KNIT LINES OR MARKS– A knit line is any line, visible or not, where two resin flows meet. Depending on the design of the mold and the material being injected, a knit line may: present no problem at all, be a cosmetic issue, or cause a potentially serious structural problem.
Avoid weld lines in areas which need strength, or which need to appear smooth. This can be done by changing the polymer injection location or altering wall thicknesses to set up a different fill time. With a different fill time, flow fronts may meet at a different location and therefore the weld/meld line will move.
KNOTS – Lumps which appear in a stretched rubber part, generally due to poor dispersion of a curative, such as sulfur.
Kettle bottom – A smooth, rounded piece of rock, cylindrical in shape, which may drop out of the roof of a mine without warning. The origin of this feature is thought to be the remains of the stump of a tree that has been replaced by sediments so that the original form has been rather well preserved.
Kerf – The undercut of a coal face.