Metal Casting Zone Info Blog

Posts Tagged ‘Techniques’

Metal fabrication refers to the process of constructing metal by changing the standard raw metal materials with the use of specialized tools and equipment. Metal fabrication techniques, depending on the temperature at which the metal is processed, can be either be cold, hot or warm.

Examples of metal-fabricated products are everywhere. In fact, many of the common objects that we see and use in the house or office such as paper clips, nails and bolts are made using metal fabrication processes. Machines, automobiles, computers, heavy equipment, structural frames, hand railing and stairs of buildings are also constructed through metal fabrication.

Metal fabrication techniques are different from other metal methods such as, for instance, casting where you need to use some kind of mold to create the structure. In the case of fabrication, you utilize hand tools or machinery and a little elbow grease to come up with the desired output.

There are various techniques in fabricating metal components. One of them is metal forming. It is said to the oldest form of metal fabrication. Ancient civilization used the art of metal forming to create armaments. By just utilizing simple tools such as wooden mallet and metal hammer, Greek and Roman craftsmen were able to produce helmets and cuirrasses. The category of metal forming consists of forging, rolling, extrusion, drawing, deep drawing, bending, spinning, and many others.

Another metal fabrication process is called machining or material removal, which involves the use of a cutting tool to remove unwanted metal materials from a workpiece to come up with the desired shape. This is an application that is designed to perfect metal surfaces, ranging from abrasive techniques to precise spot removal methods for parts as small as jewelry.

Common metal removal processes include sawing, tapping, broaching, boring, turning, drilling, milling and grinding. All of them are a common part of most manufacturing processes.

With the advent of modern technology, advanced metal fabrication techniques have also been invented to make the job easier and reduce production time. Nowadays, laser cutting, electro discharge machining, wire electro discharge machining and waterjet cutting are becoming more and more popular among metal fabricators and hobbyists.

The most fundamental of all definitions to ceramic casting is: It is a process used in order to shape ceramics. It is known in many companies like those for tableware and teapots. Even computer parts, heat engine sections and recuperators find this process very helpful. The development is also very essential to a lot of technological areas.

Ceramic casting utilizes a wide range of materials like stainless steel, bronze, cutting tools and plastic casts to form impellers. Other items appropriate in the process are epoxy, silica, metal, water, zirconia and even wood. In order to make the process enhanced, surface quality, uniformity and density should be attained. Know more about the different techniques to make the method more functional to some industries.

Methods behind ceramic casting

Two of the most popular methods in ceramic creation are slip casting and ceramic shell casting.

First method – slip casting. This is a technique making use of slip and liquid clay. It is being poured into a cast created from plaster of Paris. Traditionally, it utilizes a potter’s wheel cast. The wheel is very vital in making symmetrical alterations to any part. This is said to use pure ceramic powder thus causing this ceramic casting method the most popular among other techniques. In fact, you no longer have to spend on chemical additions just to perform and complete the process.

2nd method termed as ceramic shell casting. This ceramic casting skill is popular in the development of metal pieces. The net casting method is performed with a mixture of refractory items, silica and zirconia. Subcategories for this skill are wet dripping and dry coating. The method results to dimensional steadiness for aerospace and liquefied metal casting companies. With the automation procedure, other objects such as wax patterns, slurry mixers and powder beds are employed for dipping.

Apart from these two techniques, there are other ceramic casting skills. Several of those included in the list are coil creation and soft and hard slabs. Threading procedures are utilized in accomplishing these skills. Threading is a ceramic casting process that utilizes animal and artificial wool fibers to make several layers out of an existing object.

What really happens here that a rubber mold the size of a disc is spun around its central axis at very high speeds. The casting material is most often thermoset plastic which is in liquid form or its molten metal. This liquid material is poured into the mold through its opening which is in the center of the mold. So in order for solidification of the metal or the setting of the plastic as it’s called the filled mold is spun. This is essentially the spin casting process in short.

Usually the mold making substrate in spin casting is organic rubber or its vulcanized silicone. The rubber vulcanizes usually in the middle of the mold making process. Once the vulcanization process has been completed the venting and the gating process must be undertaken by the mold. This requires that the channels be carved in so in order to ensure the proper flow of material and air during the process of casting. The above two processes is carried out with the help of a tool such as a knife or a scalpel. The complexity of the mold is proportional to the time it takes to implement the gating and venting of the mold.

