The idea behind solid material is to use metals which cannot be punched out of sheets but are still cheap to produce. These cut gasket generally have a much higher level of quality control than graphite sheet and generally can withstand much higher temperatures and pressures. The key downside is that a solid metal must be greatly compressed in order to become flush with the flange head and prevent leakage. The material choice is more difficult; because metals are primarily used, process contamination and oxidation are risks. An additional downside is that the metal used must be softer than the flange – in order to ensure that the flange does not warp and thereby prevent sealing with future cut gasket. Even so, these gaskets have found a place in industry, although not a large one.
2010-01-19
2010-01-04
What are Cooker Hoods?
The kitchen is often the focal point of the modern home. An essential part of an attractive and functional kitchen is the range hood or cooker hood. A cooker hood is installed above the stove to collect and vent smoke or other fumes and odors from the air above the cooking surface. Cooker hoods come with many options, such as varied types of lighting, fans, and filters.
For ideal efficiency, a cooker hood needs to be at least as wide as the stove it covers. Since the idea is to remove smoky air, it also needs to be equipped with a good exhaust system gasket. This is the most important part to consider. Cooker hoods with a good exhaust system gasket quickly draw smoke and vapors up from the cooking surface and out of the house through ductwork. Some prefer to forego the hassle of ductwork and opt instead for a recirculating exhaust.
Instead of venting smoky air outdoors, these cooker hoods recirculate the air through a filter which removes impurities and deposits the air back into the kitchen. These filters must be cleaned or replaced periodically. Many home improvement experts advise against installing recirculating cooker hoods, for the reason that no filter is quite as effective as removing the smoky air from the house altogether, and many are quite ineffective. Filters are also present in cooker hoods which vent the smoke outdoors. These are needed to keep airborne grease from collecting in the ductwork and becoming a fire hazard.
The efficiency of an exhaust fan depends on how it is designed. An axial exhaust fan is shaped somewhat like a ceiling fan. It is less expensive than a centrifugal fan, which is more barrel-shaped. Centrifugal fans move more air and are quieter in operation than axial fans. Some higher-end cooker hoods include timers to shut off the fan after a specific amount of time has passed.
Lighting is included in most cooker hoods, in the form of one or two incandescent or halogen bulbs. This type of feature adds another light source to a kitchen and can make it easier to see the food under the shadow of the hood itself. Often there are adjustable settings to brighten or dim the lighting, such as for use as a kitchen night-light.
Counter space is at a premium in any kitchen, leading some to install a microwave above the stove, equipped with a small exhaust system gasket on the bottom. What is gained in counter space, though, is lost in smoke-capturing ability. No microwave-mounted fan will remove smoke and steam as well as even a rudimentary cooker hood, but the convenience and space savings make it worth the trade-off in some cases.
2009-12-31
Split Mechanical Seal
A Split Mechanical Seal Packing is used to seal rotating equipment such as pumps, mixers, agitators, stern tubes, and reactors. It is designed with a split rotating and split non-rotating lapped ring which combine to form the primary seal. These rings or Seal Packing faces are sealed to the drive element and gland element via split secondary seals. These secondary seals may be molded for easy installation or vulcanized in place for custom seal designs. A series of springs are used to load the Seal Packing faces to prevent leakage from the primary seal. The splits may be machined to a polished finish to form a seal or may be sealed by a gasket.
The Split Mechanical Seal is often mounted in place of mechanical Seal Packing or a conventional shaft seal because the equipment remains assembled while the seal is mounted.
It is primarily used to seal non-volatile fluids but can be used to Seal Packing aggressive fluids in top entry vessels via the use of a gas blanket.
2009-12-27
Daytona Engine Failures
Another Daytona 500 watched from a hotel bar, thanks to the long standing tradition of the American Association for the Advancement of Science to schedule their meeting opposite the Daytona 500. I would have loved to have seen the race in person, but between TrackPass and television coverage, I’ll be skipping out of sessions long enough to keep enough track of what’s happening.
Daytona and Talladega are such fast tracks that NASCAR has to limit speeds. Restrictor plates reduce the amount of air that can flow into the engine. The chemical reactions that are combustion are annoyingly picky. For example, two octane molecules require exactly 25 oxygen molecules to undergo combustion. The oxygen molecules come from the air, so how much air gets into the engine determines how much gasoline can be let into the engine and that determines how much power the engine produces. The restrictor plates lower engine horsepower at Daytona and ‘Dega from 850 hp to about 460 hp. I remain amused by the fact that the pace car actually has a more powerful engine than the cars it will lead around the track under caution.
