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Table 15-3.—Average Cooling Rates of Some Liquids and Gases Used for Cooling, as Compared with Cooling Rate of Water at 65°F Cooling Medium Cooling Rate, as Compared to Water at 65°F 10-percent brine solution at 65°F ........... 1.96 10-percent caustic soda solution ............ 1.38 Water at 65°F ..................... 1.00 Prepared oil ...................... 0.44 Fuel oil ......................... 0.36 Cottonseed oil ..................... 0.36 Neatsfoot oil ...................... 0.33 Sperm oil ........................ 0.33 Fish oil ......................... 0.31 Castor oil ........................ 0.29 Machine oil ...................... 0.22 Lard oil ........................ 0.19 Circulated oil ...................... 0.032 Still air ......................... 0.015 Special temperature-indicating crayons or other materials may be available for use in connection with heat treatment. These materials give a much more accurate indication of temperature than can be obtained by merely observing the color of the metal. Temperature-indicating crayons are made of materials that melt rapidly and clearly at specified temperatures. A series of crayons is supplied to cover a wide range of temperatures. The crayons are easy to use. You select the crayon that is labeled with the temperature you want. As the metal is being heated, stroke the work with the crayon. When the metal is below the temperature rating of the crayon, the crayon will leave a dry or chalky mark on the surface. When the proper temperature is reached or exceeded, the crayon will melt quickly, leaving a liquid smear on the metal. Do not forget that the crayons indicate only the skin or surface temperature of the metal. The interior of the piece may be at quite a 15-10 different temperature unless the piece has been soaking for some time. COOLING EQUIPMENT The rate of cooling is controlled by selecting an appropriate cooling medium and cooling procedure. The equipment required for cooling includes the substances used for cooling, a tank or other container to hold the cooling medium, and various kinds of tongs, baskets, and other devices for handling and holding the work. The rate at which a metal cools depends upon a number of factors. The size, shape, temperature, and composition of the material and the temperature and composition of the cooling medium are the major factors involved. The rate at which a cooling medium can absorb heat is also greatly influenced by circulation. When the cooling medium is agitated, the rate of
Figure 15-10.—Portable quenching tank for use in heat-treating. cooling is much faster than when the cooling medium is not in motion. The volume of the cooling medium is also important. As the metal cools, the cooling medium absorbs heat. If the volume is insufficient, the cooling medium will become too hot to cool the work at the required rate. In regular heat-treating shops where the cooling mediums must be used continuously, mechanical cooling systems are used to maintain the cooling medium at the correct temperature. Liquids, gases, and solids are all used as cooling mediums for heat-treating operations. Table 15-3 shows the relative cooling rates of some commonly used liquids and gases. Solid materials such as lime, sand, ashes, and cast-iron chips are sometimes used when the rate of cooling must be slower than that produced by liquids or gases. Liquid quenching is accomplished either by STILL-BATH QUENCHING or by FLUSH QUENCHING. In still-bath quenching the metal is cooled in a tank of still liquid. The only movement of the liquid is that caused by the movement of the hot metal. Flush quenching is used for parts that have recesses or cavities that would not be properly quenched by the still-bath method. In flush quenching, the liquid is sprayed under pressure onto the surface of the piece and into every cavity or recess. This procedure is often used to minimize distortion by providing a relatively uniform quench to all parts of the piece. Portable quenching tanks of the type shown in figure 15-10 are sometimes used in small shops that do not have permanent, built-in equipment. Portable quenching tanks may have one compartment or several. When more than one quenching medium is to be used, the seal between the compartments must be absolutely 15-11 tight to prevent mixing of the mediums. Each compartment is equipped with a drain plug, a screen in the bottom to catch scale and other foreign matter, and a mesh basket to hold the parts being quenched. The mesh basket and the wire screen are suspended in the tank and held in position by clips that fit over the rim of the tank A portable electric pump may be attached to the rim of the tank to circulate the liquid. Stationary quenching tanks are usually designed to contain only one liquid. In a stationary quenching tank, the mesh basket that holds the work is usually raised and lowered by air pressure and is controlled by a threeway air valve. The basket can usually be positioned at any level and can be raised above the level of the liquid so the parts can be drained after they have been cooled. Stationary quenching tanks usually have built-in electric pumps to circulate the liquid. WATER is often used as a quenching medium for plain-carbon steels and for aluminum and other nonferrous metals. The water must be kept clean by frequent changing. The temperature most often used for water quenching is about 65°F. Normally, the volume of water in the tank should prevent a temperature rise of more than 20°F. When very heavy pieces are being quenched, the temperature rise may exceed 20°F, but it should always be kept as low as possible. BRINE is used for many quenching operations. At any given temperature, brine cannot hold as much dissolved air as fresh water can hold. With brine, therefore, there are fewer air bubbles or gas pockets on the surface of the work Brine wets the surface more thoroughly and cools the work more rapidly and more uniformly than plain water. Brine solutions usually contain from 7 to 10 percent salt by weight or 3/4 of a pound of salt for each gallon of water. The correct temperature for a brine quench ranges from 65° to 100°F. Plain-carbon steels and lowalloy steels are often quenched in brine. High-carbon steels and all alloy steels that are uneven in cross section must be quenched very carefully if brine is the cooling medium. Brine cools the material so rapidly that great internal stresses may develop and crack the work Brine is not used as a quenching medium for nonferrous metals because of its high corrosive effect on these metals. OIL is used to quench high-speed steels and oil-hardened steels. It is also the preferred quenching medium for almost all other steels except where the necessary hardness cannot be obtained by such a relatively slow quench. Although nonferrous metals are not normally quenched in oil, they may be in special
