Release: June 28, 1999
NGK DEVELOPS DRYING AND FIRING KILNS FOR PDP MANUFACTURING
NGK INSULATORS, LTD. (President: Masaharu Shibata, Head Office: Nagoya) has developed two types of kilns for manufacturing plasma display panels (PDPs); a drying kiln and a firing kiln.
Demand for PDPs is expected to increasingly grow because flat displays with large, thin and light-weight screens are required for advanced electrical equipment such as next generation TVs. Glass substrates utilized for PDPs require a highly clean production process. To satisfy such requirement, NGK has developed drying and firing kilns which abide by high cleanliness standards. These kilns are planned to be exhibited at the "9th FINEPROCESS TECHNOLOGY JAPAN '99", which will be held from Wednesday, June 30 to Friday, July 2 at the Tokyo Big Site. This exhibition presents manufacturing technology of displays, such as LCDs and PDPs
NGK's drying kiln for PDP production
NGK's drying kiln for PDP production which dries paste painted on substrates, qualifies for Cleanliness Class 1000. The kiln employs a heating system using a far infrared ray heater called "INFRASTEIN®", a downward blowing system to maintain cleanliness inside the kiln, and a walking beam transportation system for conveyance of products.
NGK's firing kiln for PDP production
To abide by Cleanliness Class 1000, NGK's firing kiln for PDP production employs an air-tight structure. By jointly using gas heating and electric heating, energy cost can be reduced. In addition, NGK's firing kiln consumes half as much energy as the conventional electric heating firing kiln by employing a radiant tube burner type HRS. As a result, NGK's firing kiln realizes energy savings. For muffles inside the kiln, NEWSIC® with high far infrared ray emissivity is used, so that rapid heating of products is possible. NEWSIC is also used for rollers which convey products within the kiln. Due to superior stiffness of NEWSIC, the rollers are capable of bearing heavy loads of large substrates of sizes up to 60 inches into two or three layers.
To meet customer demand, NGK has prepared drying and firing kilns for evaluation, and tests can be conducted upon customer request. NGK and ITOCHU TEXMAC Corporation will jointly sell the newly developed kilns and expect net sales of 2 billion yen in 2002.
Descriptions of terminology
NKG's drying kiln for PDP
- NGK's drying kiln utilizes a ceramic heater called INFRASTEIN for its heating system. The clean heater, INFRASTEIN is superior in its far infrared radiation. Since this system directly heats products, it is possible to dry them efficiently.
- Downward blowing system
- Within the kiln, a downward blowing system produces an up-to-down flow of air which is filtered beforehand through a HEPA filter (High Efficiency Particle Air Filter). By providing such clean air, this system maintains clean condition throughout the kiln. In addition, drying time is cut by accelerating removal of solvent in the paste.
- Walking beam transportation system
- The walking beam transportation system is a conveyance system which utilizes a carrying beam. Inside the kiln, a carrying beam moves forward to a designated place with a load of products, then unloads them and returns. By repeating this movement, the carrying beam conveys products. Since products do not have to be rolled onto the equipment, this system does not create dust, therefore the inside of the kiln can be kept clean.
NGK's firing kiln for PDP
- HRS (Hi-cycle Regenerative combustion System)
- HRS is an energy saving combustion system which utilizes ceramic honeycombs as heat reservoirs and is operated by switching between two built-in burners. This system was developed by Nippon Furnace Kogyo Kaisha Ltd.(President: Hisayoshi Tomura, Head Office: Yokohama-city). While one burner is firing products, the firing gas is exhausted through the other burner. The exhaust heat of such firing gas is stored in the honeycomb ceramic which is built in the burner. Then, the heat stored in the ceramic honeycomb is used to heat the air for firing. Such exhaust heat recovery enables HRS to cut conventional energy consumption by approximately 50% as well as emission of CO2 by the same percentage due to a decrease of exhaust gas.
- NEWSIC is a refractory with high stiffness, whose porosity has become close to zero by impregnating the silicon carbide with metallic silicon. NEWSIC is utilized both for muffles inside the kiln and rollers which convey products. When NEWSIC is used as the material for muffles, because of its high far infrared ray emissivity, the kiln with NEWSIC-made muffles can heat products more rapidly than other kilns with conventional crystallized glass-made muffles. When NEWSIC is used as material for the conveyance rollers, due to its high stiffness, the NEWSIC-made rollers can bear loads of products in two or three layers because they are more difficult to bend than conventional rollers. Compared with loads of one layer, the conveyance capacity of NEWSIC-made rollers is two or three times more, therefore productivity drastically increased. The two-layer conveyance of 60-inch substrates, which used to be difficult, is now available.
- Air-tight structure
- In order to achieve greater than Cleanliness Class 1000, NEWSIC, a dust-free material, is used inside the kiln and an air-tight structure prevents dust contamination caused by air flow.
Picture of NGK's drying kiln for PDP
Picture of NGK's firing kiln for PDP
Explanation chart of walking beam transportation system
Explanation chart of radiant tube burner type HRSs