The word "glass" is a very broad term that can be applied to a wide range of typically transparent or translucent non-crystalline amorphous solids with uses in industrial, practical, scientific and decorative industries alike.
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Glass Manufacturing History and Applications
Glass has been around for thousands of years, with the use of volcanic obsidian glass dating back to the Stone Age and the use of silica glass dating back to the mid third millennium BC in the areas of Mesopotamia and Egypt. It was not until around the fifteenth century, however, that glass became widely used. During the Middle Ages and Renaissance, glass was heavily used in church architecture. Today, glass manufacturers are enlisted to make countless products. Some of these products include: window panes, mirrors, glassware and eating vessels, jars, vases and paperweights. Over the years, glass has been made using many different methods and formulas. The oldest and most traditional types of glass are made from silica, which is one of the many components of sand. Today, the top three most common ingredients that modern glass manufacturers use to make glass are silica, lime from limestone and alkali-based sodium bicarbonate, also known as soda ash.
Silicate glass, or glass composed primarily of silica, can be divided into several subgroups, based on its additives. These subgroups are as follows: fused quartz or fused silica glass, soda lime silica glass or window glass, sodium borosilicate glass or Pyrex, lead-oxide glass or crystal glass, aluminosilicate glass and germanium oxide glass. All of these glass types have different positive qualities, the ranges of which include characteristics like: weather resistance, low thermal expansion, high temperature resistance, hardness, transparency, formability, water erosion resistance, dimensional stability, thermal shock resistance and clarity.
Glass Production Processes
- Float Glass and Glassblowing
- Glass manufacturers produce glass products using two main processes: the float glass process and the glassblowing. The first process creates sheet glass. It works by pouring molten glass into a tank filled molten metal, typically tin, where the glass floats. This process creates glass of even thicknesses that are extremely flat. To make sure that the glass remains clear and colorless, glass manufacturers typically add less than 0.1% dolomite to the mixture. Mostly, float glass is used in window pane production. Next, glassblowing is a procedure that involves inflating molten glass into a bubble, also known as a parison, around or into a mold. Glassblowing is used to make bottles, jars, vacuum tubes, laboratory glassware and light bulbs.
- Other Production Processes
- In addition to these main methods, glass manufacturers use other forming processes including but not limited to: the blow and blow process, the press and blow method, mold blowing, pressing and drawing. Regardless of the forming method used, a glass product will be reheated again and again throughout in order to strengthen it. This reheating and strengthening act is known as annealing. As it is being formed into its final iteration, the glass product may undergo other tempering processes, like reheating it then cooling it with sudden blasts of cold air. Some glass products, especially glass bottles that will go on to contain alcohol, undergo a process called dealkalization. This process is intended to improve the chemical resistance of the interior glass bottles. Finally, at the cold end of the glass manufacturing process, glass manufacturers spray on a polyethylene coating that increases lubricity and abrasion resistance. Following this, they send their products on to be inspected for defects, packaged for shipment and properly labeled.
Glass Manufacturing Three-Part Operations
To create glass types such as these, most modern glass manufacturers work in three-part operations: the batch house, the hot end and the cold end. Inside the glass house are stored all the raw glass materials. Usually, one to five days worth of supplies can be found there. Glass manufacturers (or automated machines) who work in the batch house assemble, mix and deliver the raw glass materials to the hot end, or the furnace. The raw materials, or batch arrive, in the furnace via a series of chutes, conveyors and scales. They are fed slowly and in deliberate increments into the fuel oil-fired or natural gas-fed furnaces. Inside the furnaces, which are usually heated to around 2500, the ingredients that make up the batch fuse together into a new composition. If glass manufacturers wish to add additional ingredients to modify the glass’s color or shine, they do so while it is still hot. Once the glass has been fused to satisfaction, it is cooled by several hundred degrees, but remains hot. At cooler (but not cold) temperatures, the glass is easier to shape and mold. Thus, at this point, the newly created glass is sent on to be shaped into a usable product.
Glass Manufacturers Terms
- Glass Cutting
- Is used for every glass function, such as clear float glass (flat glass), decorative and obscure glass used by window manufacturers and framers for building construction and art housing.
- Flat Glass
- Is a rather common type of glass, known for being the type of glass that is found in windows and other similar applications. Flat glass is also known as sheet glass or even plate glass.
- Gauge Glass
- Is a tool that is used to gauge the level of gases or fluids within a system.
- Glass Fabricators
- Are able to process glass and glass products in a range of ways that include design assistance, glass blowing and assembly, glass part fabrication with coated glass, safety glass and laminated glass, glass cutting or etching, glass repair and recycling.
- Glass Rod
- Rods made from glass. These typically come in a cylindrical shape but are also offered in other shapes.
- Glass Tube
- Refers to those hollow cylinders that are made of glass of any kind.
- Laminated Glass
- When glass is laminated, it becomes a product that is much stronger, can withstand much greater impacts and exhibits much improved tensile capacities.
- Optical Glass
- Is specifically designed for applications such as telescopes, glasses, binoculars, and similar applications.
- Plate Glass
- Is very similar to flat glass as it is often used to make windows and other similar applications such as tables or mirrors.
- Quartz Glass
- Is made from silicon dioxide and is a highly pure material that looks similar to standard glass but has superior thermal and optical properties and thus is used for a number of specific applications. Quartz glass does not have a crystalline structure; rather it is amorphous and produced from silicon compounds during the vaporization stage of the chemical reaction.
- Safety Glass
- Does not shatter into sharp, jagged and often small pieces when broken. This important characteristic makes it the preferred choice of many glass buyers.
- Sight Glass
- Is used in industrial plants and machines in order to visually observe and monitor liquid and material levels, colors, flows or direction.
- Tempered Glass
- Is a type of safety glass, which is glass that is modified in some way to become less likely to break and/or less likely to cause harm when broken.
- Transparent Glass
- Allows things to be viewed from either side of the glass, which can come in handy in applications where certain workers must perform a dangerous task while others supervise behind the safety of the glass.