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Score Rule Geometry
Crease Depth
Folding carton production relies on score rule geometry to control the angular displacement of paperboard along a defined hinge line. Cylinder height and channel width establish the mechanical displacement during the creasing cycle, which dictates the force required to make a clean fold without cracking the outer liner. Die makers calculate these dimensions using caliper measurements of the target substrate, matching the caliper to the channel depth to prevent fibre delamination on the face stock.
Carton geometry depends entirely on this physical interaction between steel rule profiles and corresponding matrix boards, setting the mechanical limits for subsequent high speed gluing operations on the packing line.
Die Clearance
Substrate thickness dictates the lateral spacing between the creasing rule and the opposing channel walls during mechanical compression. Excessive clearance leaves the hinge poorly defined and causes the carton to spring back from the target folding angle, while insufficient clearance exerts excessive crushing forces that weaken the structural integrity of the paperboard. Production engineers adjust this parameter to accommodate varying moisture levels within the paper stock, ensuring the corrugated or solid board maintains its bending stiffness through the converting process.
Channel Selection
Folding resistance varies directly with the cross sectional area of the matrix groove assigned to the corresponding steel rule. Converting plants select narrow channels for lightweight folding boxboards to achieve sharp, crack free creases, whereas heavy containerboards require wider matrix profiles to accommodate displaced mass without rupturing the interior plies. Carton stiffness profiles depend on this precise selection, governing the operational torque of automated packaging machinery during final erection.