Without regular inspection and maintenance, CNC machines gradually lose positioning accuracy and introduce errors over time. To process complex, high-value aircraft fuselage components, BAE Systems uses the wireless ballbar system to provide the required machine tools Diagnostic data to maximize product quality and productivity.
background
The manufacture of fuselage components for modern aircraft has stringent requirements on accuracy and quality consistency, and the life expectancy of fuselage components must match the life expectancy of the aircraft, thus ensuring production quality and reliability in the machining of metals and composites It is very important.
At Tyrrhenian Akrotiri Airport at dawn, a typhoon fighter from the 11th Air Force Squadron is ready to take off (photo courtesy of BAE Systems)
BAE Systems, a global defense, aerospace and security company, produces a number of key fuselage components for the European typhoon fighter, a twin-engine, delta wing multi-role fighter that has been included since its service in 2003 Air Force in many countries in the world.
In the state-of-the-art manufacturing facility at Somersbury Airport near Blackburn, UK, more than 80 CNC machine tools from BAE Systems are in high gear to produce the high-value fuselage components required for Typhoon fighters and other aircraft.
To ensure consistent part quality, minimize material waste and increase productivity, maintaining the performance and yield of five-axis machine tools has become one of the primary responsibilities of the company's line engineers.
As a result, regular CNC machine tool inspection and calibration inspections are paramount. "BAE Systems used Renishaw's QC10 ballbar machine diagnostic system long ago, and since then, to enhance flexibility and ease of use, Started the second generation of wireless ballbar system.
QC20-W ballbar system
If the positioning of CNC machine tools to achieve the desired state, then in any two-axis combination, circular interpolation will be set exactly the same circular trajectory. QC20-W wireless ballbar can provide a more realistic trajectory and set the trajectory Method, in order to determine whether there is error.
Renishaw QC20-W wireless ballbar for machine tool diagnostics
Ball bar instrument contains high-precision linear sensors, each end has a precision ball, respectively, fixed in the two precision magnetic bowl: a magnetic bowl mounted on the machine table, and the other installed on the spindle. In the layout, when the CNC machine runs on a set circular path, the ballbar can measure subtle changes in radius.
European typhoon fighter in flight (Photo: BAE Systems)
Signal processing takes place inside the ballbar and the data is transferred to the personal computer via a wireless connection.The collected data are used to calculate the overall performance of the positioning accuracy (roundness and roundness deviation) in accordance with international standards and Renishaw's own Analysis of the standard report.
The ballbar data is further displayed in both graphical and digital formats to help diagnose machine errors.The ballbar assembly includes 50 mm, 150 mm and 300 mm extension bars for diagnosing CNC machine tools of all sizes.
challenge
Regardless of the type, size, workload, and utilization of the machine, positioning accuracy can degrade over time even without the best CNC machine tools, resulting in machining errors. Damage, installation errors, and even changes in pedestal vibration and ambient temperature can adversely affect accuracy.
It is very expensive to find a machine tool problem after the parts have been machined, and a large percentage of the body components manufactured by BAE Systems are made of titanium alloy material, which is high strength, lightweight, high temperature resistant Corrosive metal materials are expensive and increasingly scarce and need to be booked with suppliers one year in advance to protect the supply.
In addition to the loss caused by scrapped expensive materials, the loss of CNC machining time caused by machine error is even more difficult to recover.
A complex titanium alloy body assembly typically requires 40 hours of machining, and repeated production of end-of-life components can have a serious impact on productivity.
A typical example is that BAE Systems' manufacturing engineers have found that on one of many machine tools, the precision of one of the machine tools is slowly declining, and shop operators are losing confidence in their performance. As it becomes increasingly difficult to produce the required parts , The problem machine is gradually idle, and its original workload was diverted to other machine tools.
To solve these challenges, we need to regularly check the performance of CNC machine tools to maintain the positioning accuracy of the machine is essential for ensuring quality and production efficiency.
solution
To assist in the regular performance diagnosis of CNC machine tools, BAE Systems previously used Renishaw's QC10 ballbar system to identify specific machine tool performance errors.
Renishaw QC20-W ballbar
BAE Systems is now using the second-generation QC20-W wireless ballbar and has also launched a preventative maintenance program that covers the entire plant, providing for periodic inspections of more than 60 CNC machines on a weekly, monthly and yearly basis .
By interpreting the QC20-W diagnostic data trends across all machine tools in detail, BAE Systems has developed a robust benchmark of error range to quickly check the performance of all machine tools and allow operators to make 'continue / not suitable' use of machine tools Of the decision.Once the positioning accuracy of CNC machine any roundness error greater than 30 μm, you need to immediately investigate.
Machine operators trained on ballbar tools use the QC20-W to run diagnostic tests efficiently, which means that these inspections can be done with production gaps with little or no impact on throughput.
At the same time, BAE Systems also determined the optimum ratio of ballbar test components to CNC machine tools, at a ratio of 1:15, which means that at some point, a ballbar can leave the factory and go to a professional facility for annual calibration checks , While other ball gauges perform performance checks on different machine tools in the shop at the same time.
With the knowledge and experience gained from using the QC20-W ballbar on different types of machine tools, BAE Systems is now able to dig deeper into the machine tool described above that actually exited the production sequence.
Using a ballbar, BAE Systems observed an XY roundness error of 200 μm using the ballbar diagnostic software to determine that the main failure mode of the machine was caused by a mismatch in the servo, followed by a second error source that was larger Backlash error. BAE Systems maintenance engineers corrected the servo mismatch problems by optimizing the X-axis drive parameters and then they checked again with the ballbar to quantify the adjustments made after the adjustments.
However, the re-inspection showed that there was a serious error in the machine even after the servo mismatch had been eliminated. Engineers then checked and measured with the ballbar and conventional gauges and found that the error was due to ball screw wear on the X-axis After retrofitting the ball screws and resetting the backlash compensation, the machine reached an XY roundness of 30 μm this time and rejoined the production sequence.
Jim Walsh, BAE Systems 'specialist manufacturing engineer, commented:' Making ballbar inspection an integral part of machine tool inspection not only helps to ensure consistent parts quality, but for machines that have been deemed unsuitable for work, The ballbar can also help us rejuvenate.
He continued: 'The ballbar diagnostic software automatically analyzes results and diagnoses errors, meaning that machine operators no longer have to work hard to calculate the true meaning of the data themselves, determine the location of the problem and find a remedy based on the principles and formulas This will save a lot of time in actual production.
result
BAE Systems faces many challenges in the fabrication of high-value aircraft fuselage components, and incorporating the QC20-W wireless ballbar system into a dedicated CNC machine preventive maintenance program is a beneficial step toward addressing these challenges.
Jim Walsh, a BAE Systems employee, is using the Renishaw QC20-W ballbar
Renishaw is also continually updating the functionality of the ballbar diagnostic software. With the new software, BAE Systems will proactively maintain its proactive maintenance program to reduce material waste and increase production efficiency. The root causes of machine errors do not have to be taken by surprise when the problem actually occurs.
In the past, long and costly machine inspections and repairs resulted in a significant amount of machine downtime that was unaffordable to the business, and now BAE Systems' machine error diagnostics can be done almost instantaneously, resulting in a significant reduction in downtime.In addition, With the ballbar diagnostic data, companies no longer rely solely on the service and support of the machine tool builder to solve the problem.
With the help of the Renishaw ballbar diagnostics, significant improvements have been made in the re-energizing of a failed CNC machine and in the productivity and quality compliance of the shop, which has benefited BAE Systems.
For more information, visit www.renishaw.com/calibration