What Are Castings?

Being one of the oldest manufacturing techniques that still survives today, casting is the process in which a molten liquid is poured into a cast to achieve a desired shape. After the molten liquid harden, the cast can be taken away and the end product which can also be referred to as a casting is sent to be polished and distributed. The reason for this ancient technique being able to survive up to the present can be because of the need for metal customization or economical setup. Casting is more economical than having to shape items by hand or other methods. The most common type of casting in the industry today is for metals. In this article I would not be concentrating on castings of other sorts besides metal.

The process of casting starts with a mould that is going to shape the molten metal being created. As moulds are manufactured in foundries, manufacturers develop designs of mould that relate to the final casting product they would want to achieve and take them to the foundries. Casters then develop the desired moulds that manufacturers want. Thereafter comes the melting down of the metal that is to be shaped. The melting process also takes in the foundry. The liquefied metal is poured into the cast or mould with the help of machines and equipments. These machines can also monitor the rate at which the metal is poured into the cast as to avoid overflowing. The metal is then left to cool and once it has hardened, the cast can be removed for the metal to be cleaned.

The application of metal casting is done for products that require identical, precise and complex shaped products. As a mould can be reused over and over again, a manufacturer can create several products that look exactly the same. Also molding metals by hand into complex shapes would not be as economical to manufacturers as casting as them would require extra man power and equipment. If some metals require precise detail, molding can ensure that as well. Some manufacturers nowadays make use of machinery to shape the mould precisely so that it can capture details and imprint them onto castings.

Although the job may sound to be quite easy, it is not a simple task after all. Casters have to be aware that there are impurities in the air and they might be present inside where the metal is being cast or on the mould itself. Impurities can mix with the molten metal and as it hardens will solidify within the metal. This would affect the quality of the casting and eventually may even cause it to break. The molten metal has to be poured into the mould carefully to avoid any air bubbles. If the bubbles were to be trapped inside the casting as it hardens, the casting would not be of best quality and may break easily. The caster must take note that the poured liquid metal does not harden immediately so he would not have any problem pouring it slowly and carefully. This is to ensure that the casting is of the best quality.

Fake Casting In World Of Warcraft

Fake Casting in WoW PvP is an advanced tactic to bate enemy players into advantageous situations. Fake Casting is basically exactly what it sounds like. To master this, you should start casting a spell, wait for it to get around half way through, and then move your character to prevent it from casting. You can also make a macro to stop casting, or jump in the air. The main purpose of this is to try to get your enemy to waste an interrupt spell early in the battle, or to move in a way that is beneficial to you. It is also referred to as juking by some players in PvP.

After you have mastered other tactics such as focus targeting and how to properly move around the arena, you should move onto this. Try to fake cast spells that you wouldn’t mind getting interrupted.

This is key. If you are a frost mage, you can fake cast polymorph or a fire spell. This way if you get silenced, sometimes it won’t affect all of your spells. Another good tip is to cast spells that have names that are easy to recognize. If you cast something with the name Heal, an opponent knows exactly what this is, and is much more likely to interrupt it. It is also better to cast long spells, to give time for the opponent to take the bait. This is usually done in the beginning of a battle but can be done later on. It takes some serious practice to figure out when you should be fake casting and when you should be regular casting. The general rule is to do it in a way that seems like you don’t know what you are doing. Run up to an enemy and immediately cast a spell from a school of magic that you don’t use very often. Most people that have their interrupt up, will try to interrupt this. If they do not interrupt, it is usually safe to cast a normal spell.

If you are the one trying to interrupt a spell caster, there are many things to remember. Never interrupt a player in the first half of their cast. Once they have passed the half way mark, it is much more likely that they intend to cast the spell. If you are an advanced player, you can use an add on to tell you which spell your opponent is casting. If you do not know what they are casting, it makes it very difficult to know whether you should interrupt or not. If the player is casting a major move, such as a heal, lightning bolt, fear, or frost bolt, you know they most likely have the intent of completely this cast. If you see a frost mage casting Fireball, you know he is probably trying to juke you. Mastering these concepts will make you an effective Fake Caster or Fake Cast interrupter.

