The second is the crowning of molded plastics gears
. The recent introduction of crowned molded plastic gears has required significant development in new tooling and processing methods. The new tooling includes the construction of the mold cavity with varying cross-section, smallest at the ends and largest at the center of the face width. And the new processing covers the ejection of the molded gear while preserving the modified tooth surfaces. This requires the optimum control of the ejection timing so as to take advantage of the initial shrinkage and the limited elasticity of the still hot plastic material. This researched process is readily available for spur gears and some helical gears.