A riving knife is a blade of high grade steel with a smooth surface set behind and in line with the saw blade. Its main purpose is to prevent the sides of an incomplete cut from closing on the up-running part of the saw blade thereby reducing the risk of the workpiece being thrown back at the operator. This hazard is commonly known as a 'kickback'.
The riving knife also affords a measure of protection against the contact with the teeth when the operator or the person assisting the operator removes the workpiece from the back of the saw.
There is no difference in the likelihood of a kick back occurring when panel boards are being cut compared to solid timber therefore the riving knife is not to be removed unless trenching, grooving or rebating or in accordance with the manufacturer's instructions.