1. Raw Material Making
Since it calls for high hardness for the rod porcelain insulator, we adopt high-strength alumina ceramic material to produce the insulator.
With the 3-stage iron filtering and removing technique, this equipment imported from ERIZE (America) is able to effectively remove the iron powder content in the mixture.
When the water content in the mud has reached our standards (about 20%), we will discharge the mud from the conveyor to the disc and preserve it using plastic sheeting for 48h.
2. Raw Material Processing
Zibo Domaster owns 2 vacuum pug pills (500mm). The qualified mud will be put into the mud tank of the vacuum pug pill with an appropriate mud feeding amount and speed. After a series of treatment with the reamer, the mud will become flat strip type and enter the vacuum chamber, which offers an enough vacuum degree to ensure the air existed in mud strip will be evacuated clearly. Then the evacuated mud will be intruded into the extruding barrel and form into compact and uniform small mud parts after series of screw extruding process. Finally, the mud pieces with prescribed diameters will be extruded from the nozzle.
3. Shade Drying
There are 2 shade drying methods provided:
Small mud pieces are dried in shade drying chamber. The small parts will be arranged orderly on the shelves in the chamber. With an appropriate temperature and the circulating air, it will be done when the water content in these parts have reached our standards.
Electric shade drying method is suggested for large mud pieces. We put the mud on trays in a closed electric shade drying area. By controlling the current passing through the mud, we will get the mud parts that are effectively dried.
We have imported a photoelectric molding machine from Germany to treat the blank with a forming knife according to the drawings. Forming knives are generally hook shape making from alloy materials to realize little dimensional error, high working efficiency, and good flexibility.
Zibo Domaster possesses 14 fully-automatic drying chambers. The formed wet blank will be placed and fixed on the trolley in a certain sequence and then put into the drying chamber, which will determine the drying curves basing on insulators’ sheds and rod diameter. The blank will be dried with circulating hot air. With the PLC control system for the temperature and moisture of the chamber, the drying uniformity and pass rate will be effectively guaranteed.
Glazing process refers to coating a certain proportion of raw glaze slurry on the dried blank surface in an oil immersing or glaze pouring way. End face grinding treatment can be given for the dried blank of electric column products to precisely control the products’ height. The glaze pouring method will ensure a uniform porcelain surface.
At the gluing section, we add some glaze-coated sand to enhance the compatibility between the blank, the glaze, and the sand, as well as improve the insulators’ hardness and strength.
7. Kiln Firing
Zibo Domaster has introduced 2 fully-automatic shuttle kilns from GFC (Australia). Kiln firing is one of the core techniques in the porcelain manufacturing process. We determine the loading way and the firing curves according to height and rod diameter of the glaze blank. The firing process is controlled by computer, which has largely ensured the firing quality.
8. Porcelain Inspection
After kiln firing is over, operators will inspect the porcelain products one by one to filter out those defected ones. Also flaw detection test will be given for each of the ceramic pieces. After a porosity test, those qualified porcelain products will be sent to the next procedure.
To ensure the traceability of our insulators, job number of the inspectors as well as the kiln number will be printed.
9. Glue binding
This process involves filling the adhesive into the gap between the porcelain pieces and the spare parts to make them an integrated structure. The adhesive we use is 525R Portland cement and the glue binding machine in Zibo Domaster is from NGK (Japan), effectively ensuring the geometric tolerance of our insulators. When glue binding is done, the products will be put into a steam curing chamber whose temperature is 70°C to guarantee our insulators’ strength.
10. Flexural Strength Test
After glue binding and steam curing, each of the insulators has to undergo a flexural strength test (parts of the insulators allowing breakdown will be given spark testing additionally) to improve the reliability of our insulators.
The packaging step incorporates appearance detection, cleaning, and accessory installing. The ceramic insulator products are generally packed with wooden boxes and trays for convenient loading and shipping.