Mill-turns make the difference at decanter specialist

A Hiller decanter centrifuge
A Hiller decanter centrifuge

When German liquid separation specialist Hiller GmbH needed to improve production of its decanter systems it found WFL with its versatile mill-turn machining technology the answer. PES reports.

Decanter 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 juice, olive oil, fish processing, dairy products, kitchen waste, sewage sludge treatment, algae harvesting, oil preparation or even the production of plant extracts, you wouldn’t immediately know what connects these different activities – 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. For example, 80 - 90% of Spanish olive oil has likely gone through a Hiller decanter.

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 waterways.

One of the centrifuge drum components being machined on a WFL MillTurn
One of the centrifuge drum components being machined on a WFL MillTurn

Decanter assembly   

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 an effective, 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.

Hiller machines many different components for its decanter centrifuges using MillTurn turn-mill centres from WFL – available in the UK from Market Harborough-based Kyal Machine Tools. At the heart of the decanter is a rotor, which comprises a screw conveyor, bowl and drive unit made entirely using WFL MillTurn machines. And the new M50 MillTurn with 2,000mm centre distance is now used to produce additional parts that were previously bought in.

In-house production

Hiller’s insourcing strategy is one of its top priorities. In light of the supply shortages that have cropped up often 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, explains: “The aim with the new WFL MillTurn is to produce larger batches and make optimal use of the machine’s capacity. We had a lot more machinery before we introduced complete machining; the turn-mill machines have enabled us to significantly cut down the amount of equipment that we use. We have replaced several machining centres with the new WFL.

. The project team next to the MillTurn at Hiller
. The project team next to the MillTurn at Hiller

“The major benefit of making this change is that it simplifies the production process which used to be lengthy. 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.”

Staff in production at Hiller have become big fans of the WFL 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. The M50 meanwhile is currently used to produce gear components.

The larger machines – the M80 and M120 – produce smaller batch sizes of between five 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 shorter set-up times and reduced lead-times really make a difference.

Andreas Lehner, WFL sales manager, adds: “One of the unique selling points of our machines includes excellent stability thanks to the inclined bed concept. The machines have short distances between the machining point and the guideways, so maximum metalcutting efficiency and high-precision finishing are guaranteed.”

Hi-tech service and support

When Hiller was purchasing the MillTurn centres, key objectives 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 M120 is the largest WFL MillTurn machine at Hiller
The M120 is the largest WFL MillTurn machine at Hiller

“The highly knowledgeable advisors at the other end of the phone who are able to provide expert assistance should a problem 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 Mr Brauner.

Mr 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 optimum support on site also.”

As the quality of its products is extremely important to Hiller, it was crucial to get the design of the technology right. 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.

Technologically speaking, the MillTurn machines are extremely flexible. Work is currently underway to integrate the technological process of shaping. The idea would be for the 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 between 1.5 and 3.5 hours.

The majority of the workpieces are manufactured from stainless steel and the gear components predominantly from steel: these are materials that are ideal for processing with the WFL machines.

A decanter gearbox component being machined on one of the WFL machines
A decanter gearbox component being machined on one of the WFL machines

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 on the control system, so even the smallest irregularity can be spotted immediately. If a wear-related overload or a tool breakage is detected, the machine stops automatically. In addition, the possibility of integrated measurement enables tools to be corrected automatically for the perfect machining process.

The WFL 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 programs.

Summing up

Hiller makes products that help the environment to regenerate and 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 which helps to minimise waste and conserve resources. The highly efficient WFL machines are therefore the perfect fit for Hiller’s sustainable philosophy.


Kyal Machine Tools

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