1.1 Liquid penetrant testing
Liquid penetrant testing is used to check all openings on the surface of the casting defects, such as surface cracks, pinholes and other surface defects difficult to find the naked eye. Penetration testing is commonly used color test, which is colored with a high permeability (usually red) liquid (penetrant) soaked or sprayed in the casting surface, penetrating into the open defects inside, quickly wipe the surface of liquid penetration layer, then the display easy to dry agent (also known as imaging agents) sprayed on the surface of the casting, to be defective will be left in the open suck out the penetrant, the show was staining agent, which may reflect defects in shape, size and distribution. It should be noted that the penetration test accuracy was seized with an increase in surface roughness decreased, the more light that is detected the better the surface, the surface finish grinding the highest detection accuracy, or even detect intergranular cracks. In addition to color detection, fluorescent penetrant testing is commonly used in liquid penetrant testing method, it needs to configure the UV light irradiation observed higher detection sensitivity than color.
1.2 Eddy Current Testing
Surface eddy current inspection for the following general not more than 6 ~ 7MM deep defects. Sub-coil eddy current testing method and placed through the coil method two kinds. : When the specimen is placed in an alternating current through a coil near, the specimen into the alternating magnetic field can give birth in the sense of the specimen in the magnetic field perpendicular to the direction and motivation, and was vortex-like flow of current (eddy current), vortex will produce a magnetic field in the opposite direction with the magnetic field excitation, the coil part of the original magnetic field reduction, causing the coil impedance change. If the casting surface defects, the electrical characteristics of eddy current distortion will occur, to detect the presence of defects, the main disadvantage of eddy current testing can not detect defects in visual display size and shape, generally only determine the location and depth of surface defects which In addition it has a small opening on the surface defect detection sensitivity as penetration testing.
1.3 Magnetic Particle Testing
Magnetic particle testing for detection of surface defects and surface defects in the following few millimeters deep, it needs to DC (or AC) magnetic devices and magnetic (or magnetic liquid) in order to test operation. External magnetic device used in the casting surface magnetic field, magnetic or magnetic fluid is used to show defects. When casting a range of magnetic field, the magnetic defects within the region will produce leakage magnetic field, when sprinkled with powder or suspension, the powder was suck, so you can show a defect to. This shows that the defects are basically cross-section of magnetic field lines of the defects, parallel to the magnetic field lines for the long-type defects are not showing up, this operation requires changing the magnetization direction in order to ensure to check out the various defects in the direction of the unknown .
Thursday, 15 December 2011
Saturday, 11 December 2010
metal casting
Families most likely to work in metal casting metal in One and was the trophy. It melts at low temperatures than silver, and less expensive. Some caution: Make sure you only purchase your items free trophy. Although you can melt in your trophy stoves, metal craft is the best retention and separation of food preparation area. Use of hand-held welding torch or oil furnace. Work only in the bench or old table; liquid energy and overflow! Use a shallow baking dish filled with the sand under your mold. Ventilation and good work in a regional and do not forget your safety glasses.
As a simple example, suppose you want to cast with a large hole in a flat, star trophy piece in the middle. You will need to do two pieces of plywood and wood molds. Need to be very dry wood, so by a welding torch burning in it a little it.
Cut out a star in the shape of plywood and a run through the saw. (From the edge of plywood cut to make a straight line on the insurance switch star; it is completed after removal of the fragments would be useful.) Firmly nailed on a piece of plywood in the wood. Now you have the star pours down into the cup. Star left in the middle of a round hole to cut out the circle shape in plywood (thickness as the other segments and the first fragment). Nail it into the star shape of the center.
Melting trophy, was put it into a small, was handled tools, such as ladle. Reported in a sieve ladle cup parts. This will help prevent any large debris or only trophy then pour the liquid. Now heat welding torch in your oil furnace in the ladle or hand. When the trophy melted, carefully pour it into the mold. You may need to tilt or gently tap the mold to flow into the star's points trophy. When the star completely cooled, use a screwdriver or similar tool to pry wood plywood. Gently remove the trophy stars. That is all there is to it! In silver Casting is more challenging, but a high degree of satisfaction. Using centrifugal force, one of the most common die casting method, "lost wax" wax model by replacing the metal to melt. Buy casting equipment; you can buy pieces separately or buy starter kits.
