Rules of Thumb for Mechanical Engineers 2010 Part 17 ppt

390 Rules of Thumb for Mechanical Engineers XYZ Company Balance Sheet As of March 31, 1994 ASSETS Current Assets: Cash $25,000.00 Accounts Receivable $268,000.00 Inventory $1 63,000.00 Total CurrentAssets $456,000.00 Property, Plant &Equipment Building $600,000.00 Equipment $300,000.00 Land - $100,000.00 less Accumulated Depreciation ( $250,000.00) $350,000.00 less Accumulated Depreciation ($1 25,000.00) $1 75,000.00 Toial Properly, Plant & Equipment $625,000.00 To tal Assets 81,087,LkXl.tW Liabilities Current Liabilties: Accounts Payable Salaries Payable Interest Payable Income Tax Payable Total Current Liabilities Notes Payable Long- Term Liabilities: Total Liabilities $275,000.00 $1 95,000.00 $1 3,000.00 $36,000.00 $519,000.00 $260,000.00 $779,000.00 owner’s tstockholder’s) Capital Stock $200,000.00 Retained Earnings $102,000.00 Total Owneris Equity $302,000.00 $1,08l,~.tW Total Liabilities & Owner’s Equity tal by expensing the portion of each asset “consumed” during each income statement’s time period. Depreciation is a noncash expense, since no cash flow actually occurs to pay for this expense. The book value of an asset is shown in the balance sheet, and is simply the purchase price of the asset minus its accumulated depreciation. There are several methods used to calculate depreciation, but the easiest and most frequently used method is straight-line depreciation, which is calculated with the following formula: Cost - Salvage Value Expected Life of Asset Depreciation Expense = Straight-line depreciation allocates the same amount of depreciation expense each year throughout the life of the asset. SaZvage value (residual value) is the amount that a company can sell (or trade in) an asset for at the end of its useful life. “Accelerated” depreciation methods (such as sum-of-the-yearsy-d&ts and declining balance methods) are available and may sometimes be used to expense the cost of an asset faster than straight-line depreciation. Howev- Engineering Economics 391 XYZ Company Income StaWnent For the Quar&r Ended Mbrch 31, 1994 Sales Revenues Less: Cost of Goods sold Gross Margin Less: Operating Expenses Selling expenses $295,000.00 Salaries expense $526,000.00 Insurance expense 832,000.00 Property Taxes $27,000.00 Depreciation, Building $70,000.00 Depreciation, Equipment $35,000.00 Income from Operations Other Income Sale of Assets $1 6,000.00 Interest Revenue $2,000.00 Less: Interest Expense Income before Taxes Less: lnwme Tax Expense Net Income $2,450,000.00 ( 81,3~,~.~1 $1,075,000.00 ($985,000.001 $90,000.00 $1 8,000.00 $108,O00.00 ($22,0.001 $86,o0O.00 ( $34,400.001 $5 1,,6yx) OO XYZ Company Statement of Changes in Retained Earnings For the Quamr Ended Mbrch 31, 1994 Retained Earnings, Dec. 31,1993 $50,400.00 Net Income, Quarter 1,1994 Retained Earnings, March 31, 1994 er, the use of accelerated depreciation methods is gov- erned by the tax laws applicable to various types of assets. A recent accounting textbook and tax laws can be consulted for further information about the use of accelerated de- preciation methods. The pfit (or loss) for the time period of the income state- ment is carried over as retained earnings and added to (or subtracted from) owner’s equity, in the “statement of changes in retained earnings” illustration. If the company paid out any dividends to its stuckholders dur- ing this time period, that amount would be shown as a de- duction to retained earnings in this financial statement. This new retained earnings amount is also reflected as the retained earnings account balance