Broken bit in microwave oven

Often there are "Parts Catalogues" for Domestic Appliances which show all the parts in exploded views. This is the one for my NEFF..

I though they were mica?

I don't think they "do" anything apart from keep stuff out of the tube side?

Yes it's a mica sheet and generic sheets are available from many sources

What I found is that if a food cover is not used on fatty food the fat sticks to the mica and over time carbonises which in turn results in a burn hole in the sheet.

Handy to know. Ta.

Over-enthusiastic cleaning of my microwave resulted in the protective mica sheet coming loose. I taped it into position and have been more careful about not dislodging it.

However the OP's mica sheet has broken in half and needs replacing.

I notice some advice sites suggest keeping an eye on the sheet for burns or holes although I'm not sure how they would have occurred.

This vid shows a typical defect.

"Replacement guide" [ This just shows the square guide output, and there is no cutoff filter there ]

If you get a "factory" one, then it is pre-cut. The only way you can foul up then, is if the microwave design requires you to "bend" the item to fit into the holder.

You can stick your caliper on it, and measure the thickness of the original. A holder designed for a particular thickness of sheet, might not tolerate a thin one (wobbles a bit). Or a thick sheet might not fit at all.

And the Panny one with the one screw, don't over-tighten that. This is not a job for a mechanic with an air-wrench. You can apply a lot of pressure to mica -- but it should be uniform pressure, not trying to tear a hole through the sheet. The screw would bruise all around the hole, if overtightened.

By using one screw, there is no issue with the sheet going to high temperature during a run. There is enough slack it can expand (whatever the tempco is).

Paul

My microwave's mica sheet came loose and wouldn't stay in its original place, so it's now held in position by a short strip of PVC electrical tape. I hope that's sufficient.

It's not a very secure fixing but it holds. I now take extra care when wiping the inside.

I thought they were natural mica, I didn't know they had a resin component. We used to buy sheets of it and cut to size.

Fun fact, a stack of sheets makes an awesome Rolf Harris Wobble-Board.

Cheers, I'll have a searh.

Great - now I know what it's called I can look for one (or more - mine has to be flexed to get it in).

Why does it have to be mica? Surely any reasonably heat resistant insulator would do. My Daewoo oven has some kind of moulded pale grey panel.

Mica has some very good dielectric properties that stop it getting hot.

Other insulators are not as good

Maybe for dual function microwave ovens that contain a grill element?

Tim

RF transparent at microwave frequencies, but then (see capenhurst tower) so is fibreglass ...

Some consideration has to be given to what gets attached to the surface of the cover. Unless the food is religiously covered while cooking the surface of the cover is going to get a layer of splattered food, especially splattered fat. It's this layer that continues to cook and gets hotter while the microwave is on. The most common failure of the cover is a burn through where the seed was the splattered food getting carbonised and burning.

Here is my microwave guide cover:

I cook very little fat and always cover food, except for a30 sec warm-up. I've found some covers, thanks to informarion posted here. Will continue searh after half a bottle of rum has cleared my system!