Solid Height - Spring Manufacturers Institute

A clamshell furnace opened to reveal the heat shield, which
prevents heat loss and reflects heat back onto parts.
a regular maintenance program and replace them
approximately once a year.
Heat Shield
The next item that warrants attention is the heat
shield. A cheap furnace may not have one, but most
of the major oven makers have them in one form or
another. The heat shield does pretty much what its
namesake indicates. Its purpose is to keep as much
24 SPRINGS July 2006
heat in the heat chamber as possible and not let it
leak into other areas. Heat can bounce off a heat
shield and reflect back onto your parts, assisting
in the heat-treatment process. A good heat shield
that can reflect heat will reduce the need for the
elements to stay on, thus improving the useful life
of an element.
As with thermocouples, the heat shield should be
checked for any buildup of materials on its surface.
The more “gunk” that lodges up in the heat shield,
the less heat that will reflect back down. Further,
too much buildup of oil can potentially cause a fire.
Standard cleansers that work on stainless steel can
be used to restore a heat shield, but make sure the
chamber is cool before applying them, and follow the
directions on the cleanser’s label for further safety.
Fan Motor and Fan Blades
These items can vary dramatically among oven
makers and even from model to model from the same
maker. All inline ovens need circulating air to even
out the temperature inside the heat chamber. Without
such air circulation, you will only have radiant
heat coming from the heating elements, and very
little heat transfer (heat treatment) will take place.
The most common method to circulate air is with
a fan blade unit attached to a motor. Smaller ovens
can be connected directly to a good-quality motor.