Think of the South West of England and it’s difficult to get past images of sandy beaches and stunning scenery – but it’s easy to forget the region’s rich heritage in world trade and innovation. From its purpose-built facility in Bodmin on the edge of the Moor, Flann Microwave is testament to the fact that 21st Century technology is certainly alive and kicking in the region. Solutions reports.

Founded in 1956, Flann Microwave relocated to Bodmin 40 years ago and is today a world leader in the design, and manufacture of antennas, precision microwave components, test, and measurement systems operating up to frequencies as high as 500GHz.

The diverse application of Flann products includes military, broadcasting, aerospace, telecommunications, satellite communications, academic/scientific institutions, utilities and manufacturing. From its UK and US facilities the company supports a global customer base including such household names as Ericsson, Siemens, EADS, Alcatel, Astrium and Nokia.
Today’s technical and commercial considerations create an increasing demand for ever higher frequency equipment – one simple example being the switch from analogue to digital in TV broadcasting.

Ian Crane, CEO of Flann Microwave explains the associated engineering problems: “The issue is a combination of accuracy and scale,” he explains. “Put simply, wave guides are chambers of differing size and shape in both section and length, and for any size chamber, dimensional accuracy and geometry are critical performance factors.

“The higher the frequency, the smaller the chamber and its features are required, and that is where the micro engineering begins. Producing a chamber for lower frequencies of say 10mm rectangular section with no corner radii to a tolerance of 10µm is perhaps one thing. However, consider the challenge in scaling down the product by a factor of 10 to produce a chamber in gold plated copper 1mm across, rectangular at one end and changing form to a circular cavity at the other. The size reduction translates to a tolerance reduction to 1µm.”

He continues: “Such challenges require not just high technology tools but the people with the skills to use them and develop the processes that optimise their use. Further, to utilise the best of these technologies and integrate them into the design process for current and future generations of Flann products.”

Procurement project

Tasked with this remit, engineer Lee Osborne and his manufacturing colleagues recently entered into a procurement project which culminated in the supply of a new manufacturing cell from Suppliers RK International Machine Tools of Erith, Kent.

The equipment supplied comprised of two Fanuc F Series RoboDrill VMCs with Fanuc 31i A5 controls. Having spindle speeds of 10,000rpm the RoboDrill is designed for high speed, high precision applications and features a nano CNC system which uses an ultra precision pulse coder for control with interpolation and feedback in nanometres. Feedrate and acceleration control are facilitated by Ai contour control capable of reading up to 30 blocks in advance.

Also included in the RK International solution was Rengage technology in the form of two Renishaw OMP 400 high accuracy optical machine probes. This latest compact product from Renishaw features the miniaturisation of the strain gauge technology pioneered and proven in the company’s successful MP700 probe.

Virtual elimination of lobing errors and high repeatability are some of the significant benefits offered over and above traditional probe design and, according to Mr Osborne, this ultimately influenced the choice. The probes, housed in the RoboDrill’s 21 station vertical tool turrets are used for workpiece set-up and are regularly used with 0.5mm styli diameter. In keeping with the micro milling set-up the machines use single point diamond tools, end mills of 0.2mm and drills of 0.1mm diameter. Tools are set via Renishaw’s TS27 wireless toolsetting system, included on each machine.

RK also supplied wash guns and hoods for each machine and organised the appropriate training which was straightforward since the new RoboDrills join an existing installation and the Flann engineers were already competent with Fanuc controls.

Fine art

The offline programmed RoboDrill cell is engaged specifically in the production of minute mandrels, machined to take the intricate and often highly complex internal form of waveguide chambers. These may be helical, contoured or blends from rectangular to circular. Machined from solid the mandrels represent a very small percentage of the original stock material and are extremely delicate, requiring high spindle speeds and low feed rates.

In addition to the 10,000rpm spindle speed capacity an air turbine spindle attachment, capable of speeds to 90,000rpm is also utilised and can be moved from machine to machine. The low feed rates mean a single mandrel may take several hours to produce. Considerable time is then spent on deburring which at Flann is truly a fine art. Indeed so specialised is the design and manufacturing process that Flann undertakes its engineering almost exclusively in house and to support this the company is currently training three apprentices,

Completed mandrels are used to produce wave guides using an electroforming process – in itself a simple enough technology similar to electro-plating. Flann however takes this process to another level and is able to produce a complete component comprising wave guide and flange that requires no further machining. Typically formed from copper, the components are then coated in 24 carat gold or silver.

Attention to detail

The entire procurement project took just six weeks from enquiry to production and serves to emphasise the value in partnering with the right supplier. Mr Osborne comments: “The cell involved not only the machines, but all of the other associated equipment critical to the installation and subsequent process. To this end we have been very satisfied with the efforts and attention to detail of the RK International team.”

Dick Aldrich, sales director at RK International emphasises how such a project illustrates RK’s longstanding commitment to the manufacturing community, stating: “Throughout our 60 years the name RK has been and continues to be recognised for understanding and fulfilling the customer’s needs. Longstanding and strong relationships with globally recognised principal suppliers enable us to provide a comprehensive choice of brands reliable in operation and trustworthy in aftersales support. From a single new or used machine through to a turnkey package we aim to balance the best available technology with budgetary and time considerations to provide solutions that add value and profitability.”

Serving to underline the importance of a timely and efficient project completion Mr Crane further adds that: “Following the difficulties experienced by us all over the last two years it was as though someone flicked a switch in September 2009, since Flann Microwave in 2010 looks set to enjoy its best year since 1996.”

RK International
www.rk-int.com