왜 머플 use double-layer sheet metal? what is the benefit?

All-in-one intelligent muffle furnace adopts double-layer sheet metal, hot chamber + furnace lining + insulation layer + inner tank + air insulation layer + outer shell. There is also forced cooling by a fan between the inner tank and the outer shell, which greatly improves the problem of hot hands on the outer shell of the furnace body. The upper part of the furnace is the heating zone, and the lower part is the circuit zone. The control circuit has been connected to the heating circuit inside the furnace, and the user can directly plug in and use it. The installation and connection are very simple. The circuits are protected in the shell, and the circuit can not be seen outside, and the safety has been greatly improved.