Cost-effective Central Vacuum Supply for the Entire Production Line

At its plant in Solingen, Wilkinson Sword GmbH manufactures razor blades and razors, with vacuum for the complete production line supplied via a ring main routed through all the production buildings. The vacuum is generated by two centralized vacuum systems supplied by Busch, fitted exclusively with dry Mink claw vacuum pumps. The production engineers at Wilkinson Sword were left in no doubt that the Busch system was the most reliable and cost-effective solution for supplying vacuum to the production line around the clock.

Vacuum is required along the entire production line for handling and transporting the different razor components and when packaging the end product. The steel for the blades is delivered on coils, after which it is subjected to a hardening process, before the blades are die cut and sharpened. The blades are then conveyed to the assembly machines where they are inserted into the moulds in a fully automatic process.

The plastic-coated razor blades are only one of many parts that go to make up a finished razor. As they pass along the production lines, the components are assembled to produce each complete razor and then packaged. Production at Wilkinson Sword runs in a three-shift operation, 24 hours a day, seven days a week. At each stage of the production process a variety of pick and place, clamping and handling devices are used that join or assemble an extremely wide range of parts. All these devices are supplied with vacuum via the ring main.

Two central units are used to generate the vacuum. These are housed far apart from each other in two different production buildings. Originally, each of the two buildings had its own vacuum supply but, following the construction of a new production unit between the two existing buildings, a vacuum ring main was installed for all three units. However, the company specifically opted to retain the two centralized vacuum systems supplied by two different power networks. This means that if there is a power failure in one network, the second vacuum system will remain operational and ensure that the vacuum supply to the production line is maintained. Originally, the two vacuum systems were equipped with oil-lubricated rotary vane vacuum pumps. These demanded a high level of maintenance and, as a result, the company started to look at how savings could be made on maintenance costs. Another area of concern at the time was the potential for cutting energy costs. The company sought external advice, consulting a vacuum specialist from Busch who recommended a vacuum supply with dry Mink claw technology. A sample pump was then extensively trialed at Wilkinson Sword in 2003 and 2004.

Mink claw vacuum pumps are a non-contact and completely oil-free system. This means that moving parts in the vacuum pump do not come into contact with each other. Consequently, no oil or other operating fluid is required to lubricate contacting parts, while wear in the vacuum pump compression chamber is completely eliminated. The trials with the sample pump yielded highly satisfactory results: the search had successfully identified a vacuum pump that operated extremely reliably and was almost maintenance-free. Also a high saving of operating costs was to realize using the Mink claw technology.

The first two Mink claw vacuum pumps were commissioned in 2004, and over the following years all oil-lubricated rotary vane vacuum pumps were replaced with Mink claw vacuum pumps. Today, one of the centralized vacuum systems has two pumps and the other has six Mink claw vacuum pumps. The production engineering team at Wilkinson Sword carried out the installation themselves. The control system was also programmed in house, as was the connection to the building control technology. The operating pressure in the vacuum network is kept at a steady 700 mbar, with two Mink vacuum pumps carrying the base load. This means that even if the large centralized vacuum system were to fail – for example, due to a power failure – the base load could still be maintained.

"This makes us extremely flexible and self-reliant", is the consensus among the production engineers at Wilkinson Sword, who added that the redundancy in the two vacuum systems brings benefits in terms of maintenance work since this can be carried out without halting production. Additional vacuum pumps are only switched on if required. The control system is programmed to ensure that all vacuum pumps are evenly loaded: this means that all vacuum pumps have roughly the same operating time. All these measures taken together have produced annual energy savings of 103,200 kWh. At calculated electricity prices (2014), this represents an annual saving of EUR 13,416 in energy costs.

The reliability of the vacuum supply is extremely important for Wilkinson Sword, since many of the processes rely directly on the vacuum supply. As well as the importance of the two independent centralized vacuum systems, great value is attached to the continuous monitoring of the vacuum supply by the production control system. Data on the following parameters can be viewed at any time: vacuum level, operating times for individual vacuum pumps, trends and failures. The process control system can also be used to control the vacuum or to manually switch pumps on or off.

Mink claw vacuum pumps require significantly less maintenance work. Oil-free operation means there is no need for maintenance work such as oil and filter changes. Since the Mink claw vacuum pumps are a non-contact, wear-free system, there is no need to replace wearing parts. The sole maintenance work required is that of replacing the air-filter cartridges once a year, which is carried out in house. The gear oil is changed in a two-year cycle by a Busch service technician. This occurs as a preventative measure, as the operating time of each Mink vacuum pump after two years amounts to approximately 6,000 hours. Busch recommends changing the gear oil after 20,000 operating hours. Wilkinson Sword GmbH has expressed its full satisfaction with the new vacuum supply system: the anticipated benefits and savings have all been achieved, with the help of the Busch vacuum specialists.

About Wilkinson Sword
Wilkinson Sword, now part of the Energizer Group, has had a production facility at Solingen since 1961. The company's origins go back to the 1800s when Wilkinson Sword began making weapons in England. The first 'safety' razor was developed in 1889 and was manufactured in London. Since then innovations have continued to revolutionize the razor technology developed by Wilkinson. Every year, several hundred million razors leave the plant in Solingen destined for sale throughout the world.

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