QMT Features: March 2011
Value added metrology
Aerospace company, GKN Aerospace - Filton, is ramping up to manufacture advanced carbon fibre composite spars for the new Airbus A350XWB. Metrology skills are key to its production success. By Brendan Coyne, QMT.

Composite parts are the future. Aerospace manufacturing is tooling up to produce aircraft that employ increasing amounts of carbon composite parts as the benefits are considerable - better, more efficient  aircraft performance due to lighter materials.  GKN Aerospace’s plant at Western Approach is gearing up to produce 12 metre long composite spars for the new Airbus A350 XWB. GKN has been developing composites for aerospace for years but the A350XWB programme is biggest commitment yet.

The manufacturing challenge is how to make large numbers as production ramps up.  Composed of layers of composite carbon fibres, technology and techniques are being developed to successful layer and debulk the fibres in a production environment.  The resulting woven spars will weigh less than conventional metal components.  Key to meeting this challenge is metrology.

Andy Fall is the product assurance manager at GKN Aerospace Engineering, Filton and has responsibility for its Conformance Engineering Centre. Established in 2007, the Conformance Engineering Centre (CEC) provides a manufacturing centre of excellence for data driven improvements and provides a single point of contact and authority for dimensional assessments, calibration, re-certification, process capability studies and supplier verification. It also defines future metrology strategy, techniques and equipment.

Since 2009, when GKN Aerospace took ownership and operational control of the former Airbus UK, Filton wing component and assemblies manufacturing facility, the site ethos has become much more focussed on value streams. Metrology has been kept as a core activity as the level of skills required and the cost of equipment is high. It is not cost effective for each lineside activity to have its own metrology facility. Hence the CEC.

 A key task for Andy Fall and his team at CEC is to demonstrate how measurement is a value added activity. “At CEC, we can measure and calibrate pretty much anything on the GKN Aerospace - Filton and Western Approach sites, from small sub-micron measurement up to 50 metres in dimension,” says Andy Fall. ”We help in a lot of problem investigation and cost avoidance through non-conformance management, in terms of reducing scrap and rework,  by being able to give good, objective data measurement.” 

With a skilled team of metrology staff,  800m2   of temperature controlled environments and a sophisticated array of metrology instruments, from Leica laser trackers and scanners to gap guns, the CEC plays a pivotal role in the A350XWB spar build up as well as supporting other activities at the Filton site, the Composite Technology Centre and its supply chain.

The challenge of the next 12 months is to drive the first article of the  Airbus A350 XWB spar composite manufacture.  “We’ve got the production start of the A350  and  we are the core function for first article inspection. To support the demanding production programme, we are looking at six or seven laser tracker teams on double shifts,“ says Andy Fall.  CEC has nine trackers with associated software already on board.

The challenge is one of people and skills. People from the various areas and different backgrounds, from jigs, tooling, wherever,  have to be skilled up to be rounded metrology engineers in order to meet that sort of demand.

The production ramp up starts now and is expected to reach 13 sets of spars per month by 2015 (each set consists six spars) with spar sizes varying from 9m to 12m. Every set presents a new measurement challenge which in turn tests the abilities of the CEC measurement engineers. “We have a little saying here,

“Everyday is a school day”, and so the ability to learn is critical.” says Andy Fall. 
Recruiting, training and retaining the right people with the right skills set is key.   “We look for people who are flexible, with a thirst for knowledge.  It’s a case of where technology moves forward, keeping people abreast of that technology, making sure they have a good grounding and understanding of metrology.”

Completing a three day course provided by the  measurement equipment supplier doesn’t necessarily produce metrology experts. Helping the engineers to absorb the technology encountered on a course, CEC gives them time to play with the technology so that they can become proficient. But if the metrology operatives are to handle the measurement applications successfully, they require more that just the specific application knowledge. They require a deeper understanding of the principles of metrology.   To address these issues and produce rounded engineers, Andy Fall recommends that the engineers and operatives undergo a National Physical Laboratory Level 1 (and 2)  metrology course. 

