Clear water with Hiller centrifuges


WFL-LOGODecanter technology uses a process that separates liquids and solids. It is often used in industry to remove solid particles from liquids or to separate different liquids from one another. Hiller GmbH has been developing and producing decanter centrifuges for over 50 years, using its expertise to solve separation tasks across a wide range of industries.

If someone were to mention fruit and vegetable juices, olive oil, fish processing, dairy products, kitchen waste, sewage sludge treatment, algae harvesting, oil preparation or even the production of plant extracts to you, you wouldn’t immediately know what connected all these different areas. But these are precisely the areas that Hiller is involved in. Hiller decanters are used to separate milk and cream in the food industry, for instance, and to produce olive oil. You can assume that 80–90% of Spanish olive oil has gone through a Hiller decanter, for example. Another interesting application is in the chemicals industry, where decanters are used to separate solvents or to treat wastewater. In fact, wastewater treatment is probably the most important and sustainable area of use for this technology. Decanters are used to separate solids and liquids in sewage treatment plants. The accumulating sewage is cleaned using decanters so that it can then be released back into the waterways. It’s a topic that we know very little about but one that affects us all.

Spotlight on the separation of solids and liquids

What actually is a decanter and what is behind this phenomenal technology? A decanter consists of a cylindrical housing with a rotating bowl inside. The bowl is divided into two sections by a partition wall. The liquid to be separated is fed into one section, while the end product and the solid material from the separation process are fed out into the other. When the bowl rotates, this creates a centrifugal force which pushes the solids to the outside. At the same time, the heavier liquids, such as water, sink toward the outer wall of the bowl where they then flow out. Lighter liquids like oil float to the surface of the heavier liquid and are also separated. Essentially, decanter technology offers a very effective, very energy-efficient means of separating liquids and solids. Hiller produces the decanters in house, manufacturing the majority of the decanter components at its Vilsbiburg site.

Schematic illustration of a Hiller centrifuge
Hiller GmbH has been developing decanter centrifuges and complete systems for the separation of solids and liquids in the small town of Vilsbiburg, Bavaria, for more than 50 years. Over 6500 centrifuges are already in use around the world, and around 200 decanter centrifuges are delivered to customers every year.

Incorporating complete machining

Hiller GmbH machines many different components for its decanter centrifuges using MILLTURN turning/milling centres from WFL. At the heart of the decanter is a rotor, which comprises a screw conveyor, bowl and drive unit and is made entirely using WFL’s multi-talented machines. And the new M50 MILLTURN with 2000 mm centre distance is now used to produce additional parts that were previously bought in. Hiller’s insourcing strategy is one of its top priorities. In light of the supply shortages that have cropped up again and again in recent times, the company’s strategic aim is independence. Vertical integration is also being brought further inwards in order to generate more added value.

Stefan Brauner, Head of Production, provides an insight into production: “The aim with the new WFL is to produce larger batches and to make optimal use of the machine’s capacity. We had a lot more machinery before we introduced complete machining. The turning/milling machines have enabled us to really cut down the amount of equipment that we use. We have replaced several machining centres with the new WFL. The major benefit of making this change is that it simplifies the production process. This process used to be a long one: A component would be turned on one machine, then milled, and then turned again. Depending on requirements, the different production steps would be spread across different machining centres. Now everything is done on one machine, so there’s no need for repositioning.”

The employees in production are also big fans of the machines. The M50, M80 and M120 trio makes a solid team and can handle a wide range of part sizes between them. On the larger WFLs, for example, the same chucks are used, with the machines mainly producing conical bowls, cylindrical bowls, screw conveyor bodies and front walls, etc. The M50 meanwhile is currently used to produce gear components.

The large machines – the M80 and M120 – produce smaller batch sizes of between 5 and 10 pieces, while the new M50 produces 20 to 50 pieces in two-shift operation. The benefits of complete machining are clear: the entire production process for a workpiece – including quality checks – takes place on one machine. The possibility of integrating a variety of tools in the machine speaks for itself. Overall, with complete machining it is the shorter set-up times and generally short lead times that really make the difference.

Andreas Lehner, WFL Sales Manager, adds: “The USPs of our machines include excellent stability thanks to the inclined bed concept. The machines have short distances between the machining point and the guideways, so maximum metal cutting efficiency and high-precision finishing are guaranteed.”

High quality and reliable

When purchasing the complete machining centres, the key criteria were process reliability, service availability and, most importantly, the high quality of the machines. As Hiller had already been using an M80 and M120 for some time, the company knew that they could rely on the machines to run smoothly. This was a key factor behind the decision to purchase another MILLTURN.

“The very capable men and women at the other end of the phone who are able to provide expert assistance should problems arise and the additional remote diagnostics service are great solutions. The user can establish a secure connection to WFL via PIN code, enabling a WFL service technician to quickly access the machine control system, identify the problem and perform diagnostics. This connectivity and the fast response times are simply fantastic,” says Stefan Brauner.

Andreas Lehner adds: “It’s not only important for someone to be on site as quickly as possible when servicing is required in order to swiftly resolve the problem. What is particularly important for our customers is the time taken to resume production. All of our service employees are trained in all machine types and can therefore provide our customers with the best support on site.”

As the quality of its products is extremely important to Hiller, it was crucial to get the design of the technology right. CNC Programmer Stefan Geiger explains that the machining process was developed in cooperation with WFL beforehand to ensure that the required gear components could be produced to the necessary degree of accuracy. “WFL performed a very detailed preliminary examination of the component, so we could be confident that our production would be extremely accurate.”

Technological versatility that matters

Technologically speaking, the MILLTURNs really do have everything covered. Work is currently under way to integrate the technological process of shaping. The idea would be for the complete machining centres to handle the internal gears of the gear components as well. External gears have already been successfully implemented with WFL’s technology cycles. The machining times for the different workpieces vary depending on the size of the component. The machining time for the bowl parts, for example, is a little longer – between 1.5 and 3.5 hours. The majority of the workpieces are made from stainless steel, and the gear components predominantly from steel: these are materials that are ideal for processing with the WFL complete machining centre.

Process reliability is guaranteed on the M50 thanks to iControl Advanced+, which means that the machine can run completely automatically. The machine enables process signals to be monitored continuously at the machine control system, so even the smallest irregularity can be spotted immediately. If a wear-related overload or tool breakage is detected, the machine stops automatically. In addition, the possibility of integrated measurements enables tools to be corrected automatically – for the perfect machining process. The CAD/CAM programming system TopSolid is used for programming. Hiller is also now increasingly incorporating the WFL simulation and programming software CrashGuard Studio into its processes, using this software for the final optimisation of programmes.

Sustainability is key

Hiller makes products that help the environment to regenerate. The decanter technology supports this process by treating contaminated water and returning it to drinking water quality. In the food industry, the shelf life of foodstuffs can be extended, which helps to reduce food waste and improve resource efficiency. Essentially, decanters facilitate the efficient separation of solids and liquids so that they can be reused or disposed of. This helps to minimise waste and conserve resources. The highly efficient WFL machines are therefore the perfect fit for Hiller’s sustainable philosophy.

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