Manufacturing of glass bottles

 

Glass bottles are made by melting sand, blowing the molten viscous material into the desired shape with a mould, and then cooling it. Although the procedure appears straightforward, numerous technologies are used in glass bottle production companies to produce defect-free glass bottles.

Culinary sauces, soda, liquor, cosmetics, pickling, and preservation are all frequent uses for glass bottles. These bottles are useful and serve a purpose in the workplace. We will look at the step-by-step procedure of making glass bottles in this article.

Preparation of raw materials

Sand, soda ash, limestone, and cullet are the key raw materials used in the production of glass bottles.

• Sand: Sand is the body former that provides the glass its strength once it is formed. The percentage of silica or sand in a glass bottle varies depending on the type and use of the container. The Silica percentage is 70 percent plus or minus ten percent. The melting temperature of the glass is inversely proportional to the amount of silica in the mixture. Silica is crushed and processed to a tiny particle size before being placed in a hopper. The quartz is reduced to a size of 50#.

• Soda ash: As a fluxing agent, soda ash is utilized. As a result, the melting point of the silica in the glass is lowered.

• Limestone: Limestone (Calcium Carbonate) is a key component in the production of glass. Its major purpose is to add Calcium Oxide to the glass composition in order to improve chemical resistance and durability. It's also used as a flux in the glass industry.

• Cullet refers to recycled glass. One of the most advantageous characteristics of glass is that it can be recycled. Depending on the property required for the glass, 10% to 20% cullet is added to the mixture. Culets could be a by-product of the manufacturing process or a repurposed item from the real world market. Glass is recycled in both directions to minimize environmental impact. Cullets are originally stored before being broken down into smaller pieces by crushers. Size-reduced recycled glass material is transported by belt conveyor from the hopper to another storage hopper. Foreign elements will be manually removed, and iron will be removed using magnets in these conveyors.

• By adding oxide to the compositions, the color glass will be created.

Batching

• Because the glass bottle manufacturing process is a continuous one, batching is done on a regular basis to feed the furnace. Until the furnace starts, raw material is continuously fed into the furnace through a belt conveyor.

• The hopers are proportionally fed raw materials, which are subsequently mixed, emptied, and transferred to the furnace.

• A magnet is employed in the conveyor to remove any iron particulates that may be present.

• Foreign contamination, such as iron, should not be allowed in raw materials. Metal will not burn off and will leave spots in the clear bottle. During the initial melting process, any additional organic materials will be burnt. Air bubbles can also be eliminated at a later stage of the melting process.

• The raw materials mixer will be added to the furnace in batches. The rationale for this is to ensure that the mixer's composition is consistent across all products.

Melting process

• Every batch of raw materials supplied into the furnace is heated and melted and then sent to the next operation in a continuous loop.

• The glass melting furnace's max temperature varies depending on the composition. Temperatures often range between 1400 to 1600 degrees Celsius.

• There are three processes that take place inside the furnace.

1)    Melting, 2) Clarification, or Soaking, and 3) Cooling

Melting

• Melting is the first stage, in which raw components are heated and melted to form a viscous substance. The process begins with water evaporation, then moves on to organic matter burn off, silica change, and finally melting of the composition.

• To avoid contamination of the raw materials, the glass bottle melting furnace is composed of silica-based refractories. The air and fuel ratios will be closely maintained in order to retain the good firing curve and improve fuel efficiency.

• Fuel atomization in the burner aids in achieving improved fuel economy. The cost-effectiveness of the process is controlled by these controls. This is due to the cost of glass making is heavily influenced by the fuel used in the process. The gasoline utilized accounts for roughly 40% of the entire cost of the glass.

• The contemporary furnace does an excellent job of maximizing fuel economy. The controllers work automatically, and if there is a problem with the machinery, an alarm will sound.

Soaking or clarification:

• Because a portion of the composition may not melt due to the quick heating, the mixture is kept at a peak temperature for 3 to 8 hours, depending on the composition, to ensure that everything is melted.

• Furthermore, the generated air bubbles are permitted to travel through the melted glass at this point. A fault in the product will result from trapped air. During the soaking period, it is critical to eliminate any air bubbles that may have formed inside the molten glass.

Cooling

• To create the viscous condition, the molten glass is cooled to a lower temperature. Because it is difficult to blow the glass into the required form if it is in a fluid state. It will turn viscous after cooling, and it will be sent to the feeders.

Feeders

• The feeding of the glass blowers is the next step in the glass bottle manufacturing process.

• This is done by feeders. The bottom of the furnace end has apertures for feeders.

• These openings are controlled by low shear panels. The molten glass is continually chopped by these shear panels in order to obtain the needed quantity of viscous mass for blowing.

• The sheer panels' speed can be used to manage the amount of mass that passes through the hole. When different sizes of glass bottles are required, the rate of the shear panel is regulated. If a large glass is required, the sheer panel speed will be reduced, and vice versa.

• Garbs are the cut glass masses that create an extended shape during the cut from the furnace.

• The garbs are now ready for the following phase, which is obtaining the desired shape. Blowing is the next phase.

Blowing

• The garbs will be transferred into containers by the shaping machine.

• When the garbs are placed within moulds, the air is blown through the shaping machine.

• Hot air is now blown into the garbs to establish the mould’s shape. To prevent the glass from collapsing or experiencing a thermal shock, hot air is employed.

• The moulded shape is taken out of the mould. When this temperature is reached, a second part can be joined based on the desired shape. We can't join anything to the glass body after this temperature. If you need to do anything to the body, you'll have to re-melt the bottle.

• The bottle cap sealer line is marked or connected to the body at this point.

• After completing the shape formation, it was sent to next process called hot end coating

Hot end coating

• During the process, a thin layer of tin is added. The coating is utilized to give the glass bottle more strength.

• The tin coating is applied to the glass bottle's body at a temperature of roughly 350 degrees Celsius.

Annealing

• The exterior surface of the glass container cools faster than the inside side when it is produced, generating tension in the glass.

• The annealing procedure is used to avoid this problem. To avoid stress, the inside and outside of the bottle are cooled equally throughout the annealing process.

Cold end coating

• The glass container is coated with a thin coating of polymer. The polymer coating has a temperature of roughly 100 degrees Celsius.

• This coating is applied to the glass container to protect the bottles outside surface from scratches.

Inspection

• Any unwanted contamination in the glass and air bubbles in the glass is examined on all glass containers.

• The inspection is carried out on several levels. To ensure that the product quality is optimal for the clients, both automatic and manual checks are performed.

• The dimensions and design of the object, as well as flaws in the body, pinholes, contaminants, and air trapped inside the bottles, are all checked during this process. These are the most common flaws found during the glass bottle manufacturing process.

• All of this inspection takes place on a continuous conveyor as the bottles travel through, with many inspectors checking for faults.

• The good products are sent to the next stage for packing once they have been classified.

• Bottles that have been infected are recycled and used as cullet in the batch composition.

• In addition, all defects are recorded to provide feedback to production to reduce defects.

Packing

All of the nice bottles are packed according to the customer's specifications. Glass bottles are typically packaged in a cardboard box with various segments separated by corrugated sheets. To avoid any damage during the preparation, the packing is done by automation.

In all manufacturers, the procedure is nearly identical. The only variation is whether the production is automated or done manually. However, the general principle of glass manufacture remains the same. I hope you find this article useful and informative.