Inspection Systems and IfG collaborate on powder application

More than 700 EPS powdering system are working world wide at all major glass manufacturers with float, coating, laminating, automotive and tempering lines.IQ-EPS gives the customer confidence that the powder coverage is correct and consistent across the entire plate surface, and the non-contact real-time validation ensures there is no damage to the glass, an especially important consideration given the sensitivity of coatings now produced within the glass market.The powder application (EPS powdering system) process is very simple.Before sheets of glass are stacked for storage and distribution, a thin film of spherical polyethylene or polymethyl methacrylate (PMMA) beads and adipic or boric acid powder is applied to their surface by the IQ-EPS applicator. The beads ensure that the sheets of glass do not adhere to or scratch one another and the acid guarantees that even glass stored in high humidity warehouse conditions will remain free of stains.

Ensuring that the glass is evenly coated with the correct amount and ratio of beads to acid is of paramount importance to glass manufacturers. If too much powder is applied it will not only add to manufacturing expenses, but may also present a hazard for machine operators. It can also cause problems for downstream processors who must wash the glass before performing further value-added work. If there is inadequate coverage of the powder a customer may reject the glass plates due to stains or scratches, or plates adhering to one another.

To verify the powder coverage in terms of the total number of bead and acid particles, as well as the coverage mass and density, the IQ-EPS system then takes real-time measurements of the glass surface as it travels down the line and feeds the results back to the applicator so that closed loop control can be established.

Coverage Verification

As a sheet of glass moves under the IQ-EPS inspection station a camera triggers a set of strobe lights to illuminate the powder whilst capturing a sequence of one square inch images of it. The sensor head is then indexed incrementally across the width of the conveyor to the next capture position.

By capturing a strip of images along the plate of each of the pieces of glass under the inspection station, the software is capable of creating an average map of the powder coverage across all of the plates, indicating its uniformity and distribution across the entire line.

Closed Loop Control

The IQ-EPS system provides the glass maker with an indication of the overall coverage of powder on the glass. To help visualize whether an adequate amount of powder is being deposited, the system software produces what is known as a zone map that illustrates graphically how evenly the powder is being deposited onto the glass plates across the conveyor.

In addition, the software can ascertain whether or not the correct balance of particle types has been deposited across the glass surface by performing a simple ratiometric analysis of the particles that have been identified as beads and those that have not.

The data on the particle size and type can be used to determine the mass and density of the particle types that have been deposited, and also be correlated with the information supplied by the powder manufacturers to validate that the powder meets any given specification, such as the correct ratio of beads to acid. All the data can then be displayed on a set of histograms that highlight averages over a run and/or simply the last reading taken.

The partnership between IfG/Grafix and Inspection Systems also allows coverage information to be relayed back to the applicator so that fine control of the amount of powder being deposited can be established with no operator intervention.