Diy Canoe Building Plans Meaning

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The was simply a Class A version of the engine, physically the same on the outside only the bore was different and the piston had a small groove in the skirt to bleed off just enough power to exactly equal an so no trim changes would be required to free flight models [ citation required] this groove also visually differentiates the from the but this was of secondary importance.

The also had a RED carb body. This engine had a proper RC carby and a full sized standard muffler and was designed specifically for RC flying. It had no Sub Piston Induction. Only two production runs of each were done so there are only of these in existence, making them the second rarest production engine next to the Venom.

Note: Although the box said Tee Dee. Cox also built Tee Dee's in. All these engines were very successful. The original Tee Dee 15 immediately became the engine to use in FAI FF with vastly higher performance than the Olympic, which had supplanted the European diesels used at the time. They proved fragile, particularly the thin-wall cylinder, and ball-and-socket connecting rod, and were replaced by beefed-up versions as noted below.

One of the things Cox wanted Atwood to do was make him a. Cox had already tried to halve the size of the Pee Wee. The suspicion surrounded a problem with the tiny reed valve.

Atwood found that the front rotary valve worked well on the. Also known as the "Poor man's Tee Dee" these were similar to the Tee Dee in appearance but had cheaper parts on them, making them cheaper to buy.

The cylinder was a non-tapered twin bypass with no boost ports like the one used on the Black Widow , the crankshaft was drilled out rather than milled like the Tee Dee, and the carb body was a one-piece unit with a conventional needle valve and spray bar. These are a great reliable easy to use little engine even today. The Medallion engine was also produced in Cat Cat Medallion. This particular.

It was a gentleman's agreement done on a handshake and it nearly didn't happen when Cox was sold to Estes. But the determination of the NFFS resulted in the deal happening, however, Estes-Cox only came through with engines. The NFFS engraved each engine with a serial number and kept a record of who purchased each engine. These are probably the rarest of all Cox Engines due to the small size of the production run.

These engines have a unique piston and cylinder setup that occurs on no other Cox engine, before or after. The cylinder has a straight bore 0. These are all variations of the Baby Bee with different back-plates and other parts designed for different RTF aircraft, cars and boats. There were literally hundreds of different models with subtle differences.

Listed below are just a few of the more common ones. Early version had 'P40' stamped on the cylinder. It had a standard Babe Bee tank. Similar to the Super Bee but it had a larger 8cc non-vented fuel tank. It did not have P40 stamped on the cylinder but it did have the twin bypass ports.

This engine came with the Spitfire RTF airplane. Babe Bee type engine with "postage stamp" type Delrin backplate and brass needle valve instead of the integral Babe Bee fuel tank.

Various shapes were used depending on the model they were fitted to. Each time they made a modification for a new model that was built a new Cat number was produced.

Babe Bee type engine with "horseshoe" type Delrin backplate and brass needle valve. The horseshoe backplate had additional mounting holes drilled in the plate allowed fitting to after market and kit aircraft. Various shapes and colours were produced depending on the model they were fitted to. Some had dual bypass port cylinders while others had single, it depended on the airplane. Similar in appearance to the series engine, produced for the Wings series of air craft.

Came on a blister pack as a "Two Ninety" replacement engine. Basically a replacement engine. An aluminium back plate was used for the "Spook" flying wing combat model kit engine Another variation of the modern Babe Bee. These were pretty good because they have a choke tube attached to the grey plastic backplate. The choke tube makes the engine even easier to start.

They were fitted to the very last RTFs e. PT19 and Hyper Viper before they went out of production. Over the years some Cox model engines were sold to other companies for use in their products and sold under the other companies names. Australia and Tissan Haifa in Israel. Of all of the above-mentioned companies, only Tissan Haifa assembled their own engines called the Banana. All the rest used motors manufactured by Cox themselves. The Cox Banana. It also had a spring starter and red aluminium spinner, and the fuel intake tube was extended below the plastic backplate.

Cox also supplied a specially printed "Banana. Third version of the Tee Dee. Prototyped only 50 made by Bill Atwood They were handed out to various people to try out and as such a few still exist today and appear from time to time for sale at swap meets and on eBay.

This engine took over from the Tee Dee. This engine was patterned on the Australian designed Taipan 2. Samples do exist and the Conquest. Rear reed valve RC engine. Uses a standard glow plug. Power output is similar to Tee Dee. Came out Mid and is listed in Cox Catalog. There was a wide range of cylinders produced with three different wall thicknesses. Most are interchangeable between all engine types which can create problems when buying a used engine. All early cylinders had a thin wall which was later found to need improvement because they bent easily in a crash or when trying to undo with a Cox wrench.

Some people refer to these as Mk1 cylinders. The next type was thickened at the exhaust ports and are also known by some people as Mk2. The third type was thick wall the way down from the cooling fins to the bottom. This one facilitated the exhaust throttle ring and some people refer to this as a Mk3 although Cox never referred to them in this way.

Note: The chart does not differentiate between specific modifications and changes made over the years as the company changed hands. The most powerful cylinder piston combination without a doubt is the number 4 Tee Dee cylinder. This cylinder has a tapered grind and tapered and lightened piston so the piston fit gets tighter as the piston reaches top dead center TDC.

The intake or bypass porting is 2 deep ports with 2 bypass booster ports on each bypass. This setup causes a swirling of the intake fuel air mixture which promotes better combustion. The early engines that were produced before had a light alloy piston rod which is retained in its socket by a slotted steel retaining cup which in turn is held in place by a steel circlip located in a shallow groove in the interior piston wall.

This arrangement known as a three-piece piston was abandoned as of in favour of a hardened steel rod that was swaged into a bearing cup formed integrally in the piston interior. The advantage of this latter set-up was that it simplified assembly and the bearing could be re-set to take up play using a suitable "reset" tool to re-swage the cup.

The engines that used the early-style three-piece piston are any engines produced prior to , i. Since the Space Bug, Space Bug Jr and Thermal Hopper were produced up until you will find versions of these early engines around with the later-style pistons.

The post piston is coated with copper on the inside and top. This was done to prevent the nitrile hardening process from hardening the ball socket joint area. The outside wall of the piston was then finely machined and polished to produce a chromed appearance. The correct free play is. On the Bee engines there were 3 types of crankshaft produced. A third 'Car' crankshaft will only fit into a car crankcase with wide neck.