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Naval Education and Training Comman
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MACHINERY REPAIRMAN NAVEDTRA 12204-
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PREFACE This Training Manual (TRAMA
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CONTENTS CHAPTER PAGE 1. 2. 3. 4. 5
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Another job description found in pr
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1-2, and 1-3 show some of the commo
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You must know the location of tools
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The correct way to measure an insid
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appropriate sides of the jaws on th
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Dial Bore Gauge The dial bore gauge
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Gear Tooth Vernier Use a gear tooth
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Surface Gauge A surface gauge (fig.
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Figure 1-20.—Center gauge. angle
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accuracy. They generally come in ma
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MICROMETERS is essentially the same
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meanings of these terms and the imp
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number is shown for roughness heigh
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Figure 2-7.—Master roughness scal
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Figure 2-11.—Checking surface fin
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Figure 2-17.—Laying out a 45-degr
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Figure 2-24.—Setting and using a
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Figure 2-29.—Bisecting an angle.
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prick-punch “witness marks” aro
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Figure 2-35.—Filing. The crosshat
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keyway broach requires a bushing th
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The steps involved in repairing a d
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SETTING UP OXYACETYLENE EQUIPMENT T
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GREASE IN THE PRESENCE OF OXYGEN UN
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Strength metal into thin sheets. Le
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and forming into plates, billets, b
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Each of the aluminum alloys has pro
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with an average carbon content of 1
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The manufacturer is required to mak
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with that of known specimens. Many
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Gray cast iron produces a spark str
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Table 3-4.—Major Groups of Plasti
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Lathe Operations Lathe operations a
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mechanism is also attached to the s
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Band Selection and Installation The
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File Bands A file band consists of
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This prevents sagging of the file b
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Figure 4-16.—Butt welder-grinder
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paragraphs contain the procedures f
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Figure 4-22.—Disk-cutting attachm
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Figure 4-26.—Sensitive drill pres
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shops are the Morse taper shank, sh
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Figure 4-30.—Common types of clam
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Figure 4-34.—Two types of counter
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andomly follow the straight sides a
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CHAPTER 5 OFFHAND GRINDING OF TOOLS
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Figure 5-4.—Standard marking syst
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DIAMOND WHEELS Diamond grinding whe
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WHEEL CARE AND STORAGE It’s easy
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allows cutting speeds approximately
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Figure 5-13.—Surface finish vs no
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Figure 5-17.—Boring bars for carb
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Figure 5-19.—Chip breakers. a rad
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Internal-threading tool: The intern
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Downcutting tool: You may grind and
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Figure 5-32.—Grinding drill lip c
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Figure 5-37.—Grinding a twist dri
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ways in alignment with the headstoc
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Figure 6-4 shows this plate for the
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Before you insert a center or tooli
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FEED ROD The feed rod transmits pow
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lower lever has eight positions, ea
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Figure 6-14.—Quick-change toolpos
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Figure 6-21.—Three-jaw universal
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Figure 6-26.—Cutaway showing the
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Figure 6-32.—Thread dial indicato
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TRACING ATTACHMENTS A tracing attac
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2. Place the level across the bed a
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Figure 6-41.—Aligning lathe cente
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Figure 6-45.—Boring center hole.
