Depending on the method of future manifold glass units heating, the vacuum lamination furnaces may be divided into 4 types:

•  Convectional heating furnace – blanks heating is carried out at the account of the heat, given up by the heat transfer agent – air, circulating in the furnace. There are two options: with forced and natural circulation.
•  Radiation heating furnaces (IR) – there is applied for vacuum bag with the unit of future laminate the powerful flow of infrared radiation.
•  Contact heating furnaces – there is applied for blanks heating the uniformly distributed along the entire surface of vacuum bag base electrical heater or massive steel plate heated by circulating in its channels heat transfer agent.
•  Combined type – combination of several heating methods. Usually, it is the combination of radiation and convectional methods.

Examples of various types of vacuum lamination furnaces:

Convectional

IR-furnace

Contact furnace

Comparative analysis of vacuum lamination furnaces:

	Convection	IR-furnace	Contact furnace
Possibility of multilevel charge
Possibility pf simultaneous production of various thickness workpieces
		Design and peculiarities of heating elements location give no possibility to carry out simultaneous lamination of blanks of various thickness due to problems with uniform temperature distribution
Possibility of multilevel charge without additional equipment (lifting tables and pallet accumulator)
		Due to heating elements location	There are no multilevel
Immunity to electrical power drops and quality of input voltage
No loss of heating elements power at long-term operation
	No loss of heating elements power at all, as heating elements are designed for higher operation temperature and are constantly blown with air flow, so they are operated in part load mode	There is drop of heating lamps power that leads to considerable increase of process and not uniform distribution of temperatures at heating
Possibility of further operation in case of heating elements failure
	Possibility of equipment operation in case of 75% of heating elements failure	There is no possibility of further operation as in such a case there emerges the area without heating that leads to 100% rejection of the finished products	Usually, there is one heating element
Saving at heating elements replacement
	In case of failure, there is replaced only failed heating element that is considerable cheaper than heating lamp for IR furnace and heating coil for contact furnace	In case of failure of one of the heating elements it is recommended to replace all of them. Otherwise there will be constant problem with uniformity of temperatures distribution	There shall be replaced the entire heating system
Ease of operation and maintenance
		Special requirements for heating elements maintenance
Possibility of production of the shaped glass
		Problems with production of laminated glass from shaped (bended) blanks that is explained by the necessity to locate infrared heater strictly parallel to the blank unit surface to ensure uniformity of infrared radiation flow	Conceptual impossibility of production of laminated glass from shaped (bended) blanks that is explained by the necessity of close contact between blank, vacuum bag and heater
Cooling process
		In case of forced cooling usage there emerges the problem with heating elements life duration
Electrical power consumption economy
			Very energy-consuming heating system
Silicone covers value
	Possibility of any silicone usage	There is required special silicone with usage of inserts for higher attraction of IR beams	Possibility of any silicone usage
Value of furnace and operating costs
	Average value of the equipment is the cheapest in terms of operation and maintenance. The highest reliability and performance. Minimal number of rejected products	The most expensive at initial investment and the most expensive in terms of long-term operation. The average level of rejected products	The cheapest, but has a lot of shortfalls at operation. High % of rejected products

Summarizing comparative analysis of the main advantages and disadvantages of the lamination glass production furnaces of various types, one may make the conclusion that the most rational choice is appropriately designed convectional furnace with forced air circulation as it is the most reliable, versatile and has the best quality-to-price ratio.