The production of glass bottles is a precision industrial process involving multiple steps, and the following is a detailed description of its typical production process:
1 Raw material preparation and mixing
Core components: The main raw materials are silicon dioxide (quartz sand, accounting for about 70%), sodium carbonate (baking soda, reducing melting point), and limestone (enhancing chemical stability).
Auxiliary materials: Add broken glass (up to 30% 50% recycled material), metal oxides (such as brown bottles made of iron oxide and blue bottles made of cobalt oxide), and clarifying agents (such as sodium sulfate) as needed.
Mixing process: After precise weighing of the raw materials, they enter the mixer through a screw conveyor to form a uniform mixture.
2 High temperature melting
Furnace type: using gas or electric heating pool kiln, temperature gradient zoning (1400, 1600 ℃).
Melting process: The mixture undergoes silicate reaction in the furnace, forming a homogeneous glass liquid without bubbles. The melting time is about 24 hours, and temperature and chemical uniformity need to be strictly controlled.
3 Forming process
Blowing method (small mouth bottle)
IS machine station: loading material → inflation → reverse blowing → forming. For example, during the production of beer bottles, glass droplets are dropped into the mold and compressed air is blown twice to form it.
Mold treatment: the inner wall is sprayed with graphite lotion to prevent adhesion and ensure smooth surface.
Pressure blowing method (wide mouthed bottle)
The punch in the initial mold presses the bottle mouth and transfers it to the molding mold for blowing the bottle body, suitable for wide mouth containers such as sauce bottles.
Other technologies
NNPB process: Neck less compression molding and blowing, used for high-precision pharmaceutical bottles.
4 Annealing treatment
Annealing furnace parameters: Approximately 30 meters in length, with precise temperature curve control (heating section 550 ℃ → slow cooling section → fast cooling section).
Stress relief: The glass molecular structure is reorganized, and residual stress is reduced to ≤ 4 μ m optical path difference to prevent spontaneous rupture.
5 Surface strengthening and processing
Hot end coating: Spray tin tetrachloride at 500 ℃ to form a tin oxide hard film (thickness 0.10.3 μ m) to enhance wear resistance.
Cold end coating: After annealing, spray polyethylene or oleic acid to reduce the friction coefficient to below 0.15 and improve the smoothness of transportation.
Secondary processing: screen printing (temperature resistant ink at 600 ℃), laser etching (accuracy ± 0.1mm) or labeling.
6 Quality inspection
Online detection system:
Laser contour scanner: detects dimensional deviation (± 0.2mm).
Machine vision: Identify defects ≥ 0.1mm at a speed of 300 bottles/minute.
Pressure test: Inflate to 0.8MPa and hold for 30 seconds to detect microcracks.
Sampling testing: chemical stability (ISO 4802 water resistance test), impact resistance (5J impact test).
7 Packaging and Environmental Protection
Packaging method: Automatic palletizing machine combined with PE wrapping film, shock-absorbing paper partition spacing design.
Circular economy: For every 10% increase in broken glass, melting energy consumption decreases by 2.5%, and CO ₂ emissions decrease by 5%.
Technological innovation direction
Electric melting technology: The CO ₂ emissions from fully electric melting furnaces are reduced by 60% compared to gas furnaces.
Lightweight: Through structural optimization, the weight of 330ml beer bottles has been reduced from 210g to 170g, while maintaining a strength of 12MPa.
This process integrates materials science, thermodynamics, and precision mechanical control. Modern production lines can produce over 50000 glass bottles per hour, combining efficiency and quality. The sustainability of glass bottles (which can be infinitely recycled) continues to occupy an important position in the high-end packaging fields of food and medicine.