Glass production involves two main methods - floating glass processes that produce sheet glass, and glassblowing that produces bottles and other containers.
Video Glass production
Production of glass containers
Glass container factory
In general, the modern glass container plant is a three-part operation: batch house , hot tip , and cold end . Home restaurant handles raw materials; hot end handles precise manufacture - forehearth, annealing ovens, and forming machines; and cold ends handle product inspection and packaging equipment. Hot end
The following table lists general viscosity fixpoints, applicable to large-scale glass production and experimental glass smelting in laboratories:
Batch processing system
Batch processing is one of the first steps of the glass-making process. Home batches only house raw materials in large silos (fed by truck or railcar) and apply anywhere from 1-5 days of material. Some batch systems include material processing such as filtering/filtering of raw materials, drying, or preheating (eg, Cullet). Whether automatic or manual, the batch home measures, assembles, mixes, and prescribes the batch material through a series of launches, conveyors, and scale to the furnace. Batch enters the stove in 'dog house' or 'filler batch'. Different types of glass, color, desired quality, purity/availability of raw materials, and furnace design will affect batch recipes.
Furnace
The hot end of a glass factory is where a liquid glass is formed into a glass product, starting when the batch is put into the furnace at a slow rate, controlled by a batch processing system. The furnace is a natural gas or oil-fired fuel, and operates at temperatures up to 1.575 ° C (2.867 ° F). Temperature is limited only by the quality of furnace superstructure materials and by the composition of the glass. The types of furnaces used in the manufacture of container glass include end-fired, side-port and oxy-fuel. Typically, "size" furnaces are classified by metric ton per day (MTPD) production capability.
Formation process
Currently there are two main methods of making glass containers: blow & amp; destroy method only for narrow neck containers, and press & amp; blow method used for jars and tapered narrow-neck containers.
Figure 1: Steps during the Blow & amp; Container forming process Blow
In both methods, the flow of a glass of liquid, at its plastic temperature (1,050-1,200 ° C [1,920-2,190 ° F]), is cut with a shear knife to form a solid glass cylinder, called i> gob . Dirt is a weight that has been determined just enough to make a bottle. Both processes begin with the falling gob, by gravity, and guided, through the trough and launch, into the empty mold, the two covered parts are closed and then sealed by the "baffle" from above.
In the process of blowing and blowing, the glass was first detonated through the valve in the baffle, forcing it into a three-part "ring mold" held in the "neck arm" beneath the empty dots. , to form "finish", [The term "finish" describes details (such as the sealing cap surface, screw thread, rib holder for tamper-proof lid, etc.) on the open end of the container.] The compressed air is blown through the glass, hollow containers and partly formed. The compressed air is then blown again in the second stage to give the final shape.
The container is made in two main stages. The first stage forms all the details ("completed") around the opening, but the body of the container is initially made much smaller than its final size. These partially produced containers are called parisons , and quite quickly, they are formed with blow-molded to the final shape.
Referring to the mechanism, the "ring" is sealed from the bottom by a short thruster. After completion of "settleblow", the plunger shortens slightly, to allow the softened skin to form. The air "Counterblow" then appears through the thrusters, to create a parison. Baffle up and empty open. This comparison is reversed in the arc to the "mold side" by the "neck arm", which holds the parison with "finish".
As the neckring arm reaches the end of its arc, two parts of the mold close around the parison. Neckring arms open slightly to release his grip on "finish", then back to the empty side. The last blow , applied through "blowhead", blowing glass, extending to mold, to make last container shape.
In the tap and blow process , the parison is formed by the rising long metal plunger and pressing the exit glass, to fill the ring and blank prints. The process then continues as before, with the parison transferred to the final shape mold, and the glass being blown out into the mold.
The container is then taken from a mold with a "take-out" mechanism, and stored on a "deadplate", where cooling air helps cool the still soft glass. Finally, the bottles were swept into the conveyor belt by "pushing out the paddle" which had air pockets to keep the bottles standing after landing on the "death plate"; they are now ready for annealing.
Forming machine
The forming machines hold and move the parts that make up the container. This machine consists of 19 basic mechanisms that operate to form a bottle and are generally supported by compressed air (high pressure - 3.2 bar and low pressure - 2.8 bar), this mechanism is electronically timed to coordinate all mechanism movements. The most commonly used forming machine is the individual machine (or IS engine). This machine has an identical 5-20 parts bank, each of which contains a complete set of mechanisms for making containers. The sections are successive, and the gobokan enters into each section through the mobile channel, called the distributor gob . Parts create one, two, three or four containers simultaneously. (Called as single , double , triple and quad gob). In the case of several blobs, the shears cuts gobs simultaneously, and they fall into the blank print in parallel. Internal care
After the formation process, some containers - especially those intended for alcoholics - undergo maintenance to improve chemical resistance inside, called internal care or dealkalization. This is usually done by injection of a sulfur or fluorine gas mixture into the bottle at high temperatures. The gas is usually sent to the container either in the air used in the forming process (ie, during the final blow of the container), or through the nozzle directing the gas stream to the bottle's mouth after it is formed. Treatment makes the container more resistant to alkali extraction, which may lead to increased product pH, and in some cases container degradation.