in the current balance sheet. The last financial statement is the statement of cash flows, which summarizes the cash inflows and outflows of the company (or other accounting entity) for the same time period as the income statement. This statement’s purpose 392 Rules of Thumb for Mechanical Engineers Statement Of c8Sb FIOHW For the Quartet Ended Mrch 31,194 Net hcome $51,600.00 Adjustments to reconcile net income to cash flowfrom op. advities: Decrease in accounts receivable $5,000.00 Increase in inventory ( $1 5,000.00) Increase in accounts payable $25,000.00 Decrease in salaries payable $5,000.00 Depreciation expense, equipment $35,000.00 Depreciation expense, building $70,000.00 Total Adjustments: $1 25,000.00 Net cash ffo w Iiom opefating ac6vi~es: Sl76,sOo.al is to show where the company has acquired cash (inflows) and to what activities its cash has been utilized (outflows) during this time period. The statement divides and classi- fies cash flows into three categories: (1) cash provided by or used by operating activities; (2) cash provided by or used by investing activities; and (3) cash provided by or used by financing activities. Cash flow from operations is the cash generated (or lost) from the normal day-to-day operations of a company, such as producing and selling goods or ser- vices. Cash flow from investing activities includes selling or purchasing long-term assets, and sales or purchases of investments. Cash flow hm financing activities covers the issuance of long-term debt or stock to acquire capital, pay- ment of dividends to stockholders, and repayment of prin- cipal on long-term debt. The statement of cash flows complements the income Statement, because although income and cash flow are related, their amounts are seldom equal. Cash flow is also a better measure of a company’s performance than net income, be- cause net income relies upon arbitrary expense allocations (such as depreciation expense). Net income can also be ma- nipulated by a company (for example, by reducing R&D spending, reducing inventory levels, or changing accouflting methods to make its “bottom lie” look better in the short- term. Therefore, analysis of a company’s cash flows and cash flow trends is frequently the best method to evaluate a com- pany’s performance. Additionally, cash flow rather than net income should be used to determine the rate of return earned on the initial investment, or to determine the value of a company or financial project. (Value is determined by dis- counting cash flows at the required rate of return.) The statement of cash flows can be prepared directly by reporting a company’s gross cash inflows and outflows over a time period, or indirectly by adjusting a company’s net income to net cash flow for the same time period. Ad- justments to net income are required for (1) changes in as- sets and liability account balances, and (2) the effects of non- cash revenues and expenses in the income statement. For example, in comparing XYZ Company’s current balance sheet with the previous quarter, the following in- formation is obtained about current assets and liabilities: Cash increased by $10,000 Accounts receivable decreased by $5,000 Inventory increased by $15,000 Accounts payable increased by $25,000 9 Salaries payable increased by $5,000 Additionally, the balance sheets show that the company has paid off $166,600 of long-tern debt this quarter. This in- - Cash flow from financing activities: Retirement of longkrm debt (notes payable) Net cash flow hm financing acUviiies: ($1 66,600.00) ($1 66,m.00 Net hcreese in cash: $10,000.00 81 5,000.00 $25,000.00 