The Different Types of Aerospace Castings

The different types of Aerospace Castings

Cast irons are generally formed either in discrete parts using moulds or by continuous casting of a generic shape of constant cross-section. Mould casting has been successfully employed for centuries with little change in a process that involves the pouring of molten steel into a fixed shaped cavity to produce aerospace technical castings. There are six commonly used methods:

Sand castings

– as implied by the name, this process involves the use of sand as a means of handling the molten iron as it cools into a desired form. A wooden pattern is used to first define the shape in the sand, then it is removed and the cavity filled with molten iron. This is an inexpensive method for limited volume applications.

Permanent mould castings

– similar to a sand casting but done using permanent mould made from a water-cooled steel mould. This is a costly method that is best suited for high volume applications.

Die castings

– a process similar to plastic injection moulding involving the pressurized injection of molten metal into a mould. This is expensive, requiring a large number of parts to amortize the high tooling cost.

Shell castings

– this process involves first making a casing or shell of the pattern (or actual part), splitting it to remove it, reassembling the pieces and finally placing shell in sand. The sand supports the shell while the molten metal is poured into it. After cooling, the part is removed by breaking the shell to expose the completed part. This process is labour intensive but is a good one for intricate parts that are produced in low volumes.

Investment castings

– this casting process produces similar results as shell casting but is aimed at higher volumes. A mould is built to form a wax pattern which is then removed, coated with a ceramic material, heated to remove the wax, and then placed in sand. The molten metal is then poured inside, allowed to cool, and then the ceramic shell is removed. This is the method most frequently used to produce aerospace aluminium castings.

Centrifugal castings

– this process involves producing a part by using a rotating drum with the mould being the inner diameter of the drum. It is rotated while molten metal is poured inside, forming the desired part which is removed when cooled by splitting the mould. This is most commonly used to form pipes.

Continuous casting is a relatively newer process which was fully developed after the World War II. As the name states, the process involves continuously pouring molten metal from the bottom of the crucible on to a water-cooled mould, forming a skin that allows it to be further handled down the line. The process inherently produces high quality castings, because the material is drawn from the bottom of the crucible, away from the slag and other impurities that float on the surface. It is also subjected to differential cooling results which produces varied cross-sectional material properties, with the outer region generally being made up of a finer graphite structure than the core to give a combined surface hardness and overall toughness. Two forms of graphite are typically produced, flakes (present in gray iron) and nodules (present in ductile iron). The solubility limit at which these form involve many factors that are not easy or economical to control, requiring additions, known as inoculants to be added which force the graphite out of solution and make it possible to control the size and shape of the graphite particles.

The casting process requires careful consideration of three parameters of the cast part that will often determine the method of casting selected. These are part size, required tolerances and surface finish. Generally, the larger the part, the more expensive the tooling and handling equipment. Those processes which require hard tooling such as die castings or investment castings, are not used to produce large parts, while sand castings have no such limitation. The tradeoff here is the quality of the part and the surface finish. Larger parts can have internal cavities caused by shrinkage while sand castings do not have the improved surface finish afforded by hard tooled processes.

The Factors in Distance Casting

In shallow water fishing, it is vital to get the bait or lure to the fish by casting it, so it follows that the farther one can cast, the better his chances will be in catching fish. For one, his bait or lure stays longer in the water per cast, thereby improving his chances of catching fish. For another, the angler has more time to work his lure, imparting to it the necessary motion to entice the fish to strike. The motion can be varied, so the longer his cast the more motions he can impart to the lure. These and other advantages of long casts encourage anglers to try for them, so it is appropriate to learn how to achieve long casts consistently.

Distance casting is influenced by many factors, among them the rod, reel, lure, angler skill, wind conditions and line. Perhaps we should detail each factor.

Rod. The primary element is length. The longer the rod, the larger is the arc of movement in the casting stroke, and the farther the lure will fly, given the correct lure weight and appropriate casting motion.

The secondary element is rod action: the more limber rods cast lures of lighter weight. Obviously, the rod action must be paired with the right lure weight to cast correctly. This is the reason rods have recommended lure weights information.

The last element is guides: the smoother and larger diameter the guides are, the faster the line passes through them, resulting in longer casts.

