Mould arrangement and method for compression moulding fiber reinforced preforms

A compression moulding arrangement comprising:

• a pre-impregnated pre-form having uncured resin with continuous un-chopped reinforcements that extend across one of an entire length, width, or both the length and width of the pre-impregnated pre-form;
• a compression moulding tool having a bottom half and a top half movable between an open position and a closed position, wherein the compression moulding tool has a forming cavity that is defined by a forming surface of the top half, a forming surface of the bottom half when the compression moulding tool is in the closed position, wherein there is further provided a run-off edge which terminates at an upshear which is a portion of the forming cavity;
• and
• wherein the forming surface of the bottom half has a boundary defined by the run-off edge and the upshear, wherein said upshear is a portion of the forming surface that extends upward relative to the finished surface of the part and is located adjacent the run-off edge and the upshear limits molten material from the pre-impregnated pre-form from migrating further out of the forming cavity, thereby preventing the compression moulding tool from being locked in place by the use of the pre-impregnated pre-form.