Nikon Metrology Laser Radar, the next-generation CMM for shop floor automotive BIW inspection
June 5, 2015
With the need for shorter and more flexible production cycles, automotive manufacturers are continuously looking to cut time and costs whilst improving product quality. Nikon Metrology – in close cooperation with key automotive OEM and integration partners- addresses these challenges by introducing an innovative approach to body-in-white (BIW) inspection based upon its non-contact Laser Radar system.
This shop floor system provides accurate, dimensional measurements in the car coordinate system allowing direct comparison to CAD without the need for a reference part. Unlike horizontal-arm CMM, its high-speed measurements fit within short production cycle times. At the same time it is a more flexible solution to adapt with changes in model mix and factory layout.
Flexible solution for next to the line or in-line inspection
In automotive body-in-white (BIW) assembly, locations of holes, slots, studs and other features need to be measured and monitored to ensure that vehicles are built within the stringent automotive tolerances. Today, such critical measurements are performed by either off-line horizontal-arm CMMs which are very slow and expensive or by dozens of sensors in the production line that need manual configuration and provide relative measurements with low accuracy. These solutions are not fast and flexible enough to cope with the current production challenges.
However, the combination of the Nikon Metrology Laser Radar with common industrial automation provides a unique alternative. A typical full BIW inspection solution consists of two Laser Radars - one on each side of the vehicle - mounted on a 6-axis industrial robot with a horizontal rail. These robots are used to automatically reposition the Laser Radar to provide 360o visibility around the vehicle. The Laser Radar has a large measurement volume, meaning multiple features can be measured from a single robot position keeping the number of robot movements to a minimum.
The Laser Radar can be used directly on the production line and doesn’t need any special protection. Industrial robots are common place in automotive production facilities, are very robust and are easy to reprogram. This results in a flexible solution that can be easily reprogrammed off-line without the need for manual tuning when vehicle models are added or changes in the inspection plan need to be made.
Accurate, absolute measurements in car coordinate system
The Laser Radar uses a focused laser beam to perform accurate, contactless measurements on almost any surface, including highly reflective bare body panels as well as shiny painted surfaces. It measures up to 2.000 points / second and has an absolute accuracy <0.1 mm over the volume of a car. After each robot move the Laser Radar automatically measures alignment points on the vehicle or pallet, guaranteeing that all measurements are collected in car coordinates and ensuring measurement accuracy is independent of the robot repeatability.
The measurement accuracy and repeatability of the Laser Radar is comparable to measurements taken with a traditional horizontal arm touch probe, while it is many times faster. Two Laser Radars working in parallel can measure 700 features on a BIW vehicle in less than one hour; this can take a full shift for traditional CMM. These cycle times will be further slashed with the newly introduced “High-speed scanning engine” making Laser Radar suited for true in-line inspection.