Reel. For spinning reels, the opinion is that the shallower the spool, the farther cast one will make, compared to deeper spools. The principal reason is that in a deeper spool, the line path assumes a more acute angle so the friction is infinitesimally greater as the line rubs against the spool lip, somewhat slowing down the line movement.

However, because the cast is made when the spool l is full, many anglers contend spool depth is of no consequence. What matters is how slick the spool lip is, to reduce friction.

For bait casting or conventional reels, the smoothness of spool rotation is the primary factor. Next is the amount of energy required to start the spool turning, which is related to the first item. Thus the better reels incorporate ball bearings in the spool axle for smoother and longer casts.

Lure. Obviously, the heavier the lure, the farther it will cast, given the correct rod and cast stroke. Still, many lure manufacturers also consider aerodynamics, designing their lures to reduce drag while in the air for longer distance casts.

Wind factor. The stronger the wind, the slower the lure will fly through it.

Line. Smoother lines speed through the guides faster due to reduced friction. Thinner lines are lighter, more easily pulled forward by the lure. Heavier lines have greater surfaces to create friction as they go through the guides. However small, they influence casting distance.

Angler skill. Correct casting stroke and accuracy are essential to distance casting, no matter how perfect the other factors are.

So to make long distance casts, study the factors and balance them correctly. Then practice your casting continuously until you achieve what you desire. It is possible.

The Basics of Malleable Iron, Ductile Iron and Gray Iron Sand Casting Processes

Basic Iron Sand Casting Process

Sand casting is the most widely used process to form simple or complex metal parts that can be made of nearly any metal or alloy. The process is used to produce a wide variety of metal components with complex geometries. These parts can vary greatly in size and weight, ranging from a couple ounces to several tons.

Gears, pulleys, crank shafts and connecting rods are some of the smaller sand cast components. Larger applications include housings for large equipment and heavy machine bases. Sand casting is also commonly used for producing automobile components, such as engine blocks, engine manifolds, cylinder heads, and transmission cases.

The sand casting process involves just a few basic steps.
Melt scrap steel, pig iron and necessary metallurgical additives to arrive at the chemistry for either malleable iron,gray iron or ductile iron
Prepare a sand mold utilizing a permanent pattern that replicates the desired part shape
Cool the mold, break the mold open (shakeout)Clean, grind and finish the casting to final shape
Heat treat castings as necessary
Inspection
Pattern Design, Mold Preparation

Pattern design and mold preparation are critical in sand casting. A pattern is prepared to match the size and shape of the final product. Some allowances are kept to allow final machining of mating parts, shrinkage and to allow free flow of molten metal.

There are two main types of sand used for molding. “Green sand” is a mixture of silica sand, clay, moisture and other additives. The “air set” method uses dry sand bonded to materials other than clay, using fast curing adhesives. When these are used, they are collectively called “air set” sand castings to distinguish these from “green sand” castings.

Two types of molding sands that are generally preferred are, naturally bonded (bank sand) and synthetic (lake sand) due to their consistent composition. The type of sand and the molding process used limits the accuracy of castings. Sand castings made from coarse green sand impart a rough texture on the surface of the casting, and this makes them easy to identify.

Air-set molds produce castings with much smoother surfaces. Some of the components of the sand mixture are lost in the thermal casting process. Green sand can be reused after adjusting its composition to replenish the lost moisture and additives.

The pattern itself can be reused indefinitely to produce new sand molds.

Advantages of Sand Casting

The advantages of sand casting could be summarized as follows:

Low tooling cost, since low cost material such as sand, clay, wood etc are being used.
Largest casting sizes are achievable, limited by handling equipment and furnace capabilities.
Low cost process compared to others.
Castings are capable of holding detail and resist deformation when heated.
Handles a diverse product range than any other casting method.
Produces both small precision castings and heavy castings.
Can achieve very close tolerances in high quality castings.
Mold preparation time is relatively short.
Process is simple and suitable for mechanization.
Recycling of process material is possible.
Relatively less waste generation.

