A cooling bed is part of a rolling mill, at the end of the rolling mill that supports and permits the hot rolled products from the hot mill to cool hot rolled and cast steel products. A walking beam cooling bed is the most common type of cooling bed. What one wants to happen is for all the temperature of the bar to all cool at the same time. If not, it develops stresses in the bar. If part of the bar stays continually in touch with the metal supports, then it will cool at a different rate than the parts of the bar that is continually open to the ambient air. A walking beam cooling bed consists of moving and stationery skids which lift, traverse and lower the product numerous times so that where it touches continually changes permitting all the bar to cool at the same rate. The bar walks its way to the end of the bed where it is placed on a set of roller tables. Walking beam cooling beds have a saw tooth pattern which is why it is also known as a rake type cooling bed. When cooling billets, walking beam turn over cooling beds have a feature that continually rotates the billet so that where it touches the bed changes continuously, thus the billet does not distort its shape in the cooling process. Cooling beds that are used for blooms and plate do not have a rake pattern, but may use a chain transfer as the traversing method. Cooling beds are sized so that the product will cool within a particular cycle time.