A smooth Development

Text: Thomas Masuch; Photos: Zikomm — 2020/10/29

For small and midsize companies, industrial 3D printing isn’t just an applicable technology – it’s a real field of business. For a perfect example, look no further than Bernstein Mechanische Fertigung of Grüna, Germany. While it was purely a contract manufacturer a decade ago (and still makes use of its machining centers), BMF now produces 20 surface-treatment machines each year, which account for half of its annual turnover.

People who visit Grüna might not expect to find a local company with a good bit of sway in the world of additive manufacturing. The village is located along an arterial road to the west of Chemnitz – an eastern German city that, despite its rich industrial heritage, has only just dug itself out of the prolonged hard times that followed the fall of the Iron Curtain. Here, one finds single-family homes with flowery front yards nestled among the rolling hills just to the northwest of the Ore Mountains.

Grüna has one bakery, two hotels, and a brick church steeple that is likely the highest point in the town. BMF’s modern facilities are located right next to a garden that features thriving tomatoes and vegetables in the summer. Its main building efficiently combines several machining centers, a training area, and development and assembly departments. Following its foundation 13 years ago, the family-owned company evolved into a specialized contractor in CNC manufacturing. Among other things, it now produces sophisticated parts for luxury items, high-end vehicles, and medical technology.

»Post-processing is becoming increasingly important in additive manufacturing, including from a financial perspective.«

»We used to have problems all the time with sandblasting because it would leave parts with an inconsistent surface,« recalls Ronny Bernstein, BMF’s 41-year-old managing director. He points out that particularly in the luxury segment, this makes components unusable. Ever the entrepreneurial engineer, Bernstein then started looking for a solution of his own along with his team. This led to the development of an installation the company began using to meet its internal needs in 2013. »We eventually had a customer come by who asked what the unit was and ended up wanting one of his own,« Bernstein says.

BMF thus turned the system into a full-fledged product: the Twister blasting installation. At its heart is a rotary plate with rotating component mounts. In the middle of this carousel, a rapidly rotating blast wheel featuring patented blade geometry ensures that the blasting material is evenly distributed within the unit.

After delivering the first of its new systems to machining companies in its region, BMF gradually realized that the Twister had the potential to make a bigger impact. »Post-processing is becoming increasingly important in additive manufacturing, including from a financial perspective,« explains Marc Krause, an employee of BMF Vertriebs GmbH who has been helping the Twister achieve further success by handling sales and process development for the past three years. »With components produced using AM, post-processing now accounts for between 30 and 40 percent of the total manufacturing costs. The printing process has gotten less and less expensive in recent years, but post-processing has stayed about the same because 90 percent of the work involved is done manually.«

Since BMF discovered additive manufacturing through the Twister and began presenting it at exhibitions like Formnext, sales have really started to pick up. So far, 80 of these systems have been installed – not just in numerous European countries, but in India and (since the fall of 2020) the United States, as well.

Krause attributes the success of BMF’s blasting systems, 90 percent of which are manufactured in-house at the company, to technical advantages that sound like the Holy Grail of blasting itself. »We’ve achieved reproducible results in an automated process that can also be incorporated into automated proponents duction,« he says with pride. In addition, the blasting material is shot by the aforementioned blasting wheel instead of using pressurized air, which Krause says already saves a great deal of energy. The wheel’s rotation speed can be configured to produce different levels of surface quality in terms of Ra (average roughness) and Rz (average roughness depth).  

»requirements with regard to surface quality have risen«

This is how the Twister – and its big brother, the Tornado, which was unveiled in 2016 – ensure that the right type of surface is applied to shifting forks for transmissions, trays for blood plasma centrifuges, dental implants, retrofits for automotive engine comproponents, and many other products. These blasting units continue to be used for machined parts, as well. »Our customers’ requirements with regard to surface quality have generally risen over the past several years,« Krause reveals. »More and more often, functional components you normally can’t see are also being blasted to improve their appearance and promote sales.« At the same time, the 49-year-old (who already has 25 years of experience in building prototypes) is seeing increased demand from AM service providers, whose expectations have also changed. »Instead of just one part, customers are now ordering 50 or more, and they all need to look the same,« he reports.

The innovative ways in which BMF is taking advantage of additive manufacturing are also apparent in the area of spare parts. The drive wheels of the Twister’s rotating component mounts, for example, were created in a 3D printer from Markforged. To make sure that replacements for these wear parts will always be readily available, identical printers have been installed at customer facilities in places like Denmark and India to produce the spares required on-site when ordered. The printers are controlled from Grüna; the customers only have to insert fresh spools and remove the parts when finished. »We don’t have to ship anything, and nothing has to go through customs checks,« points out a pleased Ronny Bernstein. For Markforged, this innovation was so compelling that the global manufacturer made the trip all the way from bustling Boston to BMF’s peaceful hometown to check out its applications in person before adding them to its international marketing campaign.

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