Platen chatter and drift

[SoupToNuts]

Demag Van Dorn Extra 55-200 (or at least that's what it looks like) mold will open but not reach set point. just prior to set point hydraulics will chatter. Can manually stay on open button to reach set boy. Moment button is released the hydraulics drift forward. This happens regardless of the value of the set point. Have tried purging any air from the lines using the procedure in the manual.

[tommyboyfl]

How long did you continue the air bleed procedure? It can take longer than you might think, especially if it has been sitting for an extended time (like months). May need to repeat daily for several days.

[rickbatey]

Is it a toggle? I’ve seen the mechanical stop set and cause some issues. Also the valve spool zero voltage may need adjusting. I haven’t done that in many years but someone else can probably walk you through it.
Rick.