Tag: <span>cooling process</span>

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Cast gold bars are usually produced directly from melted gold. However, the way in which melted gold is used to manufacture these bars can vary. The three main types of gold bars being manufactured are:

(1) Large cast bars with approximate weights.

(2) Small cast bars (1000 g or less) with specific weights.

(3) Long flat cast bars, notably for the manufacture of minted bars.

Large Cast Bars:

Large cast gold bars are usually manufactured to an approximate weight, so the refined gold at the required purity is directly poured into the casts

Induction furnaces are usually used to melt gold. Gold is melted in bulks in large holding crucibles. Gold crucibles are then tilted, and a relatively small amount is poured into pre-heated transfer crucible. At this stage, using vacuum tubes, small samples of gold are tested. Melted gold in the transfer crucible is then shifted to pre-heated, dressed bar moulds (generally cast-iron) of the required size. During pouring process, the mould sits on a balance. When the balance records the required weight of gold, the pouring is stopped. A few seconds after pouring process, the bar is dropped into a tank of water for cooling. Alternatively, the mould can be allowed to cool gradually. This cooling procedure is called “quenching”. The bar is then cleaned to remove stains of any kind and then weighed.

Small Cast Bars:

Small cast bars, having specific weight, are produced using refined gold, which has been tested for the required impurity. Refined gold is usually available in two basic forms: granules and small cut pieces. The choice of basic form depends on the method of manufacturing.

First of all, the required form of gold is balanced and the required amount is weighed. Usually, gold is weighed slightly more than the weight of the bar, in order to cater for manufacture losses.

Traditional method: In traditional small cast bar manufacture method, melted gold is poured into moulds; this method is still used by many manufacturers. Gold is first placed in a crucible of appropriate volume and is then melted in a furnace at a controlled temperature of 1200C. Care should be taken to avoid contamination of gold. The melted gold is then poured into a pre-heated bar mould, which has been dressed with carbon smoke or graphite. After that, the mould is cooled and the bar is cleaned and weighed.

Modern method: Using modern methods, a lot of small cast bars can be manufactured simultaneously. The gold is poured into bar moulds of the required size. A number of moulds are simultaneously fed into induction furnace for melting at controlled temperature of 1200C. Melted gold is then pushed into a “Cooling Tunnel”. When it comes out, the bars are removed from casts, cleaned and then carefully weighed.

Long Flat Cast Bars:

Long flat cast bars can be manufactured either from cast iron moulds in a pack or from a continuous casting machine.

Traditional Method: A number of cast iron blocks of required width, thickness and length are clamped together vertically, so that the flat base of one mould forms the side of the other mould. These moulds are filled with melted gold and then cooled. When the gold has solidified, the moulds are unclamped and the bars are removed.

Modern Method: Continuous casting machine

The modern methods of manufacturing use casting machines to produce bar stock of required width and thickness on a continuous basis.

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Source by Jack Wogan

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It is August. It is summer. It is hot, and it is kick-off time across the country as pre-season football practice begins. Players will expect to get hot and sweaty, as their coaches attempt to whip them into shape. However a combination of hot/humid weather, tough conditioning drills and players unaccustomed to practicing in the heat, can make August a deadly and dangerous month.

Despite all the warnings, the National Center for Catastrophic Sport Injury Research reports that 24 football players (19 high school, 3 college and 2 professional) have died from heatstroke since 1995.

The main problem associated with exercising in the hot weather is the water loss through sweating. However drinking water is simply not enough. In extremely hot weather the body will sweat at a rate faster than water can be absorbed into the system. So how can we reduce the amount of sweating, while at the same time help the body to regulate its core body temperature?

The answer is the Arctic Heat Body Cooling Vest. A lightweight cool vest which will not only help to protect athletes from heat related illness, but it will also allow athletes to work harder for longer.

The Arctic Heat cooling vest was originally developed for football players in Australia and it now used by International teams in every other major football code in the world. Rugby League, Rugby Union, Soccer and Australian Rules Football all use the cooling vest to protect their athletes and to improve their performance. It was also used at the Athens Olympics by all the major sporting countries, including many of the USA teams. The military in Iraq are even using the Arctic Heat cooling vests.

“The Arctic Heat Cooling Vest, designed for football, will legally improve performance and will also help protect an athlete’s health,” said Dr John Surie, President of Arctic Heat USA.

The ice cold cooling vest can be worn underneath playing uniforms, it can be used as a pre-cooling device before conditioning drills, and it can be used as a recovery tool in between or after sessions.

Yet enquiries from local football teams have so far been limited. “There seems to be a different mentality in football that you have to run players hard and make them sweat, in order to toughen them up. We believe it is better to cool down and fire up athletes. Most other sporting codes in the world now agree with us,” said Dean Sainsbury from the Arctic Heat company.

Arctic Heat has also developed a range of unique cooling blankets and cooling caps which can be used to immediately treat players who have overheated. “The cooling caps can be used during a game to cool players down. When they come to the bench they can remove their helmets, put the cool cap on, and cool down,” said Dr Surie.