They found under the heavier torque loads caused by running diesel fuel, that the pins would break also; hence they produced their own killer crank. The same Killer cranks are now being produced again by Cox International. On the Tee Dees and Medallions the cranks are also interchangeable but quite different. The Tee Dee has a large square hole at the intake end of the crank whereas the Medallion has a smaller round hole. The timing is also different. There are some minor variations to the above-mentioned heads, including different thickness cooling fins and thicker centre electrodes on later model OEM glow plugs.

However, the internal shape and glow plug filament remained the same. Later variants of the star and oval reeds were made of Mylar and Teflon. Some say Mylar is the best while others prefer the stainless steel and then others prefer the Teflon. Claims are that Mylar and Teflon are lighter and make the engine easier to start and go faster, but they do not last as long as the stainless ones. To get any suitable speed for mouse racing a 4-inch pitch prop is required at high revs but to do this plenty of nitro-methane is also required, for example, a 4.

Texaco engines are designed to use bigger props, e. Acceptable performance can be had without nitromethane, although the engine will be very sensitive to needle adjustments making it more difficult to operate. With high nitromethane nitro fuel it may be necessary to lower the compression by installing up to six or more additional head gaskets.

When using castor oil it is advisable to clean the engine cylinder wall with a Scotch-Brite pad to remove castor oil varnish buildup that will occur, especially after lean running. This buildup of varnish will cause the engine to run inconsistently. To avoid this problem, it is advised to use a synthetic oil or a synthetic and castor oil blend.

Synthetic oil contains detergents that will keep the cylinder wall clean; however, these small engines do rely on some castor oil buildup to maintain high compression at higher running temperatures. Using clean fuel and keeping everything clean and free from dust and dirt particles is also very important for consistent running in an engine of such small size as these.

Cox fuel formula: [34]. Davis Diesel Development [35] manufactures and sells heavy duty Bee cranks Killer cranks and diesel conversion heads.

These can be purchased direct from their web site or from eBay. These use an o-ring seal rather than a Teflon disk. At the time Cox developed the first Cox engines, they were used in control line and free flight model planes as there was no market for throttled radio control engines back then.

Radio control, although first developed in the s it was not available for model airplanes until the s and did not become economically viable for small model planes until the mids and even then was for the modelers who could afford it. It was certainly out of reach of the hands of most children. From the mids Cox produced throttle control devices for some of their engines; [37] however, these were not as effective as throttles on other brand engines as the Cox throttle worked by restricting exhaust flow.

Exhaust throttles were produced for most Bee and all Medallion engines but not Tee Dee. The throttle attached to the choke tube on Sure Start.

The throttle was developed by Saras Associates [40] and was marketed through Cox International. Over the years, as well as producing millions of model engines Cox also produced a similar number of ready to fly RTF airplanes, as well as boats, cars, helicopters, and trains.

Notes: Part numbers appear to skip and jump, however, cars and boats produced around the same times had numbers similar to the airplanes, therefore causing gaps. From Wikipedia, the free encyclopedia. Cox Cylinder cross-sections. Cox Company. Howard G. Editor and Publisher. December, Page Compute the amount of heat that must be added to the metal to heat it to a temperature of F for pouring.

The molten metal overflows the pouring cup and flows into the downsprue. If the sprue is 25 cm long, determine the proper diameter at its base so as to maintain the same volume flow rate.

At the end of pouring the sprue is filled and there is negligible metal in the pouring cup. The downsprue is 6. It takes a total of 3. This is more than the theoretical time required, indicating a loss of velocity due to friction in the sprue and runner. Find: a the theoretical velocity and flow rate at the base of the downsprue; b the total volume of the mold; c the actual velocity and flow rate at the base of the sprue; and d the loss of head in the gating system due to friction.

Determine the dimensions and volume of the final cube after cooling to room temperature if the cast metal is copper. Assume that the mold is full at the start of solidification and that shrinkage occurs uniformly in all directions. Solution: For copper, solidification shrinkage is 4. Express your answer in terms of decimal fraction inches of elongation per foot of length compared to a standard rule. Express your answer in terms of millimeters of elongation per meter of length compared to a standard rule.

Solution: For brass, solidification shrinkage is 4. The gray cast iron has a volumetric contraction of Determine how long it will take for the casting to solidify. The cube was 50 mm on a side. The same casting alloy is used in the three cases.

Accordingly, we might revise our answer to part b and choose the sphere on the basis that it wastes less metal than the other shapes. For a given cylinder volume, determine the diameter-to-length ratio that will maximize the time to solidify.

If the total solidification time of the casting itself is known to be 3. The length of the cylinder is to be 1. The casting geometry is illustrated in Figure P In true centrifugal casting, a tubular mold is used and a tubular part is produced.

In semicentrifugal casting, the shape is solid; an example is a railway wheel. The mold is rotated so that centrifugal force is used to distribute the molten metal to the exterior of the mold so that the density of the final metal is greater at the outer sections. What is a cupola? A cupola is a vertical cylindrical furnace equipped with a tapping spout near its base.

Cupolas are used for melting cast irons. These operations include: 1 trimming, in which the sprues, runners, risers, and flash are removed, 2 core removal, 3 surface cleaning, 4 inspection, 5 repair if needed, 6 heat treatment, and 7 machining.

General defects include: 1 misruns, 2 cold shuts, 3 cold shots, 4 shrinkage cavity, 5 microporosity, and 6 hot tearing.

See Article Multiple Choice QuizThere are a total of 28 correct answers in the following multiple choice questions some questions have multiple answers that are correct.

It is used in the casting of a cast iron pump housing. Determine the buoyancy force that will tend to lift the core during pouring. The design of the caplets and the manner in which they are placed in the mold cavity surface allows each caplet to sustain a force of 10 lbs. Several caplets are located beneath the core to support it before pouring; and several other caplets are placed above the core to resist the buoyancy force during pouring.

Since the G-factor is less than 60, the rotational speed is not sufficient, and the operation is likely to be unsuccessful. Solution:The mass of molten metal would be unaffected by the absence of gravity, but its weight would be zero. Thus, it should be possible to force the metal against the walls of the mold in centrifugal casting without the nuisance of "raining" inside the cavity. However, this all assumes that the metal is inside the mold and rotating with it.

In the absence of gravity, there would be a problem in pouring the molten metal into the mold cavity and getting it to adhere to the mold wall as the mold begins to rotate. With no gravity the liquid metal would not be forced against the lower surface of the mold to initiate the centrifugal action.

