ISAR is ready for take-off!

Company:       Isar Gears
Product:          Electronic Drives
Industry:         Aerospace
Service:           Direct Metal Laser Sintering

Aerospace engineering has always been one of the most innovative industries. Every design is characterised by exceptional load capacity with minimum weight and space requirements. The increasing demand for electric drives brings further challenges. Isar Gears in Ismaning, Germany, is only too happy to take these challenges on - with expert knowledge and support from Protolabs.

An aircraft with an electric drive and a propeller transmission that works both horizontally and vertically. That is the brief for the latest development faced by Isar Gears Managing Director Albert Wimmer and his team. "It is very exciting because the delivery of transmission oil must be guaranteed at all points." The reason why the client chose the small team at Isar is immediately obvious if you take a look at its previous projects.

Transmission specialists

Drives with speeds of well over 100,000 rpm, turbo transmissions in the megawatt range and high-performance drives and gearboxes in general are among the specialist areas of Isar Getriebetechnik KG. They develop mainly prototype drives with short production runs. Customers appreciate the very short development times and use their drives in aviation technology, the automotive industry or research. The firm’s product spectrum ranges from small and micro drives to massive test rigs which are designed for extreme loads. A 1.9 megawatt adaptor drive for a helicopter test rig is one such example of its sophisticated drive engineering. Another area of the business is concerned more with pioneering services in the form of preliminary developments for future products. Delicate lightweight constructions can still deliver considerable performance.

An electric drive for aviation

No wonder then that managing director Albert Wimmer was entrusted with the new propeller drive. "Our aviation customer came up with the idea of ​​a completely new, relatively high-speed electric motor. They appointed us to design the speed reduction transmission to drive a propeller. The difficulty is the pivoting of the entire unit. i.e. there must be lubrication in every position."

To achieve this, the Isar team has constructed a fine-veined channel system with outlet nozzles for the oil which is pumped around the system. The theoretical solution was initially presented via the creation and display of the system in the 3D CAD system Creo. Subsequently, a robust prototype was needed. Conventional CNC manufacturing techniques were ruled out as much of the complex geometry is difficult to achieve with milling or requires hugely complicated technical designs. Albert Wimmer therefore sought out a powerful 3D production service provider and found what he wanted at Protolabs: "We opted for the metal sintering process, which is carried out in nearby Eschenlohe by Protolabs. We were impressed by the unbelievable speed of both the quote and the fulfillment of the order in just 15 working days."

Immediate results

The first prototypes immediately brought important insights for further development. The labyrinthine oil channels left residues of the sinter powder that could not be removed. Therefore, in the next development cycle wider exits were created to enable the emptying of the channels. These can be closed again later with inserts. The wall thickness was also thickened in certain areas to increase stability.

"The necessary revisions were carried out much faster with Protolabs than would have been possible with traditional providers," says Albert Wimmer. "Protolabs also provided first class advice for production-oriented designs with special support geometries, etc. All this contributed to a speedy production process. We now have a functioning unit consisting of motor, drive, integrated pump and output flange. There is already a next stage of development in which the pump not only circulates the drive oil, but immediately cools the engine" says Albert Wimmer.

Time savings and precision are important factors in the award of contracts for manufacturing services, as shown by another critical part: "An internally helical ring gear carrier has very sophisticated gear geometry which means extremely long tooling times in standard production processes. Not so with Protolabs. They produced a fully functional part by metal sintering in the usual short time" says managing director Wimmer enthusiastically.

The data from the model is simply uploaded to the Protolabs quoting platform, where it undergoes a feasibility check. Working closely with the customer, the design is optimised. This analysis is free. As soon as the green light is given, production begins.

3D manufacturing at the touch of a button

Albert Wimmer is happy to have found a partner with the resources to master the complexity of additive manufacturing: "For us, Protolabs is simply the 3D manufacturer at the touch of a button. We have a supplier with a full range of procedures and materials and who is always up to date with the latest technology. In addition, they offer sound advice and simple order processing. It means we can always find the optimal method for any requirement. Their comprehensive services and extremely fast and punctual production take a lot of pressure off us. They allow us to focus fully on our projects while benefiting from state-of-the-art technology."

Greetings from the future

Where exactly the new drive will be installed and where the futuristic aircraft is to be used, Albert Wimmer cannot yet reveal. But he is sure that it will be spectacular: "Isar Getriebetechnik is always called in for brand new developments. It's always a great feeling when you see your own ideas translated into prototypes. For us, Protolabs is an essential member of the team when it comes to turning ideas and computer models into high-performance products."