Spin casting machines

There are two types of commercial spin casting machines. Once type is known as a front loading machine and the second is a top loading machine. Now because of the bulkiness and the weight of these spin casting molds there are several advantages to using a front loading machine. The biggest of all advantages is its easy to use and a big time saver. As the diameter of the rubber mold grows so does its weight and when metal is cast it can become extremely heavy. Now because the loading and the unloading of is usually done the hand, people find it easier to manipulate the mold when it’s at waist level which is usually one in one swift fluid motion which is allowed by the front loading spin caster. When it comes to spin casting for commercial requirements this type of behavior is very important as it will maximize the number of casts per hour, hence making it more productive. Also top loading machines are cheaper and don’t have much of a restriction on mold thickness. This means that they are flexible.

What is Spin Casting good for?

Spin casting is a great method if you want to fabricate items with materials that are either thermoset plastics or low temperature metals. Spin casting has many advantages over other process such as Zinc die casting, and injecting molding in terms of costs as well as ease of use. There are cases in which spin casting is used as an alternative to plaster mold casting, sand casting and investment casting.

Silver is extremely malleable and ductile and as such, it is highly preferred by silversmiths for making silverware and silver jewelery. Silver craft takes years to learn as an apprentice to a silversmith, or in some college or university offering such courses. Perfection comes only with practice. However, the basic techniques can be learned by anyone who has patience, and the right tools!

Piercing: Silver is cut to form a basic shape or to make a decorative pattern with a piercing saw. When creating a pattern, a small hole is drilled in the silver sheet to allow the blade of the saw to be positioned. The blade is then attached to the piercing saw, under tension. Blades can be coarse allowing fast cutting or very fine for detailed work. The blades are delicate and can be easily snapped. As such, work must be done slowly. The blade is held vertically and metal is moved slowly to make curves or corners. Blades are also lubricated by passing them through beeswax, which makes cutting smoother. The work is supported on a bench peg which is screwed to a workbench having a V cut into it so that both the sides of the cut are supported. Small shavings of metal called lemel are collected from under the piercing onto a leather or paper cloth, which are then recycled into new silver.

Soldering: Pieces of silver are joined by soldering. Silver solder, that comes in various alloy mixes but mainly containing silver, is used for soldering. Silver solder melts at a very high temperature and so a blow torch is used. The temperature required to melt silver solder is very close to the temperature at which the piece being worked upon would itself melt. To manage the temperatures, soldering and other torch work is usually done in darkness so that the color of the metal, as it heats, can be used to measure the temperature of the piece. Silver solder come in soft, medium and hard versions having lower, higher and highest melting points. Pieces where multiple soldering is required use hard solder at first, and work down the grades with subsequent soldering so that each addition does not melt or distort the previous one. Lead solder should never be used as its high temperatures cause the solder to run all over the silver, damaging and making it useless.

Annealing: The more a piece is worked, the harder and more brittle it becomes. Repeated annealing keeps silver soft, malleable and easier to work with. It is done with a torch in darkness. Silver is heated until it gives soft pinkish red glow, which is the point just before melting. The piece is then immediately cooled in cold water, which freezes the molecules into the alignment they were in when almost molten, and thus makes it easier to work. However, working with a torch leaves fire stain on silver which is removed by pickling.

Pickling: Fire stained silver piece is placed in acid bath, mostly sulphuric acid, to remove any oxidization before working on it. Pickling salts are used for works done on smaller scale. The pickling solution is kept warm to speed the process. The piece is then rinsed in running water, and cleaned with pumice powder to remove any remaining traces.

Shaping: The work is shaped into finished form in many ways, depending on the desired shape. Tubular shapes like rings and bangles are formed on mandrels that are held in a vice, while the annealed metal is hammered with a mallet of wood or hide. Bowls and other such curved pieces are domed on leather sandbags, wooden or metal doming blocks, using wooden or shaped metal hammers.

Polishing: Polishing is a long process, where a piece is rubbed with progressively finer wet and dry papers to remove any tool marks. It can then be wheel polished, polished with a fine polishing mop on a pendant drill, or barrel polished, where it is soaked in a soap solution with steel shot and rotated for 10 minutes or so. Polishing makes the piece smooth and shiny, free of all marks.

These were the basic techniques of silver craft. Silversmith, however, adopt many other advanced techniques also like hand fabrication, lost wax casting, die striking, and electroforming etc. For beginners, initially its better to work in a base metal such as brass or copper, as they are much cheaper metals to allow for mistakes.