New Technology Promises Quicker, More Accurate Defect Measurement

Improving upon the limitations of existing interferometry technology, which uses a light beam split between two surfaces to measure the differences between the two, 4D’s PSL technique takes only tens of microseconds to measure defects. Traditional interferometry measurement takes much longer—making it susceptible to interference from vibration in noisy manufacturing environments—so 4D’s system is unique in enabling accurate, handheld measurements in MRO settings. Additionally, the technique increases the measurement range from hundreds of nanometers to several millimeters.

Using 4D’s handheld InSpec Surface Gauge, the new technique can measure defects such as pits, scratches and paint thickness. The gauge can be mounted on a robotic manipulator for fully automated measurements of aircraft components and data is transferred to an MRO’s quality control systems via LAN, USB or Wi-Fi. The InSpec system comes with optional accessories such as a portable workstation and a rechargeable lithium-ion battery with up to eight hours of operational time, giving technicians more flexibility.

According to the company, operation of the equipment is simple and only requires a few minutes of training. To complete most measurements, technicians place the InSpec Surface Gauge’s alignment tip on the surface of a component, tilt the gauge until the on-screen image of the defect area turns green and then click a button on the gauge.

Measurement results will appear on the system’s computer screen and the accompanying software automatically locates defects and displays their measurement parameters. Measurement “recipes” can be created and stored to limit variability between operators.

4D says the new technology provides cost savings by performing more accurate, repeatable measurements. Instead of scrapping parts that actually meet specification due to the extra caution required with other inspection methods, 4D’s technology leaves less open to interpretation, resulting in fewer rejected parts. Additionally, 4D says the technology provides labor savings by shortening the measurement cycle from many minutes to mere seconds.

According to the company, the new measurement technique and equipment are currently in use on components such as turbine blades and engine casings at two of the top three jet engine manufacturers. 4D says a PSL gauge is typically priced under $50,000, which is roughly half the price of a 3D microscope.