Annealing
As the glass cools, it shrinks and hardens. Uneven cooling causes a weak glass due to stress. Even cooling is achieved by annealing. The annealing oven (known in the industry as Lehr) heats the container to about 580 ° C (1.076 ° F), then cools it, depending on the thickness of the glass, over a period of 20-60 minutes.
Cold end
The role of cold ends is to spray on polyethylene coating for abrasion resistance and increase lubrication, check container for defects, packets containers for delivery, and label container.
Inspection equipment
Glass container checked 100%; automatic machines, or sometimes people, checking each container for errors. Common errors include small cracks in the glass called checks and foreign inclusions called stones that are part of the refractory brick lining of the melting furnace that breaks and falls into the pond. liquid glass, or larger silica grains of oversized (sand) that have failed to melt and which are then incorporated in the final product. It's very important to choose because of the fact that they can provide destructive elements to the final glass products. For example, because these materials can withstand large amounts of heat energy, they can cause glass products to support thermal shocks that produce explosive destruction when heated. Other defects include a bubble in a glass called blister and an excessively thin wall. Another common flaw in glass manufacturing is referred to as tears . In the formation of press and blow, if the plunger and the mold are not parallel, or heated to the wrong temperature, the glass will stick to one object and become torn. In addition to refusing the damaged container, the inspection equipment collects the statistical information and sends it to the shaper machine operator at the hot end. The computer system collects error information and tracks it to the mold that generates the container. This is done by reading the printed number on the container, which is encoded (as a number, or binary dot code) on the container with the prints that make it. Operators perform various manual checks on the container samples, usually visual and dimensional checks. Secondary processing
Sometimes container factories will offer services like labeling . Several labeling technologies are available. Unique to glass is the process of Applied Ceramic Labeling (ACL). It is decorative screen printing into a container with vitreous enamel paint, which is then baked. An example of this is the original Coca-Cola bottle. Absolut Vodka Bottles has a variety of additional services such as: Etching (Absolut Citron/) Coating (Absolut Raspberry/Ruby Red) and Applied Ceramic Labeling (Absolute Blue/P/Red/Black).
Packaging
Glass containers are packed in various ways. Popular in Europe is a bulk palette with 1000 and 4000 containers each. This is done by automatic machines (palletisers) that organize and stack the containers separated by sheet sheets. Other possibilities include boxes and even sacks stitched by hand. Once packaged, new "stock units" are labeled and warehoused.
Coating
Glass containers typically receive two surface layers, one in hot ends, just before annealing and one on the cold end just after the annealing. At the hot ends, very thin tin (IV) oxide coatings are used either using safe organic compounds or inorganic stannic chloride. Tin-based systems are not the only ones used, though the most popular. Titanium tetrachloride or organo titanate can also be used. In all cases, the coating makes the glass surface more attached to the cold end layer . At the cold end the usual layer, polyethylene wax, is applied through a water-based emulsion. This makes the glass slippery, protecting it from scratches and stopping the containers from sticking together when transferred to the conveyor. Unseen combination coatings produce a surface that can hardly be scrawled onto the glass. Due to the reduction in in-service surface damage, the coating is often described as a reinforcement, but a more precise definition may be a strengthening coating.
Additional process - compressor and cooling
Forming machines are mostly supported by compressed air and typical glass work will have some large compressors (at 30k-60k cfm) to provide the required compressed air. Furnaces, compressors and forming machines produce the amount of waste heat that is generally water-cooled. Unused hot glass in the forming machine is diverted and the transfused glass (called cullet ) is generally cooled by water, and sometimes even processed and destroyed in a bath water setting. Often the cooling requirements divided over the cooling tower banks are set to allow backup during maintenance.
