Based in Viersen, Germany, Dietermann is a specialist non-ferrous foundry pouring mostly aluminum but also a range of copper alloys in green sand. The foundry is incredibly versatile, able to cast single large items or handle runs from 200 up to 20,000 pieces per year. By handling every process in-house, Owner and Managing Director Franz Georg Reiners aims to completely control casting quality, from CAD and modelling through molding and pouring to fettling, machining and heat treatment.
“We can produce small items down to around 150g and go up to 200kg castings up to 2m in diameter,” he says. “We use hand molding for large components, semi-automatic machines and automated molding lines for series production. All are fed by one sand plant and mixer.”
In 2009, Dietermann decided to completely revamp its sand system, moving from natural green sand to mixing specified sand and bentonite for greater control over sand composition. It was also time to replace its old turbine sand mixer.
“The mixer was too small and we had downtime waiting for sand,” Franz explains. “We were upgrading the rest of the sand plant and we wanted a larger capacity mixer with the best technology. The challenge was to get a sand mixer that can produce the different sand qualities that we need for the automated molding and for the hand molding as well. Each type of molding requires very different types of sand mix.”
Dietermann conducted a comprehensive survey of the mixers on offer and one option stood out immediately: the Simpson Mix-Muller with the Hartley dosing system.
“Muller-type mixers are quite unusual in Europe but we saw it as a superior mixer technology,” states Franz emphatically. “Though it’s an older style of mixer design, we were convinced that a muller is, first, the most energy-efficient way to mix sand and, second, the most gentle way to treat the sand.”
“The more energy you put into mixing, the more you break down each individual sand grain and heat up the sand,” he explains. “A muller’s gentle but complete mixing doesn’t crush the sand grains so it keeps the original sand properties, consumes less energy and uses less bentonite. Simpson were the obvious people to speak to.”
Simpson have long believed in – and proven – the superiority of mullers over turbine mixers for sand and many other mixing applications. A Simpson muller’s lower sand temperatures and thorough mixing deliver more consistent, higher quality sand during a run for lower scrap and improved casting surface quality. Per ton of sand mixed, mullers consume less new sand, power and bentonite than turbine mixers.
“I visited Simpson in the USA and looked at the machines running at some of their customer sites,” says Franz. “That confirmed that the Mix-Muller was the right equipment for us. Meeting Bruce and his team was very important too. I got a good understanding of how Simpson works and what they stand for – I came away with a very good impression. They were very strong in the US, Japan and South America, and I thought their equipment would also be a good choice for European foundries.”
The Hartley controller was also a big attraction, letting Dietermann completely automate and control the dosing and mixing process. “The availability of the Hartley was certainly important, indeed decisive,” says Franz. “It’s a great favorite with our customers who love the idea that we have a little robot in our mixer taking samples and controlling the quality of each batch automatically.”
The new sand plant was installed in 2010. The Mix-Muller, one of the first in Europe, rapidly proved that the foundry had indeed bought a superior mixing technology.
“It performed very well, and both sand and casting quality improved significantly,” says Franz. “Mold cracking was a problem before, especially with tall molds and flasks, and meant we often had to do a lot of manual grinding. With the new muller, we had far fewer small cracks in the molds which really reduced the amount of hand finishing required.”
Dietermann only needs to add small amounts of new sand and bentonite after shakeout to maintain sand quality. The muller has also required far less maintenance work to keep it running well over the last 13 years.
“The machine is very reliable and we have very low downtime,” says Franz. “Its components last a long time, in fact, there is very low wear on any part of the equipment.”
With Simpson now part of Norican and investing heavily in its European operation, Dietermann is can expect many more years of top quality sand mixing. “Simpson really are the sand experts,” says Franz.