If the rotational speed computed in that problem were used in the steel casting operation, determine the G-factor and c centrifugal force per square meter Pa on the mold wall. At what speed must the tube be rotated during the operation in order to achieve these specifications?

Solution: Use Eq. If the rotational speed during solidification is rpm, determine the inside diameter at the top of the bushing if the diameter at the bottom is mm. Defects and Design Considerations The larger component has the shape of a dish sink and the second component is a flat cover that is attached to the first component to create an enclosed space for the machine parts.

Sand casting is used to produce the two castings, both of which are plagued by defects in the form of misruns and cold shuts. The foreman complains that the thickness of the parts are too thin, and that is the reason for the defects.

However, it is known that the same components are cast successfully in other foundries. What other explanation can be given for the defects? Solution: Misruns and cold shuts result from low fluidity. One possible reason for the defects in this case is that the thickness of the casting cross-sections is too small. However, given that the casting of these parts is successfully accomplished at other foundries, two other possible explanations are: 1 the pouring temperature is too low, and 2 the pouring operation is performed too slowly.

Solution: a What are the possible corrective steps? In the case of step 1 , the risk is for cold shuts and misruns. Steps 2 and 3 would reduce permeability of the sand, thus increasing the risk of sand blows and pin holes. What is the difference? Glass is vitreous -it is in the glassy state, whereas traditional and new ceramics are, by and large, polycrystalline materials.

Silica -SiO 2. Spinning in glassworking is similar to centrifugal casting in metalworking. A gob of molten glass is dropped in to a conical mold which spins, causing centrifugal force to spread the glass upward onto the mold surface. In the press-and-blow process, the initial forming step is pressing of the part, while the first step in the blow-and-blow process is blowing. Name and briefly describe one of them.

The methods described in this test are: 1 rolling, in which the hot glass is squeezed between opposing cylindrical rolls; and 2 the float process, in which the melted glass flows onto a molten tin surface to achieve uniform thickness and smoothness. Describe the Danner process? In the Danner process, molten glass flows around a rotating hollow mandrel through which air is blown while the glass is being drawn.

The temperature of the air and its volumetric flow rate as well as the drawing velocity determine the diameter and wall thickness of the tubular cross-section. During hardening, the glass tube is supported by a series of rollers extending beyond the mandrel. The two processes in the text are: 1 drawing, in which fine glass fibers are pulled through small orifices in a heated plate; and 2 centrifugal spraying, in which molten glass is forced to flow through small orifices in a rapidly rotating bowl to form glass fibers.

Annealing is performed on glass to remove internal stresses that result from shaping and solidification. The glass is heated to a temperature above the annealing temperature and the surfaces are then quenched by air jets to cool and harden them while the interior of the piece remains plastic; as the interior cools and contracts, it puts the previously hardened surfaces in compression, which strengthens it.

Laminated glass, in which two sheets of glass are laminated on either side of a polymer sheet. This has good impact resistance and does not splinter when broken. The guidelines are: 1 subject ceramic parts to compressive, not tensile loads; 2 ceramics are brittle, so avoid impact loading; 3 use large radii on inside and outside corners; 4 screw threads should be course. See Section Multiple Choice QuizThere are a total of 10 correct answers in the following multiple choice questions some questions have multiple answers that are correct.

That would indicate an annealing time of 0. The functions are: 1 filter dirt and lumps, 2 build pressure, 3 straighten the flow and remove memory. Sheet stock has a thickness greater than 0. The blown-film process is a widely used process for making thin polyethylene film for packaging. It combines extrusion and blowing to produce a tube of thin film.

The process begins with the extrusion of a tube which is immediately drawn upward while still molten and simultaneously expanded in size by air inflated into it through the die mandrel. Calendering is a process for producing sheet and film stock out of rubber or rubbery thermoplastics such as plasticized PVC. In the process, the initial feedstock is passed through a series of rolls to work the material and reduce its thickness to the desired gage.

See Figure As the mold opens, the three-plate mold automatically separates the molded part s from the runner system. The defects include: short shots, in which the polymer melt solidifies before filling the cavity; flashing, in which the polymer melt is squeezed into the parting surfaces between the mold halves and around ejection pins; sink marks, in which the surface is drawn into the molding by contraction of internal material; and weld lines where the melt has flowed around a core or Structural foam molding is an injection molding process in which a gas or gas-producing ingredient is mixed with the polymer melt prior to injection into the mold cavity; this results in the part having a tough outer skin surrounded by a foam core.

The differences in injection molding of thermosets are: 1 shorter barrel length, 2 lower temperatures in the barrel, these first two reasons to prevent premature curing; and 3 use of a heated mold to cause cross-linking of the TS polymer. What is reaction injection molding? Reaction injection molding involves the mixing of two highly reactive liquid ingredients and immediately injecting the mixture into a mold cavity where chemical reactions leading to solidification occur.

The two ingredients form the components used in catalyst-activated or mixing-activated thermoset systems Section 8. Blow molding is used to produce hollow, seamless containers, such as bottles. Thermoforming starts with a thermoplastic sheet or film.

A positive mold has a convex shape; a negative mold has a concave cavity. In mechanical thermoforming, matching mold halves are required; while in other thermoforming processes, only one mold form is required. There are several foaming processes: 1 mechanical agitation -mixing a liquid resin with air by, then hardening the polymer by means of heat or chemical reaction; 2 mixing a physical blowing agent with the polymer -a gas such as nitrogen N 2 or pentane C 5 H 12 which can be dissolved in the polymer melt under pressure, so that the gas comes out of solution and expands when the pressure is subsequently reduced; and 3 mixing the polymer with chemical compounds, called chemical blowing agents, that decompose at elevated temperatures to liberate gases such as CO 2 or N 2 within the melt.

Some of the general considerations are : 1 Plastics are not as strong or stiff as metals and should not be used in applications where high stresses will be encountered. Also, some plastics degrade in oxygen and ozone atmospheres. Finally, plastics are soluble in many common solvents. Multiple Choice QuizThere are a total of 36 correct answers in the following multiple choice questions some questions have multiple answers that are correct.

Degree of polymerization a is correlated with molecular weight, and rate of flow c is related to shear rate. The other parameters, b and d , are probably more recognizable to the reader as correct answers to this question. The resistance to forward flow is called back pressure flow. ProblemsExtrusion The head pressure at the die end of the barrel is 5.

