Clay Pitted Prunes Spurs Polyurethane Tires
The origin of so many useful things is muddy-- from bricks to tiles to dinnerware. Even the kitchen sink can be made from clay. Clay is a component of soil that, when wet, has a certain plasticity that allows it to be shaped into hundreds of things. There are many shades of clay. The whitest is the purest and used to manufacture things like dinnerware, sinks, and tiles. Clay isn't just dirt. It's one of the most valuable resources on earth. To find it, they excavate topsoil and gravel at this site in kentucky. They dig down as far as 80 feet. The deeper they go, the whiter the clay. A loader transfers it to a truck for transport. Fresh from the earth, the moisture content of the clay is between 15% and 22%. The particles of clay clump together, but the clumps can be easily broken up. The clay will now be processed to a workable form. It's a short drive from the clay pit to the factory. They unload it in a building without walls so it will air dry a bit. They do a visual inspection of the color and consistency. Every few loads, they also do a chemical analysis of the mineral content. This allows them to categorize the clay for specific purposes and for blending in different clay recipes. Next, they transfer the clay to a revolving tub. The tub has knives that protrude up into it. As it spins, the knives hit the lumps of clay to chop them into smaller pieces. These smaller clay chunks flow out of the chopper and ride a conveyor into a hopper. The hopper feeds the clay to a mill. En route to the mill, the clay travels through fire-- a flame generated by a furnace below. This is called flash drying, and it brings the moisture content down to 1% to 2%-- the right consistency to now grind it into a fine powder. The grinding mill is a shaft with numerous hammers sandwiched between steel plates. As the shaft turns, the hammers will swing to grind the clay lumps into a powder. The mill will also blend different kinds of clay to create specific products. They put the cover on the mill and set it in motion. The hammers pulverize the different clays into a powder. Overhead, a machine sucks up the ground clay, using spinning blades and a vacuum. The cyclone effect lifts up the clay particles and leaves heavier impurities like sand behind. The result is a purer clay blend. Here are various clays now dried, pulverized, and purified. They run numerous tests on clay. For this one, the technician presses the clay powder into a cake-like disc, using a hydraulic press. At the same time, he weighs the clay. Weight can indicate the clay's pliability and the speed at which it can be cast. He fires the clay disc in an oven overnight and examines the color to confirm that it's the desired hue. Over at the packaging station, a worker hangs open bags on spouts, which will fill the bags full of dry powdered clay. The customer will add water and other ingredients to turn this particular blend into a glaze for things like tiles and sinks. In powdered form, the clay is lighter and cheaper to ship. Some customers prefer wet-processed clay, even though it's heavier. For that, they add water and chemicals to make a slurry. They pump the slurry through a sieve to screen out impurities. The clay slurry now flows into big mixing tanks, where it remains in a constant state of agitation. Continuous mixing keeps it fluid. Without it, the clay would thicken to the consistency of peanut butter. On delivery day, they pump it into tanker trucks. At another factory, this particular batch will be used to make sinks or tubs. The next trucks will likely be headed somewhere else. You never know what will be made from this product of the earth. Among dried fruits, none inspires a gut reaction like prunes. Eating them is one way to kick-start a lethargic gastrointestinal system. High in fiber, sweet and chewy, prunes are actually dried plums, and they're a delicacy that's as old as civilization itself. Prunes have been found in ancient egyptian tombs, placed there to snack on during the journey to the next world. Fast-forward to today, and people are still snacking on prunes. They also add them to salads, muffins, and main-course recipes. It all starts with the growing stock. Not all varieties of plums are suitable for drying. At this california orchard, they grow the d'agen plum--  a european variety. Harvesting machines shake the trees by the trunks, and the fruit rains down onto a conveyor, which delivers it to bins. They then truck the plums to the receiving plant... And unload them directly into a washing system. Tree leaves float to the surface of the water to be removed. The plums exit onto a table that vibrates to distribute them evenly so they land on trays in fairly equal amounts. A paddle overhead levels them on the trays. Machinery stacks the trays of plums on racks. The plums are now ready to dry. They're about 80% water when they enter the dryer. 