It follows from needles per meter of board width, strokes per minute and fabric advance speed, and it is usually quoted as penetrations per cm2. More punches tighten and strengthen the fabric up to a point, after which fibers start to break and strength falls. Engineers set punch density and penetration depth together to reach a target thickness and air permeability.
Punch density is about 150 per square centimeter on the finisher, and going higher just starts cutting fiber.
Also heard as
- needling density
- penetrations per square centimeter
Related terms
Needlepunch
Mechanical bonding in which barbed needles punch repeatedly through a batt, dragging fibers through and tangling it.
Needle loom
Machine that drives boards of barbed needles through a moving batt to bond it mechanically.
Barb
Small notch cut into the working blade of a felting needle that catches fibers and carries them through the batt.