The viscosity of the polymer melt is given as Pas. Find the volume flow rate of the plastic in the barrel. The viscosity of the polymer melt is 75 Pas, and the head pressure in the barrel is 4.

Determine the extruder characteristic by computing Q max and p max and then finding the equation of the straight line between them.

This is called the "square" angle in plastics extrusion -the angle that provides a flight advance equal to one diameter for each rotation of the screw.

From Eq. Determine the volume flow rate of the plastic in the barrel. Note that we are not using the parameter S from Table Its intended use is to compute the oversized dimension of a mold cavity in injection molding. Instead, we are using the shrinkage term to calculate the amount of volumetric reduction in size of the part after the polymer is injected into the cavity.

In fact, a slightly different shrinkage parameter value may apply in this case. Compute the corresponding dimension to which the mold cavity should be machined, using the value of shrinkage given in Table Compute the corresponding dimension to which the mold cavity should be machined, using the value of shrinkage given in The observed die swell is 1.

Using a micrometer, measure the wall thickness to compare with your answer in a. Some wall thickness are less. The inside and outside diameters of the die that produced the parison are 18 mm and 22 mm, respectively.

If the minimum wall thickness of the blow molded container is to be 0. The ball will be 1. What weight of PE powder should be loaded into the mold in order to meet these specifications? The specific gravity of the PE grade is 0. The operation is conventional pressure thermoforming using a positive mold, and the plastic is an ABS sheet with an initial thickness of 3.

SolutionSolution: a As the starting flat sheet is draped over the convex cup-shaped mold, the portion contacting the base of the cup experiences little stretching. However, the remaining portions of the sheet must be stretched significantly to conform to the sides of the cup.

Hence, thinning in these sides results. The rubber industry is organized into three parts: 1 rubber growing plantations produce natural rubber, 2 the petrochemical industry produces synthetic rubber, and 3 fabricators take the NR and SR and produce finished rubber goods.

The rubber is usually recovered as follows: 1 the latex is collected into tanks and diluted to half natural concentration; 2 formic or acetic or other acid is added to the solution which causes the rubber to coagulate; 3 the coagulum is then squeezed through rolls to drive off water; and 4 the resulting sheets are dried in smokehouses for several days. The resulting raw rubber is called ribbed smoked sheet.

The typical sequence is: 1 production of the raw rubber, 2 compounding, 3 mixing, 4 shaping, and 5 vulcanization. The additives and functions are: vulcanizing chemicals, reinforcing fillers, extenders to reduce cost, antioxidants, coloring pigments, plasticizers to soften the rubber, and blowing agents to make foam rubber.

The categories are: 1 extrusion, 2 calendering, 3 coating, and 4 molding. Calendering, skimming, dipping, and spraying; see Article Vulcanization causes cross-linking of the rubber molecules; this strengthens and stiffens the rubber while extensibility is retained.

Diagonal ply and belted bias both have their carcass plys running in a diagonal direction relative to the tire circumference; radial ply has its carcass plies running in a radial direction; belted bias and radial ply tires use belts, which are additional plies around the outside circumference of the tire; whereas diagonal ply tires do not have these belts.

The three steps are: 1 preform the components, 2 building the carcass and adding the rubber for the sidewall and treads, and 3 molding and curing. The bead coil provides a rigid support for the tire when it is mounted onto the wheel rim. TPE stands for thermoplastic elastomer; it is a thermoplastic polymer that behaves like a rubber.

However, the extreme flexibility of rubber results in certain differences. What are some examples of these differences? Three examples: 1 no draft is needed on the part for mold removal; 2 holes should be molded into rubber parts rather than machined, whereas holes can be machined or molded in a plastic part; and 3 screw threads are not normally used on rubber parts. Multiple Choice QuizThere are a total of 11 correct answers in the following multiple choice questions some questions have multiple answers that are correct.

Principal polymer matrices in FRPs are unsaturated polyesters and epoxies. A roving consists of untwisted filaments, while a yarn consists of twisted fibers. In the context of fiber reinforcement, what is a mat? A mat is a felt consisting of randomly oriented fibers held loosely together in a binder.

Flakes are simply particles that possess very low width-to-thickness ratios. What is sheet molding compound SMC? Prepregs have continuous fibers rather than chopped fibers as in molding compounds.

Because in hand lay-up, orientation of the fibers is controlled; whereas in spray-up, the fibers in each layer are randomly oriented. In wet lay-up, the layer of fiber reinforcement is placed into the mold dry, and the uncured resin is then applied to it to form the composite laminate.

In the prepreg approach, layers of fiber preimpregnated with resin are laid into the mold. What is an autoclave? Characteristics include: 1 they use molds consisting of two halves that open and close during the molding cycle; 2 high pressure is generally associated with the process; and 3 the geometric shapes of the moldings are more complex in three dimensions. Preform molding is a compression molding process in which a precut mat is placed into the lower half of a mold together with a charge of thermosetting resin; the materials are then pressed between heated molds to cure the resin and produce a fiber-reinforced molding.

Describe reinforced reaction injection molding RRIM. RRIM involves the injection of resins that cure by chemical reaction together with reinforcing fibers into a closed mold. The resulting part is a fiber-reinforced usually glass fiber plastic molding.

Filament winding is a process in which resin-impregnated continuous fibers are wrapped around a rotating mandrel with the internal shape of the FRP product; the resin is cured and the mandrel is removed.

CNC allows independent control over mandrel rotation and carriage speed for greater flexibility in relative motions. Pultrusion is a process in which continuous fibers are dipped into a resin and pulled through a shaping die somewhat like an extrusion die where the resin cures.

The resulting sections are similar to extruded parts except that they are reinforced with continuous fibers. Pulforming is pultrusion with the added operation of a shape change in the length straight length becomes curved and cross-section different cross-sections throughout the length. Typical products include: bicycle frames and space trusses.

Uncured FRPs are cut by methods which include: knives, scissors, power shears, steel-rule blanking dies, laser beam cutting, and water jet cutting. Multiple Choice QuizThere are a total of 12 correct answers in the following multiple choice questions some questions have multiple answers that are correct.

Using Eq. Solution:The aspect ratio is the ratio of the maximum dimension to the minimum dimension of the particle shape. The minimum dimension is the edge of any face of the cube; call it L. Find diameter D of a sphere of equivalent volume. For this cylinder shape, 0. Assume the same packing factor. Given this distribution, what is the total surface area of all the particles in the pile. What is the percentage increase in total surface area if the diameter of each particle is 0.