Cash account balance, Dec. 31,1993 Cash account balance, March 31,1994 Engineeting Economics 3Q3 formation from the balance sheets, along with the non- cash expenses (depreciation) from the current income state- ment, are used to prepare the “statement of cash flows.” The example demonstrates the value of the statement of cash flows because it shows precisely the sources and uses of XYZ Company’s cash. Additionally, it reconciles the cash account balance hm the previous quarter to the amount on the current quarter’s balance sheet. Engineering Economics 1. Newman, D. G., Engineering Economic Analysis. San Jose, CA Engineering Press, 1976. 2. Canada, J. R. and White, J. A., Capital Investment De- cision Analysis for Management and Engineering. En- glewmd Cliffs, NJ: PrenticeHall, 1980. 3. Park, W. R., Cost Engineering Analysis: A Guide to Economic Evaluation of Engineering Projects, 2nd ed. New York Wiley, 1984. 4. Taylor, 6. A., Managerial and Engineering Economy: Economic Decision-Making, 3rd ed. New York: Van Nostrand, 1980. 5. Riggs, J: L., Engineering Economics. New York Mc- 6. Barish, N., Economic Analysis for Engineering and Managerial Decision Making. New York: McGraw- Hill, 1962. Graw-Hill, 1977. Finance 1. Bdey, R. A. and Myers, S. C., Principles ofcorporate 2. Kroeger, H. E., Using Discounted Cash Flow Efective- Finance, 3rd ed. New York McGraw-Hill, 1988. Zy. Homewood, IL: Dow Jones-Irwin, 1984. Accounting 1. Chasteen, L.G., Flaherty, R.E., and O’Conner, M.C. In- termediate Accounting, 3rd ed. New Yo& McGraw- Hill, 1989. 2. Eskew, R.K. and Jensen, D.L., Financial Accounting, 3rd ed. New York Random House, 1989. Addltional References Owner’s Manual from any Hewlett-Packard, Texas In- struments, or other make businesdfmancial calculator. Note: A business or financial calculator is an absolute must for those serious about analyzing investments and fi- nancial projects on anything more than an occasional basis. In addition to performing simple PV, FV, and mortgage or loan payment calculations, modem financial calculators can instantly calculate NPVs and IRRs (including multiple roots) for the most complex cash flow problems. Many cal- culators can also tabulate loan amortization schedules and depreciation schedules, and perform statistical analysis on data. The owner’s manuals from these calculators are ex- cellent resources and give numerous examples of how to solve and analyze various investment problems. Appendix Laurence D. Morris, Senior Technical Marketing Engineer-Large Commercial Engines, Allison Engine Company, Rolls-Royce Aerospace Group Conversion F~C~O~S " 395 Decimal Multiples and Fractions of SI units , 399 Systems of Basic Unifs 399 Temperature Conversion Equations 399 394 Appendix 395 Category Multiply BY To Obtain Acceleration Angle Area Density EnergyNVork ft/sec2 in/sec2 m/sec2 m/sec2 degrees degrees degrees degrees minutes radians revolutions seconds ft2 in2 yard2 mile2 acres m2 m2 m2 m2 m2 acres acres acres acres gram/cm3 ibrn/ft3 Ib,,.Jgallon (U.S. liquid) sluglft3 kg/m3 kg/m3 kg/m3 kg/m3 Btu erg ft-lb kilowatt-hour calorie newton-meter watt-second joule ioule 0.3048 0.0254 3.2808 39.3701 6.0000 1.745328 x 1 0-2 2.777778 x 1 0-3 3600.00 0.1 667 57.2958 360 2.77778 x 1 0-4 0.0929 6.451 6 x 1 0-4 0.8361 2.590 x 1 O6 4.047 x 1 O3 10.7643 1550.0 1.1 960 3.861 0 x 1 0-7 2.471 x 0.4047 4.356 x 1 O4 4.047 x 1 O3 1.562 x 1 0-3 1000 16.01 85 11 9.826 51 5.379 0.001 0.0624 8.3454 x 1 0-3 1.9403 x 1 0-3 1055.06 1.3558 3.600 x 1 O6 4.1 859 1 .ooo 1 .ooo 9.4781 x 1 0-4 1 .ooo x I 0-7 1.000 x 107 m/sec2 m/sec2 ft/sec2 in/sec2 minutes radians