The inherent tug-of-war at Daytona is between the force the engine exerts to make the car move forward and the opposing forces of friction and air resistance. Having even a few extra horsepower can make a big difference in how you race, which is why we’re hearing complaints from the Chevy, Dodge and Ford camps about recent chassis dyno results showing Toyota has anywhere from a 15-30 peak hp advantage. More about what those numbers actually mean in a later post.
We heard a lot about engines this week for another reason, which is that a number of Chevy and Toyota teams either had engines expire or opted to change engines just before the Gatorade Dual 150s. While there is still some speculation about whether the Toyotas and the Chevys are suffering from the same problem, there has been a lot of talk about lifter and cam coatings, so I asked a few questions of my engine consultant, Dr. Andy Randolph of Bill Davis Racing, while I was at Daytona earlier this week.
A sociological note: Engine builders are interesting NASCAR archetypes. I found that vehicle dynamicists often will answer a question, and then ask me not to use, for example, specific spring rates they mentioned. The engine culture is different. You can tell you’re onto something interesting when they a) get sly little grins on their faces and clam up or b) yell loudly at you to stop looking under the hood of their car. Luckily for me, Andy is in the former category. Between the information from Andy and a search of Google patents, I think I can shed a little light on the problems teams have been having this week with engines.
Engines are full of parts that move against each other at high temperature and/or high pressure. The ideal material for such parts would be lightweight, strong and hard. This ideal material, unfortunately, doesn’t exist. This is one of those compromise issues, just like the trade-off between brittleness and strength in chassis steel.
The camshaft has egg-shaped lobes on which the lifters ride. The lifters lift the pushrods and the pushrods activate the rocker arms that open the valves. The cams and the lifters are in constant moving contact. Restrictor plate engines run at about 8000 rpms at Daytona pretty much continuously during green flag racing. Any time two pieces rub against each other, friction between the parts produces heat and wear. Wear removes atoms from one part due to rubbing by the other part. Wear is a great thing if you’re trying to sand a piece of wood; however, wear is a major problem for engines.
Cams and lifters usually are made of tool steel, a fairly hard material that doesn’t expand much when it gets hot. But tool steel isn’t durable enough for a NASCAR engine. If you run two pieces of tool steel against each other at the temperatures and pressure found in a high-performance engine, you’ll end up with either much smaller pieces, or the two pieces will cold weld and you’ll have a single stationary piece of steel where the two moving pieces used to be.
There are materials harder than tool steel; however, making parts from these materials presents its own challenges. First, ‘exotic’ materials like these tend to also be expensive. Second, what kind of tool do you use to cut something that’s really hard? It’s like the ancient quest for the alkahest. What would you store it in if you found it?
Tungsten carbide tooling often is made by combining very small pieces of tungsten carbide powder with cobalt powder. The mixture is pressed into the desired shape at very high temperature and pressure. This works well for tungsten carbide, but tungsten carbide isn’t as hard as diamond and, unfortunately, the heating/pressing process doesn’t work very well with diamond. So how might you be able to take advantage of the low cost and pretty respectable properties of tool steel, while giving your parts the extra hardness a material like diamond would provide?
The answer is to coat the part made from the base metal with a thin, but effective, layer of the material with the desired properties. Vermeil, for example, is sterling silver coated with a thin layer of gold. The outside of a piece of jewelry, for example, looks like gold, but its cost reflects the silver interior. Gold-colored drill bits are usually tungsten carbide coated with titanium nitride, another wear-resistant material.
Diamond, which is a form of carbon, is very hard. Graphite Sheet, which is used as a lubricant, is also made of carbon atoms. Why is one very hard and the other very soft? The answer lies in their crystal structure. In graphite, the carbon atoms are arranged into sheets of hexagons, with a carbon atom at the vertex of each hexagon. I’ve shown one such Graphite sheet in the diagram below.
If you lifted that sheet, you’d find similar sheets below it. The carbon atoms make four bonds. Each carbon atom in Graphite Sheet has three bonds within the plane and one bond between its plane and the plane above or below it. The weak interplanar bonds are pretty easy to break. A graphite Sheet pencil writes because the shearing action of the pencil scrapes off layers of carbon atoms onto the paper.
Diamond, on the other hand, has carbon atoms connected by four covalent bonds of equal strength, each pointing in different directions, as shown in the diagram below. This type of bonding makes diamond incredibly hard, even though it is made of the same carbon atoms as graphite Sheet . Natural diamond is mostly found in the cubic crystal structure I drew above, but there also is a much less common hexagonal crystal structure called lonsdaleite. Both have sp3 bonding.
