Technological History

The historical roots of the Tridelta Thermprozess GmbH are closely connected with the over 110 years lasting history of manufacturing of technical ceramics in Hermsdorf and related sites. In 1889 Kahla AG, the manufacturer of china, founded a porcelain plant in the small town of Hermsdorf - an outstanding place due to the abundance of wood and an attractive location with regard to transport links.

The initial production of china was soon replaced by electro-technical porcelain and after a short time the company already worked with 21 firing kilns and 800 employees.

In the beginning of 1924 in one of the porcelain plants of the Kahla AG in Freiberg a department for thermal and firing technologies was founded and managed by Friedrich Dettmer as chief engineer. He started to work out the fundamentals of the theoretical and technical control of the burning process.

The first basic result of his activities was the technological control of tunnel kiln processes demonstrated by the operation of 3 tunnel kilns for electrical porcelain in the plant “Margarethenhütte” in Großdubrau. After the shutdown of the production line of porcelain in Freiberg, Dettmer and other scientists, technicians, and skilled workers went to the HESCHO (Hermsdorf-Schomburg Isolatorengesellschaft) in Thuringia. After a short period of activity in the porcelain plant, Dettmer started his own business as consultative engineer for ceramics in the technological fields of drying, firing technique, construction of kilns, thermal economy, and organisation in the neighbouring village Bad Klosterlausnitz.

Until 1937 he also acted as chairman of the thermo-technical committee of the German Ceramic Society and reported frequently on problems of firing technology, kiln construction, and thermal economy.

It can be assumed that the work of Dettmer influenced the development of the HESCHO because the plant in Hermsdorf underwent fundamental structural changes from a porcelain manufactory to a ceramic plant after 1930.

For the ongoing development of special ceramic materials and products (especially ceramic dielectrics), under direction of Dr. Werner Rath material- and product-specific furnaces for sintering and metallisation burn-in in various gas atmospheres were necessary. Therefore new sintering techniques had to be developed.

The official foundation of a department for burning technologies of the HESCHO-Kahla in the plant in Hermsdorf under direction of the engineer Fritz Garbe in 1947 is an indicator of the tremendous upturn of technical ceramics after the Second World War.

New product groups and departments like hard- and soft-magnetic ferrites, dielectrics and passive semiconductors, piezoelectric ceramics, sintered metals, microelectronics, and oxide ceramics were formed in Hermsdorf. These new product lines were based on specific self-developed equipment for annealing, firing, sintering, metallizing, and soldering in various atmospheres at temperatures up to 2100°C. The development process is outlined chronologically in the following table:

bis 1930

coal heated beehive kilns for china, electro-porcelain, and chemical porcelain


use of electrically heated kilns for special ceramic materials, firstly spiral heated firing and glaze kilns, later plate-push-through kilns and small-chamber kilns


first kiln with SiC heating elements for tube capacitors


first channel kiln with SiC heating elements; then reconstructed to a push-through channel kiln for plates (length 6 meters) with bottom and top heating; further developed to a two-channel kiln it was the dominating sintering aggregate for the production of ceramic parts and the mass production of ferrites for decades after world war II

after 1945

installation of a self-production of pyrometric cones

since 1948

2 tunnel kilns and 12- and 16-chamber ring kilns with generator gas for electro-porcelain, resetting of the beehive kilns to the use of generator gas


construction of three tunnel kilns (each with a length of 60 meters)


use of the first kiln with a protective hydrogen atmosphere for powder-metallurgical products on the base of W, Mo, Ta and according alloys (push-through channel kiln with Mo-sheet metal boats and gliding path and Mo wire-coil heating elements)


high temperature channel kiln (length 30 meters) with oil firing for temperatures up to 1600°C; a specific development was necessary for the production of soft-magnetic ferrites: mixed nitrogen/oxygen atmosphere, precise temperature control, fire-proof steel channels, simple airlock technique


resetting of all fuel heated kilns to the use of natural gas


first implementations of the fast burning technology for electro-porcelain and oxide ceramics in bonnet and hearth bogie furnaces


introduction of gas impulse firing, towers for joining of big porcelain bodies by adhesive bonding


multi-tower furnaces, rotary hearth furnaces for electronic components

Due to measurements during the sintering process the relationships between the product and process parameters could be understood better and an improvement of product quality and yield as well as design and processing of kilns could be achieved.