A Vacuum Drying System for Green Hardwood Parts

Abstract

A vacuum drying system was designed and fabricated and that system was used to dry green rough hardwood dimension. The red oak samples, 76.2 (long) × 7.62 (wide) × 2.54 (thick) cm, were dried from green moisture content (MC) to 7% MC in this system. They were dried at a pressure of 12 mm Hg and temperatures ranging from 30 to 50°C within 25 to 70 h. Drying quality tested included warp, internal checking, and surface checking. Moisture gradients along the length and thickness were measured. The standard prong test was used to assess the drying stresses. Vacuum drying was fast and the drying rate increased as the temperature increased. It was found that the general drying quality was good with no color change. Drying stresses including longitudinal and transverse stresses were small. There were no internal checks.

Keywords:

• Drying quality
• Drying rate
• Part drying
• Red oak
• Wood drying
• Stresses