Pure water jet cutting is the original water cutting method. The first commercial applications were in the early to mid 1970s, and involved the cutting of corrugated cardboard. The largest uses for pure water jet cutting are disposable diapers, tissue paper, and automotive interiors. In the cases of tissue paper and disposable diapers the water jet process creates less moisture on the material than touching or breathing on it. Unplanned down time, common to other cutting processes, cost over $20,000 per hour in some diaper or tissue plants. The water jet provides the 24-hour per day, 7 day per week, 360 day per year operation required by such applications, maintenance could be scheduled into production.

In water jet cutting, the material removal process can be described as a supersonic erosion process. It is not pressure, but stream velocity that tears away microscopic pieces or grains of material. Pressure and velocity are two distinct forms of energy.

A jewel is affixed to the end of the plumbing tubing. The jewel has a tiny hole in it. The pressurized water passes through this tiny opening changing the pressure to velocity. At approximately 40,000 psi the resulting stream that passes out of the orifice is traveling at Mach 2. And at 60,000 psi the speed is over Mach 3.

Pure water jet orifice diameter ranges from 0.004 to 0.010 inch for typical cutting. When water-blasting concrete with a nozzle traversing back and forth on a tractor, a single large orifice of up to 1/10 Th of an inch is often used.

The three common types of orifice materials, sapphire, ruby, diamond, each have their own unique attributes. Sapphire is the most common orifice material used today. It is a man-made, single crystal jewel. It has a fairly good quality stream, and has a life, with good water quality, of approximately 50 to 100 cutting hours. In abrasive water jet applications the Sapphire's life is ½ that of pure water jet applications. Sapphires typically cost between $15 and $30 each.

Ruby can also be used in abrasive water jet applications. The stream characteristics are well suited for abrasive jets, but are not well suited for pure water jet cutting. The cost is approximately the same as the sapphire.

Diamond has considerably longer run life, 800 to 2,000 hours but is 10 to 20 times more costly. Diamond is especially useful where 24 hour per day operation is required. Diamonds, unlike the other orifice types, can sometimes be ultrasonically cleaned and reused. The abrasive water jet differs from the pure water jet in just a few ways. In pure water jet, the supersonic stream erodes the material.

In the abrasive water jet, the water jet stream accelerates abrasive particles and those particles, not the water, erode the material. The abrasive water jet is hundreds of times more powerful than a pure water jet. Both the water jet and the abrasive water jet have their place. Where the pure water jet cuts soft materials, the abrasive water jet cuts hard materials, such as metals, stone, composites and ceramics. Abrasive water jets using standard parameters can cut materials with hardness up to and slightly beyond aluminum oxide ceramic.

Within every abrasive water jet is a pure water jet. Abrasive is added after the pure water jet stream is created. Then the abrasive particles are accelerated, like a bullet in a rifle, down the mixing tube.

The abrasive used in abrasive water jet cutting is hard sand that is specially screened and sized. The most common abrasive is garnet. Garnet is hard, tough and inexpensive. Like the pink colored sandpaper found at the hardware store, different mesh sizes are used for different jobs:

120 Mesh - produces smooth surface
80 Mesh - most common, general purpose
50 Mesh - cuts a little faster than 80, with slightly rougher surface

The mixing tube acts like a rifle barrel to accelerate the abrasive particles. They, like the orifice, come in many different sizes and replacement life. Mixing tubes are approximately 3 inches long, ¼ inch in diameter, and have internal diameters ranging from 0.020 to 0.060 inch, with the most common being 0.040 inch.

Although the abrasive water jet machine typically is considered simple to operate and bullet proof, the mixing tube does require operator attention. A major technological advancement in water jet was the invention of truly long-life mixing tubes. Unfortunately, the longer life tubes are far more brittle than their predecessors, tungsten carbide tubes. If the cutting head comes in contact with clamps, weights, or the target material the tube may be broken. Broken tubes cannot be repaired. Today's most advanced systems incorporate collision detection to spare the mixing tube.

• Open die: In open die forging, the actual metal is place in an open area where it is compressed with a hammer and press. Metal parts forged this way may be large parts such as shafts, sleeves, and disks. Many open die forgings are actually produced on flat dies. There are different methods of using open die forging such as compression between flat dies, compression between narrow dies, roll forging, and impression die.
• Closed die: This is like or is a form of impression die forging. When using this type of forging material is deformed in a very tight cavity where there is no room for moment or escape for any type of liquid.
• Ring rolling: This type of process is controlled by a strict engineering process. Any kind of forging making equipment can be used for this process. The good points about this process are it makes rings that have strength and ductility. Plus, they are cheap to manufacture.
• Extrusion: With extrusion, the metal is placed in a container and compressed until enough pressure in the metal reaches the level where the metal is forced through an orifice and into a form where it is extruded.

