7.0 Repairs and Replacements
7.6
VMF Element Replacement
See section 7.2 - wearing a face mask is required.
The heating elements are vacuum formed modules; they are fragile, so spare elements
are supplied complete in an insulation box to avoid damage.
Disconnect the furnace, remove the back panel, make a plan of all the internal
connections to the back of the heating chamber and disconnect. Remove the
thermocouple(s) and support tube(s).
Using a socket spanner undo the four bolts that fasten the insulation box. These are
located under the insulation box in the two cross supports. Remove the chimney prior to
removal of insulation box.
Remove the insulation box by carefully sliding it out through the back of the furnace
case.
Carefully slide in the new insulation box and fasten the four bolts. DO NOT support the
element by putting your hand inside the chamber – the element is fragile.
As necessary, shorten the element tails by clipping to length. Remake all the
thermocouple and element connections according to the individual plan.
Refit the back panel and operate the furnace for 30 minutes at 800 °C without
interruption to ensure complete burn-off of any organic binders. Some smoke may be
observed during this process, which should be carried out in a well ventilated area.
Check that the furnace is controlling properly to rule out the possibility that the previous
element failed because of a fault elsewhere in the control circuit.
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