Thermal Variable
Heat levels maintained on the pressing surfaces of a die cutter or foil stamper influence the flow of adhesives and the deformation of fibres. Maintaining a consistent platen temperature is required for high-quality hot foil stamping where a metallic layer must release from a carrier and bond to the substrate. Sensors embedded in the metal plate monitor the heat and trigger heaters to compensate for the cooling effect of the ambient air.
Even small fluctuations can lead to poor adhesion or image blurring.
Process Impact
Thermal energy softens the lignin in the paperboard to allow for deeper and crisper embossing without fracturing the surface. When using heated dies, platen temperature must be high enough to make the board pliable but low enough to avoid scorching the stock. The dwell time, or the duration the plates remain closed, works in conjunction with the heat to set the final shape.
Material Limit
Overheating the metal components causes thermal expansion that can throw the cutting or stamping tools out of alignment. If the temperature exceeds the flash point of the inks or the melting point of the coatings, the sheet may stick to the die. Uniform heat distribution across the entire surface is difficult to achieve on very large format machines.
