Process reliability was one of the primary objectives of Heinrich GmbH from Berlin: The turned parts contractor recently purchased a Bumotec s181 machining centre from the Swiss company Starrag to manufacture high-precision components for respiratory protective devices.

Although much lower-priced machine tools are available, precision was not the only reason why managing partner Christian Pooch chose the Bumotec s181, a 5-axis simultaneous turn-mill centre with a total of nine CNC axes for the complete machining of complex and high-precision workpieces. It is fitted with a CNC FANUC 31i panel and a retaking unit.

Absolute roundness and a high level of surface quality

The Berliners want to use the new machines, the company's largest investment to date, to break new ground. A regular customer asked the Berliners, after a competitor had already decided not to bid, if they would be willing to produce a distributor for a respiratory protective device. "It is a component that has extremely high demands with regard to tolerances and the absence of burrs," Pooch explains. "Because it is not acceptable for a fireman to inhale small pieces of burrs during use." The new component is the centrepiece that connects the oxygen bottle to the respirator mask. The initial material is a forging blank made from a special aluminium alloy that contains silicon (AlSi05). One example of the precision offered is the H7 opening, which is cut to exactly 14 µm. Christian Pooch: "It's astonishing that a drilled hole can be cut so precisely - with absolute roundness and a high level of surface quality." According to Michael Paulus, Product Sales Manager at the Starrag-TechCenter for Medical Technology and Precision Mechanics, Oberhausen office (Upper Bavaria), however, the biggest challenge lies in ensuring that "there are no burrs in the many interconnecting channels."

The newcomer to Berlin is also impressive in terms of ergonomics: Pooch finds the main spindle to be very smart, because it makes it easier for operators to transition from a standalone lathe to the machining centre. With its HSK-40 tool spindle (30,000 rpm), very small components can be machined precisely to 1.5 µm either bespoke or off the shelf (maximum diameter: 32 mm). Pooch has two sons who work alongside him, one of whom speaks very enthusiastically about the new possibilities. "On its own, our former core business of lathing nuts and screws has not been enough to sustain us for a long time," says production engineer and general manager Tobias Pooch. "But now, with the Bumotec, we can position ourselves even better than before with high-precision components, and also establish ourselves internationally." There is great resonance with the customer base, because the Bumotec has allowed Heinrich to open the gateway to completely new worlds, meaning growth.

"What's special about this is that the machine cuts not only bar parts but also inserts," explains Starrag employee Paulus. "The Bumotec inserts the blank automatically, processes all six sides and then automatically transports it onward." An exacerbating factor here was that the initial part is a pressed piece with very high tolerances; these parts can be cut precisely, not least thanks to a specifically designed clamping system adapted to the machine. Paulus: "We developed and ran-in the clamping system specifically for this component and this machine."

All in all, the new Swiss addition lives up to the Starrag claim "Engineering precisely what you value" in many different ways. Heinrich has put a special emphasis on profitability, reliability and growth. The Berliners have already achieved one of their goals: since its first hour of operation, the s181 has run reliably and without any tolerance deviations. "With this process reliability we can capture a new customer base," says the senior partner.