QMT Features: March 2009
Aerospace SPC catch up
Is a lack of understanding to blame for slow up-take of quality control tools in aerospace manufacturing?  By Ben Allister, Infodream

Robust quality control standards achieved through continuous improvements tools (CITs) and techniques have been a successful feature of the manufacturing industry for many years, having been originally championed by the automotive primes.

However, the aerospace industry still lags some way behind in this area.  The time has come for it to embrace proven Continuous Improvement (CI) methodology to increase productivity through helping eliminating poor quality products that remain unnecessarily prevalent across the aerospace manufacturing industry.

Although aerospace manufacturing is leading the way in terms of technology development, particularly in the use carbon composites, it is a long way behind other industries in terms of robust process planning and process control with many companies being very slow on the up-take of proven Continuous Improvement methodology such as Statistical Process Control (SPC), Failure Mode & Effects Analysis (FMEA) and other quality tools which can help increase productivity. This is especially true within the supply chain.

A good example is the way in which process performance is measured.  In many aerospace companies, quality is only measured in terms of number of scrap or concessions (where the product fails to achieve the quality standard but is allowed to pass through the process anyway where is may be repaired further down the line or, worst case, at the customers final assembly line). 

This type of measure is purely re-active and although providing a measure of ‘bad quality’ actually does very little to pro-actively reduce or avoid errors.  There is a clear need for a system in place to monitor the causes as well as the effects of bad quality.  This includes monitoring ‘right firsts time’ yield (RFT), re-work, process capability (Cp & Cpk) and SPC alarms and trends. These are the measures that really identify waste and drive process improvement and if they are taken care of, ‘bad quality’ will naturally reduce and productivity increase.  At the moment it is undoubtedly a case of ‘wrong metrics driving wrong behaviour’ whereby manufacturing errors are simply managed rather than their root causes investigated and eliminated.

This behaviour was recently identified by Infodream while implementing its trademark software -  SPC Vision - on  a new project at a major aerospace company that was experiencing repeated problems while manufacturing a large complex component.  The problem was so endemic that the component had never been manufactured ‘right first time’.  

Whilst implementing Infodream’s SPC Vision software the company’s quality control professionals began the task of analysing old non-conformance reports to identify specific problem areas and repeat problems.  After inputting all historical inspection data into SPC Vision, the system clearly  identified some areas of concern in that specific areas had a  very low process capability.  This SPC & process capability data correlated exactly with the non-conformance reports.  The problems are now being addressed and the root cause investigated but had a preventative measure, such as process capability, been in place from the beginning, substantial costs could have been saved.

One of the root causes of the problem of poor quality is a lack of understanding of quality engineering at all levels of the business.  Only recently has the aerospace industry moved away from the old concept of quality control through inspection.  In addition, many professionals continue to believe that quality tools are of relevance solely to the automotive industry rather than being applicable to aerospace manufacturing. 

This misconception stems from a fundamental lack of understanding of how the tools can help. Although many professionals are familiar with SPC and statistical terms  such as Cp (potential process capability) & Cpk (actual process capability), they often don’t fully appreciate their proper use and therefore struggle to relate them to process performance or product quality. 
Likewise, other tools such as failure mode & effects analysis which are the backbone of the automotive quality process are rarely implemented in the aerospace world although Airbus has used this tool to great effect, especially during new product introduction where FMEA is used during the development and industrialisation phases of the project to identify, quantify and manage risk in terms of health and safety, product and process design and quality.

Additionally, many companies are focusing all of their effort on implementing lean manufacturing  without realising that all of  the different tools need to be used in conjunction with each other to deliver maximum benefit. Undeniably, implementing lean manufacturing principles can yield huge business benefits but lean tools do not focus on root cause analysis, variation management or process control, which is where 6 Sigma, SPC and other quality tools are required. 

Although European quality standards such as ISO EN9100 are integrating quality tools  into their standards, a major culture change still needs to take place so that there is an acceptance that a benefits driven ‘pull’ is far more effective than a simplistic quality standard requirement -  which is how some of the tools have received a bad reputation to date.  For the tools to be effective they really have to be accepted at all echelons of the business, from the shop floor to the managing director.

In practice, this means having a clear strategy and plan which has been openly developed and communicated across the entire company, the result being a well organised workforce that has been trained to the required level and that possess clear objectives and metrics which are aligned to the overall business deliverables.  All of these points are critical to successful product output and, ultimately, to a company’s success as all too often critical projects fail due these fundamental issues.

Such is the documented evidence compiled by Infodream on the pivotal role of Continuous Improvement tools in a company’s performance, Infodream has decided to broaden its core business from continuous improvement training and consulting services relating to SPC Vision to a broader range of Continuous Improvement tools.  They are offering basic one day training in SPC, FMEA, Measurement Systems Analysis and Effective Root Cause Analysis as well as more advanced 6 Sigma training and management introduction courses.  They are offering a free days consultancy to provide an outside view of current CI processes and  identify potential opportunities for improvements. l

E-mail: Ben.allister@infodream.co.uk

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