Die Casting Aluminum – A Closer Look at Its Finer Nuances

The introduction of die casting aluminum goes back to 1914, when aluminum was invented for the first time. Though die casting was developed way back in the 1800s, yet only alloys of various compositions of tin and lead were used. However, aluminum revolutionized the whole concept of this amazing process.

Aluminum is Ideal for Die Casting:

The reason for the growing popularity of aluminum in die casting aluminum industry is for its lightweight and anti-corrosion properties. Apart from that, this metal possesses high dimensional stability for complex shapes and thin walls. High thermal and electrical conductivity, as well as ability to withstand high temperatures have made aluminum die casting a much-preferred option these days.

Cold Chamber Machines and Aluminum Die Casting:

Usually cold chamber machines are used for die casting aluminum, aluminum come with high melting points. The process involves pouring molten metal into a ‘cold chamber,’ or cylindrical sleeve. This can be done either manually by a hand ladle or by an automatic ladle. The next step involves sealing the cold chamber port and forcing metal into the locked die at high pressures with the help of a hydraulically operated plunger.

Automated machines in Die Casting:

Die casting aluminum these days have improved a lot and manual operations have rightly replaced automated quality control. Today there are many different types of machines utilized in die casting method, which can make your work easy, save your time and increase your productivity. While some die-casters use different tools to lubricate dies, ladle metal into cold chamber machines others use them to integrate other functions like quenching and trimming castings.

Even for adjusting Casting machines and assuring steady castings there are microprocessors these days. You can obtain metal velocity, shot rod position, hydraulic pressure and other data through these machines. Finally, all these helps in proper statistical analysis in quality control.

Proper designing for quality Die Casting:

Apart from using automated machines, for getting the right Casting Aluminum products it is necessary to have a great team of designers who take proper care to collaborate with casting experts. This is an essential prerogative during the early stages of designing in order to get a quality final product eventually. This also helps in cutting down unnecessary expenditures during the tooling and the production phase in Aluminum Casting. Designing and proper planning always results in proper execution, which in turn provides products that are of quality and have longer shelf life. This applies to Zinc Casting as well.

These are the prerogatives to get the best casting aluminum products today.

The Development of China Casting Industry

Casting products occupy a large ratio in various auto parts. There are various kinds of casting products such as automotive engine block, cylinder head, gearbox housing, intake manifold, exhaust manifold, crankshaft, camshaft, piston, and wheel hub, etc. However, in comparison with developed industrial countries, China’s automotive castings products still accounted for little as to the total output. According to statistics, American auto castings account for 33% of the total production, while ours only account for less than 20%. There are many situations about this industry.

Firstly, the rapid development of auto industry drives the automotive castings industry which is one of the major downstream industries. About 10.5% parts of a vehicle are iron castings, and 6.4% are aluminum castings. These castings not only have large quantities, but also have high quality requirements. With the continuous development of China’s automobile industry, automotive castings production also increases. According to statistics, in 2009, China’s automobile production and sales volume exceeded 13.5 million, and the automotive casting production reached 10.33 million tons. It is expected that the production of them will reach 11.48 million tons if the auto output in 2010 reached 15 million.

The rapid development of the automobile industry provides a lot of opportunities for our automotive casting products. At the same time, with the requirements for lighter and energy-saving, the demands for non-ferrous castings will be further expanded. Since 2000, China has become a veritable casting manufacturing country with the largest production in the world.

Secondly, the export of these products is in the downward trend. Although China is the world’s leading casting manufacturing country, we are still far from casting power. The rapid growth of our production is at the expense of the high energy consumption, high resource consumption, and pollution of the environment, etc. In addition, compared to some other products such as stamping parts and fasteners, our automotive castings are still at a low-end level. And they can be easily affected by the market fluctuations. The financial crisis in 2008 had much impact on our casting industry. As a result, it had a sharp decline.

Thirdly, the procurement services help to improve the export of the casting products. The decline in export of the automotive castings has various causes. On one hand, the quality of our products is not high enough. On the other hand, there are too many domestic manufacturers of automotive castings so that foreign buyers can not find the satisfied suppliers. According to statistics, there are about 26,000 of foundry enterprises, most of which are low in specialization and productivity. Beside, those enterprises also lack professional management and marketing capabilities. As a result, buyers can not make the right choice.