Midsize users provide ideal examples of the suitability of additive manufacturing for industrial applications. That’s because the technology has to deliver a return relatively rapidly at companies of this kind. Rolf Lenk Werkzeug- und Maschinenbau in Ahrensburg, Germany, has achieved this: Its additive metal manufacturing is growing rapidly, thanks not least to its good interplay with the company’s conventional production activities.
A key pillar of additive manufacturing at Lenk can be found right next door to the company’s laser sintering machines. The production halls adjoining the AM department are home to many milling, turning, and erosion machines. »A good additive contract manufacturer needs expertise in machining,« explains Gregor Sodeikat, Managing Director and shareholder at Lenk Werkzeugbau. »It’s about more than just setting up a 3D printing machine. Customers generally expect fully functional components.«
After the additive manufacturing process, supporting structures usually have to be removed, holes or threads drilled, or individual surfaces milled. The printed metal parts are often intricate, irregularly shaped and have a rather rough surface, making them difficult to clamp. »If you don’t think about postprocessing during additive design, it will cost you further down the line,« says Gregor Sodeikat with a smile. That’s why his company optimizes components for production at the design stage. In addition to the milling machines, the tool shop contains numerous jigs that gently clamp additive components for postprocessing.
»You can’t create a good additive product if you’re not in contact with the customer«
As the company name shows (»Werkzeugbau « is German for »toolmaking«), Lenk’s roots are in toolmaking and traditional metalworking. Over the years, the midsize enterprise, which is based in Ahrensburg, about halfway between Hamburg and Lübeck, has also built up extensive expertise in additive manufacturing and, according to Managing Director Sodeikat, is »northern Germany’s largest service provider for additive metal production.«
»We deliver everything from the initial idea right through to the finished component,« adds Matthias Otte, who has been responsible for additive manufacturing at Lenk for two years as project manager. For some customers, Lenk prints according to customer specifications and delivers the parts as they leave the machine; for others, the service ranges from component optimization to postprocessing.
No powder-related risks
The company’s large-scale projects include aluminum engine mounts for the Bugatti Chiron. Each year, 125 units are produced in Ahrensburg. Because production volumes generally tend to be in the single-digit range, Sodeikat refers to this as a »series«. The order also includes a measurement report for every fifth part. »The process is running smoothly,« states Otte. Powder is also an important element in the process: Lenk Werkzeugbau purchases the material directly from the machine manufacturer. Specific powder suppliers are cheaper, says Sodeikat, but then you have to check each batch yourself. »And with a part costing several thousand euros, it makes little sense to jeopardize process reliability and ultimately the entire build job just to save €40 on powder.«
AM established as a growing business area
Managing Director Sodeikat first came into contact with the world of 3D printing back in 2006, when he received an order for conventional prototype components from SLM Solutions in Lübeck, just 40 kilometers away. Since then, the 59-year-old has been fascinated by additive manufacturing. »That’s why I’m actively driving it forward,« he says – adding that it is, of course, important that »it all pays its way«.
»Once the additive manufacturing process was running smoothly, we bought our own machine.« Two more followed in 2016 and the fourth in 2018. All powder bed machines are from SLM Solutions. These currently include two SLM280 Twin and two SLM500, which are equipped with four lasers. In the meantime, Lenk has also acquired a Gefertec deposition welding system and uses it to manufacture ship propellers, for example.
At the company, which has 29 employees in Ahrensburg, additive manufacturing has now developed into an important business area, alongside toolmaking and mechanical engineering. Seven employees work exclusively with 3D printing: four in production, and three in customer service. »And additive manufacturing is growing faster than the other areas,« says Matthias Otte.
It takes time to develop expertise
The first orders were placed through trade fairs, with some also coming from the classic car scene. Sodeikat recalls that it took »a good year to develop the technical expertise for additive production. And during that time, we had to throw a lot into the scrap bin«. Today, the production level is significantly higher, »but the scrap bin isn’t empty yet,« Otte openly admits. »Producing 100 percent good parts remains a challenge.«
Thanks to the manufacturing knowledge they have acquired, Lenk’s employees can also suggest optimizations of individual components to existing customers and manufacture these using additive manufacturing methods. Components of this kind include a grabber originally milled from aluminum: Otte was able to persuade the customer to print the grabber using titanium. This makes the component a little more expensive, but it now has around four times the former service life.
»Involve customers in design«
Sodeikat and Otte can now cite numerous examples of optimized components. The prerequisite for optimization, however, is to continually convince customers of the advantages of additive design. »If we are to succeed in this, customers need to understand how to make additive products,« explains Otte. »That’s why we try to involve customers in the design process,« he adds. This approach gave rise to the idea of constructing a scraper for meat processing that was hollow on the inside. »That meant we had less distortion, needed less material, and could manufacture the product faster.« Sodeikat therefore considers dialog with customers essential. »You can’t create a good additive product if you’re not in contact with the customer.«
Otte now regularly visits customers to train design engineers in the special features of additive manufacturing and has seen dynamic development in this area. »The training enables customers to give their imagination free rein when it comes to additive parts.« However, the process takes time and is often also a generational issue.
Sodeikat does not expect customers to draw on their enhanced knowledge of additive manufacturing to establish their own production facilities, though some occasionally consider doing this where large volume are involved. »But they often give up on the idea because of the high investment.« Just having a machine is not enough. »You also need the peripherals, the machining, a saw, and a whole lot of expertise. « Even if you only take the costs for the technology into account, an AM system has to be used to at least 75 percent of its capacity. »And that means you first have to have the right number of parts.«