Marketing
Making glass containers in developed countries is a mature market business. World demand for sheet glass is about 52 million tonnes in 2009. The United States, Europe and China accounted for 75% of the demand, with Chinese consumption rising from 20% in the early 1990s to 50%. Glass container making is also a geographic business; these products are heavy and large volumes, and the main raw materials (sand, soda ash and limestone) are generally available, therefore production facilities should be placed close to their markets. A typical glass stove holds hundreds of tons of liquid glass, and therefore it is not practical to turn it off every night, or even in less than a month. The factory therefore runs 24 hours a day 7 days a week. This means that there is little chance of increasing or lowering production levels by more than a few percent. New furnaces and costing machines cost tens of millions of dollars and require at least 18 months of planning. With this fact, and the fact that there are usually more products than the machine line means that the product is sold from stock. Therefore, the marketing/production challenge is to be able to predict good demand in the short term 4- to 12 weeks and over a period of 24 to 48 months. The plant is generally sized to serve city requirements; in developed countries there is usually a factory per 1-2 million people. The typical plant will produce 1-3 million containers per day. Despite its position as a mature market product, glass does enjoy a high level of consumer acceptance and is considered a "premium" quality packaging format.
Life cycle impact
The glass containers are fully recyclable and the glass industry in many countries maintains a policy, sometimes mandated by government regulations, to maintain a high price on the cullet to ensure a high rate of return. The 95% return rate is not uncommon in Nordic countries (Sweden, Norway, Denmark and Finland). A rate of return of less than 50% is common in other countries. Of course glass containers can also be reused, and in developing countries this is common, but the environmental impact of washing the containers on re-melting is uncertain. Factors to consider here are the chemicals and freshwater used in the washing, and the fact that disposable containers can be made much lighter, using less than half a glass (and therefore the energy content) of a multiuse container. Also, a significant factor in the consideration of advanced world reuse is the manufacturers' concerns over the risks and obligations of the consequential products using components (reusable containers) of unknown and unqualified safety. How glass containers compare to other types of packaging (plastic, cardboard, aluminum) is hard to say; conclusive life cycle studies have not yet been produced.
Maps Glass production
Float glass process
Floating glass is a sheet of glass made with a melt glass floating above a metal bed of liquid, usually lead, although tin and various low melting point alloys are used in the past. This method provides a uniform sheet thickness and a very flat surface. Modern windows are made of float glass. Most float glass is glass-lime soda, but relatively small amounts of specialty borosilicates and flat panel display glass are also manufactured using a float glass process. The float glass process is also known as the Pilkington process, named after the English glass maker Pilkington, who pioneered the technique (invented by Sir Alastair Pilkington) in the 1950s.
Environmental impact
Local impact
As with all highly concentrated industries, glass factories suffer from high local environmental impacts. This is because they are mature market players, they are often in the same location for a long time and this has resulted in the encroachment of housing. The main impacts on housing and residential cities are noise, clean water use, water pollution, NOx and SOx air pollution, and dust.
Noise is created by forming machines. Operated by compressed air, they can generate noise levels up to 106dBA. How this noise is brought to the local environment is highly dependent on the factory layout. Another factor in noise production is the movement of trucks. The typical factory will process 600T of material a day. This means that about 600T of raw materials must come to the site and the same from the site again as the finished product.
Water is used to cool the furnace, compressor and unused liquid glass. The use of water in the plant varies greatly; it can be as little as a ton of water used per ton of melted glass. Of a ton, about half is evaporated to provide a coolant, the rest form a stream of waste water.
Most manufacturers use water containing emulsified oil to cool and lubricate gob cutting the sliding knife . The oil-filled water mixes with the flow of water out, thus contaminating it. The plant usually has some type of water treatment equipment that removes this emulsified oil to varying degrees of effectiveness.
Nitrogen oxide is a natural product of gas combustion in the air and is produced in large quantities by a gas-fired furnace. Some factories in cities with certain air pollution problems will reduce this by using liquid oxygen, but this logic keeps in mind that carbon costs (1) do not use regenerators and (2) should dilute and transport oxygen highly questionable. Sulfur oxide is produced as a result of the glass melting process. Manipulating the batch formula can affect some of these limited mitigations; or provide other exhaust can be used.
The raw materials for glass manufacture are all dusty materials and are delivered either as powder or as fine-grained materials. The system for controlling dusty materials tends to be difficult to maintain, and given the large amount of material moves on a daily basis, only a small number must go out due to dust problems. Cullet is also engaged in glass mills and tends to produce fine glass particles when shoveled or broken.
See also
References
External links
- Beatson Clark's page on glass manufacturing
- The Society of Glass Technology
- English Glass homepage
- The Glass Processing
- Bucher Emhart Glass page on glass manufacturing
- The Glass Packing Institute
- The Benefits of Vacuum for Glass Bottle Production
- The Antique Bottle Mystery
- Alerts & amp; Glass Manufacturer logo seen on antiques & amp; modern container & amp; other glassware (especially American companies)
- What you need to know about the glass-forming defects - #GCFDA
Source of the article : Wikipedia
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