High-end manufacturing has always required feedback of reliable measurements to adjust parameters precisely and keep components within tolerance. The better and more regular the data provided, the more tightly a production line can be controlled. Nikon’s Laser Radar technology – capable of providing fast, automated, accurate, absolute measurements – clears the way for faster feedback of quality information, leading to exceptional levels of accuracy, high manufacturing efficiency, reduced rework and less scrap.
Offline Versus Inline Quality Control
The move from an offline metrology strategy to an inline one is a challenging jump. Traditional CMMs are a trusted, well-known technology providing the master reference for all measurements throughout production. Traditional inline measurement systems (fixed or robot mounted scanners) are a fast way of getting relative measurement data from every car going down the line.
So Why Change?
A large automotive OEM had the same question. Using CMMs and traditional inline inspection solutions, it was a struggle to achieve its goal of a faster quality ramp-up in pre-production and breaking through a barrier into very high-performance dimensional quality during production.
Implementation of traditional CMMs was costly and effective throughput was low. The first process adjustments were carried out based on very little CMM data, so iterative changes were constantly needed as a result of a lack of complete and relevant feedback information. With the relative inline measurement system they were able to acquire a lot of data, but they could not make it fully functional until after production started. Also much of their sheet metal and other hang-on components were bought-in and limited detailed evaluation was carried out in-house.
Optical Inspection as Paradigm to Increase Productivity
The company was insistent upon adopting optical inspection, moving away from tactile probing. Additionally, it wanted to remove the bottleneck of the offline CMM room to make a paradigm change to achieve breakthrough improvements. The ultimate goal was better metrology performance yielding faster feedback of data during the initial phases before a new vehicle enters full production. Laser Radar was the solution to achieve this goal.
Laser Radar was implemented in 2 key areas: shop floor, inline and bypass measurement cells were installed in the production line to give absolute measurement data right from day one of pre-production. This allowed them to measure 50% of the bodies produced in pre-series (in previous launches less than 10 were measured) and fewer adjustments are needed during full production to maintain tolerance.
Offline – Laser Radar on lift and rotate cells were installed to perform component, sub-assembly and full body checks in the CMM room. Multiple turntables can be tended from a single Laser Radar, reducing measurement dead-time while loading or changing fixtures. This approach optimizes productivity and reduces the traditional CMM room bottleneck.
The ability to provide accurate, absolute inline measurements during pre-production not only allowed to exceed their goal of bodies in tolerance by start of production, but also helped to significantly reduce the pre-production time. Also during production, the highest levels of quality are achieved and maintained due to the amount of good quality measurement data directly from Laser Radar cells at the production line. The number of features measured inline has gone from 190 (relative measurements) to 1,500 (absolute measurements) achieved through a sampling measurement strategy and automatic bypass stations resulting in precise process decisions down to 0.1 mm.
About Laser Radar
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
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. Features such as holes, slots, pins, studs can be quickly inspected using the Laser Radar.
For more information: www.nikonmetrology.com