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ends of the mandrel when you press
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Figure 6-52.—Centering work with
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Figure 6-56.—Work mounted on a ca
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FEED is the amount the tool advance
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Rough Turning Figure 6-62.—Rough
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Square, round, and “V” grooves
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Figure 6-69.—Knurled impressions.
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machined surfaces that could become
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produced by the same amount of seto
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cross-feed screw and the cross-slid
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When special threads are required b
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Figure 6-83.—Acme thread and form
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where An example of a pipe thread i
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The wire size you should use to mea
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Using the Thread-Cutting Stop Becau
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Figure 6-96.—Finishing the end of
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shown in figure 6-101. Two slots ar
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Figure 7-1.—Universal milling mac
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A. Spindle G. Spindle speed selecto
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with a split clamp to the overarm a
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to the table of the milling machine
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that most index heads have a 40 to
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Rapid indexing is used when a large
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or one complete turn plus 36 holes
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allows you to index divisions from
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from the one in which the pin is in
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Figure 7-24.—Side milling cutter.
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A. B. C. D. E. Figure 7-32.—Doubl
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Figure 7-36.—Inserted tooth face
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Figure 7-43.—Sprocket wheel cutte
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Figure 7-48.—Stub arbor. or on th
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Figure 7-54.—Spring collet chuck
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Figure 7-56.—Face milling. FACE M
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11. 12. 13. 14. 15. 16. 17. 18. 19.
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A. Lock screw for dog D. End mill B
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8. 9. 10. 11. 12. 13. 14. 15. 16. 1
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11. 12. 13. 14. 15. 16. 17. 18. 19.
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Figure 7-71.—Visual alignment of
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machine table. You will hold the cu
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Figure 7-77.—Boring with a fly cu
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Figure 7-79.—Vertical milling att
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Table 7-2.—Surface Cutting Speeds
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Table 7-4 shows recommended chip lo
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Figure 8-2.—A 36-inch vertical tu
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28.194 Figure 8-3.—Refacing a val
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HORIZONTAL BORING MILL The horizont
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7. After you have tightened the mou
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The table can be power driven to pr
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CHAPTER 9 SHAPERS, PLANERS, AND ENG
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Figure 9-3.—Swiveled and tilted t
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extent in planer and shaper work To
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the cutting speeds and related mach
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Figure 9-10.—Internal keyway: A.
