The Key to Great Olive Oil?

German precision and powerful centrifugal force

Published: Thursday, August 8, 2019 - 12:02

Decanter centrifuges from Hiller GmbH, headquartered in Vilsbiburg, Germany, are in demand globally. These centrifuges separate solid and fluid materials, such as in the production of olive oil or wine, or for wastewater treatment. The multiton machines achieve high yields unmatched by competitors, thanks to Hiller’s unwavering commitment to precision. Recently, the company acquired a ZEISS ACCURA to help it deliver on this promise.

Dietmar Heller, Hiller’s plant manager, holds up a small bottle to the light and gently shakes the liquid inside back and forth. It has a golden yellow color with just a hint of green. Any gourmand would identify the substance immediately: olive oil, the best kind, even. A brief taste confirms this: the premium oil has a pronounced olive flavor, but there is no stinging aftertaste. “Extra virgin, extra natural” is written on the bottle, and Heller would swear this is true. He knows the producer of this outstanding olive oil from the south of Spain personally. Moreover, Heller knows a lot about the decanter centrifuge, in which the oil is separated from the solids and water found in the olive paste following the harvest.

Whoever purchases Spanish olive oil can be relatively certain that it has been processed in a Hiller decanter centrifuge because the company is almost the only game in town on the Iberian Peninsula. This makes the German enterprise a global market leader as well, since more than 80 percent of the world’s olive oil comes from Spain.

The decanter centrifuges from Vilsbiburg are considered the best on the market. They separate mixtures into their fluid and solid components, transforming olive paste into fragrant oil, water, and pomace, a less odoriferous, more solid residue.

Hiller’s success is the result of cutting-edge technology and an uncompromising commitment to quality.

25 years with ZEISS

The measuring lab, a key part of ensuring top-notch quality, is Josef Pichlmair’s domain. The engineer has been working at the company for 19 years and is one of the driving forces behind Hiller’s rising fortunes. A NUMEREX system from ZEISS stands next to the entrance. In use at the company for a quarter of a century, it continues to work without a hitch and regularly performs coordinate measurements.

Stephan Schneider (at left) and Josef Pichlmair from the quality assurance area at Hiller discussing the ZEISS ACCURA measurement report for the centrifuge drum lid.

Pichlmair’s new favorite system is located right across from the old one: a brand-new ZEISS ACCURA 9/16/8—a larger, faster and more precise machine than its predecessor. The ACCURA is in operation almost 24/7. The last employee to leave the measuring lab in the evening places multiple components on the measuring machine and starts the automated measurement program. The next day, all measurement values have been captured and analyzed, and the machine is ready for the next measuring job. “The automated measurements, large measuring range, and user-friendly CALYPSO software have really impressed us,” says Pichlmair.

Powerful centrifugal forces at work

And, of course, there is the machine’s precision. The team cannot afford to make any mistakes, as these could have serious consequences. A look inside the decanter centrifuge gives you an idea of what might happen if the dimensions were even slightly off. It can weigh up to 12 tons and looks like an elongated washing machine drum that rotates at very high speeds.

Maximum precision is a must: Processing the drum lid for a Hiller decanter centrifuge.

Inside the decanter centrifuge is a rotating scroll or screw that vaguely resembles an Archimedean screw pump. The Greek mathematician designed this device to transfer low-lying water to higher elevations during the third century BCE. The solid and thicker matter is pressed to the outside of the machine by the enormous centrifugal forces at work. Then, a scroll that tapers off at the end transports the solid and thicker particles toward the end of the decanter centrifuge and out through a discharge opening. The lighter fluid travels along the shaft of the screw and, thanks to downward pressure, is moved in the opposite direction. The vegetable water is separated into solids and clear water. There are also three-phase centrifuges, such as in those used for olive oil. Here, the heavy pomace, the lighter water, and the even lighter oil are separated before leaving the decanter.

