Customized Knee Replacements Leaf Springs Lavender Rivets and Rivet Tools
The typical candidate for a knee replacement has osteoarthritis, where the cartilage in the knee has worn away. Knee replacement surgery restores the worn areas with an implant. To help place the implant properly, the surgeon can use an instrument custom-designed for the patient's damaged anatomy. A successful knee replacement depends on its alignment with the femur and tibia, the upper and lower leg bones that connect at the knee. That's a challenge because knee implants are standard, while every patient's bones are unique. So starting with an mri scan of the patient's knee, this medical device company produces custom-made surgical templates, plastic devices the surgeon uses to sculpt the surface the patient's bones to align the knee implant accurately. The surgeon no longer has to visually calculate the bone cuts on the spot in the operating room, which takes more time and is more invasive. An engineer uses the mri scan to create 3-d models of the patient's femur and tibia. The patient's cartilage has worn out in between these bones, causing painful rubbing that erodes the bone surface. The implant effectively replaces the damaged bone and cartilage. Once each bone model is ready, another engineer applies a 3-d model of the correct-size implant, then, following directions the surgeon has provided, performs virtual surgery on the bone model. This will properly align the implant to the patient's specific anatomy and fit it to the angle at which that particular knee moves. During the surgery simulation, the computer records every bone cut. The surgeon reviews and approves this surgical plan only once before manufacturing begins. The computer, which recorded the bone cuts, guides a 3-d printer to produce plastic templates for both the femur and tibia. The surgeon will use these to repeat the same exact cuts in real life. The 3-d printer applies a layer of powdered plastic, then following the computer model, solidifies select areas with a laser. This process keeps repeating, building up the shape of these surgical templates layer by layer. One printer run produces personalized templates for up to 50 patients at a time, so the laser inscribes the patient's name and identification code on each part. Once the printing's done, it's just a matter of breaking up the unsolidified powdered plastic... And fishing out the templates. They brush off the bulk of the remaining powder. The posts on the bottom are the points at which pins affix the template to the bone during surgery. Next, the templates go into a tumbler containing plastic balls and air jets. As the drum rotates for 20 minutes, the balls knock off and the air jets blows off most of the remaining powder. The templates exit the tumbler 90% clean. They go through two wash cycles to remove the last remnants of powder. Before packaging, they'll be sterilized. But first, every template must pass a quality-control inspection. Using a laser, a technician scans it to make sure the manufacturing process produced an exact match to the patient's bone. This model shows how the femur and tibia form the knee joint and how the surgeon secures the customized template onto each of these bones. Thanks to these devices, the surgeon doesn't have to figure out the bone cuts on the fly in the operating room. They're all pre-calculated by the computer model. This method eliminates several steps required in standard surgery. The operation takes less time and requires half as many instruments to set up and clean up. And because the surgeon no longer has to drill a hole in the bone to check the knee implant's alignment, the patient experiences less pain and bleeding and a smaller chance of developing complications. The earliest version of leaf springs were likely flexible wooden poles used in carriages in ancient rome. In the early 19th century, metal leaf springs were developed. Today the journey continues, and it's fairly smooth thanks to these suspension springs. A leaf spring is a stack of curved plates or leaves, or sometimes even just one. This spring has the flex to absorb bumps and dips in the road, but it's strong enough to provide serious support. Today these super-strong suspension springs are generally used for trucks and other heavy vehicles more than cars. Production starts with spring steel. It's an alloy that has elasticity. Big shears cut the steel to various lengths for a multi-leaf spring. It's one of the two kinds of leaf springs. Using a band saw, they cut steel for the other kind of leaf spring, known as a full taper spring. It's made of one to four leaves that are approximately the same length but various thicknesses. After cutting, they rapidly heat the ends. Computerized machinery rolls and stretches the piece to a tapered profile. This achieves the same flex effect as the progressively shorter leaves on the multi-leaf spring, but the end product will be lighter and not as stiff. Next, it's into a press that trims the stretched ends and punches holes for various components. It takes about an hour for the steel to cool down for the next operation. Meanwhile, other members of the team are hard at work on the multi-leaf spring. They feed the heated tip of the main leaf to a machine that wraps it around a die form. This creates an eye mount for attaching the spring to the vehicle. They create an eye mount on the other end, as well. Next they curl the ends of a slightly longer steel bar into a loose "c" shape. This piece will serve as an outer protective wrap for the main leaf and protect the eye mounts. Back to the taper spring, hydraulic machinery bends it to the final "z" shape so it will fit around a vehicle axle. They soak both the taper and multi-leaf springs in oil and temper them in a furnace to strengthen the steel. Then it's time for a process known as peening. Machinery clamps the steel leaf onto a carriage, which takes it through a chamber for blasting with tiny steel pellets. The blasting changes the surface tension, further strengthening the metal. A worker now assembles the multi-leaf spring. He inserts a pin through the center of the main leaf and wrap to align them. Each of the next leaves is shorter than the last. They're known as graduated leaves. It's a design that will make the spring more flexible. He transfers the stack to a hydraulic station... And inserts a different pin for more precise alignment. He activates the hydraulic mechanism, and it squeezes the leaves together. The mechanism maintains the leaves under tension as he removes the pin and now bolts them together. He pounds clips installed at specific locations on the spring to close them around the leaves. The clips tighten the stack all the way across and will stop the leaves from twisting or turning. Next, another hydraulic device applies pressure, this time to simulate the load the spring will carry. This sets the spring to a specific height and compresses it to stiffen the overall performance. The worker measures the spring to confirm that it meets the specifications. The assembled leaf springs now take a quick dip in a tank of black paint. The paint coats the leaves, clips, and fasteners to give these suspension springs a uniform finish. Painted black, they