Abstract: Apparatus and methods are provided for reducing the variability of stress levels in glass sheets (11) cut from a moving glass ribbon (13). The reductions in variability are achieved by constraining the edge regions (53,55) of the ribbon (13) from movement in a horizontal plane at at least one location below the location where a separating assembly (20) forms a separation line (47) in the ribbon (13). Sets of vertically arranged wheels (35) which engage the edge regions (53,55) of the ribbon (13) can be used to provide the horizontal constraint without compromising the central, quality area (51) of the glass ribbon (13).

Abstract: A method (300) is described herein for producing a glass substrate (105) by melting (302) batch materials to form molten glass (126) and delivering (304) the molten glass (126) to a forming apparatus (135) that has a body (210) with an inlet (136) that receives the molten glass (126) which flows into a trough (137) formed in the body (210) and then overflows two top surfaces (212? and 212?) of the trough (137) and runs down two sides (138? and 138?) of the body (210) before fusing together where the two sides (138? and 138?) come together to form a glass sheet (216). The delivering step (304) also includes a step where the mass flow rate of molten glass (126) that flows over a predetermined length at both end sections of the trough (137) is managed to avoid temporal variations in the glass mass, distribution of the glass mass and thermal energy from the glass mass. In particular, the managing step includes ensuring that more than 17.6 lbs/hour and preferably more than 20.