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Most Innovative Machine/Equipment 2023

Graf Industries' SL4FF EVO Seamless Welder


The Product

SL4FF EVO is a seamless welder for PVC that can obtain aesthetically perfect welded corners. The traditional way of welding PVC windows and doors is by using a welder, then moving the welded rectangle to a corner cleaner machine for the removal of the welding seam from the corners. This movement can be done either manually with one operator or automatically. Still, after the corner cleaner, there's always the need for additional operators to manually remove parts of welding seam that couldn't be removed by the corner cleaner machine. This is a slow and dangerous process involving chisels and cutters. And, in addition, if the profile is painted or foiled, the operator will have to use a marker or a brush with paint to try to touch-up the corner.

Thanks to GRAF SL4FF EVO seamless welder with V-Perfect technology, all of the aforementioned processes are not necessary anymore: the welder does it all. So the welded rectangle is already perfect to go into assembly, with no need for corner cleaning or operators cleaning and touch up. Even more, if the production involves PVC windows and doors with aluminum cover, the SL4FF EVO technology allows to insert the four profiles in the welder with the aluminum cover on them. This allows for the cutting of PVC and aluminum earlier, which comes out as a perfect cut. 

What the judges say

  • The machine cleaning the weld line is a great safety feature!
  • The ability of one machine to eliminate separate corner welding, corner cleaning and manual corner touchup would be a big time and money saver.
  • Great idea to solve a long-term concern with welded vinyl.


Rachel Vitello

Rachel Vitello

Rachel Vitello is the Assistant Editor & Researcher for Window + Door and Glass Magazine.