should blend in with all the other components on the vehicle's undercarriage. Now complete, these leaf springs can be depended on for support when the going gets rough. Lavandula angustifolia might sound like a name of an ancient roman emperor, but it's actually the scientific name for the lavender plant. The leaves and striking blue petals of this aromatic flowering shrub are used to make lavender essential oil, an ingredient in many health and beauty products. Lavender essential oil has antiviral, antibacterial, and anti-inflammatory properties. No wonder it's long been a natural remedy for many ailments. And with its flowery fragrance and relaxing effects, it's a common ingredient in lotions, soaps, and bath oils. Lavender is a perennial plant that begins flowering in its second year. Harvest time at this canadian farm is in july, at the peak of the first bloom. There's a second bloom afterward, but not significant enough to warrant another harvest. Weeds like to grow at the base of lavender plants, siphoning off water and important soil nutrients. So between may and september, killing those weeds is a vital daily ritual. The weeding machine lifts the lavender stems out of the way, then blasts the weeds around the base with hot steam. To determine the right time to harvest, the producer looks at the quantity of blooms and the color of the flowers. They should be purple-blue, on the verge of turning grayish-brown. The producer also crushes a few petals to see how much oil comes out. The harvester is specially designed for cutting lavender. Like a stylist cutting hair, it pulls the stem straight up, then snips near the base. The cut stems, about 15 inches long, fall onto a conveyer belt, which moves them into a tray. From there, workers manually transfer the lavender to the harvester's trailer. When the trailer is full, the harvester delivers its load to the on-site distillery. Workers load the lavender into a still, a large stainless-steel vessel typically used to produce alcoholic spirits. They compact as much lavender as possible into the still to prevent the formation of air pockets. The less air, the greater the oil yield. Once the still is stuffed to compacted capacity, they close it tightly and start up an oil-fired boiler. The boiler heats water into steam, which they then inject into the bottom of the still at very low pressure. Over the course of about 15 minutes, the steam slowly rises to the top of the still, heating the lavender along the way. They continue the steam for another half-hour or so. This bursts the glands located primarily in the petals, releasing the oil. To collect that extracted oil, they feed cold water into a coiled pipe running through the still. When the hot steam hits that cold pipe, it condenses, transforming back into water. Only now, the water contains lavender oil. They open the still's tap and let the water flow into a holding tank. On average, the proportions are one part lavender oil to 40 parts water. In the holding tank over the next hour or so, the oil naturally separates and rises to the surface. At that point, they begin pumping the water to another container, stopping at the first sign of oil. What remains in the tank is the final product-- pure lavender essential oil. The pumped-out water is a secondary product called lavender flower water. The producer sends both products to a laboratory to be filtered. Producers primarily sell lavender oil and floral water as ingredients to manufacturers of health and beauty products, but they also often design their own lines of lavender creations for pampering the body and soul. Rivets hold a lot of things together. Product fabricated with rivets include aircraft, cars, computers, and household appliances. Installed with a rivet tool, these fasteners create strong and permanent joints. Without rivets, a lot of things might fall apart. Whether the job is large or small, chances are there's a rivet for it. And using a special rivet tool, it's possible to form strong attachments quickly and easily. The two together make a perfect match. The rivet tool starts with a precast aluminum handle. A technician inserts a steel sleeve. It will serve as a chamber for hydraulic fluid. The spring for the tool's trigger is next. She screws an aluminum plate to the base to enclose the two parts and the handle. This is the pulling-head assembly. It has tiny jaws to grab the rivet stem. She lubricates it and presses it into the main bore of the rivet tool. She installs a fill screw in the top of the handle casting for top-offs of hydraulic fluid during servicing. But the initial supply of hydraulic fluid is added through the steel sleeve at the bottom. She inserts an air-piston assembly into the fluid-filled chamber. She threads a screw into the nose of the rivet tool. This keeps the internal workings in the correct position for the next step. She places the base of the tool into an air chamber, then hooks up an air hose and secures it with steel clamps. She plugs the tool into an air supply and pulls the trigger. The air puts pressure on the hydraulic fluid inside to activate the riveting mechanism. And now the test-- she places a rivet in the nose of the tool, then inserts the other end of the rivet into a hole on the test plate and presses the trigger. The tool efficiently installs the rivet in the hole. It's time to stock up on rivets. They make them from round wire. A machine cuts the wire to length and then punches it into a die twice to form a rivet stem blank. Here's the cutting and forming action in slow motion. The machine operates in a blur, producing 200 rivet stem blanks a minute. The stem blanks move between serrated rolling dies. The dies form grooves to allow the stem to be gripped by a rivet tool. They also make ridges that will serve as a breaking point during rivet installation. This is a slow-motion close-up of the serrated rolling dies in action. Here's the rivet stem before and after forming. The next machine creates the rivet body. It cuts wire to the correct length and forces it into dies. It takes five punches to transform the solid wire into a hollow rivet body. These machines can produce up to 300 parts a minute. Next, the rivet bodies go for a tumble in a cleaning solution to remove oily residue left by the forming. The rivet stems also undergo this thorough washing. The rivet bodies then travel through a furnace. The intense heat followed by a gradual cooling hardens the metal to free it from internal stresses. After zinc-plating, the rivet bodies head towards the next station. The rivet stems are also on the move. They travel through a channel that gradually widens to sort out stems that are too big or small. The undersized stems fall through at the beginning, and oversized ones fall off the end. A magnet loader collects the correctly sized stems, and rejects are discarded. The rivet stems cling to the loader, which is stopped at the moment. The rivet bodies now ride a carrousel. It pauses briefly to allow a stem to be inserted into a body. These are slow-motion shots, and back in real time. These machines work fast. They pump out millions of rivets a day. The rivets are now ready to leave this factory for another, where they could be used to make almost anything.