How much total surface area is added by the process if the diameter of each particle is microns assume that all particles are the same size? Solution:The maximum packing factor is achieved when the spherical particles are arranged as a face-centered cubic unit cell, similar to the atomic structure of FCC metals; see Figure 2. The unit cell of the FCC structure contains 8 spheres at the corners of the cube and 6 spheres on each face.

Our approach to determine the packing factor will consist of: 1 finding the volume of the spheres and portions thereof that are contained in the cell, and 2 finding the volume of the unit cell cube. The ratio of 1 over 2 is the packing factor.

The unit cell contains 6 half spheres in the faces of the cube and 8 one-eighth spheres in corners. Consider that the diagonal of any face of the unit cell contains one full diameter the sphere in the center of the cube face and two half diameters the spheres at the corners of the face. The volume of the unit cell is therefore 1. Given that these are the only factors that affect the structure of the finished part, determine its final porosity.

What is the required press tonnage to perform this operation? Figure P Dimensions are inches. Assume shrinkage during sintering can be neglected. SolutionSolution: a Most appropriate pressing direction is parallel to the part axis. Dimensions are mm. Solution: a Class II, 2 directions because of axial thickness, one level of press control. The traditional ceramics are based on hydrous aluminum silicates clay , whereas the new ceramics are based on man-made simpler compounds such as oxides, nitrides, and carbides.

The sequence is: 1 preparation of raw materials, 2 shaping, 3 drying, and 4 firing. Crushing is performed to reduce large lumps of mineral to smaller size. Grinding is a secondary process which further reduces the particle size to fine powder. In slip casting a slurry of clay is poured into a plaster of Paris mold, whereupon water is absorbed from the slurry into the plaster to form a clay layer against the mold wall.

The remaining slurry is usually poured out to leave a hollow part. The plastic forming methods include: 1 hand modeling, molding, and throwing; 2 jiggering, which is a mechanized extension of hand throwing used to manufacture bowls and plates; 3 plastic pressing, in which a clay slug is pressed in a mold; and 4 extrusion, in which the clay is compressed through a die opening to make long sections of uniform cross-sectional shape.

Jiggering is a clay forming process that uses a convex mold on a potters wheel. The clay is first pressed into rough shape and then rotated and formed with a jigger tool to final shape. It is suited to the manufacture of flatware. The difference is in the starting clay. Dry clay has virtually no plasticity, and so this imposes certain limitations on part geometry in dry pressing. Sintering of green ceramics or powdered metals causes bonding between the ceramic grains, which is accompanied by densification and reduction of porosity.

Glazing refers to the process of putting a ceramic coating on the surface of the ceramic piece. The coating, usually consisting of ceramic oxides, is referred to as a glaze. Because water is usually not one of the ingredients in the new ceramics during forming. Drying is only needed when the green piece contains water.

Because the requirements on the strength of the finished product are usually more demanding for new ceramics. In freeze drying, salts are dissolved in water and sprayed into small droplets which are immediately frozen; the water is then removed from the droplets in a vacuum chamber, and the freeze-dried salt is decomposed by heating to form the ceramic powders.

In the doctor-blade process, a ceramic slurry is flowed onto a moving film which flows under a wiper blade, so that the resulting ceramic is in the form of a thin green sheet which is dried and reeled onto a spool for subsequent shaping and sintering. How is this possible?

The melting point of cobalt is reduced when WC is dissolved in it. At the sintering temperatures used for WC-Co, WC gradually dissolves in the cobalt, reducing its melting point to the sintering temperature. Thus does liquid phase sintering occur in the WC-Co system. The guidelines include: 1 subject ceramic parts to compressive, not tensile loads; 2 ceramics are brittle, so avoid impact loading; 3 part geometries should be simple; 4 use large radii on inside and outside corners; 5 take into account shrinkage; 6 no screw threads.

Multiple Choice QuizThere are a total of 15 correct answers in the following multiple choice questions some questions have multiple answers that are correct. Which one of the pieces listed is used for grinding?

In bulk deformation, the shape changes are significant, and the workparts have a low area-to-volume ratio. In sheet metal processes, the area-to-volume ratio is high. Describe it. Extrusion is a compression process in which the work material is forced to flow through a die orifice, thereby forcing its cross-section to assume the profile of the orifice. Because these operations are generally performed on presses. Deep drawing is a sheet metal forming process used to fabricate cup-shaped parts; bar drawing is a bulk deformation process used to reduce the diameter of a cylindrical workpart.

The flow curve is defined in Eq. Increasing temperature decreases both K and n in the flow curve equation. Advantages of cold working are: 1 better accuracy, 2 better surface finish, 3 increased strength due to work hardening, 4 possible directional properties due to grain flow, and 5 no heating of work required. What is isothermal forming? An isothermal forming operation is performed in such a way as to eliminate surface cooling and thermal gradients in the workpart.

This is accomplished by preheating the forming tools. Increasing strain rate tends to increase the resistance to deformation. The tendency is especially prominent in hot forming operations. Reasons why friction is undesirable in metal forming: 1 inhibits metal flow during deformation, causing residual stresses and product defects; 2 increases forces and power required; and 3 wearing of the tools. Sticking friction is when the work surface adheres to the surface of the tool rather than slides against it; it occurs when the friction stress is greater than the shear flow stress of the metal.

There are a total of 13 correct answers in the following multiple choice questions some questions have multiple answers that are correct.

Problems Flow Curve in Forming Determine the flow stress at this strain and the average flow stress that the metal experienced during the operation. Determine the flow stress at the new length and the average flow stress that the metal has been subjected to during the deformation.

Determine the average flow stress that the metal experiences if it is subjected to a stress that is equal to its strength coefficient K. Reasons why the bulk deformation processes are important include: 1 they are capable of significant shape change when hot working is used, 2 they have a positive effect on part strength when cold working is used, and 3 most of the processes produce little material waste; some are net shape processes.

Rolled products include flat sheet and plate stock, round bar and rod stock, rails, structural shapes such as I-beams and channels. Ways to reduce force in flat rolling include: 1 use hot rolling, 2 reduce draft in each pass, and 3 use smaller diameter rolls. What is a two-high rolling mill? A two-high rolling mill consists of two opposing rolls between which the work is compressed.