Diamond-like carbon is an amorphous material, which means that it doesn’t have a regular crystalline structure. Amorphous and crystalline can be compared using an analogy of the seating of graduates and guests at commencement. The graduates are ushered in by the marshals and every seat is filled. The seating is highly ordered. The families, on the other hand, sit where they want and fill seats in a random way. There are regions where all seats are filled; however, there are also empty seats. The long-range order of the seated graduates is not there. DLC is the same way: There are some locally ordered regions, but there is no long-range order.
There are a number of different forms of DLC, but all share the property of being amorphous and having significant amounts of the sp3 bonding that gives diamond its hardness. There is only one type of DLC that is all sp3 bonding, which is a tetrahedral hydrogen-free amorphous carbon. Most other forms have either a mix of graphitic and diamond bonding, while others include hydrogen and/or other metals. These variations aren’t as strong as ‘pure’ DLC’, but they can have other advantages that can compensate for slight decreases in hardness. DLC coatings are also used on hard disk read heads to protect them in case of head crashes.
Wear is characterized by the wear factor, which is measured by scraping a piece of the material and seeing how much comes off. DLC has a wear factor about 300 times less than steel and about 10 times less than titanium nitride, which means that the DLC film will last much longer than a titanium-nitride-coated or an uncoated part.
In addition to being hard, DLC coatings also significantly reduce friction between the moving parts. The coefficient of friction characterizes the interaction between two materials. The larger the coefficient of friction, the harder it is to slide the two past each other. Steel on steel has a coefficient of friction of 0.7. Titanium nitride on steel has a coefficient of friction of 0.3 and DLC has a coefficient of friction of 0.2 with steel. Nanocomposite coatings can have coefficients of friction with steel as low as 0.1. There is a lot of interest in these coatings from the perspective of energy savings, since friction losses in the engine account for 15-20% of the energy expenditures in commercial cars.
DLC films are grown using processes such as PVD or PACVD. These techniques avoid forming the longer sp2 bond by sending carbon atoms really quickly at the part to be coated. The speed of the deposition process forces the atoms to bond in ways they wouldn’t bond if given time to do otherwise. Growing good DLC films is part science and part art. The type of DLC used on most engine parts for motorsports is a form that has a fair amount of hydrogen, which means that there is a combination of sp2 and sp3 bonding.
It’s not as easy as grabbing a camshaft and some lifters off the shelf, sticking them in a high-vacuum chamber and tossing carbon atoms at them. At the high temperatures encountered in an engine, carbon atoms from the DLC coating can migrate into the steel and form iron carbides like Fe3C. Cementite is extremely brittle and that compromises the durability of the coating, so you can’t coat steels directly with DLC. One solution is to coat the tool steel with an intermediate material that serves as a diffusion barrier, meaning that it prevents carbon atoms from getting into the tool steel. Amorphous silicon oxide is an ideal material for this role because it provides good high-temperature stability.
Another problem with coating is the internal stress of the coating. If you look at a DLC coating at very high magnification, you find that the surface of a DLC film resembles cobblestones, with each stone having a diameter of a few micrometers. This randomness introduces large internal stress, making the film behave like a piece of paper that’s been stored rolled up. If you try to make the paper lie flat, it doesn’t want to: It wants to curl up. The internal stress makes the coating harder, but it also makes the coating want to pop off the surface it is supposed to be covering.
The coatings used on camshafts and lifters are thus multilayered coatings. On top of the amorphous Si:O diffusion barrier, for example, you might use titanium nitride to help with adhesion, or just to have something hard underneath in case there was a breach, as has been done for piston skirt coating applications. A DLC coating follows as the top coat, to provide hardness and decrease the friction.
It doesn’t take much of a coating to improve the part’s hardness. Coatings usually are on the order of a few to tens of microns. For comparison, a typical human hair is about 70 microns in diameter. The parts have to be polished extremely well – if the surface roughness is greater than the coating thickness, some of the part won’t have any coating on it. The thickness of the coating applied is determined by how much is likely to be worn through during the lifetime of the part and how well you can get the DLC coating to stick.