The lightweight Arctic Heat Cooling Vest uses a two stage cooling process. The vests contain a gel-like substance that can be frozen or chilled. The cooling vests are manufactured using Woolmark’s Sportwool, a special body cooling fabric which incorporates Vapor Management Technology, helping to wick moisture away from the skin, allowing the user to keep dry.

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Source by John Surie

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The most common of the causes of these failures tends to be damaged or “cold” solder points under the graphics processing chip (known as the GPU).

Manufacturing game consoles comes with lots of intricacies. One of these is the ecological effect of your item. Because of this, 360′s are produced using lead free solder. This is good for the planet but bad for the life of the console. There is a heat cycle involved in using gadgets with processor’s (CPU’s and GPU’s). During these heating and cooling periods, there is pressure on solder joints as the motherboard tends to move a little bit when cooling. This is regular and usually does not cause damage. The insufficient amount of lead in the solder makes the joints much less flexible, and they usually break a little. Sure this can occur with leaded solder, and it does all the time. The difference is when it happens; 500 power cycles in comparison to 4000 power cycles is the difference between your 360 console lasting 18 months and your 360 console lasting 6-8 years. Now that is a lot difference! There are several ways to fix these production problems. Some are useless and some are worth the weight of a 360 in silver…

“The Penny Fix”

This is where you put a penny in between the GPU chip and the heat sink. This may have worked for someone, somewhere, who had a loose x-clamp, but it doesn’t fix the overheating or the breaks in the processor solder and it is a bad idea. It may tighten the x-clamp, and resolve the present error, but it causes bigger problems. There is a layer of thermal paste between the chip and the heat sink that is very critical to the cooling of the chip. The penny will not only physically damage the chip, but also disturbs the cooling process and leads to burns on the chip. I have seen the penny under the x-clamps on the bottom of the motherboard as well. This is even worse as it makes tons of shorts and damages many of the tiny components. This fix will render your Xbox 360 useless and irreparable.

“The Towel Fix”

This idea came from the thought that wrapping a towel around the cooling vents of your Xbox 360 would heat the solder hot enough to reflow the chip. This is not possible. There are many factors involved in performing a successful reflow. The motherboard has to be preheated to a workable temp in order for the solder to dispense evenly, there is a specific method to heating the chip itself, there needs to be industry specific flux for the solder to adhere correctly and on… and on… and on. The only thing I have heard the towel method do, is nothing.

“The Oven Reflow”

This fix is accomplished by putting your motherboard on a baking sheet in the oven. This is the biggest nightmare repair I have ever had to date. DO NOT DO THIS!!! It does not work and it destroys many of the components on the motherboard!!! Your capacitors will burst, your resistors will fall off and your motherboard will curl up like bacon. This will render your Xbox 360 useless and irreparable. Enough said I hope!

“The Hotplate Reflow”

See above…

“The Hairdryer Reflow”

This fix is ridiculous. I have seen a lot of exploded capacitors from this as well. Do not attempt this method. Not only does it not fix your Xbox 360, it can damage you DVD drive as well. This will render your Xbox 360 useless and irreparable.

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Source by Josh B Manion

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The principle of evaporative air cooling is the best idea to think of the air as a type of sponge. An air comes into water; it will absorb and becomes humid air.

This method is the best way for the cooling purposes. It is similar to breeze flowing over a lake and this breeze lowers the temperature and it has helped to relax cooling effect on to the people. This method cools the air by means of the evaporation of water. Where the water evaporates to the air, then the result will come to a mixture of air and water molecules. This will requires heat and it is taken from the air molecules stopping the actual temperature of the air. The maximum humidity level becomes sixty percent or less the temperature decreases. It will help people to feel more comfortable. In dryer climates, the temperature decreases largely because of the lower humidity, heavy evaporations will occur. A great evaporative air cooler provides the biggest surface area over the air that can travel and evaporate the water.

When used for cooling purposes, the cooler should not be used in detached spaces and it must be kept level and there can be water in the tank. The rooms should have to well-equip with doors and windows because the free air will flow through the room and it keeps the room cool. An evaporative air cooler operates best when you have placed the nearby window. The free air is filled on to cooler and the cooler circulates in the room and exits through the door. If the maximum cooling purpose effect is felt when a person is in the flow or air coming out of the cooler. These coolers can be used to humidify dry air during the weather of cooled seasons. Used for humidity, the doors and windows should have to be kept in close. This will allow the humidity air to accumulate on the surface.

This cooler is not an air conditioner and it does not use a refrigerant gas and compressor. Once you should not expect an evaporative air cooler to operate as effectively as refrigerated air conditioning. The benefits of this cooler over refrigerated air conditioning are low purchase cost, maximum portability, low electricity usage and it has no refrigerant gas. These coolers can be only used in the best natural ventilation and the cold does not make cooling efficiency difference in an evaporative cooler.

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Source by Devendra Pandey