A reversing mill is a two-high rolling mill in which the direction of rotation of the rolls can be reversed to allow the work to pass through from either side. Some other processes that use rolls are ring rolling, thread rolling, gear rolling, roll piercing, and roll forging.

By this classification, name the three basic types. The three basic types are: 1 open die forging, 2 impression die forging, and 3 closed die forging. Because its presence constrains the metal in the die to fill the details of the die cavity.

The two types of forging machines are hammers, which impact the workpart, and presses, which apply a gradual pressure to the work. What is isothermal forging?

Isothermal forging is a hot forging operation in which the die surfaces are heated to reduce heat transfer from the work into the tooling. Distinguish between direct and indirect extrusion.

Products produced by continuous extrusion include: structural shapes window frames, shower stalls, channels , tubes and pipes, and rods of various cross-section. Products made by discrete extrusion include: toothpaste tubes, aluminum beverage cans, and battery cases. They are both examples of how compressive stresses applied to the outside surface of a solid cylindrical cross-section can create high tensile stresses in the interior of the cylinder.

Because if the drawing stress exceeded the yield strength, the metal on the exit side of the draw die would stretch rather than force metal to be drawn through the die opening.

Multiple Choice QuizThere are a total of 22 correct answers in the following multiple choice questions some questions have multiple answers that are correct. Bar and wire drawing a is the only tricky answer; although tensile stresses are applied to the work, the work is squeezed through the die opening by compressionthe term indirect compression is sometimes used.

Flash causes build-up of pressure inside the die which causes the work metal to fill the cavity. Tube and pipe cross-sections can be produced by either direct or indirect extrusion.

Bar stock is rolled, drawn into wire stock, and upset forged to form the nail head. Thickness is to be reduced in three steps in a hot rolling operation. Final thickness is to be 13 mm. Equal drafts of 6 mm are to be taken at each stand. The plate is wide enough relative to its thickness that no increase in width occurs.

Under the assumption that the forward slip is equal at each stand, determine: a speed v r at each stand, and b forward slip s. Compare the results with the previous two problems, and note the important effect of roll radius on force, torque and power.

Note that this is the same power value within calculation error as in Problems In fact, power would probably increase because of lower mechanical efficiency in the cluster type rolling mill. Determine: a roll force, b roll torque, and c power required to accomplish this operation.

Measure the head diameter and thickness, as well as the diameter of the nail shank. Solution: Student exercise. Calculations similar to those above for the data developed by the student. A cylindrical workpart is to be cold upset forged. Need to try a value of h f between 10 and 20, closer to The projected area of the part, including flash, is 15 in 2. Part geometry is relatively simple. Determine the maximum force required to perform the forging operation.

From Table The projected area of the part is 6, mm 2. The design of the die will cause flash to form during forging, so that the area, including flash, will be 9, mm 2. The part geometry is considered to be complex. As heated the work material yields at 75 MPa, and has no tendency to strain harden. Determine the maximum force required to perform the operation.

The first operation would have to be operated at well below its maximum possible speed; or the second draw die could be powered by a higher horsepower motor; or the reductions to achieve the two stages could be reallocated to achieve a higher reduction in the first drawing operation. The three operations are: 1 cutting, 2 bending, and 3 drawing. A cutoff operation separates parts from a strip by shearing one edge of each part in sequence. A parting operation cuts a slug between adjacent parts in the strip.

Describe V-bending and edge bending. In V-bending, a simple punch and die which have the included angle Aluminum Boats Done Deal Price are used to bend the part. In edge bending, the punch force a cantilevered sheet metal section over a die edge to obtain the desired bend angle. What is springback in sheet metal bending? Springback is the elastic recovery of the sheet metal after bending; it is usually measured as the difference between the final included angle of the bent part and the angle of the tooling used to make the bend, divided by the angle of the tooling.

In redrawing, the shape change is significant enough e. In reverse drawing, two draws are accomplished on the part, one in one direction, the second in the opposite direction. Stretch forming of sheet metal involves stretching and simultaneous bending of the workpart to achieve shape change. Two press frame types are: 1 gap frame, also called C-frame, and 2 straight-sided frame. Advantage of mechanical presses: faster cycle rates.

Advantages of hydraulic presses: longer ram strokes and uniform force throughout stroke. The Guerin process is a sheet metal forming process that uses a rubber die which flexes to force the sheet metal to take the shape of a form block punch. A major technical problem in tube bending is collapse of the tube walls during the process. Roll bending involves the forming of large sheet and plate metal sections into curved forms.

Roll forming involves feeding a lone strip or coil through rotating rolls so that the shape of the rolls is imparted to the strip. Multiple Choice QuizThere are a total of 17 correct answers in the following multiple choice questions some questions have multiple answers that are correct. Determine: a the punch and die sizes for the blanking operation, and b the punch and die sizes for the punching operation. Table 20 1 clearance between punch and die is too large for the material and stock thickness.

Solution: From 2 Punch and die cutting edges are worn rounded which has the same effect as excessive clearance. To correct the problem: 1 Check the punch and die cutting edges to see if they are worn. If they are, regrind the faces to sharpen the cutting edges.

If not, die maker must rebuild the punch and die. Bending The part drawing is given in Figure P Determine the blank size required. Therefore, the length of the neutral axis of the part will be 2 1. However, the operation is not feasible because the mm diameter blank size does not provide sufficient metal to draw a 75 mm cup height. The actual cup height possible with a mm diameter blank can be determined by comparing surface areas one side only for convenience between the cup and the starting blank.

To compute the cup surface area, let us divide the cup into two sections: 1 walls, and 2 base, assuming the corner radius on the punch has a negligible effect in our calculations and there is no earing of the cup. This is less than the specified 75 mm height. Determine: a drawing ratio, b reduction, c drawing force, and d blankholder force. Is the operation feasible ignoring the fact that the punch radius is too small?

Of course, the zero punch radius makes this operation infeasible anyway. With a rounded punch radius, the blank size would be slightly smaller, which would reduce DR. Solution: Use surface area computation, assuming thickness t remains constant.

Whereas the operation in Problem Since the DR is greater than 2. Solution:Use surface area computation, assuming thickness t remains constant. The samples have various defects. One has ears, another has wrinkles, and still a third has torn sections at its base. What are the causes of each of these defects and what remedies would you propose?

