Calculated risk

Promac discusses how the addition of linesscanners could save you £thousands a year in avoided remakes.

Glass is getting bigger. The cost of getting it wrong – regardless of whether that’s a defect in edge quality, dimensional or surface defects or anisotropy – is also far greater, not to mention the reputational damage and potential loss of future business that these can cause.

“If the customer is on the end of the phone it’s too late,” Joe Hague, managing director of the Promac Group, said. “Glass defects are notoriously difficult to spot; they slip through the production process and quality control unchecked.

“If you’re dealing with something like anisotropy, you can only see it in certain lights. It’s why it’s often only picked up in daylight frequencies and at certain angles to the sun – by which time it’s on the side of a building and too late.

“Quality control, not simply at final inspection but at key stages throughout the manufacturing process, can deliver significant savings, avoid remakes and the reputational damage caused by supply of products with underlying and hidden faults.”

This has driven SoftSolution’s development of its linescanner technology. The automatic glass defect systems company has developed a new all-in-one system, which is designed to pick-up all quality issues which have the potential to impact on glass, and particularly IGU supply.

“The case for introducing a line scanner as part of your manufacturing process makes itself,” Joe said. “Picking up any defects earlier in the production cycle or before installation, reduces costs and risk.

“What’s so impressive about this new solution from SoftSolution is its flexibility and the range of checks it can perform through a single platform. This includes surface and edge quality, checks for dimensional defects and optical errors, anisotropy and edge stress on a tempering furnace, plus a range of other quality checks.”

“You’re picking up defects before they become problems.”

And the list of potential problems that the SoftSolution All-in-One Linescanner can pick up is a comprehensive one.

At the start of the manufacturing process, this includes glass thickness and coating composition. It also provides checks for edge and surface quality, picking up a range of defects from inclusions, scratches, finger prints, coating defects and dirt.

It also introduces new dimensional checks on cut and processed glass, without impacting on cycle time. Achieved using telecentric imaging technologies, this includes external contours, inner contours and edge cut-outs. The SoftSolution LineScanner will also inspect drill hole location and diameter.

“A really key feature of this platform is its ability to monitor and check tempering quality, isotropy and edge stress,” Joe said. “The real plus is that this is delivered in real-time, providing critical feedback to glass processors and IGU manufacturers on the performance of their tempering furnaces.

“This means that it not only picks up faults but gives them the insight and data to optimise production and avoid imperfections and edge stress in toughened glass before they become a problem.”

Checks on tempering quality include not only edge stress and anisotropy but the anisotropy pattern, and overall bending. This includes calculating the light delay for each individual pixel (0.015mm²) of a glass sheet, then calculating the stress direction per pixel and corresponding light delay to map the anisotropy pattern.

“At some level, anisotropy is an inevitable part of the heat-treating process. Anisotropy-free heat-treated glass doesn’t exist, as the glass responds to different stress levels, caused by the heating process.

“The data the SoftSolution LineScanner delivers, however, allows glass processors to minimise anisotropy by optimising the initial quenching and oscillation speed but also to understand its impact, what percentage of the glass is affected, and if it’s going to be likely to be a problem in position and when exposed to polarized light.

“This is an exceptionally high-value insight, particularly in manufacture of large and over-sized IGUs, because you can reduce wastage and eliminate unnecessary process if you need to by cutting your losses after toughening.”

At the other end of the process the SoftSolution LineScaner can also deliver a series of QC checks. This includes the composition and build of the IGU, including particles in the cavity and butyl defects, in addition to further checks for edge defects, scratches and contaminates.

It will also pick-up on-screen printing errors and errors on logos, including position and rotation, even down to ink thickness.

“With the direction of travel of the market, the manufacture of larger IGUs and increased use of architectural glass, quality is key because you’re dealing in bigger units and more product so cost is higher,” Joe said.

“The visibility to optimise your furnace to reduce anisotropy or edge stress, or to pick up imperfections earlier in the production cycle, without impacting on cycle times, is a very tangible benefit to any glass processing or IGU business.”