• Open die: In open die forging, the metal is place in an area where a hammer or press is used to compress the metal. Metal parts forged this way may be large parts such as shafts, sleeves, and disks. Many open die forgings are actually produced on flat dies. But round swaging and V dies can also be used. There are different methods of using open die forging such as compression between flat dies, compression between narrow dies, roll forging, and impression die. When all parts have been forged in this matter, they are taken to another machine for finalization.
• Closed die: This is like or is a form of impression die forging. When using this type of forging material is deformed in a very tight cavity where there is no room for moment or escape for any type of liquid.
• Ring rolling: This type of process is controlled by a strict engineering process. Any kind of forging making equipment can be used for this process. The good points about this process are it makes rings that have strength and ductility. Plus, they are cheap to manufacture. When using the ring rolling process, a preform is heated up to a certain type of temperature that is good fro forging. It is then placed over the internal idler roll of the rolling machine. Next pressure is placed on the wall by the external roll. And this happens while the ring rotates.

• Drawing: In drawing mode the diameter of the drawing ring can be a little smaller than the outer ring. This helps to control or reduce the thickness of the wall and allows for the metal's height to be increased.
• Bending: This is a process that can actually be done at any time of the forging process, whether the process is completed or not. Bending of small parts is economical and helps to gain in productivity while producing desired parts. But bending metal that is too large will require special type of mechanical or hydraulic presses to form the bend.
• Trimming: After the metal has been formed in the die, it is taken out of the machine and placed in another machine where excess trim is removed. This may involve grinding, milling, sawing, or flame cutting to get the trim off.
• Coining: This is a type of sizing operation. It is where pressure is applied to the most critical areas of the surface of the metal to make the surface smooth or eliminate inconsistencies in the metal.
• Swaging: When using the open die process and the process has been completed, the stock or material is taken out between the flat, narrow dies. But before this happens, the hammer is rotated and strikes the surface of the metal. This ensures of a smooth surface free from cracks and other problems.

• Forgings are stronger: Forgings supply strength in the metal that is used. Parts that are made by using forging are stronger and last longer.
• Forgings are more reliable: Since metal is put under extreme heat while being forged, this makes the metal more reliable and don't require high costs in manufacturing.
• More stability: Metal made by forging handles heat better than any other factory method of producing parts. This makes it more stable as well.

• Physical function: An LED is made of a special type of semiconductor diode. It consists of a chip of semiconducting material that is doped, or made more conductive, to create two regions that are separated by a junction. There is a positive region that has many positive electronic charges, while there is a negative region that has negative electric charges. The junction works as a barrier to control the flow of both negative and positive electrical charges.
• Light emission: Because of the makeup of the p-n junction, there are negative electrons on one side of the chip, and positive electrons (also known in electronics as holes) on the other side. When current is applied to the p-n junction, the negative electrons flow to the positive side of the chip. When the negative electron meets a hole, the electron releases energy in the form of a photon (form of light).
• Uses for the diode: LEDs, because of the type of chip built inside, work like diodes and therefore require the use of DC voltage of the correct polarity. If the voltage is of the correct polarity, current flows and the LED will light. If the polarity is reversed, the diode can be damaged.

A diode is a semiconductor device. It has various amounts of semiconductor material that is doped to allow for better conductivity. An LED is a semiconductor device that when hooked to a DC circuit, will emit light. The light's color depends solely on the chemical composition of the semiconducting material used.

While most diodes emit light, if you notice many of them don't do it as effectively as they should. The semiconductor in the diode seems to absorb much of the energy giving off. But with the LED, they are constructed so the energy released is not absorbed but released outward. And because the LED is contained in a bulb, the light is concentrated in a more certain direction.

Most LEDs operate at no more than 30-60 milliwatts of power. After 1999, more sophisticated LEDs were made that were able to operate with up to one watt of power. To do this they used large semiconductor die sizes that were able to handle the larger power applied to them. As time went on, LEDs were made better so as to produce stronger and brighter light.

