Breaking Down the Process: A Step-by-Step Guide to Glass Bottle Making

The use of glass bottles is increasing each year. It is a trending yet stunning product that one can recycle, reuse, and refill endlessly.


Glass bottles have a low natural impact. Moreover, it is inert and contains no synthetic chemicals. Thus, storing food and beverages in glass bottles is safe.


But how are these glass bottles made in factories? All glass bottles have the same components regardless of size, design, and color. Though, the actual production method depends on the final product.


The making of glass bottles is a clear-cut operation. Yet, companies use several types of advanced methods to ensure each product is free of flaws.


So let’s understand the production of glass bottles in this thorough guide. We’ll explore everything from the initial hot-end process to the final cooling.


How Are Glass Bottles Made in Factories?


Many specialized glassware makers use glass-blowing and blow-molding techniques. But factories now prefer automation. Automation has replaced many processes in producing most glass bottles.


The arrival of feed and flow machinery has changed everything. It has marked a decisive point in the history of glass products making. It allows factories to produce significant quantities of bottles.


Modern factories separate the production of glass bottles into three phases:


  1. The Batch House: This first stage manages the materials procurement and storage.
  2. The Hot End: The operator performs the production and molding in this stage.
  3. The Cold End: The third stage involves inspecting and packing the glass bottles.


How Long Does It Take to Produce Glass Bottles?


It can take longer to produce even a single glass bottle without setup. Production plants often have all materials, equipment, and technology in place. They have the workforce to perform various tasks involved in making glass bottles.


Thus, they can carry out bulk production of glass bottles in a short timeframe.


In about 10-15 seconds, a glass gob transforms into a glass bottle. The operator then transports it to an annealing process for 1 to 2 hours. This process helps remove surface tensions.


To make molten glass, an operator heats raw materials in a furnace. The heating takes place at roughly 1550 degrees Celsius. The furnace operates around the clock, every day of the week, and can melt hundreds of tons of glass.


This way, a glass bottle can be ready in less than 24 hours, provided all requisites are in place. A professional supplier can handle the bulk production of glass bottles.


What Are the Major Steps Involved in Making a Glass Bottle?


Only glass is entirely recyclable without any degradation in quality. That’s why we call it the cleanest and longest-lasting material for packaging.


Below are the crucial steps involved in producing glass bottles.


Step 1: Arrangement of the Raw Materials


First, the ingredients and raw materials must be ready for use. There are primarily three distinct varieties of glass:


  • Borosilicate glass, i.e., Type I
  • Processed soda-lime glass, i.e., Type II,
  • Soda-lime glass, i.e., Type III


The various ingredients involved in making glass bottles range from seven to twelve. But the main ingredients are sand, soda ash, limestone, and cullet. You can also consider adding oxide to the mixture to produce colored glass.


Let’s check out the essential ingredients one by one.


A) Sand


Sand is the body-forming element that gives the finished glass its endurance. The amount of sand or silica usually varies with the glass bottle’s intended use.


You’ll often find it at a ratio of 70%. Besides, there will be several other natural ingredients too.


B) Soda Ash


As a fluxing agent, it lowers the melting point of the silica, making it easier to work with.


C) Cullet


Cullets are nothing but reused or recycled glass. It is a material that emerged as a scrap or recyclable items. The majority of cullets or recycled glasses help support natural safety.


Step 2: Batch Processing


Since making glass is a constant process, so will the batching procedures. In this step, the operator measures and combines raw components. After that, the operator transports them to the melting furnace’s hopper.


Many factories now use a grinding machine to prepare the batch. A grinder processes the cullet, raw material, and color ingredients. Then, the operator measures each ingredient and weighs them precisely before combining them.


These components are often mixed in a mixer till they form a uniform batch or frit. Large vertical silos hold batches until they are put into the kiln.


In the end, the operator transports the lot to a melting furnace to complete the procedure.


Step 3: The Melting Stage


Processing of raw materials in the furnace begins after the batching process. Machines use very high temperatures to create and shape the glass.


The highest temperature of the furnace is between 1400 and 1600 degrees Celsius. Of course, this range depends on the composition.


Forehearths serve as conduits for delivering molten glass to the forming machine. Lastly, the cutting of the glass flow into pieces occurs near the end of the forehearths.


Step 4: The Forming Process


There are two ways to shape glass after we heat it in the furnace. Factories can form glass using either a press or blow mold.


Method 1: Press-and-Blow Molding


The majority of companies that use this way of shaping make glass containers. The formation occurs within an IS machine.


One machine may have five to twenty independent yet synchronized processing units. This process begins when the glass’s temperature reaches the plastic stage (1050-1200 degrees Celsius).


Using a shearing blade, you may form the glass into a gob. A metal plunger forces the sliced gob into a mold as it drops. This way, we get a parison, i.e., the molded gob. The finished parison goes in the final mold to take its shape.


Method 2: Blow-and-Blow Molding


An IS machine performs the blow-and-blow molding process. The same basic idea applies here. The gob cuts in the plastic phase before transferring to molds.


Compressed air pushes the gob into the blank mold in this method. The final mold is used once the gob transforms into a parison. Lastly, air compression forms the glass bottle’s interior.


Step 5: Internal Treatment


Alcohol or beverage bottles made of glass need an internal treatment process. The process strengthens the bottle’s resistance to chemicals.


Internal treatment lets you store alcohol or other drinks that contain corrosive substances.


Step 6: The Annealing Process


Glass bottles cool at different rates on their outside and inner surfaces. Also, the glass may crack due to temperature disparity.


Thus, annealing is necessary to ensure that the glass bottles are defect-free. The glass bottles are heated in annealing furnaces to relieve tension.


Step 7: Cool End Process


The final phase in making glass bottles is the cool end procedure. It not only prevents scratches but also strengthens the glass bottles.


The glass bottles get two different coatings: a hot end layer and a cold end layer.


Glass bottles get many benefits with these coatings. First, they serve as a scratch-resistant element. Besides, they offer a slippery finish to the glass.


Step 8: Inspecting/Testing of Glass Bottles


All glass bottles undergo automated and human inspections to ensure they are defect-free. But glass bottles may exhibit flaws in various forms.


The quality of the finished glass product is something operators should always check.


Checks (small cracks) in the glass are common. Moreover, foreign particles like stones can break through it and enter the container. Tiny fissures, filth, and tangling bubbles are some more flaws.


Crushing and recycling the flawed bottles is what happens next. The leftovers from this batch will make cullets for the following one. The inspected goods are ready for packaging if they have no flaws.


Step 9: Secondary Processing


Some companies that make glass bottles also label them for their customers. Several marking methods are available these days.


But, the Applied Ceramic Marking (ACL) procedure is tailor-made for glass. Also, glass enamel paint is suitable for screen-printed designs.


Step 10: Packaging


The final step in creating glass bottles is the packaging phase. Companies must ensure proper packaging, especially for delicate items like glass bottles.


The sheets between each bottle and the cardboard box keep them from breaking. After production is complete, automated packing occurs to avoid any potential harm.


Final Thoughts!


So, that’s all about making glass bottles. We have now seen the entire production cycle for making glass bottles. All production plants follow a very similar procedure.


The only determining factor is the amount of machine intervention vs. human effort. Yet, the primary method of making glass remains the same.


The best thing about automation is its success. It helps reduce human involvement and lessens the chance of errors. You can look for a reliable company with an automated glass bottle manufacturing process.


Do you want to buy wholesale glass bottles? Do you have specific size and design needs? We use many advanced methods to produce glass bottles of varying sizes and designs. Feel free to contact us for the most affordable quote for your requirements.