These courses,  run for GKN Aerospace by Hexagon Metrology, who are a NPL certified training company,  give the participants a basic understanding which allows them to challenge how things are measured,  making  sure measurements are carried out appropriately  according to datum instructions and tolerances in the models and drawings given. “NPL training is being able to understand why you are doing something as opposed to how. You can get measurements wrong very easily by just applying a slightly different technique,” explains Andy Fall. “NPL level 1 and level 2 courses are a good base line for training metrology engineers but, clearly, there are more specialised areas of knowledge required for specific technology, such as for laser trackers, CMMs and portable arms -  or  for measurement software, such as Spatial Analyzer,   PC-DMIS or Verisurf.”  On the shopfloor , the intention is to train operatives on the A350 programme to take measurements as part of the production process.

 One of the big advantages of instruments such as laser trackers is their portability. “If there is an issue on the shopfloor, we are able to take the measurement systems down to help determine where the problem lies, such as the stack up of tolerances between two parts. But without determining where things are in their tolerance bands, you are never going to know that. It could be part A or part B is faulty - there is a non compliance somewhere,”  explains Andy Fall. 

With so many sets of metrology equipment  and people to be ferried round to shopfloor applications,  good planning of the logistics will be essential for successful support. The task will be greater as there will also be a lot of inter-process measurement as well as finished part inspection.

2D or digital manufacturing?
Although the future is digital, there are  still plenty of 2D drawings around. GKN Aerospace is required to use both 2D and digital  models. “It’s about 50/50 split. For example, single aisle aircraft, such as the Airbus A320, which is still the biggest production item for Airbus, uses 2D drawings,” says Andy Fall.  “For me, one the biggest challenges is here - how do we measure using modern technology parts and assemblies which have been made with lofts ( a life-sized drawing) using  red masters (agreed) parts? This is one of the reasons why we have just invested in the Leica T-scan probe for use with the laser trackers. This will allow us to do good quality comparative measurement. For example, if you have got a red master of a pressed part, its difficult (and time consuming) to take enough points with a single point measurement system  to determine where you sit in the tolerance band. With the T-Scan scanning system we can get plenty of good data to generate a good comparative analysis.”

Andy Fall used to be a Lean engineer.” Whenever we were going to go out and do a Kaizen  or something similar, the first thing we would do was Gemba.   Get the people together in the work environment and ask, “What’s wrong?” Certainly, when it came to Gemba here at GKN, the big concern was that calibration was too slow. When we looked at it, we were turning tools around in 17 days, which was woeful.  Through applying a basic Lean approach using simple visual management techniques, turnaround is now  less than five days.”

Included in the CEC is a tool room with a small machine shop . “If we are certifying a jig and find something needs adjusting, then we’re able to correct it and give it back to production quickly.”  Inventory has been reduced by 40%. and toolroom throughput of mechanical calibration times  improved by 70%. Process safety is  zero with no near miss or accident reported for the CEC last year. “We’ve taken more work into the facility, expanding its range.  At the same time, we have carried out our strategy & training plan to develop our people.”  When it comes to metrology, Andy Fall believes the CEC has clearly demonstrated it is a value added activity.l
email: andy.fall@gknaerospace.com

*Gemba is a Japanese term meaning "the real place." Japanese detectives call the crime scene, gemba, and Japanese TV reporters may refer to themselves as reporting from gemba. In manufacturing, gemba refers to the place where value is created on the factory floor. The concept is that to be customer-driven, one must go to the customer's gemba to understand his problems and opportunities, using all one's senses to gather and process data. In quality management, gemba means the manufacturing floor and  if a problem occurs, the engineers must go there to understand the full impact of the problem, gathering data from all sources.

Similarly, in lean manufacturing, the idea of gemba is that the problems are visible, and the best improvement ideas will come from going to the gemba. Gemba visits are not scripted or bound by what one wants to ask.

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