Emerald Group Publishing Limited
Copyright © 2008, Emerald Group Publishing Limited
Edgecam instrumental in satellite manufacturing processes
Article Type: Aerospace technology From: Aircraft Engineering and Aerospace Technology: An International Journal, Volume 80, Issue 3.
Launching a satellite into space requires sophisticated and innovative technology as does the design to manufacturing process preceding it. Surrey Satellite Technology Ltd (SSTL) is said to be the first professional organisation to offer low-cost small satellites within rapid time scales, using advanced terrestrial technology. The company's Sevenoaks-based Optical Payload Group is using Edgecam's software solution to machine electro-optical instruments for space applications.
The range of instruments developed by the optics group includes multispectral and hyperspectral imagers for environmental, commercial and military applications; environmental ozone monitors; infrared fire and hotspot detection imagers; space debris monitoring cameras; and satellite-to- satellite broadband optical communication instruments.
“All of our manufacturing is bespoke and before we had our own four-man workshop operation at Sevenoaks this was subbed out,” explains manufacturing manager Geoff Cooper. “The bread and butter work is still often placed with third- party subcontractors, but specialist optics projects are handled in-house.”
The Group manufactures to order for a broad customer base, which includes the European Space Agency, commercial companies and governments of countries that are keen to join the space race. SSTL designed, built and delivered the first European Galileo satellite, GIOVE-A (Figures 9 and 10), launched in December 2005 and vigorously pursues its vision of providing customers with affordable, frequent and rapid access to space.
Figure 9 GIOVE-A designed and built by SSTL, GIOVE-A, the first satellite in orbit for Europe's Galileo navigation system
Figure 10 GIOVE-A satellite
Edgecam is used in the manufacture of structures for mounting the optics and for avionics modules basically, metal boxes which house the electronics machined in one piece from a billet or as “honeycomb” panels. Two thin skins bonded together with a honeycomb core form a light but rigid structure, which can be used for solar panels and other parts of the satellite platform.
“A 3D design is generated within SolidEdge or SolidWorks and imported directly into Edgecam,” says Cooper. “The platform is made from a combination of heritage units and new designs and developments. Inevitably we have changes during the programming cycle; Edgecam gives us the flexibility to easily update machine code to the latest release.”
Metal enclosures are designed according to the customer's specification to accommodate the optical modules required. Each job is quite different from another, often involving numerous angles, with pockets cut out of the metal wherever possible in order to reduce weight a vital consideration with aerospace applications. A wide range of standard and exotic materials is used from stainless steels to aircraft grade aluminium and titanium each presenting particular machining requirements.
“We had been using a competitor system for some time but it didn't quite give us all the technology we were looking for,” explains Bob Pearce, programmer/operator on NC milling machines at SSTL. “After viewing demonstrations and having discussions with Edgecam, we decided its advanced system would meet all our criteria in the most efficient way possible.”
Pearce and his team get involved at the design stage to ensure the synergy is right between drawing and model. With confirmation that the product can be manufactured to meet all the customer's specification, Pearce takes the model into Edgecam to generate the machining program.
Before pressing the button to start machining, the simulation mode in Edgecam ensures the entire NC program is correct. The solid model can also be used for inspection purposes once the item has been made, as it will contain all the relevant dimensions and co-ordinates for the part.
The machine cycle simulations identify ways to assign work to the Haas CNC and thereby balance the workload.
“Any erroneous cut will show up on the simulation which can be overlaid onto the solid model,” says Pearce. “This facility enables us to see where the clamping is and ensure collision avoidance eliminating idle time both for machine and operator.”
The manufacturing team at SSTL finds Edgecam very user friendly and straightforward for machining the complex shapes for the metal housings.
“There is usually more than one way to do a job and the system gives you the choice of using feature or milling cycles,” notes Pearce. “Not only that, it is intelligent and intuitive with Windows drag and drop and the ability to change dimensions accordingly.”
“The tool library function has proved invaluable for our manufacturing processes. If the tool isn't there it can be created to handle certain forms and sizes. The system works this out automatically, provided the operator has entered the correct information to start with.”
A further key advantage with the Edgecam package is the support and training provided, enabling SSTL to get the very best from its investment.
“The facility on Edgecam's web site to submit suggestions and post questions, is brilliant,” explains Pearce. “It creates a resource whereby users share their problems and solutions. Training and customer care days are also useful in this regard, providing plenty of opportunities to interact.”
“Being able to have any problems solved remotely is fantastic. It's not efficient to have the machine standing idle when it should be machining parts, so if we do need to know the best way to tackle a particular job, the fact that it is not necessary to wait for an engineer to turn up is a big plus for us.”
“Faster and more efficient Edgecam has made an enormous difference to the efficiency of our manufacturing processes. In terms of ROI, we are seeing a 60-70 per cent saving on what it would cost to have multi-off orders handled by outside subcontractors.”