Swedish company, DST Control manufactures embedded electromechanical systems for unmanned aerial and ground vehicles, including helicopters, airships and spherical ground robots, and offers core competencies in areas such as motion control and inertial navigation. This is a demanding sector, with clients often requiring sophisticated, customised products on a fast track basis.
Until recently, the company used CNC milling to produce the aluminium parts for its products, which had become problematic on three levels. Firstly, the cost of producing increasingly sophisticated parts via classical CNC techniques was rising exponentially. Secondly, there was a critical dependence on sub-suppliers of CNC milled parts and these suppliers tended to prioritise high volume contracts, resulting in a slower turnaround for DST Control's smaller orders. Thirdly, some parts have to be customised, meaning even lower volumes and increased costs.
Following a review early in 2008, DST Control decided to combine classical production techniques with direct digital manufacturing (DDM). Parts subject to customisation were to be produced via in-house DDM methods, while more 'standard' parts could be manufactured externally.
During this process, DST looked at one possible DDM technique - fused deposition modelling (FDM) - and, in particular, at the Stratasys FDM 360mc machine, which had only just been launched at the time. The 360mc is targeted at users with demanding applications that require the same performance in terms of accuracy, repeatability and material specification, as high-end FDM systems, but who do not need as much throughput.
"The models looked good but to get a real idea of the capabilities of the technology we ordered specific parts required by our own products," recalls DST Control's managing director, Jan-Erik Stromberg. "As the results matched up to our quality and accuracy standards we decided to purchase our own FDM 360mc." Although this machine was initially acquired to manufacture parts for DST Control's in-house developed products, it is now also contributing to the development of products on behalf of customers such as Rotundus, manufacturer of the unmanned spherical ground vehicle, Groundbot.
The first DST Control product to be built using the FDM 360mc is a miniature high-performance electro-optical gimbal called Colibri, which won the Swedish Embedded Award 2008. The first unmanned vehicle to be fitted with Colibri is the Groundbot, which comprises plastic parts manufactured directly on the FDM machine, and replacing previously CNC milled aluminium parts. An estimated 50 Colibri units will be produced per year, each comprising around 20 parts that will be manufactured on the 360mc. The machine will also be used to produce prototypes of future Colibri developments.
Colibri is designed so that only the plastic parts are affected by custom specific alterations. In this way, long lead-time items can be kept in stock and the 'just-in-time' plastic parts manufactured very rapidly in-house to customer specifications. Indeed, DST is now able to offer customers delivery of customised Colibri units in just four weeks, rather than the ten to twelve weeks quoted by competitors. Moreover, by replacing the CNC-milled parts with in-house manufactured plastic parts, part cost has been reduced to a third that of competitive offerings, and has helped DST to achieve significant reductions in production tools costs. The plastic parts also perform better technically, are lighter in weight and provide better electrical insulation.
Being able to manufacture parts in-house has helped DST Control to meet critical deadlines for deliveries that would otherwise have been severely delayed by late design changes or simply waiting for replacement or customised parts from suppliers. The FDM 360mc has not only speeded up the development process beyond DST's best expectations, but has also completely removed the overheads of third-party supplier interaction.