Hi there mc4
The microwave ovens which are sold with a metal rack are combination
ovens which have a 'browning' feature.
"Why metal rack can be used in the combination mode?
In the combination mode, the microwave is used only for a short
duration in the microwave mode when metal rack cannot and shouldn't be
used. The rack has no sharp edges and the gap between the rods of the
rack is large enough to prevent sparking and to allow the microwave to
Please note the grill rack is only to elevate the food to come closer
to quartz heater element for faster browning."
The above quoted explanation is from Bajaj Electricals - FAQ's On
( http://www.bajajelectricals.com/faq/microwavefaq.htm )
When you are just microwaving, then remove the rack. While the
sentence from the website above is rather vague, the meaning is quite
clear, the rack is for browning and any exposure to microwaves is
minimal at best.
Your combination setting may look something like this:
Combination cooking (30% microwave plus 70% grill - or - 55% microwave
plus 45% grill)- it is used only for recipes which require both
microwave for cooking/ baking and grilling for browning.
As for damage to the magnito, if you operate an empty oven, there can
be damage. The microwaves, after reflection from the empty, cavity
will fall back on the magnetron to affect its life and will lead to
magnetron failure. Food in the oven absorbs the microwaves and
protects the magnetron. Once again, don't have the rack in when just
using the microwave.
Search - google
Terms - metal rack +in microvave ovens, combination microwave ovens
If I can clarify anything, please let me know.
Clarification of Answer by
28 Nov 2002 20:42 PST
Other than re-arrange the microwaves somewhat, I doubt if the metal
rack will cause many problems if it does not have any sharp points.
"This sparking around sharp points is one of the reasons why you are
warned never to put metal in
microwave ovens. The other reason for the ban is that thin pieces
of metal can overheat as the microwaves
propel currents through them, thereby starting fires.
But metal isn't always a problem in microwave oven.
A thick, rounded item such as a
good-quality stainless steel spoon doesn't cause any significant
problems. I leave such
spoons in my coffee or tea frequently. While the spoons rearrange the
they neither spark nor overheat." - Quote from Physics Central - which
is the website mentioned by bobthedispatcher-ga in the comment below.
( http://www.physicscentral.com/lou/lou-01-6.html )
Also, not just any metal rack will do. "Metal racks are physically
proportioned so as not to disrupt the energy pattern." - Quote from
"How do Microwaves cook food"
( http://www.gallawa.com/microtech/howcook.html )
As for what happens to microwaves that bounce off the rack. 1 - The
rack re-arranges the microwaves but the microwaves still exist. 2 -
Some are absorbed by the cooking food 3 - Some are absorbed by the
The material from which the rack is made may also have quite a bit of
bearing on its use. "One of the basic characteristics of microwave
energy is that it is reflected by metal. The extent to which
microwaves are reflected varies with the type of metal. For example,
aluminum and stainless steel reflect microwaves, while certain
compositions of cold-rolled steel will absorb microwave energy to some
extent" - Quote from "Microwaves, Metal and Arcing"
( http://www.gallawa.com/microtech/metal_arc.html )
As far as damage to the magnetron from the use of the rack, I can find
nothing. Since the metal rack came with the microwave (assuming you
bought it new and the rack wasn't just added as an afterthought) It
can probably be used with no complications. Just don't operate the
I appreciate you asking the question as I have also learned somethng
new. My unit is a combination oven, I never knew metal racks came
with 'microwave only' ovens till this question. Getting around the
"no metal" barrier may also be something new enough that it hasn't
been addressed thoroughly on the Internet yet. Even such complete
websites about microwave ovens as the gallawa.com site quoted above
still list questions about metal racks and microwaves as something to
be addressed in the future.