The aerospace tubular parts manufacturer SL Engineering is continuing its investment in advanced automation with the acquisition of a second all-electric CNC tube bending machine from Unison.
The new machine enhances SL Engineering's manufacturing capabilities, especially its ability to produce more complex tubular shapes. It also extends the size range of tubing that can be bent using all-electric servomotor-controlled movement - to tube and pipe diameters up to 80 mm.
"Engine and aircraft manufacturers are taking advantage of the advanced shape forming capability of state-of-the-art tube bending machines by specifying more complex shapes and highly challenging tighter-radius bends - to save weight and space and eliminate welded joints," says Shaun Stevenson of SL Engineering. "The sophisticated bending capability of Unison machines, which allow greater control over tube clamp and carriage push forces, helps us to achieve these new levels of precision. If we did the same jobs on our old hydraulic machines we would be much more reliant on highly skilled operators to bothset up the machines, and make the parts with additional weld joints, and hence additional cost."
SL Engineering (SLE) is one of Europe's leading Tier 1 suppliers of rigid tube assemblies and precision machined parts for aerospace applications, and supplies components to major engine and airframe programs from commercial Airbus and Boeing aircraft to leading military programs such as the Joint Strike Fighter (JSF). Although the aerospace sector accounts for a large proportion of turnover, SLE also provides parts for industrial gas turbines, marine propulsion, and other critical industry applications.
SLE's business today is characterised by a need for manufacturing flexibility. The average batch is around 5 to 25 parts, and orders can even be for just a single emergency 'aircraft-on-ground' part. Demand for greater precision and shape complexity is another major facet of its work. Until recently, few tubular parts required bends with radii of less than 2D (twice the tube diameter). Today, however SLE regularly receives requests for bends of 1D, and for shapes with minimal straight sections between bends. The use of thinner walled tubing, and expensive specialist materials such as titanium and Inconel are further trends.
These demands are behind the company's moves to all-electric tube bending technology. SLE installed its first such bending machine in 2010 - a 30 mm diameter Breeze from the UK manufacturer Unison. Much of SLE's work is on diameters of 30 mm or less, and most of its current work falls into the sub-50.8 mm range. The first all-electric machine has proved critical for SLE, allowing it to handle small batch set-ups much more efficiently and quickly - with zero or minimal scrap. As a result, the company channels most new work for smaller parts onto the 30mm all-electric machine, and transfers many older parts onto the machine by creating new bending programs as orders come in. After almost four years of operation, the 30 mm machine now produces a significant proportion of SLE's business. SLE typically has anywhere from 500 to 1000 live jobs at any one time.
The latest machine that SLE has acquired, a Unison Breeze 80, now gives the company all-electric CNC tube bending options for tube diameters up to 80 mm. The machine also incorporates a multistack/multiradius tooling capability. This feature is a critical aspect of achieving some of the complex tubular part shapes and multiple bend sequences that are being specified on today's aerospace programs.
"We continue to see many challenging opportunities in the sector, but it does require significant capital investment," adds Stevenson. "The new Unison bender, along with further investments in 5-axis machining, has helped SLE take its manufacturing capability to a new level. We can meet the most complex tube assembly specifications that aerospace companies require today, and the combination of advanced machinery and our know-how gives us a platform to raise the bar even higher, and differentiate SLE from our competitors. Another service we offer to clients who are able to provide us with pre-release drawings, is evaluating manufacturability and advising on the potential for manufacturing and cost saving improvements before final drawing release."
As an example of the exacting specifications that SLE faces, one current part for a military fighter program calls for a shape with multiple 2D bends but minimal straight sections between bends, using thin wall titanium tubing. Tube ovality also has to be less than 5% after bending - as compared with an industry norm of 10% - and the part shape has a positional and length tolerance of just +/- 0.005 inches after bending and welding. As the part is made from titanium, bending must be right first time as adjustments after shape forming are almost impossible. The consistency and repeatability of the Unison machine is a critical enabler for fabricating this part, as well as other titanium tube parts that SLE currently makes.
Another aspect of the advantages of the Unison machine for a contractor such as SLE is the ease of programming. Tubes are often the last parts to be defined and designed - whether they are for an engine or airframe. Using its own bespoke macro-driven CATIA V5 closed-loop CAD/CAM facility, and Unison's three-dimensional simulator, SLE can create new CNC bending programs for the Unison machine very rapidly - providing ideal support for clients that are unable to supply tube/pipe details until the very late stages of projects.
"All-electric tube bending technology has given this client both a rapid return on investment, and a means of tackling emerging challenges such as bending exotic materials," adds Steve Haddrell of Unison.
SL Engineering Ltd has the fullrange of in-house resources required to offer complete solutions for the manufacture of specialised rigid tube assemblies and precision machined components used in some of the most demanding applications in the aerospace, industrial gas turbine, marine, oil and gas, and medical industries. Founded in 1959, SL Engineering has always specialised in high-precision tubular assemblies - from a starting point of products for motorsports applications. Today, the company employs around 50 staff. Its core capabilities include CNC tube manipulation, CMM tube inspection, multi-axis CNC machining for manufacturing complex end fittings, plus all required support processes including welding, brazing, assembly, pressure testing, and NDT (dye penetrant and x-ray inspection). To support its work in aerospace, SL Engineering has attained qualification to many key industry standards including AS9100 (Rev C) aerospace quality management systems, BS EN ISO9001, and NADCAP special process approvals for welding, brazing and NDT. To reinforce its position as a leading tube assembly specialist, SLE has also achieved SC21 award status for the last three consecutive years - making it one of the top performing aerospace organizations in the UK in terms of business performance and continual improvement. This performance has been all the more impressive as SLE also achieved 22% growth in business during 2013.