revolutions seconds degrees degrees degrees degrees m2 m2 m2 m2 m2 ft2 1n2 yard2 m11e2 acres hectares ft2 m2 m11e2 kg/m3 kg/m3 kg/m3 kg/m3 gram/cm3 ibrn/ft3 IbJgallon (U.S. liquid) slug/ft3 joule joule joule joule joule joule joule Btu erg (table continued on next page) 396 Rules of Thumb for Mechanical Engineers Category Multiply BY To Obtain EnergyNVork (cont'd) joule joule joule joule joule joule Btu kilowatt-hours Btu calorie kilowatt-hour ft-lb Force Length Mass Moment (Force) dyne pound (Ib) newton (N) newton foot (ft) inch (in) yard micron mile (mi) mile, nautical (nm) meter (m) meter meter meter meter meter mile, nautical (nm) mile mile mile pound mass (Ib,) slug ounce ton (metric) ton (2000 Ib,) kilogram (kg) kilogram kilogram kilogram kilogram pound mass ounce fOOt-pOUtId (ft-lb) dyne-centimeter newton-meter (N-m) 0.7376 2.7778 x 1 0-7 0.2389 1 .ooo 1 .ooo 2.930 x 1 O-" 341 2.97 253.0 2.655 x 1 O6 3.766 x 1 0-7 1.000 x 107 3.953 x I 0-3 1 -000 x 10-5 1.000 x 105 4.4482 0.2248 0.3048 2.540 x 1 0-2 0.91 44 1 .ooo x 10-6 1.6093 x 1 O3 1.8520 x 1 O3 3.2808 39.3701 1.0936 1 .ooo x 106 6.21 39 x 1 O4 5.3996 x 1 O-" 1.1 5076 0.86896 5280 1760 0.4536 14.5939 2.83495 x 1 0-2 1000.00 907.1 85 2.2046 0.0685 35.2739 0.001 0 1 .I 023 x 1 0-3 16 0.06250 1.35582 0.73756 I .ooo x I 0-7 ft-lb kilowatt-hour calories newton-meter dyne centimeters watt-second kilowatt-hours Btu calories Btu kilowatt-hour ft-lb newton (N) newton dyne pound (Ib) meter (m) meter meter meter meter meter foot (ft) inch (in) yards micron mile (mi) mile, nautical (nm) mile mile, nautical foot yard kilogram (kg) kilogram kilogram kilogram kilogram Ibm slug ounce ton (metric) ton (2000 Ib,) ounce pound mass newton-meter (N-m) N-m foot-pound (ft-lb) dyne-centimeter newton-meter 1 .ooo x 107 Appendix 397 Category Multiply BY To Obtain Moment of Inertia (Area) metel4 foot4 metel4 in4 Moment of Inertia (volume) mete6 foot5 mete6 in5 Moment of Inertia (Mass) m2-kg m2-kg in2-lb ft2-lb Power Pressure and Stress Btu/hour erglsecond ft-1 blsecond horsepower (HP) calories/second joulelsecond watt (W) watt watt watt watt watt ft-lb/second horsepower ft-l b/second calories/second horsepower Btu/minute atmosphere bar cm. of Hg (0%) in. of Hg (0°C) in. of H20 (4°C) dyne/cm2 Ib/ft2 Ib/in2 (psi) kilogram/cm2 (kg/cm2) newton/meteP (n/rn2) pascal (Pa) pascal pascal pascal pascal pascal pascal 1 15.861 8 8.63097 x 10s 2.40251 x lo6 4.1 6232 x 1 0-7 380.1 239 2.63072 x 1 Os 9.45870 x 1 O7 1.05723 x 1 O4 23.73034 4.21 401 3 x 1 C2 341 7.1 71 2.926397 x 1 O4 0.29307 1.35582 745.699 4.1 86 1 .ooo 3.41 21 4 0.737562 1.34102 x 103 0.2389 1.000 1.818 x los 550.06 0.32394 3.087 42.426 0.02357 1.000 x 10-7 1.000 x 107 1.01325~10~ 1333.22 3.386 x 1 O3 249.1 0 0.1 0000 47.88026 6894.757 9.8067 x 1 O4 1 .ooo 1 .ooo 9.86923 x 10-B 1.000 x 10s 7.50064 x 1 O4 2.953 x 10"' 4.01 4 x 1 O3 10.000 1.000~105 foot4 meteP in4 metel4 foot5 mete6 in5 mete6 ft2-lb m2-kg in2-lb m2-kg watt 0 watt watt watt watt watt Btu/hour erg/second ft-1 b/second horsepower caloriedsecond joule/second horsepower ft-l b/second calorieskecond ft-1 b/second Btu/minute horsepower pascal (Pa) pascal pascal pascal pascal pascal pascal pascal pascal pascal n/m2 atmosphere bar cm. of Hg (OOC) in. of Hg (OOC) in. of H20 (4°C) dyne/cm2 (table continued on next page) 398 Rules of Thumb for Mechanical Engineers Category Multiply BY To Obtain Pressure and Stress (cont’d) pascal pascal pascal bar atmosphere in. of Hg (OOC) Ib/in2 (psi) in. of H20 (4°C) Ib/in2 (psi) Velocity Volume feet/second (Wsec) inchkecond (i n/sec) kilometer/hour (km/hr) knot (nautical