Solution: 1 Ears are caused by sheet metal that has directional properties. The material is anisotropic. One remedy is to anneal the metal to reduce the directionality of the properties. This may not be possible since a design change is required. A remedy would be to provide a large punch radius. Tearing can also occur due to a die corner radius that is too small. Solution: a According to Eq. The drawn cup consists of three sections: 1 cup walls, 2 Other Operations Determine: b true strain experienced by the metal, c stretching force F, and d die force F die at the very end when the part is formed as indicated in Figure P The tubes will be used to deliver fluids in a chemical plant.

In one of the bends where the bend radius is mm, the walls of the tube are flattening badly. What can be done to correct the condition?

Solution: Possible solutions: 1 Use a mandrel to prevent collapsing of tube wall. The sand will act as an internal flexible mandrel to support the tube wall. In machining, material is removed from the workpart so that the remaining material is the desired part geometry.

The reasons include: 1 its applicability to most materials; 2 its capability to produce a variety of geometries to a part; 3 it can achieve closer tolerances than most other processes; and 4 it can create good surface finishes.

The three common machining processes are: 1 turning, 2 drilling, and 3 milling. Give an example of a machining operation that uses each of the tooling types.

The two categories are: 1 single -point tools, used in operations such as turning and boring; and 2 multiple -edge cutting tools, used in operations such as milling Aluminum Boats Done Deal Quality and drilling. Cutting conditions include: speed, feed, depth of cut, and whether or not a cutting fluid is used.

A roughing operation is used to remove large amounts of material rapidly and to produce a part geometry close to the desired shape.

A finishing operation follows roughing and is used to achieve the final geometry and surface finish. A machine tool can be defined as a power-driven machine that positions and moves a tool relative to the work to accomplish machining or other metal shaping process.

What is an orthogonal cutting operation? Orthogonal cutting involves the use of a wedge-shaped tool in which the cutting edge is perpendicular to the direction of speed motion into the work material. The three types are: 1 discontinuous, in which the chip is formed into separated segments; 2 continuous, in which the chip does not segment and is formed from a ductile metal; and 3 continuous with built-up edge, which is the same as 2 except that friction at the tool-chip interface causes adhesion of the work material to the tool rake face.

Describe in words what the Merchant equation tells us. The Merchant equation states that the shear plane angle increases when rake angle is increased and friction angle is decreased. Specific energy is the amount of energy required to remove a unit volume of the work material. The size effect refers to the fact that the specific energy increases as the cross-section area of the chip t o x w decreases. A tool-chip thermocouple is comprised of the tool and chip as the two dissimilar metallic materials forming the thermocouple junction; as the tool-chip interface heats up during cutting, an emf is emitted from the junction which can be measured to indicate cutting temperature.

Determine the cutting force and the feed force. Use the orthogonal cutting model as an approximation of the turning process. Solution: Eq. The arrowhead of F t will now be at the base of the translated base of N. A right triangle now exists in which F c is the hypotenuse and the two sides are 1 the extended F s vector and 2 the constructed line that runs between F s and the intersection of F c and F t. Power and Energy in Machining Use Table Solution: From Table Since feed is greater than 0.

Using the appropriate specific energy value from Table Solution: From Table 21 Figure The work material is an alloy steel whose hardness is in the range to HB. Based on these values, can the job be performed on the 20 hp lathe? Table 21 Solution: FromThe feed is. After the cut, the chip thickness ratio is measured to be 0. Solution: a From Table Table Cutting Temperature Using values of thermal properties found in the tables and definitions of Section 4.

Rotational parts are cylindrical or disk-shaped and are machined on a turning machine; prismatic parts are block-shaped or flat and are generally produced on a milling machine, shaper, or planer. Generating refers to the creation of work geometry due to the feed trajectory of the cutting tool; examples include straight turning, taper turning, and profile milling.

Forming involves the creation of work geometry due to the shape of the cutting tool; common examples include form turning and drilling. Two examples are thread cutting on a lathe and slot milling; both are described in Article Describe the turning process. Turning is a machining process in which a single point tool removes material from the surface of a rotating cylindrical workpiece, the tool being fed in a direction parallel to the axis of work rotation.

A threading operation is performed on a turning machine and produces an external thread, while tapping is normally performed on a drilling machine and produces an internal thread. How does a boring operation differ from a turning operation?

Boring produces an internal cylindrical shape from an existing hole, while turning produces an external cylindrical shape. A 12 x 36 lathe has a 12 inch swing maximum work diameter that can be accommodated and a 36 inch distance between centers indicating the maximum work length that can be held between centers. Methods of holding the work in a lathe include: 1 between centers, 2 chuck, 3 collet, and 4 face plate. A center holds the work during rotation at the tailstock end of the lathe.

A live center is mounted in bearings and rotates with the work, while a dead center does not rotate -the work rotates about it. A turret lathe has a toolholding turret in place of a tailstock; the tools in the turret can be brought to work to perform multiple cutting operations on the work without the need to change tools as in operating a conventional engine lathe.

A blind hole does not exit the work; by comparison, a through hole exits the opposite side of the workpart. A radial drill has a long radial arm along which the drill head can be positioned to allow the drilling of large workparts. In peripheral milling, cutting is accomplished by the peripheral teeth of the milling cutter and the tool axis is parallel to the work surface; in face milling, cutting is accomplished by the flat face of the cutter whose axis is perpendicular to the work surface.

Profile milling generally involves the milling of the outside periphery of a flat part. What is pocket milling? Pocket milling uses an end milling cutter to machine a shallow cavity pocket into a flat workpart. In up milling, the cutter speed direction is opposite the feed direction; in down milling, the direction of cutter rotation is the same as the feed direction. The universal milling machine has a worktable that can be rotated about a vertical axis to present the part at any specified angle to the cutter spindle.

A machining center is a CNC machine tool capable of performing multiple types of cutting operations involving rotating spindles e. A machining center is generally confined to rotating spindle operations e. The mill-turn center has the capacity to position a rotational workpart at a specified angular location, permitting milling or drilling to be performed at a location on the periphery of the part.

How do shaping and planing differ? In shaping, the work is stationary during the cut, and the speed motion is performed by the cutting tool; while in planing, the cutting tool is stationary, and the workpart is moved past the tool in the speed motion.

Internal broaching is accomplished on the inside surface hole of a workpart; while external broaching is performed on one of the outside surfaces of the part. The three forms of sawing are: 1 hacksawing, 2 bandsawing, and 3 circular sawing. Multiple Choice QuestionsThere are a total of 20 correct answers in the following multiple choice questions some questions have multiple answers that are correct.