To start carving your expectations model in wax out of fragments. Second, you will need to have a little melt injection port (as a channel in the melting period) and the end of the wax scale model attached to it. Note the entrance is now ready to board in the injection port base (for holding the flask in a stainless steel model specifically designed rubber bases). You are ready to invest Now, that is covered with a plaster statue of your small. Please be sure to protect yourself with rubber gloves and a good dust mask. Investment powder mixed with water (follow the label directions carefully.) Avoid bubble, when they can create in your finished piece of explosive boiling, and use the vacuum pump to remove all air from the investment. Pour investments into the flask, and then use the vacuum to get rid of all bubbles. Allowing investment in the future about hardening in half an hour, you can remove the rubber base. Wait before the next step at least two hours (overnight is best).
In a small kiln in the brick or screen down the flask, no conclusive end to the wax to flow. Of 1250 ° F (670 ° C) heat. When it reaches that temperature, after hours (exact time may vary), close the kiln. Prepare your casting machine according to manufacturer's directions. Placement of the hot flask into the machine with the pliers. Now heat your silver in the crucible with a red flame, increasing bit high tide, it begins to melt. Liquefaction of the metal when it is released into the investment hole. The centrifugal force created by the machine will be liquid metal into a mold of your every detail. Wait for the machine to stop, and then use pliers to remove the flask. Flask in a metal pail of water out. This will release some of the terrible smoke, so be sure to do it in a good area to be ventilated when wearing artificial respiration machine. Plaster will start to crack; with a blunt knife or similar tool to help it along like a piece of plastic exposed.
As a simple example, suppose you want to cast with a large hole in a flat, star trophy piece in the middle. You will need to do two pieces of plywood and wood molds. Need to be very dry wood, so by a welding torch burning in it a little it.
Cut out a star in the shape of plywood and a run through the saw. (From the edge of plywood cut to make a straight line on the insurance switch star; it is completed after removal of the fragments would be useful.) Firmly nailed on a piece of plywood in the wood. Now you have the star pours down into the cup. Star left in the middle of a round hole to cut out the circle shape in plywood (thickness as the other segments and the first fragment). Nail it into the star shape of the center.
Melting trophy, was put it into a small, was handled tools, such as ladle. Reported in a sieve ladle cup parts. This will help prevent any large debris or only trophy then pour the liquid. Now heat welding torch in your oil furnace in the ladle or hand. When the trophy melted, carefully pour it into the mold. You may need to tilt or gently tap the mold to flow into the star's points trophy. When the star completely cooled, use a screwdriver or similar tool to pry wood plywood. Gently remove the trophy stars. That is all there is to it! In silver Casting is more challenging, but a high degree of satisfaction. Using centrifugal force, one of the most common die casting method, "lost wax" wax model by replacing the metal to melt. Buy casting equipment; you can buy pieces separately or buy starter kits.
To start carving your expectations model in wax out of fragments. Second, you will need to have a little melt injection port (as a channel in the melting period) and the end of the wax scale model attached to it. Note the entrance is now ready to board in the injection port base (for holding the flask in a stainless steel model specifically designed rubber bases). You are ready to invest Now, that is covered with a plaster statue of your small. Please be sure to protect yourself with rubber gloves and a good dust mask. Investment powder mixed with water (follow the label directions carefully.) Avoid bubble, when they can create in your finished piece of explosive boiling, and use the vacuum pump to remove all air from the investment. Pour investments into the flask, and then use the vacuum to get rid of all bubbles. Allowing investment in the future about hardening in half an hour, you can remove the rubber base. Wait before the next step at least two hours (overnight is best).
In a small kiln in the brick or screen down the flask, no conclusive end to the wax to flow. Of 1250 ° F (670 ° C) heat. When it reaches that temperature, after hours (exact time may vary), close the kiln. Prepare your casting machine according to manufacturer's directions. Placement of the hot flask into the machine with the pliers. Now heat your silver in the crucible with a red flame, increasing bit high tide, it begins to melt. Liquefaction of the metal when it is released into the investment hole. The centrifugal force created by the machine will be liquid metal into a mold of your every detail. Wait for the machine to stop, and then use pliers to remove the flask. Flask in a metal pail of water out. This will release some of the terrible smoke, so be sure to do it in a good area to be ventilated when wearing artificial respiration machine. Plaster will start to crack; with a blunt knife or similar tool to help it along like a piece of plastic exposed.
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