• Burn out: LEDs are better than regular bulbs or incandescent lamps in that they don't have a filament that burns out. Therefore they last so much longer.
• More durable: LEDs are more durable because they have plastic covers that are not that easy to break. This way they can be handled differently than as you would handle regular bulbs.
• Small: They are compact and can be put into electronic circuits. This way they can be made to work with many appliances and even used in small devices. This way engineers can design small devices without worrying about the room needed for the LED.
• Efficiency: The light that is produced by the incandescent bulb produces a lot of heat. This is actually energy that goes to waste. This is because a large amount of the energy used is not serving the purpose for what it is supposed to. With an LED, no heat is generated. This way much higher amount of electrical power is going to create light. This lowers electrical demands, thereby saving on power.
• Emitting of light: LEDs can emit light of different colors without even using a color filter. This is dependant on the semiconductor material being used.
• Vibration: LEDs cannot be affected by any type of vibration or shock. So if you were to shake radio with a digital display, you would not harm the LEDs.
• Failure rate: LEDs do eventually fail, but they do so over time and not all at once as regular bulbs do. This helps when determining when it may be time to replace them.
• Light quickly: LEDs do not take long to light. As a matter of fact they can light very quickly. A LED can achieve full brightness in about 0.01 seconds. This is so much faster than an incandescent light bulb that can light up at a speed of 0.1 seconds.

• Indicators: They can be used as indicators in electronic equipment. This way they can warn you if an appliance or piece of equipment is on or not.
• Testers: They can also be used in testers to let you know when you have hit an active circuit or not. If a circuit is active, the LED would glow.
• Light bars: Emergency vehicles like police, EMTs, and fire trucks use light bars that are made of LEDs.
• Message displays: The next time you take a bus or a train and see the digital message board, realize the lights are LEDs.
• Remote controls: LEDs are also used in most remote controls to send signals to TVs, VCRs, DVD players, and others that use remote control devices.

Science Kits: Polymer crystal science kits are available to teach children about the crystals and their absorbent qualities. When water is added to the crystals, you can watch them grow. Kits are usually available with crystals and activity guides to make learning fun. Included in science kits are activities to grow your own beans, grass, or a radish with polymer crystals and soil.

Gardening: By using crystals in flowerbeds, vegetable gardens, crop fields, houseplant containers you can reduce watering requirements. Polymer crystals also can be used with shrubs, trees and lawns. Polymer crystals speed germination and help produce healthy plants. By providing the plants with water when they need it, the plants are protected from stress. Genuine water crystals are odorless and isn't susceptible to mold, bacterial growth or fungi. Over time, the water crystals decompose into the soil. The dry water crystals can absorb up to 500 times its weight in water. The crystals turn to gel when hydrated. Water content of soil and salt content can impeded the absorbent quality. When the polymer crystals are applied at the roots of the plant or shrub, they can go for longer periods of time without direct watering or irrigation. Your soil not has increased water holding capacity. The crystals also help alleviate water runoff. As the crystals swell and shrink, the soil is improved and aerated. Polymers are sold at garden centers under the names of HydroSource or SoilMoist.

Centerpiece Decorations: Polymer water crystals make beautiful arrangements for weddings and parties. Place the crystals in the desired bowl or vase and simply add water. The crystals expand and create a sparkling, beautiful centerpiece that shimmers in the light. Crystals have the appearance of cut diamonds and make a definite statement on a table. You can also add food coloring to enhance the centerpieces.

Aroma Smelly Jelly: Polymer water crystals can also be used in a recipe to make air freshener or what is sometimes called smelly jelly. Due the jelly-like quality of the hydrated crystals, the name smelly jelly has emerged. The air fresheners provide a pleasant aroma and can make a fun activity for children. The aroma jelly can be given as gifts. After soaking the crystals in water (add food coloring if you like), place them in a decorative jar or a mason jar. Add to the rim of the lid with the middle out, with decorative lace, tulle or simply cheesecloth and fragrance oil. This inexpensive aromatherapy is a clean environmental alternative to candles.

Cooling Strip: Neck scarves filled with polymer crystals is easy to make and assemble. Cut a 4" by 44" fabric strip. Fold in half lengthwise with right sides together and stitch a ½" seam along the raw edges. Leave a 3" opening to turn the scarf. Trim corners and turn right side out and press. Leave the opening at one end and then stitch across the scarf 14 ½" from the opposite end. Hold the end open and use a teaspoon to pour the crystals into the casing. Push crystals to the far end of the casing. Sew the end closed. Soak the scarf in cold or ice water for 15 to 30 minutes. After soaking, distribute the gel along the casing. Tie around your neck and enjoy the cool provided by the crystals while you work or exercise. These scarves are often made for U.S. troops who are serving in the desert conditions in the Middle East. Cooling scarves are also great sellers in craft fairs. If you wish to make scarves to sell, make sure you package them with directions for wear and washing. To wash, use a few drops of liquid detergent. Rinse and hang to dry. Don't machine wash or put in a dryer.