mi/hr) miledhour (mi/hr) meters/sec (m/sec) m/sec m/sec m/sec m/sec foot3 gallon (U.S. liquid) imperial gallon (U.K. liquid) inch3 cord board foot liter quart (U.S. liquid) barrel (U.S. liquid) centimete6 (cm3) fluid ounce (U.S. liquid) bushel (U.S. dry) peck (U.S. dry) mete? mete6 mete6 mete6 mete6 mete6 mete6 mete6 mete6 mete6 mete6 mete6 mete6 imperial gallon (U.K. liquid) gallon (U.S. liquid) gallon (U.S. liquid) liter 0.020885 1.450377 x 1 0-4 1.0197~10-~ 0.9869 1.01 32 0.491 2 2.0358 0.0361 3 27.678 0.30480 2.5400 x 1 0-2 0.27777 0.51 4444 0.447040 3.28084 39.38008 3.6001 0 1.94385 2.23694 2.831 685 x 1 0-2 3.78541 2 x 1 0-3 4.546087 x 1 0-3 1.638706 x 10” 3.62456 2.359737 x 1 0-3 9.463529 x 1 O4 0.1 589873 1 .ooo x 10-6 2.957353 x 1 0-5 3.523907 x 1 0-2 8.809768 x 1 0-3 35.31 4662 264.1 720 21 9.9694 6.1 02376 x 1 O4 0.275896 423.77604 1000.00 1056.688 6.28981 1 1.000x10~ 3.381 402 x 1 O4 28.37759 11 3.51 04 1.20095 0.83267 3.785 0.2642 1 .ooo x 10-3 I b/ft2 Ib/in2 (psi) kg/cm2 atmosphere bar Ib/in2 (psi) in. of Hg (OOC) Ib/in2 (psi) in. of H20 (4°C) meterdsec (m/sec) m/sec m/sec m/sec m/sec Wsec in/sec km/hr knot mi/hr mete6 mete6 mete6 mete6 mete6 mete6 mete6 mete? mete6 mete? mete6 mete6 mete6 foot3 gallon (U.S. liquid) gallon (U.K. liquid) inch3 cord board foot liter quart (U.S. liquid) barrel (U.S. liquid) centimeter3 fluid ounce (U.S.) bushel (US. dry) peck (U.S. dry) gallon (U.S. liquid) gallon (U.K. liquid) liter gallon (U.S. liquid) Appendix 399 Systems of Basic Units System Designation English (FPS) Metric (MKS) International (SI) Length foot (ft) meter (m) meter (rn) Mass pound (lb,,,) kilogram (kg) kilogram (kg) Time second (sec) second (s) second (s) Temperature degree Fahrenheit (OF) degree Celsius ("C) degree Kelvin (OK) Luminous intensity candela (cd) candela (cd) candela (cd) Electric Current ampere (4 ampere (4 ampere (4 Decimal Multirrles and Fractions of SI Units Factor 1 0' 1 02 10s 10s 1012 1018 1 09 1015 Prefix deka hecto kilo mega tera peta exa gigs Symbol Factor Prefix Symbol 1 0-1 1 0-2 103 10-6 10-12 10-18 1 0-9 10-15 deci centi milli micro nano pic0 fernto atto d m CI n P f a C Temperature Conversion Equations rF) ("C) ("19 ("R) (OF) = 9/5("C) + 32 ("C) = 5/9("F - 32) = "K - 273.1 5 (OK) = "C + 273.1 5 (OR) = 9/5("C) + 491.67 = "F + 459.67 = 9/5("K - 255.37) = 5/9("F + 459.67) = "R - 459.67 = 5/9("R - 491.67) = 5/9("R) = 9/5("K) Absdute zero temperature = -273.15"c = -459.6PF = 0.OO"K = 0.OO"R Fmezhg point of water = 0.00% = +3200°F = +273.15"K = +491.6PR Boiling point of water = +lOaOO"C = +212.00°F = +373.15"K = +671.6PR [...]... 389-393 decision and evaluation criteria accounting rate of return (ROR)method, 381 internal rate of return (IRR) method, 382-383 net present value (NPV) method, 383-384 payback method, 380-381 sensitivity analysis, 384-385 decision tree analysis, 385-388 time value of money 402 Rules of Thumb for Mechanical Engineers energy equation, 6 moment -of- momentum equation, 6 momentum equation, 6 boundary layer... condition monitoring cathodic protection, 197-205 coupons, 196 manual investigation, 196 pig-based monitoring systems, 195 process plant pipe 403 404 Rules of Thumb for Mechanical Engineers calculations, 189 definitions, 179 -187 pipe specifications, 187-188 sizing, 179 -187 storing pipe, 188-189 transportationpipe lines gas pipe lines, 1W191 liquid pipe lines, 192-194 steel pipe design, 190 Pitot tubes, 368,370... 