16 hours of heat exposure brings the moisture content down to 19%. Plums were once sun-dried as a means of preservation, but a modern industrial dryer produces more uniform results. The dried plums travel under a vacuum that sucks out sticks or stems. Then the prunes travel to a shaking conveyor with a lot of different-sized holes. The first holes are the smallest, and they become progressively larger to sort the prunes by size. They fall into separate bins below. The smallest fruit will be used for breakfast or diced product. The largest prunes will end up as snack food. Preserved by drying and now sorted, they can be stored for months until processing. At the processing plant, the prunes head into a super-sized steam cooker. They spend 18 minutes in there. The steam cooking partially rehydrates them, softening the prunes so the pits can be removed more easily. They must now remove the pits before the prunes start to lose moisture and become too dry for the job to be done efficiently. The prunes speed towards the pitting operation and flow into five lanes. Each one leads to a separate pitting line. With five different pitting lines, they'll process hundreds of prunes a minute. Clamps close around the prunes, securing them for knives to push out the pits. The pits will be ground up and added to animal feed. The pitted prunes make a soft landing on a rubber conveyor, which takes them into a laser-detection center. The laser finds pits or pit fragments and relays the information to a computer. The computer activates air jets that blast out the unwanted material. It happens so fast, it's all a blur. On another shaker conveyor now, the prunes bounce towards a big drum. The drum revolves slowly to gently toss the prunes as they pump in a preservative, flavorings, and oil. The prunes absorb the ingredients as they tumble around in the drum. At this point, they sample the moisture content of the prunes every 15 minutes. The technician grinds and compresses some prunes into a disc. She drives an electrode into it to gauge the moisture. It should be between 28% and 32%-- enough to improve the texture, but a lot less than fresh fruit. It's time to wrap things up. Sectioning arms open the bags. Feeders dispense a precise amount of pitted prunes into them. A heated device then melts the ends of the plastic bags together to seal them. They produce 120 bags of prunes a minute at this factory, so adding fiber to one's diet shouldn't be a problem. If you ride horses regularly, chances are you own a pair of spurs. Spurs strap onto the heels of riding boots. Each spur has a small wheel, usually spiked, with which the rider prods the horse to get it to start moving or move faster. The anatomy of a spur is elementary. The wheel, called the rawl, is mounted in the shank. The shank is connected to the heel band. The heel band is held to the boot by a leather strap. The metal parts are made from a strong, yet flexible, type of steel. A computer-guided laser cuts the starting shape for the heel bands. A quick strike of a press stamps them with the company name. Next, workers smooth and bevel the edges, using a sander outfitted with a special belt for grinding metal. Next, they hammer the piece around a steel block, cushioning the blows with a piece of wood to avoid marring the surface. The block is shaped exactly like the heel of the boots for which the spurs have been ordered, ensuring a custom fit. They heat evenly with a torch. This relaxes the steel around the block so that the heel band permanently registers this shape. Then, some final taps to lay the band completely flat against the block. This perfects the shape. They submerge the heel band in cool water. This tempers the flexible steel, rendering it hard and stiff. Then, with a fine-grit belt, they sand away any surface imperfections. A pair of spurs is made up of some two dozen steel pieces, all of which go through the same prep as the heel band. Once all the parts are ready, workers precision weld the shank to the mid-point of the heel band. Next, to each side of the heel band, they weld a pin, which holds a pivoting arm. These swingarms, as they're called, hold the leather strap that retains the spur to the boot. To make the rawls, they trace a template on steel, then cut along the lines with a metal band saw. If the rawl shape is elaborate, a computer-guided laser cuts them out. After sanding the rawl thoroughly to smooth sharp edges which could cut the horse, they mount it to the shank with a stainless-steel pin. Then they weld the back of the pin. Now the artistry begins. A craftsman creates decorative overlays in sterling silver. He cuts their shapes with a jeweler's saw, draws a design, then, using an array of engraving tools, meticulously carves it