Why the positive pressure single facer will be easy to cause flute collapse and warping? especially with higher flute profiles or heavier paper grades.

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Positive pressure single facers may be more prone to flute collapse and warping due to the way they hold the corrugated medium against 

the corrugating roll.

In a positive pressure single facer, air pressure is used to hold the paperboard against the corrugating roll during the corrugation process. 

This air pressure creates a cushion of air that supports the paperboard and keeps it in place as the corrugating rolls press the flutes into 

the paperboard.

However, with higher flute profiles or heavier paper grades, the air pressure may not be enough to fully support the paperboard during the

corrugation process. As a result, the paperboard may collapse or warp as it is pressed against the corrugating roll. This can lead to a variety

of quality issues, including uneven flutes, delamination, and reduced strength and durability of the corrugated board.

In contrast, an inner vacuum single facer uses a vacuum to hold the paperboard against the corrugating roll during the corrugation process.

This vacuum provides more consistent and reliable support for the paperboard, even with higher flute profiles or heavier paper grades. This

is why inner vacuum single facers are generally considered to be more reliable and produce higher-quality corrugated board than positive

pressure single facers, particularly for demanding applications.