163-164 oils, 1 1 6 preservation, 165-166 relubrication, 164-165 storage, 165-166 mounting bearing clearance, 172 -173 housings, 169 -171 seals, 174 shafting, 166-168 rating and life AI3MA definitions, 152-153 fatigue life, 153-54 life adjustment factors, 154-156 sleeve bearings, 175 -177 types of bearings ball bearings, 146-147 materials, 151-152 r l e bearings, 147-149 olr standardization,149-151 Beating,... 207-208 joint efficiencies, 217- 218 loadings, 208-209 materials selection guide, 224 maximum length of unstiffened shells, 221 procedure 1 general vessel formulas, 213-214 : procedure 2: stresses in heads due to internal pressure, 215-216 properties of heads, 218-220 stress, 209-212 stress analysis, 206-207 useful formulas for vessels, 222-224 volumes and surface areas of vessel sections, 220 pumps... properties, 55-56 phases of a pure substance, 52 thermodynamic properties, 53-56 types of processes, 56-57 types of systems, 56 Zeroth law of thermodynamics, 57-58 Torsion, 308 Tribology contact mechanics effect of friction on contact stress, 23 1 three-dimensional (point) Hertz contact, 229 two-dimensional ( i e Hrz contact of cylinders, 227-229 l n ) et yield and shakedown criteria for contacts, 232-233... frequencies, 256 bending (transverse) vibration of uniform beams, 253 definitions, 239-242 longitudinal and torsional vibration of uniform beams, 252 multiple degree of freedom systems, 245-246 natural frequencies of multiple DOF systems, 254 natural frequencies of simple systems, 251 one degree of freedom system, 243-245 planetary gear mesh frequencies, 255 rolling element bearing frequencies, 256 spring stifhess,... responsible for reliability, safety, supportability, maintainability, materials, warranties, life cycle cost, design, structures, instrumentation and logistics will find this book extremely useful 1996 252 pages, figures, tables, 8'h" x 11" lay-flat paperback T ISBN 0-88415-507-2 f63 #5507 $89 I I I I I I I I I I I I I I I I I I I I I MECHANICAL ENGINEERING I RULE8 OF 7 U - _ 6 W- - M FOR MECHANICAL. .. fatigue, 331 fatigue testing, 349 inspection techniques eddy-current inspection, 347 evaluation of failed parts, 347 fluorescent penetrant inspection (WI), 345 magnetic particle inspection (MPI), 345 radiography, 345-346 ultrasonic inspection, 345 liability issues, 350 nonmetallic materials, 348 stages of fatigue, 330 Finite element analysis, 246,320-327 Flexible rotor, 7 1 Flexible stator, 72 Flow... positive suction head (NPSH) and cavitation, 96 performance curves, 98-99 pump and head terminology, 93 pump design parameters and formulas, 93 pumping hydrocarbons and other fluids, 96 pumping power and efficiency, 97 pump similitude, 98 reciprocating pumps, 103-109 recirculation, 97 series and parallel pumping, 99 specific speed of pumps, 97 types ofPumps, 94 Radiation shields, 30 Radiography, 345-346... criteria for structural analysis, 305 guidelines for effective criteria, 305 strength design factors,305-306 finite element analysis, 320-327 flange analysis flush flanges, 315 undercut flanges, 3 1 6 fundamentalsof stress and strain compatibility, 297 definitions, 295-297 equilibrium, 297 plane stresslplane strain, 298 Saint-Venant’s principle, 297 superposition,298 thermal stresses, 298-299 mechanical . n/m2 atmosphere bar cm. of Hg (OOC) in. of Hg (OOC) in. of H20 (4°C) dyne/cm2 (table continued on next page) 398 Rules of Thumb for Mechanical Engineers Category Multiply. period as the income statement. This statement’s purpose 392 Rules of Thumb for Mechanical Engineers Statement Of c8Sb FIOHW For the Quartet Ended Mrch 31,194 Net hcome $51,600.00. 195 process plant pipe 404 Rules of Thumb for Mechanical Engineers calculations, 189 definitions, 179 -187 pipe specifications, 187-188 sizing, 179 -187 storing pipe, 188-189