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7. 8. 9. 10. 11. 12. 13. 14. Replac
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or housing attached on one side of
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Figure 9-18.—Engraving machine. F
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CUTTER SPEEDS The speeds listed in
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can readily see it after grinding t
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Figure 9-29.—Using an indexing at
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Any further movement of the work wi
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Figure 10-1.—Grain depth of cut;
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To select the proper work speed, ta
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Figure 10-8.—Magnetic chuck used
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can do on a surface grinder. Use th
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for straight cylindrical grinding o
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Figure 10-15.—Typical tooth rest
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of the work. Raise or lower the whe
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Figure 10-23.—Staggered-tooth sid
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Figure 10-28.—Grinding the periph
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Once the teeth are uniform, they sh
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After you have honed out the inaccu
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MACHINES With the rapid development
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Figure 11-3.—Slant bed for CNC la
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Figure 11-6.—A typical CNC contro
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Figure 11-8.—Continuous-path angl
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CHAPTER 12 METAL BUILDUP CHAPTER LE
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Figure 12-1.—Typical installation
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Figure 12-5.—A typical sandblaste
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Clean, dry air is essential for pro
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It can reduce the amount of masking
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quality assurance function of the p
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pass-fail. In our educational syste
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straighten a shaft, however, always
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Figure 13-4.—Lapping tools. has t
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pipe in which the valve is installe
Page 324 and 325: Figure 13-10.—Constant-pressure g
Page 326 and 327: When you install the control valve
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Page 330 and 331: Figure 13-17.—Removing a broken b
Page 332 and 333: Figure 13-23.—Metal disintegrator
Page 334 and 335: Figure 13-25.—Portable boring bar
Page 336 and 337: Figure 14-1.—Cutting specially sh
Page 338 and 339: For example, use the following proc
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Page 342 and 343: Figure 14-6.—Development of evenl
Page 344 and 345: Table 14-1.—"K" Factor Table Tabl
Page 346 and 347: Figure 14-11.—Standard universal
Page 348 and 349: 6. Find the NPD. 7. Find the 8. Fin
Page 350 and 351: FA - Face angle OD - Outside diamet
Page 352 and 353: 7. Pitch diameter (PD)—This is th
Page 354 and 355: SELECTING A BEVEL GEAR CUTTER To cu
Page 356 and 357: Figure 14-20.—Profiling a bevel g
Page 358 and 359: . Use the following formulas to sol
Page 360 and 361: Figure 14-25.—Milling machine set
Page 362 and 363: 9. Diametral pitch (DP) METHOD OF M
Page 364 and 365: explains the classes and the manufa
Page 366 and 367: GRAINS (irregularly shaped crystals
Page 368 and 369: Figure 15-2.—Microscopic structur
Page 370 and 371: Figure 15-5.—Typical structure of
Page 372 and 373: Figure 15-8.—Grid for heat-treati
Page 376 and 377: cases. A wide variety of quenching
Page 378 and 379: These various temperature arrests o
Page 380 and 381: known as pearlite, and the A1 tempe
Page 382 and 383: quickly cooled to and held at a som
Page 384 and 385: Available information indicates tha
Page 386 and 387: slowly from the tempering temperatu
Page 388 and 389: Table 15-4.—Heat-Treating Tempera
Page 390 and 391: Figure 15-20.—Design of a cam. A.
Page 392 and 393: In carburized steel, spalling is ca
Page 394 and 395: used to make positive identificatio
Page 396 and 397: HONING—Finishing machine operatio
Page 398 and 399: Table AII-2.—Decimal Equivalents
Page 400 and 401: Table AII-4.—Formulas for Dimensi
Page 402 and 403: Table AII-5.—Number, Letter and F
Page 404 and 405: Table AII-7.—Screw Thread and Tap
Page 406 and 407: Table AII-9.—3-Wire Method of Mea
Page 408 and 409: Table AII-11.—Circles Circumferen
Page 410 and 411: Table AII-13.—Taper Per Foot and
Page 412 and 413: p 1 I vi 2 P F \ = = a AII-16
Page 414 and 415: Table AII-16.—Drill Sizes for Tap
Page 416 and 417: Having Circular pitch Circular pitc
Page 419 and 420: APPENDIX IV DERIVATION OF FORMULAS
Page 421: (1) NT is the connecting link betwe
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Walker, John R., Machining Fundamen
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A Adjustable gauges, 1-7 adjustable
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Engine lathes, 6-1 attachments and
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Layout methods, 2-8 M forming angul
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Stub tooth gears, 14-27 American st
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