Glass items manufacturing processes at our company include:
1. Glass melting:
Fabrication of glass blocks of weight ≈ 20 kg with the diameter 175 mm, height 400 mm in gas and electric batch furnace with the capacity 200 kg per day and night period.
2. Glass items drawing:
Glass items drawing from glass melt is the most conventional technology of fabrication of glass items in the form of tubes and rods of different cross section size and geometry. A primary blank for the glass items drawing machine is a glass block placed into a glass-melting crucible with a drawing-die. The crucible is placed into a furnace and is heated up to the glass softening temperature. Then a special mechanism draws a glass tube or a rod through the drawing die. The item cross-section shape and its dimensions are determined by the drawing die geometry, the drawing speed and the heated block temperature. After being cut into the specified length ready products or preforms for further production stages are received.
3. Redrawing of glass items by similarity method:
The basis of redrawing process is the possibility of repeated reduction of dimensions of the initial preform keeping its cross section geometrical proportions (so called redrawing by a method of similarity). Preforms for redrawing may be separate tubes (rods) as well as assemblies of such elements. In the latter case the way of elements arrangement in an assembly sets the cross section geometry of the ready items.
A prepared assembly is fixed on the machine feeding mechanism platform. The mechanism moves the assembly with the specified speed through a continuous furnace. When heated up to the strictly specified temperature (specific for each glass type), the preform starts softening. With the help of a chain mechanism the preform is redrawn with the reduction of its cross-sectional dimensions making hundreds of microns.
Multiple repetition of this stage allows achieving the required dimensions. The unique character of our process is the possibility to combine materials having special properties in one item.
Drawn tubes and rods are assembled, filled with lamp-wax and rosin mixture and cut into the specified length on automatic machines of type «Almaz-4», «Almaz-6».
The received glass beads are washed using surface-active agents and acids.
This process includes a glass item etching in hydrochloric acid and soda alkali, washing in distilled water after each treatment and dehydrating.
6. Magnetron sputter deposition and thermal spraying:
Glass items are put on a base plate protected by a cover. Air pumping provides for the chamber sealing to high vacuum
1 х 10-6 mm Hg. After it argon is let in up to 1-5 х 10-3 mm Hg and metal is sputtered on the base plate. In the process of work the applied layer thickness is monitored.
7. Glass structures sintering:
Glass structures sintering is combining of separate microstructures in a unified whole under influence of heating and excessive pressure.
Multichannel elements are assembled into a unit placed into a shell that is selected on the basis of TCLE and softening temperature. The received preform is placed into an airproof furnace and heated to the glass melt viscosity state 2 х 107 Poise. Then the shell is sealed by way of gases pumping out. Excessive nitrogen pressure up to 10 kgf/cm² is fed into the chamber. The pressure, temperature in the chamber and sintering process length are selected on the basis of the glass type and dimensions.
After sintering the sintered unit is annealed and chilled. If necessary it may be cut into plates of the specified thickness and the shell may be removed.