Crimp Terminals- All are not created equal

If you are repairing items which are subject to normal temperatures, the "standard" types work fine. Butt connectors, ring terminals, etc.

BUT......

If you are working on a microwave oven, kitchen range, toaster, heater, thermal fuse replacement, then you need special HIGH TEMP crimp connectors.

The metal in them is designed to withstand high temps and not melt or crack.

Also never use "standard" thermoplastic hook up wire in ovens, dryers, etc.
 The wire needed is a high temp. insulated wire. In days gone by, it was asbestos insulated.
  I suspect the EPA has banned it as an insulation, and there is a more modern replacement for it. (That likely doesn't work as good). 
  Your local appliance store likely has the terminals and wire you need.

 Please also keep in mind that much of the wire used in today's electronics is rated at well under 220 VAC too, and ovens typically use 220V.

I have seen low temp ring terminals used on ovens, etc. and have so over heated they literally had melted spots on the terminal.