Thursday, February 1

Compressed Air Applications in the Glass Industry

The glass industry serves a large market through a variety of products. Glass is considered one of the most environmentally friendly, manufactured materials due to its full recyclability and reusability. It is also one of the major manufactured products that relies heavily on compressed air, no matter the type of product it is being manufactured for.

Glass Industry Segments

Glass Sorting

New glass products are many times derived from recycled pieces of glass. Because glass can come in a variety of transparencies and colors, the glass needs to be sorted before being put into production to manufacture a new product. This process utilizes a high-resolution camera, light, and compressed air to be completed. A light gets shone onto the glass pieces while the camera detects the color. Air is then conveyed onto the pieces to help sort them out by color in various directions.

Glass Manufacturing: Bottles & Containers

Glass bottles and similar containers are a popular consumer product choice as they are environmentally friendly and help to preserve stored food and beverages longer than plastic. The process of manufacturing these containers can take a few days to complete and almost every step in this process can use compressed air. After the collection and sorting of the glass materials is completed, the following steps begin:

  1. Quality Inspection & Batching
    The sorted raw materials are delivered to a batch house where they are inspected for quality and any mistakes that may have occurred in the sorting process. Once these materials pass the inspection process, they are sent to silos to be stored with other materials needed in glass manufacturing like sand, limestone, soda ash, and cullet. Compressed air powered pneumatic machinery is then utilized to transfer these materials to a furnace to be melted and mixed.
  2. Melting
    Compressed air and very hot gases are mixed to heat and stir the glass ingredients. Once the glass materials are fully melted and mixed, they are transferred out of the furnace, or kiln, and fed onto compressed air powered conveyors to be moved into formation machines and molds.
  3. Molding
    The now melted and mixed glass is ready to be shaped. A mold is utilized in this stage where a press first forms the base before the glass mixture gets blown with compressed air into its cylinder like shape. This formation machine will then apply more pressurized air to create all the detailed parts of the glass container, such as the lip, collar, and closure. The formation machine utilizes pneumatic tools throughout each stage to make the glass take its final shape before drying & being distributed for sale and consumption.
  4. Annealing
    Annealing is a process that reheats the drying containers and utilizes compressed air to evenly dry the inside and outside of the container. This is done, because naturally, without the annealing process, the outsides of the glass container will dry sooner than the insides. This uneven drying from natural processes can also cause impurities along the glass. Annealing is used to provide evenness in the drying process while ensuring quality. 
  5. Coating & Packing
    Now that the glass container is fully formed and dried, it gets coated with a thin layer of tin to harden and shine up the surface. Most glass bottles and containers will also be given a thin layer of polymer to create a scratch-resistant exterior. Compressed air is used to apply this thin, even coating. These now coated bottles are ready to go through the final quality inspection to either get rejected and re-recycled, or packaged up to be sent to stores or other manufacturing facilities who will store their own products in the glass bottles and containers. Throughout this entire process, these containers are most likely being transported along compressed air powered conveyor belts and blown off, or cleaned, with compressed air.
  6. Filling
    After the bottles have been packaged and shipped out, food and beverage manufacturers will utilize compressed air and pneumatic tools to fill, label, and seal these bottles and containers.

Glass Manufacturing: Sheet Glass

Sheet glass manufacturing, while it follows a similar process to glass container manufacturing, is a quicker and simpler process overall.

  1. Storing & Mixing
    Compressed air powered machinery is used to move sand that is stored in large silos to glass factories where it gets mixed with other ingredients like limestone and soda ash in preparation for melting.
  2. Melting & Flattening
    Once the glass mixture reaches the melting chamber, or kiln, temperatures increase to extremely high levels and stay this way for over ten hours to fully melt the glass mixture. Gas is utilized during this process to relieve the mixture of any bubbles that could ruin the finished product. Once all bubbles are removed and the glass is a molten substance, compressed air powered machinery is used to transport the mixture to the next stage where tin is melted into a liquid form and used as a surface for the molten glass to spread out and harden before leaving the chamber. Tin and glass don’t mix, making it the perfect substance to encourage the glass mixture to take its flat form.
  3. Hardening & Cooling
    As the glass sits, it hardens into its flat, sheet form. While the glass may have hardened, it still holds a high temperature which means it can easily be manipulated into other shapes. To avoid this, compressed air powered pneumatic blowers are used to bring the glass down in temperature to solidify its shape and prepare for cutting.
  4. Cutting
    The final stage of sheet glass manufacturing is cutting the sheets into proper sizes for their intended use, many times for use as windows or doors. Compressed air powered machinery transports the glass through this stage and powers pneumatic machinery that lifts the cut glass from the production line to be shipped out as the final product. Most sheet glass will also be coated with polymers or waxes to make it scratch-resistant and more durable. Compressed air is used to apply this coating in an even and contaminant-free manner across the sheet glass. 

Quality Standards

Of course, glass is a very specific product that needs to have a clean, clear look without contaminants. This starts all the way at the beginning with the compressed air. The compressed air needs to be oil-free, particle-free, extremely dry, and provide a consistent, steady flow of air. This ensures a clean, controlled, uniform process that enables high-quality glass production of all kinds.



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