A press machine (hereinafter referred to as “press”) typically includes large and heavy drums that are made to roll during the printing process and transfer an image onto a substrate that is pressed by and made to travel between the drums. Old presses typically include frames made of assembled planar plates forming the walls of the frame. Assembly procedures of such frames are typically prone to adjustment problems and the alignment between rear and front walls is many times not satisfactory. Features are added to walls in order to address these problems, but machining these features requires machining of walls at their narrow lateral facet. In order to accomplish this special adaptors (“knees”) on CNC machines are used, which affect precision and increase cost. On the other hand, handling, shipment and storage of machined plates in any stage of production is fairly easy. Recent frame designs are based on a “monolithic” cage. In producing a monolithic cage both rear and front sides of the cage are machined at once using a very large and precise milling machine, thus bypassing a long chain of tolerances that would have otherwise been needed, and eliminating assembly. First the cage is cast, then runners are removed and then the cage is subjected to machining in two stages—rough and final. Connecting and stabilizing beams connect the front wall to the rear wall, and bestow rigidity, stiffness and dimensional stability to the cage. In a monolithic cage those beams are cast along with the rear and front walls. Since outside dimensions of the cage determine the type and size of the milling machine capable of machining it, all connecting beams are designed to remain within the outermost perimeter of the cage. Machining requirements, especially part size and accuracy, impose a “size barrier” on the cage and there are only few machines available with such combinations of part size and accuracy.
The number and size of beams in a monolithic cage of a press are limited since the printing press is densely populated and a connecting beam may interfere with mounting and dismounting procedures of sub units of the cage. Size barrier and components density within the cage result in fewer beams, and the remaining beams have thin cross section. This consequently lowers the natural frequency of the cage. Loosing rigidity in this design also affects machining accuracy and dimensional stability of the cage, since fixing the cage on a CNC machine is more difficult. Logistics, too, is complex with monolithic cage design.