The bar will be held in a chuck and supported on the opposite end in a live center. With this workholding setup, one end must be turned to diameter; then the bar must be reversed to turn the other end. Using an overhead crane available at the lathe, the time required to load and unload the bar is 5.

For each turning cut an allowance must be added to the cut length for approach and overtravel. Determine the total cycle time to complete this turning operation. Assume that x-y moves are made at a distance of 0.

Also, the rate at which the drill is retracted from each hole is twice the penetration feed rate. Determine the time required from the beginning of the first hole to the completion of the last hole, assuming the most efficient drilling sequence will be used to accomplish the job.

It takes 4. How long will it take to perform the operation at the new cutting conditions? The length of the stroke across the work must be set up so that 10 in are allowed at both the beginning and end of the stroke for approach and overtravel. How long will it take to complete the job, assuming that the part is oriented in such a way as to minimize the time?

In addition to causing odors and health hazards, contaminated cutting fluids do not perform their lubricating function as well as when they are fresh and clean. The outside diameter of a roll for a steel rolling mill is to be turned. Units for the Taylor equation are min. It is desirable to operate at a cutting speed so that the tool will not need to be changed during the cut. Determine the cutting speed which will make the tool life equal to the time required to complete the turning operation.

Specify a non-steel finishing grade. This is a grade with no TiC and low cobalt. Choose grade 1. Problems d Machining cast iron. Cast iron is included with the non-steel grades. Specify grade 1 for finishing and grade 4 for roughing.

A slot or keyway has been milled along its entire length. The turning operation reduces the shaft diameter. For each of the following tool materials, indicate whether or not it is a reasonable candidate to use in the operation: a plain carbon steel, b high speed steel, c cemented carbide, d ceramic, and e sintered polycrystalline diamond.

For each material that is not a good candidate, give the reason why it is not. Solution:The slot will result in an interrupted cut, so toughness is important in the tool material.

A cutting oil is applied by the operator by brushing the lubricant onto the drill point and flutes prior to each hole. The foreman says that the "speed and feed are right out of the handbook" for this work material. Nevertheless, he says, "the chips are clogging in the flutes, resulting in friction heat, and the drill bit is failing prematurely due to overheating.

What do you recommend to solve it? Cutting Fluids Solution:There are several problems here. First, the depth-to-diameter ratio is 1.

As a consequence the chips produced in the hole are having difficulty exiting, thus causing overheating of the drill.

Second, the manual method of applying the cutting oil may not be particularly effective. Third, with overheating as a problem, the cutting oil may not be removing heat from the operation effectively. The depth-to-diameter ratio is a given, a requirement of the drilling operation, and we assume it cannot be changed. The twist drill might be operated in a peck-drilling mode to solve the chip clogging problem.

Peck-drilling means drilling for a distance approximately equal to one drill diameter, then retract the drill, then drill some more, etc. A twist drill with a fluid hole could be used to more effectively deliver the cutting fluid to the drill point to help extract the chips.

Finally, an emulsified oil might be tried in the operation, one with good lubricating qualities, as a substitute for the cutting oil. Since overheating is a problem, it makes sense to try a coolant.

Machinability can be defined as the relative ease with which a material can be machined using an appropriate cutting tool under appropriate cutting conditions. The machinability criteria include: 1 tool wear and tool life, 2 forces and power, 3 surface finish, and 4 ease of chip disposal. The properties mentioned in the text include: hardness, strength, and thermal diffusivity.

Why do costs tend to increase when better surface finish is required on a machined part? Because additional operations such as grinding, lapping, or similar finishing processes must be included in the manufacturing sequence at higher cost. What are the basic factors that affect surface finish in machining? The factors that affect surface finish are: 1 geometric factors such as type of operation, feed, and tool shape nose radius in particular ; 2 work material factors such as built-up edge effects, and tearing of the work surface when machining ductile materials, which factors are affected by cutting speed; and 3 vibration and machine tool factors such as setup and workpart rigidity, and backlash in the feed mechanism.

The ideal surface roughness is determined by geometric parameters of the machining operation. These parameters are: 1 the type of machining operation, e. Steps to reduce vibration in machining include: 1 increase stiffness or damping in the setup; 2 operating at speeds away from the natural frequency of the machine tool system; and 3 reducing forces in machining through changes in feed or depth and changes in cutter design.

The factors are: 1 type of tooling, 2 roughing or finishing operation, 3 limiting cutting forces, and 4 surface roughness requirements. What is the fourth term? The fourth term is the cost of purchasing and grinding, if applicable the tool. Cutting speed for minimum cost. The fourth term in the unit cost equation, dealing with the actual cost of the cutting edge, tends to push the U-shaped function toward a lower value in the case of cutting speed for minimum cost.

Multiple Choice QuizThere are a total of 14 correct answers in the following multiple choice questions some questions have multiple answers that are correct. Based on this information, and machinability data given in Determine the surface roughness for this cut. The cutter uses four inserts and its diameter is 3.

The cutter is a four-tooth insert type face milling cutter. The machine shop foreman thinks the problem is that the work material is too ductile for the job, but this property tests well within the ductility range for the material specified by the designer. Without knowing any more about the job, what changes in cutting conditions and tooling would you suggest to improve the surface finish? Determine the speed and feed combination that meets these criteria.

Increasing speed will increase MRR and reduce R a. Therefore, it stands to reason that we should operate at the highest possible v. From Fig. Assuming first that the teeth are equally spaced around the cutter, and that each tooth projects an equal distance from the axis of rotation, determine the theoretical surface roughness for a up-milling, and b down-milling.

Comment: One might conclude that such a low proportion of time spent cutting would argue against the use of the calculated cutting speed for ceramic tooling. However, note that ceramic tooling provides a significant advantage in terms of unit cost, batch time, and production rate compared to HSS tooling and even carbide tooling. The very small cutting time T m and resulting low proportion of time spent cutting for ceramic tooling focuses attention on the nonproductive work elements in the batch time, specifically, setup time and workpart handling time; and puts pressure on management to seek ways to reduce these nonproductive elements.

Is that possible? Assume that feed must remain unchanged in order to achieve the required surface finish. What is the current production rate and the maximum possible production rate for this job? Solution: Starting with Eq.

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