Cutting adhesive back foam

DougW

We cut a lot of foam that has adhesive backing, which naturally gums up the knife and causes us to shut down numerous times to clean all the adhesive off the knife and components. Has anyone experimented with the settings of the Paragon to reduce the amount of build up on knife ? I am wondering if like in "fusing " of material, does the heat of the blade contribute to the problem?

Doug Hopkins

The physics behind cutting adhesive backed materials creates challenges when using a reciprocating knife due to the friction generated from the stroking blade, which tends to melt the adhesive, causing it to transfer to the blade, then to the guidance and sharpening mechanisms.  It can be a mess!

Similarly are the challenges when cutting fusible materials, if the material has a low melting point, the heat generated from the reciprocating blade will fuse multiple plies together when the blade contacts the fusible fibers for too long.

For those reasons these applications typically do require additional attention to the knife and sharpener/presser-foot assembly/cutting parameters then when cutting a more natural type material.

That said, There are a few ways in which fusing and adhesive transfer can be controlled:

• Can the Max Knife RPM be reduced while cutting?
• Can the cut speed be increased?

Reducing the RPM will reduce friction, try reducing the Min/Max knife RPM in smaller (50-100 rpm) increments.  If possible increase the cut speed (forward velocity) so the hot blade will not be in contact with the fibers for as long.  After making adjustment also observe/determine if the material is pushing or the knife motor is laboring, if all is OK, let it cut a few pieces (2-3 yards) and observe if build up or fusing is improved.

• Make further adjustments to RPM and cut speed if there is still fusing present and the material is not pushing or the knife motor is not laboring.

Other affecting factors:

• Is your knife optimally sharp?  A dull blade creates more friction.  Can you sharpen more?
• Do you have/use a Vortex Cooler?
• Can You use wax paper co-mingled throughout the spread?  Wax paper works as a 'Lubricant" when the hot blade contacts the wax, it melts and actually lubricates the blade.
• Can You reduce plies?  Less plies equals less surface area that the knife contacts the material, reducing friction.
• Also remember,....Smaller part geometries will fuse more because the cut velocity may not get up to full speed, allowing the hot blade to contact the material fibers for longer.

DougW

Thank you for the feedback Mr Hopkins, I will experiment with some of your suggestions.