Precision For Guaranteed Stability Using 3D Scanners PERI checks key components for formwork and scaffolding systems with ZEISS COMET and ZEISS T-SCAN. Article by Carl Zeiss.
“There is always something being built here,” said Daniel Steck as he enters the extensive premises of PERI, one of the world’s largest producers and suppliers of formwork and scaffolding systems. Together with a colleague, Steck is responsible for measuring technology at company headquarters in Weißenhorn, Germany. Prototypes, reference gages and initial samples all make their way to his measuring lab.
When Steck joined the Quality Assurance department three years ago after studying to become a mechanical engineer, the company was still performing manual measurements with a profile projector. This was not only time-consuming, but also meant the measuring results could not be reproduced. “Each person had their own approach to measuring which led to different results,” recalled Steck. This is a common problem with manual measurements.
As the functionality of in Weißenhorn inspected component has to be guaranteed so that they can later be used without any problems, the company had to find a solution everyone could count on. “Ultimately, it comes down to making sure people are safe when constructing framework and scaffolding.”
Precise Acquisition Of Component Geometry With Optical 3D Scanning Systems
“We use the parts we produce ourselves as much as possible,” explained the quality assurance expert. For example: a ledger UH – the horizontal bar on the scaffolding – comprises a pipe, wedges, and wedge heads welded to both ends. This ledger UH is later mounted between the scaffolding uprights. The shape of the individual components ensures a secure fit. The resulting tension is essential for the stability of the entire solution: “Without this, the ledgers might come loose.”
Thus, PERI employs this design for all its scaffolding worldwide. To ensure optimum quality, all components are first measured individually and then again following assembly – the exact tolerances are specified in the design drawings. A thorough inspection requires an extremely exact capture of the entire component geometry.
PERI first conducted a benchmarking analysis and opted to purchase an optical solution that would meet their special requirements. They quickly set their sights on ZEISS and immediately decided to purchase two measuring systems for inspecting the entire spectrum of PERI components: ZEISS COMET and ZEISS T-SCAN. Steck was pleased with this decision. “Learning to operate these user-friendly systems was no sweat. That helped me a lot when I was still learning the ropes,” said Steck, who started using the new systems as soon as he joined the department.
He measures the smaller, individual parts like ledger heads and wedges with the ZEISS COMET. The fringe projection system captures data at a rate of 1.25 megapixels per second with great precision, speed, and largely automatically.
The parts are positioned on the rotary table and fixtured as needed. After that, the measuring system runs automatically: “It is really great knowing you can trust the system, freeing you up to do other things during the measurement.”
Measurement Of Larger Components With The Hand-Held Laser Scanner ZEISS T-SCAN
With ZEISS T-SCAN, Steck measures larger components like formwork elements and the aforementioned ledgers UH. He takes the manual laser scanner and first measures the ledger pipe by itself and later the entire welded construction, including ledger heads.
“This is also quick and easy,” he reported. Steck demonstrates how ZEISS T-SCAN achieves the perfect measuring distance, using a green dot that intersects with the red laser stripe. He then moves the scanner over the upper and lower side of the component just once.
Generating precise, repeatable results is particularly important for initial inspection. “We have suppliers from all over the world. They receive standard test protocols with the measurement reports created with the ZEISS systems – this way, everyone is on the same page if any improvements are necessary.”
If the component meets PERI’s specifications, then random sampling is performed at regular intervals. The same process applies to new potential suppliers. During the approval process, inspection gages are created for individual components so that the team in the Incoming Goods area can perform quick, reliable measurements to check the products’ dimensions and functionality.
The quality of the inspection gages is also checked with the ZEISS measuring systems prior to use, and these are then recalibrated regularly.
Reconstruction of CAD Data With Reverse Engineering
In addition to these standard requirements, reverse engineering is also part and parcel of the engineer’s work. “Until now, reverse engineering has simply not been an option when dealing with old tools and their replacement parts. Often there are not any design drawings available.” That is why Steck scans these older components with the ZEISS COMET to create drawings based on these precise 3D models, including the exact tolerances. “For us, this is more than just reverse engineering – this is how we keep knowledge in the company.”
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