The reports I’ve heard say that some of the coatings on the cams and/or lifters were flaking off. Remember that the whole point of these coatings is that they are hard. Small pieces of them are still very hard and small pieces of very hard material falling into the engine spells disaster. It’s a potentially catastrophic enough effect that a number of teams changed engines rather than take a chance. It looks now as though the problem was a single or a limited number of batches of parts, so it’s not something systemic that is likely to be a recurring problem. The coating process is so complex and dependent on precise processing conditions that if even one thing in the complex process isn’t exactly correct, the coatings won’t adhere. I’m sure there are materials engineers working overtime with lifters from the same batch trying to identify where the problem was.
Thanks to Dr. Randolph for pointing me in the right direction, and congrats to him and the No 22 team on running in the top 10 toward the end of the Daytona 500. At least, that was until the No. 22 was punted by the No. 29. Kevin Harvick thus the “Darwin’s Doghouse” list this week.
2009-12-21
Meat packing industry History
The meat seal packing industry grew with the construction of the railroads and methods of refrigeration. Railroads made possible the transport of stock to central points for processing, and the transport of products throughout the nation.
The publication of the Upton Sinclair novel The Jungle in the US in 1906, shocked the public with the poor working conditions and unsanitary practices in meat packing plants in the United States, specifically Chicago. Meat seal packing plants, like many industries in the early 20th century, were known to overwork their employees, failed to maintain adequate safety measures, and actively fought unionization. In the early part of the century, they used the most recent immigrants and migrants as strikebreakers in labor actions taken by other workers, also usually immigrants or early descendants.
In the 1930s and early 1940s, however, workers achieved unionization under the CIO’s United Packinghouse Workers of America. An interracial committee led the organizing in Chicago, where the majority of workers in the industry were black, and other major cities, such as Omaha, Nebraska, where they were an important minority in the industry. UPWA workers made important gains in wages, hours and benefits. In 1957 the stockyards and meat packing employed half the workers of Omaha. The union supported a progressive agenda, including the Civil Rights Movement of the 1960s. While the work was still difficult, for a few decades workers achieved blue-collar, middle-class lives from it.
Mid-century restructuring by the industry of the stockyards, slaughterhouses and meat seal packing led to relocating facilities closer to cattle feedlots and swine production facilities, to more rural areas, as transportation shifted from rail to truck. It has been difficult for labor to organize in such locations. In addition, the number of jobs fell sharply through technology and other changes. Wages fell during the latter part of the 20th century, and in the 1990s, both Chicago and Omaha closed their stockyards for good.
Though the meat seal packing industry has made many improvements since the early 1900s, extensive changes in the industry since the late 20th century have caused new labor issues to arise. Today, the rate of injury in the meat packing industry is three times that of private industry overall, and meat seal packing was noted by Human Rights Watch as being “the most dangerous factory job in America”. The meatpacking industry continues to employ many immigrant laborers, including some who are undocumented workers. In the early 20th century the workers were immigrants from eastern and southern Europe, and black migrants from the South. Today many are Hispanic, from Mexico, Central and South America. The more isolated areas in which the plants are located put workers at greater risk due to their limited ability to organize and to seek redress for work-related injuries.
2009-12-18
I wanna be a Maki roll!!! Yum.
here’s the stinkin’ cutest costume idea I’ve seen in a while. It seems pretty easy to make. I found this at FamilyFun.com. Here are the instructions:
MATERIALS: 3 large pieces of corrugated cardboard Yardstick Craft knife Scissors String Pushpin White double-sided carpet tape Black duct tape 2 dinner-sized paper plates seal Packing peanuts Markers Card stock or white paper Red gift bag
1. SUSHI ROLL: Use the craft knife to cut the cardboard as shown, with the corrugation running parallel to the rectangle’s short side.
2. Make a half-inch fold along one short edge. Starting there, roll the rectangle into a compact log shape, then unroll it.
3. Tie one end of a 10-inch string to a pushpin inserted into the center of a cardboard piece; tie the other end to a pencil. Hold the string taut as you draw a 17 1/2-inch circle. Cut out the circle. Repeat for a second circle.
4. Apply strips of double-sided tape along the interior edges of the roll as shown. Make a drum-shaped cylinder by pressing the roll’s taped edges around the circumference of each cardboard circle. Trim and seal packing the roll’s seam with duct tape. Add more tape inside and outside the roll to reinforce it.
5. Have your child try on the costume. Fold the underarm tabs down and inside the costume and widen any other openings as needed. Have your child remove the costume.
6. Cover the outside of the cylinder with black duct tape.
7. FILLING: On the underside of a paper plate, draw 3 sections of sushi-roll filling, extending your drawings to the plate’s edge for a three-dimensional look.
