We recently had a customer ask us for some tips on annealing cast acrylic. There are definitely some potential pitfalls when working with acrylic in both sheet and finished part form, but following the guidelines outlined below should yield excellent results.
First… What is Annealing?
Annealing is the process of relieving stresses in molded or formed plastics by heating to a predetermined temperature, maintaining this temperature for a set period, and slowly cooling the parts. Sometimes, formed parts are placed in jigs to prevent distortion as internal stresses are relieved during annealing.
Tips for Annealing Acrylic Sheet
To anneal cast acrylic sheet, heat it to 180°F (80°C), just below the deflection temperature, and cool slowly. Heat one hour per millimeter of thickness – for thin sheet, at least two hours total.
Cooling times are generally shorter than heating times – see the chart below. For sheet thickness above 8mm, cooling time in hours should equal thickness in millimeters divided by four. Cool slowly to avoid thermal stresses; the thicker the part, the slower the cooling rate.
Post time: Apr-25-2021