State-of-the-art door production with efficient vacuum supply

Maulburg - Joro Türen GmbH produces high-quality utility doors in Renchen, Germany, for protection against fire, smoke, burglary and noise up to 52 dB. The doors are sold to distributors for further sale. The high product quality, flexibility with regard to customer requirements, and quick delivery times can only be guaranteed thanks to state-of-the-art production methods. Joro Türen has automated door production to the greatest extent possible, which ensures a high degree of efficiency and a consistently high level of quality. The vacuum supply for clamping mechanisms on the CNC processing centre is supplied by a Mink claw vacuum pump from Busch, which, thanks to its high degree of reliability, contributes to the smooth production process.
Fully automated production of high-quality protective doors at joro türen.

At Joro Türen, the processing centre is operated in two shifts. The fully automatic manu-
facturing cell with automatic loading and auto-positioning tables is capable of loading and processing door panels of up to 250 kg in weight and up to 3200 mm in length and 1500 mm in width without the need for manual intervention. Originally, two liquid ring vacuum pumps were installed on the CNC processing centre – the central part of this manufacturing cell – to generate the vacuum for clamping. This had the disadvantage that the coolers became dusty quickly and required frequent cleaning. In addition, the water level had to be checked regularly and topped up if necessary. Further disadvantages included the high level of waste heat and the system's lack of reliability. One vacuum pump required a general overhaul after just three years.

Martin Rohwetter, the owner of Joro Türen, also viewed the power consumption of the liquid ring vacuum pumps in a critical light. With a daily operating time of 14 to 15 hours, this is clearly a factor that is worth taking into account when calculating economic efficiency. This is why Martin Rohwetter contacted the company Dr.-Ing. K. Busch GmbH, manufacturer of vacuum pumps and systems. The Busch vacuum specialists recommended a Mink claw vacuum pump, which is mounted on a vacuum chamber with a capacity of 1000 litres. This solution had the obvious advantage that a single vacuum pump could replace the two liquid ring vacuum pumps that had previously been used. The vacuum chamber makes it possible for a vacuum to be created immediately as soon as it is needed. As a result, the clamping process is extremely short. In addition to this, the Mink claw vacuum pump is driven by a 4.5 kW drive motor, whereas in the previous solution, the two vacuum pumps were each driven by a 7.5 kW motor.

More than 18 months after installation, sufficient experience with this vacuum generation solution has been gathered to confirm, firstly, the calculated energy saving that was achieved in full, as it was possible to reduce energy costs for vacuum generation by 80%. This represents an annual saving of around 2100 Euros. Secondly, the Mink claw vacuum pump also proved itself to be extremely robust and reliable. Since commissioning, there have not been any malfunctions let alone a vacuum pump failure.

A further advantage also became clear in practice: the Mink claw vacuum pump is almost maintenance-free. The reason for this lies in the operating principle of this vacuum generation system. Two claw-shaped pistons rotate in opposite directions inside a cylinder. The geometric shape of these claws is designed so that with each rotation movement they draw in air, compress it and expel it again. When doing so, the pistons do not touch each other or the interior surface of the cylinder in which they turn. This non-contact operation means that there is no need for operating fluids, unlike with a liquid ring vacuum pump, for example, which requires water. This also means that maintenance work associated with operating fluids is not necessary. Both claws are synchronised by a gear unit that is separated from the compression chamber. This gear unit is lubricated with oil and the gear oil should be changed every 20,000 operating hours. When calculated on the basis of the Joro Türen operating hours, this corresponds to a theoretical oil change interval of around ten years.

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