8. Cut them out. Repeat on the second plate to make filling for the roll’s back side.
9. To attach the filling and “rice,” apply closely spaced strips of double-sided tape all over the roll’s circular ends. Press the filling pieces firmly into the center of each side, securing with extra tape if needed. Cover the remaining tape with seal packing peanuts.
10. SOY?SAUCE: Draw and cut out a soy sauce label from white paper. Use double-sided tape to attach the label to the gift bag.
2009-12-04
Gasket Garlock Flange Free Gasket Coating Wins IMPOvation Award
Gaskets treated with Flange Free reduce the potential for residual particles to adversely affect the performance of replacement gaskets or to break loose, contaminate piping systems and impair the operation of downstream equipment such as pumps and valves.
Palmyra, NY– The readers of Industrial Maintenance & Plant Operation (IMPO) magazine have selected Garlock Sealing Technologies’ Flange FreeTM anti-stick gasket coating for the publication’s first annual “Top 15 IMPOvation” product technology award. Featured in the September issue, winners of the award were chosen from a field of 100 nominees.
Placing 10th in the voting, Flange Free dramatically reduces the time and effort required to remove treated gaskets. Unlike most anti-stick agents, it is fused to the surface of the gaskets, and does not contain chemicals that can cause them to crack or otherwise degrade.
In addition, gaskets treated with Flange Free reduce the potential for residual particles to adversely affect the performance of replacement gaskets or to break loose, contaminate piping systems and impair the operation of downstream equipment such as pumps and valves.
IMPO’s coverage of the awards cited a maintenance engineer with a major chemical processor who said of Flange Free, “My guys hate scraping gaskets. A little piece of something always gets stuck on the surface under the new gasket. This new technology allows us to save manpower and create a stronger seal.”
2009-09-28
Seal Packing b2b
Seal Packing: http://www.gosgoo.com/showroom/shieldsealing/
Seal Packing: http://www.Goshardware.com/showroom/shieldsealing/
Seal Packing: http://www.Gosmachinery.com/showroom/shieldsealing/
2009-02-19
Dongfeng Motor Jan vehicle sales fall 19.5% y/y
Dongfeng Motor Group Co, China’s third-largest automaker, said yesterday that
its vehicle sales in January fell 19.46% from a year earlier. It delivered
72,483 vehicles in January, down from 89,994 units of one year ago, reported
Reuters.
Sales of passenger cars dropped 3.10% year on year (y/y) to 62,560 units,
while the company’s commercial vehicle sales fell 60.99% y/y to 9,923 units.
Dongfeng operates car manufacturing ventures with PSA Peugeot-Citroen and
Honda Motor. It also makes cars and commercial vehicles with Nissan Motor.
Last month, joint venture Dongfeng Nissan sold 41,734 units, down 26.39%,
Dongfeng PSA sold 16,093 units, down 12.26%, and Dongfeng Honda sold 14,520
units, up 1.06%.
Our Products: seal packing,Exhaust System Gasket,Carbon & Graphite Packing,PTFE & Aramid Packing,Graphite Sheet,PTFE Sheet ,Non-asbestos Jointing Sheet,Cut Gasket,Spiral Wound Gasket
2009-02-10
KOLB builds China JV plant for auto fasteners
German fastener manufacturer KOLB, together with its two Chinese partners,
has begun construction of a new plant in Handan, Hebei province, a local Chinese
newspaper reported.
The three parties, including Handan Tongda Machinery Co and Beijing Golden
Five-Star Trade Group Co, plan to inject a total of 400 million yuan ($58 mln)
into the project which, after completed, will produce high-end fasteners for
automobile, airplane and machinery industries.
The joint venture plant is scheduled to have an annual production capacity of
8,000 tons after it is launched and is expected to post sales revenue of 630
million yuan per year.
KOLB started as a screw manufacturer back in 1910 and began to manufacture
fasteners of stainless steel for the automotive industry in 1979.
KOLB sold 42 percent of its annual products in Germany and 19 percent in the
U.S. The company posted sales value of more than US$25,900 in 2007.
Our Products: seal packing,
target=_blank>Exhaust System Gasket,
target=_blank>Carbon & Graphite Packing,
href="http://www.shield-sealing.com/PTFE-Aramid-Fiber-Packing-c11.html"
target=_blank>PTFE & Aramid Packing,
target=_blank>Graphite Sheet,
target=_blank>PTFE Sheet ,
target=_blank>Non-asbestos Jointing Sheet,
target=_blank>Cut Gasket,
target=_blank>Spiral Wound Gasket