Representative Papermaking Machines Figure 3.8 shows the relationship of tear, stiffness, and fold endurance to machine direction. Paper specification sheets normally show physical values measured in both directions. Package designers need to be aware of paper's directionality. Cylinder machines tend to align fibers more than fourdrinier machines. Tensile strength ratios in MD and CD for a typical fourdrinier board are about 2:1, whereas for a cylinder board the ratio might be 4:1 or higher, meaning that the MD tensile strength is four times greater than the CD tensile strength. The greater the degree of fiber alignment, the greater the difference in a given property when measured in MD and CD. The ratio of a property in the two directions is often used as a gauge of fiber alignment.Representative Papermaking Machines Figure 3.8 shows the relationship of tear, stiffness, and fold endurance to machine direction. Paper specification sheets normally show physical values measured in both directions. Package designers need to be aware of paper's directionality. Cylinder machines tend to align fibers more than fourdrinier machines. Tensile strength ratios in MD and CD for a typical fourdrinier board are about 2:1, whereas for a cylinder board the ratio might be 4:1 or higher, meaning that the MD tensile strength is four times greater than the CD tensile strength. The greater the degree of fiber alignment, the greater the difference in a given property when measured in MD and CD. The ratio of a property in the two directions is often used as a gauge of fiber alignment