out. He cleans the back of the overlays with flux-- an acidic chemical--  then coats them with solder. The trick is to apply just enough to bond the silver to the steel. Too much would overflow and ruin the front. By the time he gently applies each overlay to the spur, the solder has cooled and solidified, so he warms the steel with a torch from underneath. This reheats and liquefies the solder, which then cools and resolidifies, bonding the silver to the steel. The heat causes some discoloration, which he easily removes with a bit of flux. Once all the silver overlays are soldered to the spur, workers polish them on a cloth buffing wheel. The finishing touch-- they submerge the spurs in a tank containing a chemical solution called gun bluing. It turns the shiny steel parts black. To produce an antique brown, rather than black finish, workers heat the spurs in an oven, then apply a chemical which tints the steel. Now for the leather straps. An artisan tools the leather entirely by hand, dyes it, attaches a stainless-steel buckle, then sews tabs on both ends that hook to the swingarms on the heel band. This shiny set of spurs is ready for some horsing around. Many low-speed vehicles have tires made of polyurethane foam, rather than air-filled rubber tires. Polyurethane doesn't deteriorate in sunlight, nor does it dry out over time. And if the tire is made entirely of the closed-cell type of foam, the tire won't go flat. Polyurethane tires are designed for low-speed vehicles, such as baggage carts and ride-on lawn mowers. This particular type of polyurethane foam has a closed-cell structure, which prevents a flat, even if the tire gets punctured. Millions of air bubbles encapsulated within the foam give it the required bounce factor. The first step is to take an aluminum model of the tire and make a production mold with it. This one's for a forklift. The mold will have two halves--  each one lined with a tread ring to prevent the cast tire from getting stuck in the cavity. To make each half of the mold, they center the model in a base, then fill the space around it with polyurethane elastomer, which is a solid type of polyurethane, as opposed to the foam type they use to cast the tires. They stir gently to move air bubbles to the top... Then heat those bubbles with a small propane torch to burst them. With the help of a heated table to speed things along, the material solidifies in approximately 15 minutes, at which point, they extract the half-mold... And, with the utility knife, trim its rough edges both inside and out. Then they mate the two halves, and the production mold is ready. Whereas most companies buy foam mixtures ready-made, this one blends its own, in order to have strict control over the formulation. Technicians weigh out the chemical ingredients manually with a high-precision industrial scale that's accurate to within 1 1/2 ounces. A propeller-shaped blade mixes the ingredients for half an hour, moving everything from top to bottom more than 300 times and drawing it out of the corners of the container. This ensures the mixture is evenly blended throughout. Before using this foam to cast the tires, a quality-control test. They take a sample from the batch and let it rise and set, which takes about a minute. Then they cut a piece of a specific size, weigh it, and calculate the density. If the sample meets specifications, the batch is a go. Just before filling the two halves of the mold with polyurethane foam, they lubricate the cavity with a release agent. This prevents the tire from sticking to the mold when they extract it. A press keeps the mold closed and in place on the filling machine. The machine spins the mold while the foam flows into the cavity through a hole at the top. The spinning creates centrifugal force that distributes the foam into every nook and cranny. In less than a minute, the foam, although not yet fully cured, is solid enough to be extracted. They open the mold, remove the tread ring, then dislodge the cast tire with a short blast of an air gun. They trim the excess foam from the center. It can be ground up to make other products, such as floor mats. Here's what the tire looks like before... And after trimming. The polyurethane foam takes 24 more hours to fully cure, then the tires are ready to roll. This company sells tires with and without painted steel rims. Rim installation is simple. They place the rim on a base, followed by a mounting cone, then the tire. A press snaps the center of the tire over the edge of the rim. Besides making the tire flat-resistant, the closed-cell structure of this polyurethane foam doesn't absorb water, meaning wet conditions don't hamper performance. The tire is also u.v. resistant and withstands high abrasion, so it typically lasts two to three times longer than an air-filled tire used on the same vehicle.