A ZEISS ACCURA is used to inspect the precise dimensional accuracy of a Hiller centrifuge drum lid. The lid is one of the two primary storage locations for the centrifuge, making it critical for smooth operation.

Test run in the bunker

Before a new machine leaves the factory, it is taken to the “bunker” for a test run. Here, water mixed with a coagulant, giving it the consistency of olive paste or vegetable water, runs through the decanter centrifuge. The slightest imbalance would be evident in increased vibrations. The scroll rotates at about 6,000 revolutions per minute, subjecting it to centrifugal forces of 4,000 grams—4,000 times more force than the Earth’s gravitational pull. Every gram of material is subject to enormous centrifugal forces equaling 4 kg.

Hiller’s machines come in several different versions. For years, a modular system has been in place, which makes it easier for the customer to select a suitable model. Custom-made solutions are also available. Two motors power the scroll and the drum. These rotate at different speeds, with the scroll rotating somewhat faster. The motors require a reduction gear to ensure the right rotational speeds. Hiller used to employ hydraulic drives for this purpose, which the company started constructing itself during the 1990s. These can withstand strong stress reversals, but they are also complicated and expensive.

Stephan Schneider starts the automated program on the ACCURA, which will inspect four gear-tooth rings during the night.

As the years passed, though, the hydraulic version became less common and has been replaced by mechanical drives. These work almost as well and are significantly less expensive. Initially, the company lacked the necessary drive expertise and thus purchased finished motors from specialist manufacturers. Over time, however, the drives became increasingly important, and the quality of the suppliers proved inconsistent. Thus, in 2014, company management decided to manufacture these in-house and develop a new, more high-performing motor.

Great value for the money

Hiller still sources the individual gears. Yet this shift from buy to build has meant significantly more work for quality assurance. “We have to keep an even closer eye on our suppliers, and there were lengthy discussions with them concerning what you have to inspect and how,” recalls Pichlmair. This process was simply no longer feasible with the ZEISS NUMEREX. Hiller needed to purchase a new coordinate measuring machine. “We had a look at several different options, and the precision of the ACCURA, along with being a great value for the money, convinced us to opt for this system,” explains Pichlmair. Gear measurements are now performed on the ACCURA along with the software ZEISS GEAR PRO to ensure comprehensive gear quality control.

The ACCURA inspects the outer gear-tooth rings for a planetary gear. This rotates the scroll in the centrifuge, ensuring that this component has a different rotational speed than the drum housing.

Word has spread in the industry about the quality of Hiller’s products. Many water treatment plants interested in purchasing a decanter centrifuge had multiple suppliers bring their mobile decanters to the facility’s premises on the back of a truck. These were filled with the same wastewater, and the competition started. The supplier that achieved the best results with the lowest costs would receive the order. Although its machines are noticeably more expensive, Hiller frequently succeeds in landing these attractive contracts, thanks to its significant technological edge. Local governments have also started focusing not just on the purchasing price, but also on achieving a certain return on their investments.

In this respect, Hiller is often ahead of the rest. The customer recoups the higher initial purchasing costs after a few months, such as in the form increased dry discharge in wastewater treatment or greater quantities of olive oil.

Ready to retire

The same principle holds true for ZEISS coordinate measuring machines. Because quality measurements no longer have to be contracted out to external service providers, Hiller will recoup its investment costs in less than two years. For this reason, the next machine Hiller buys will also feature the blue ZEISS logo. As the quality assurance workload is rapidly increasing, Heller has already submitted a request to its parent company, Ferrum, headquartered in Switzerland, for another coordinate measuring machine. “As soon as this is approved, our old NUMEREX can finally be retired,” Heller says.

About The Author

ZEISS Industrial Quality Solutions

Headquartered in Oberkochen, Germany, ZEISS Industrial Quality Solutions is a member of the Carl Zeiss Group. It is a global leader in CNC coordinate measuring machines and complete, multidimensional metrology solutions for a wide variety of industrial sectors. Approximately 1,800 employees at three manufacturing locations and more than 100 sales and service centers serve customers around the world.