Toughened Or Tempered Glass (Part 1) - General

By keeping the surface of a glass plate or glass sheet under compressive stress and the interior of the glass just below the surface under tensile stress, glasses are toughened or tempered so that they do not break into smaller uneven sharp pieces which could cause damage. The high compressive stress on the surface with the tensile stress in the interior of the glass generates strength in the glass article and also the manner of breakage under external impact or force. In this article, basic ideas on toughening will be presented with some applications to highlight the importance of this particular part of the manufacturing process of tempered glass. In part II of this paper, the theory of tempering or toughening will be discussed.