of PM motors. A motor test rig able to determine the efficiency in all operating points was erected in the Neutraubling plant specifically for this purpose. The test results were shown in an efficiency diagram, providing automated digital visualisation of the values obtained at several thousand measuring points and illustrating the comparison between rpms and torques of a synchronous and an asynchronous motor to particularly vivid effect. The system of an asynchronous machine suffers massive efficiency losses especially at low rpms, meaning at low motor speeds. That would be a considerable downside for Krones conveyors, which have to adjust their speed from very high to very low at many points in a filling line. 

In the final analysis, line owners reduce their energy consumption by up to 40 per cent with ultra-efficient permanent magnet motors, compared to conventional asynchronous motors. A crucial contribution is made here by the special energy-saving mode during conveyor stops. Minimised consumption of water and lubricants, plus rigorous use of food-grade greases and oils, are yet more aspects earning these motors an enviro classification under Krones’ eponymous sustainability programme. 

Dynamic speed for a product-friendly flow in the line 

What an intelligent SynCo conveyor solution for up to 120,000 PET bottles per hour looks like in detail is vividly illustrated by the system installed at a German soft drinks producer. Here, Krones implemented a sophisticated control concept tailored to the customer’s specific needs, with function display and operator control via the line’s main touchscreen. During commissioning and initial set-up, the conveyor belt’s speed at each of the individual points – from high speed down to walking speed and stop – is precisely matched to the product concerned: Cans and PET containers travel much faster than glass bottles, and whether the containers are empty or full also makes a difference. Once the conveyor system has been correctly adjusted, its active back-up management function is able to automatically detect any irregularities and even display diagnostics on screen. For this purpose, the conveyor belts are fitted with back-up switches and proximity detectors. Signal transmission between the individual machines and continuous monitoring of the back-up situation ensure a line’s smooth overall operation, no matter the line’s size. 

Christian Paul, who heads the SynCo engineering team and works closely together with Hartmut Davidson, strongly recommends that any line owner considering changing to PM motors seek comprehensive, professional advice first: “Customers interested in SynCo conveyors can choose from a number of alternatives because the system can be used not only for Krones filling and packaging machines but for third-party kit as well. One of the options here would be to retrofit them as part of an energy and line optimisation project for a certain facility.” That is because SynCo’s energy-saving potential is not only provided by the permanent magnet motors as such but all the more so by their sheer number: A single high-speed line may sometimes include as many as 100 and in exceptional cases even up to 150 PM motors. It does not matter whether it is a greenfield or brownfield project – The SynCo conveyors are in each case optimally matched to the space available and the line layout involved. And since the components have already been pre-assembled in Krones’ plant, installation on site will not take long.

Well advised by expert consultants

SynCo conveyors featuring PM motors can be integrated not only in Krones lines but also in third-party kit. 

One of the options here would be to retrofit them as part of an energy and line optimisation project for a certain facility. Christian PaulHead of SynCo Engineering

Bottom line: powerful motors with low consumption 

To sum up: The arguments in favour of Krones conveyors featuring permanent magnet motors are obvious. Customers can order smaller sizes since PM motors boast an excellent efficiency of 90 per cent. The motor does not heat up so much, thus rendering a fan unnecessary. Since the motor can be efficiently run over a wide speed range, the number of different motor variants can be kept small. The motors themselves are also substantially smaller and can thanks to a frequency converter be individually controlled. And last but not least: Every single energy optimisation measure in a line will pay dividends in the long term.