If the hot melt shows the engraving of the roller:

The cause of this is either that the hot melt is too cold, or the MDF chipboard panel, or that insufficient pressure is present.

If only the engraving of the roller is shown on a defined part of the edge (upper, lower or center):

This is because the chipboard or MDF panel is cut incorrectly or the pressure rollers are incorrectly positioned.

If a part of the edge is smooth but the rest is without hot melt, it’s because the panel is incorrectly cut or the glue roller deflected.

When the edge presents faults in the internal part of the panel:

This is because the amount of hot melt is too low.

When the edging is correct, there should be a smooth Surface and good wetting of the hot melt in the materials: