PURPOSE: To realize a cast drawing pin resistant to corrosion and heat cycle and capable of dealing with the gnawing with a metallic mold by coating the surface of a base material heated to a specified temp. with a boron nitride film by plasma CVD.

CONSTITUTION: A pin base material is coated with a boron nitride film by plasma CVD at ≤500°C so that the size and mechanical characteristic of the base material are not damaged. The film thickness is controlled to 0.5-10μm to secure sufficient corrosion resistance and adhesion to the pin. The raw gas is obtained by diluting a mixture of gaseous boron trichloride and ammonia with hydrogen gas. Ar gas is effective in exciting the raw gas. A glow discharge of a high frequency (13.56 MHz) is most preferably used to produce plasma.