The paint-processing industry currently debates heatedly about how and where energy could be saved – when applying or drying varnish or purifying exhaust air? But most paint processors are not aware of the high cost-saving potential the stirring process has and how easy it is to exploit it. Bad for the environment. But primarily expensive for the operator. In the field of stirring technology, consequently, the potential of saving energy and money is completely unexploited so far. Thousands of Euros are wastefully blown in the air due to inefficient systems. ”Especially for the plant engineering industry, saving energy and costs does not play a major role when it comes to the requirements their systems should fulfil. But the high cost-saving potential their customers could benefit from could give them the possibility to differentiate from their competitors. Because one thing is clear: everybody wants to save money wherever possible. And not to forget how they could convince their customers with their modern advisory expertise.” PTM CEO Carsten Angermeyer says. How the investment in an efficient system and its outcome could look like, shows the way of the Czech company Plakor.
Vane motors – the hidden cost drivers
The company Plakor, with its seat in Moravia, Czech Republic, is one of the leading suppliers of automotive plastics. Their product portfolio consists of bumpers, spoilers, dashboards and other high-quality interior and exterior equipment. Stirring varnishes is one of the core processes in the daily business.
At Plakor, 120 agitators stir varnish in 200 litre containers in continuous operation. Before the commissioning of PTM mechatronics, Plakor used standard vane motors. Vane motors are known for their inexpensive purchase. This is what makes them interesting at first glance. The true costly bill must be paid much later – when receiving the electricity bill. In continuous operation, the vane motors of Plakor cost so much energy and money that Plakor had to find a much more efficient alternative soon. They found it in the high-performance and energy-efficient PTM stirrer drives. Consequently, Plakor replaced all of the vane motors of its preparation room by PTM stirrer drives.
More money for the piggy bank with PTM stirrer drives
For a period of 12 months, Plakor put the investment to the test with various performance scenarios and consumption measurements. The results:
In continuous operation, the 120 new PTM stirrer drives save €350,000 of energy costs compared to the old vane motors – per year!
It goes without saying that the comparatively low investment costs were forgotten immediately. It is important to mention that Plakor stirs with a relatively low speed of approximately 100rpm. Calculated with the highest possible speed of 300rpm, this would amount to €950,000 per year.
The vane motor’s movement is generated by compressed air flowing through vanes on a rotor. This process requires a huge amount of compressed air. The high rotational speed with low torque that is generated by vane motors, however, is not needed in stirring processes. Quite the contrary, for the most substances that must be stirred, this constellation is absolutely counterproductive and must be regulated by a transmission.
The radial piston principle, on the contrary, works with cylindrical chambers in which compressed air presses pistons towards the housing wall. The wavelike form of the housing wall now generates the rotary motion. This process only needs as much air as fits in the small chambers of the pistons. The radial piston motor generates a comparatively low speed with high torque. This makes it the perfect stirrer drive for substances of all kinds – without having to use a transmission.
PTM stirrer drives also deliver perfect mixing results
After a while, Plakor has noticed that the new PTM stirrer drives stir much more consistently than vane motors, which is very important for a perfect mixing result.
Vane motors tend to increase speed when the filling level in the stirring tank decreases. This has the following reason: when the filling level decreases, for example due to evaporation or by emptying the container through a suction lance, the resistance of the liquid against the stirrer element of the agitator decreases as well. The vane motor’s reaction is to develop more and more speed as the compressed air flowing through the rotor drives it unrestrained, to a speed of up to 1,500rpm. This could lead to air inclusions or, at worst, to foam on the surface. These air inclusions complicate any further processing of varnishes or any other liquid. They prolong the processing time because they need much time to vanish again.
In case the filling level increases, the opposite is the case: the agitator loses speed and is no longer capable to whirling up solid metallic, colour or gloss pigments.
The final product could show surface defects due to air inclusions or solid particles which influence its quality negatively. Especially water-based varnishes are vulnerable to these phenomena due to their strongly fluctuating viscosity. This is one of the main reasons why the processing of water-based varnishes is such a big challenge for the coatings industry.
PTM stirrer drives, on the contrary, stir much more consistently in case the filling level decreases. Their technical speed limit is 300rpm.
In case the filling level increases, the motor’s high torque enables it to keep speed.
Plakor noticed that the varnish stirred did not show any air inclusions or deposits anymore. Finally, the varnish has the quality that is needed for the high requirements concerning process reliability and final product.
Last but not least, one further advantage that should be mentioned: due the massive decrease of air consumption, the operating hours of Plakor’s compressors have decreased as well. Their maintenance cycles could be prolonged accordingly which again saved money.
This success story shows clearly that it is always worth reconsidering the method of stirring processes with regard to efficiency, suitability and functionality and breaking new ground.
We gladly advise you with regard to the energy-saving potential of your agitators: +49 8134 25 797 0 or email@example.com.
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