DML MIDTERM EXAM QUESTIONS WITH 100% CORRECT ANSWERS!!

which of the following are true: a. sheetmetal refers to workpieces with a high ratio of surface area to thickness b. sheets are defined as <= 1/4" in thickness c. plates are defined as >= 1/4 " in thickness d. pulling, pushing, and stretching are the most common sheetmetal operations - ANS A, B, and C The Lab has the following sheetmetal capabilities: A. shear B. Brake (bending machine) C. punch press for creating holes D. deep drawing/ stretch forming - ANS A, B, C what is the structural benefit of bending sheetmetal edges/ flanges? - ANS makes it more rigid Which of the following are key element to decision matrices? A. clearly defined & weighted objectives B. Justified magnitude assignments with traceable supporting data C. always try to use linear score assignments D. highest scoring concept wins - ANS all of the above why are separate evaluation matrices created for separate functional subunits of a design? - ANS pick the best subunits because we can combine them T/ F manufacturing time is an example of a qualitative assessment? - ANS False What are (4) the things that can cause calipers to measure inaccurately? - ANS failure to zero the calipers before use debris, chips, or burrs failure to hold the jaws perpendicular to the surface inadequate or excessive closing pressure T/ F Your group must have a fully dimensioned, appropriately toleranced part drawing for each part manufactured in the lab - ANS TRUE T/ F If anyone in your group doesn't understand how each part of your design works, that person will be instructed to stop working until they do - ANS TRUE What should do if anyone in your group makes excuses for not completing their work on time or at an acceptable quality: A. accept effort, not excuses and isntrcut the person to redo the assignment B. make a record of tehir work quality or tardiness on your meeting documentation C. if the problem isnt resolved within 48 hr., get Mike involved because youre here to learn D. wait to confront the problem in hopes that doing so may avoid conflict - ANS A, B, C T/ F Purchase orders must be submitted next week before using ANY raw materials in the lab - ANS TRUE T/ F ECN's are used to formally track design changes and corrections through the project prototyping and life- cycle phase - ANS TRUE Groups which care about their success on the course project will read the Project Tips posted on the website and do which of the following: A. review their weekly schedule and plan their individual work assignments B. review part drawings in office hours with a TA to be prepared to make the parts in lab C. complete paperwork outside their formal lab block D. print working copies of non- OTS part drawings for reference during lab E. use 80/20 wisely by selecting pre- cut pieces before cutting longer pieces to length; and only cutting the shortest over-size pieces to the necessary lengths F. bring 1:1 scale printed and trimmed sheetmetal templates to lab to expedite part fabrication G. prepare for the Tapped Hole Quiz H. have a backup plan in case a machine their group needs is being used I. always wait for their TA to answer questions - ANS A- H Use OTS/ custom part - ANS OTS use larger/ smaller feature tolerances - ANS larger use coarse/ finer surface finish specifications - ANS coarser use fewer/ more finished surfaces - ANS fewer use fewer/ more dimension datums - ANS fewer use stronger/ weaker material - ANS weaker use tapped/ thru - bolted holes - ANS thru- bolted use blind/ thru holes when reasonable - ANS thru use cone- bottomed/ flat- bottomed holes - ANS cone- bottomed use arbitrary/ nominal part dimensions - ANS nominal design parts to be larger/ smaller - ANS smaller design parts for max/ min raw stock removal - ANS min design parts to use larger/ smaller cutting tools - ANS larger design parts fewer/ more fillets - ANS fewer design around custom/ standard cutting sizes - ANS standard avoid/ use mirror image parts - ANS avoid make acceptable/ great detailed part drawings - ANS great you must come to lab each week with long ____, proper ____, and printed equipment ______ ________ - ANS pants, shoes, safety sheets never leave the ______ ______ in the lathe chuck - ANS chuck key never reach over the rotating ______ on the lathe for any reason because of the dangerously protruding ______ ______ - ANS chuck, chuck jaws always _____ and ______ the milling machine spindles before changing tools over the plastic _____ _______ - ANS raise, lock, table cover Always check the milling machines and lathes are in _____ range before turning them on - ANS high Always adjust the _____ _____ with the mills, lathes, and drill presses running - ANS spindle speed Never pull _____ off the machines using your hands; use a rag instead - ANS chips always engage the workpiece ______ to avoid chipping the fragile cutting inserts/ edges - ANS gently always wear _____ when working with sheetmetal, except when using ____ _____, such as bandsaws, drill presses, grinders, and sanders - ANS gloves, power tools never cut any material except _____ on the marvel bandsaw - ANS aluminum always take time to _____ each workpiece after cutting to remove the sharp edges which can injure a teammate or TA - ANS debur using a(n) ______ arc to heat separate pieces of _____ material to be joined to a temp high enough to cause _____ and coalescing - ANS electric, similar, melting List the three most common types of electric arc welding - ANS SMAW, GMAW, GTAW T/ F Dissimilar metals can be joined using the arc welding process if the proper filler metal is used - ANS FALSE T/F The electrode used when MIG welding process if consumed as the weld is made - ANS TRUE What is the purpose of flux or shielding gas? - ANS to prevent rapid oxidation by preventing oxygen from coming into contact with the molten metal pool list 3 advantages of MIG welding - ANS easiest to learn fastest economical list 3 advantages of TIG welding - ANS strongest welds possible no post weld clamp can weld virtually any metal that is conductive whats the primary difference between MIG and TIG welding? - ANS MIG welding automatically feeds the filler wire into the weld pool; TIG welding uses a tungsten electrode to conduct the electricity and provide the heat source, and the actual filler wire is fed manually into the molten pool T/ F Most lab motor fasteners are metric and should be obtained by telling the TAs what size you need - ANS TRUE T/ F If any fasteners do not freely thread together by hand, you should stop and ask a ta before damaging expensive components - ANS TRUE T/ F when connecting the control box to the motors for the first time you must ask a TA for help - ANS TRUE T/ F When wiring the control box each subsequent time you must turn off the main power before changing any wiring to prevent electrical damage - ANS TRUE T/ F Before changing tools in the lathe the spindle must first be raised to an locked in its uppermost position - ANS FALSE T/ F The lathe chuck key should be removed from the chuck after clamping the tool securely - ANS FALSE T/ F Before changing the lathe between HI and LOW range you must ask for TA help - ANS FALSE T/ F Lathe, mill and drill press spindle speeds must be adjusted while the machines are OFF - ANS FAlSE T/ F Safety glasses must be worn any time you are in the shop, including during TA hours - ANS TRUE List 4 features CNC machines possess that allow increased productivity - ANS automatic tool change electronic probing high pressure coolant stiffer structures and more powerful motors list 4 drawbacks of cnc machining centers - ANS debugging more expensive require more frequent and more costly maintenance often slower for making one simple part/ feature list and define the two common methods of programming CNC machines - ANS conversational programing CAM Explain the two types of parts CNC machines are better suited for over manual machines - ANS complex parts requiring multiple axes of simultaneous motion mass production for what type of parts are manual machines a better choice than CNC machines - ANS simple, low quantity T/ F CNC machines always require less time to make a part than manual machines - ANS FALSE Which of the following machines in the lab could be automated via CNC technology? 1. milling machine 2. lathe 3. welder 4. sheetmetal shear 5. sheetmetal brake 6. sheetmetal punch - ANS all of the above List the easiest mistake to make when changing tools on milling machines - ANS raise lock and spindle list 3 things you should check before/ when turning on milling machines - ANS tool clearance speed range rotation direction list the most important rule when using manual lathes - ANS never leave chuck key in chuck T/F all sheetmetal parts are razor sharp after shearing and should therefore be deburred immediately after cutting - ANS TRUE T/ F This is the point in the semester when a serious accident is most likely to occur because of how easy it is to drop our guard and forget how dangerous the equipment can be if not used properly - ANS TRUE What are the principal benefits of allocating individual member tasks via a works schedule? A. it allows the team to honestly decide if it possesses adequate resources to complete the project within the allotted timeframe B. it allows the team to prepare for each lab session and work more efficiently C. it facilitates individual accountability D. all of the above - ANS D What is the equation governing maximum peripheral tool velocity as a function of tool size? - ANS V= pi x D x N What is the purpose and benefit of peck drilling? - ANS peck drilling help chips evacuate so they dont collect inside the hole and cause the drill bit overheat, seize and break What is the limiting factor for how fast a drill or endmill can rotate in a particular material? A. maximum speed of machine spindle B. type of taper/ collet used to hold tool C. number of flutes on the cutter D. heat generated in the cutting zone - ANS D What is the limiting factor for how fast a drill or endmill can feed thru any material? A. maximum speed of machine spindle B. operator courage C. phase of the moon at that particular hour D. size / strength of cutting edges/ lips - ANS D what is the limiting factor for how deep to cut (per pass) with an endmill in a particular material (assuming sufficient flute length)? - ANS cutting tool/ workpiece/ machine stiffness (which must resist the cutting forces and subsequent vibrations) Select six factors that affect optimum cutting speed for drilling and milling: 1. strength and thermal conductivity of material 2. depth of hole 3. presence and efficiency of cutting fluid 4. type, condition, and stiffness of cutting machine 5. stiffness of workpiece, fixture and tooling 6. quality of holes desired 7. whether you pay for replacement tools - ANS 1-5, 7 Heavy/ light cuts will use lower cutting speeds - ANS light when cutting stronger/ weaker materials you will use lower cutting speed - ANS stronger to minimize/ maximize tool life, you will use lower cutting speeds - ANS maximize when cutting flexible/ rigid workpieces, you will use lower cutting speeds - ANS flexible Calculate the spindle speed for a 1/2 inch HSS drill bit in mild steel when using a manual milling machine - ANS v = 100 ft/ min N = 12 x 100 / (pi x 1/2) = 760 rpm scale back 60 % = 460rpm calculate the feed rate for a 1/2 inch HSS drill bit in mild steel when using a manual milling machine - ANS Fr = 0.008 in/ rev f = 764 x .008 = 6.1 in / min scale back 60% = 3.7 in/ min What size clearance hole would you specify for a mounting bracket that uses M6 x 1.0 fasteners in (A) aluminum using loose tolerances or (B) steel using more precise tolerances? - ANS A. 6.60 mm (G) B. 6.30 mm (E) Define what is meant by the phrase design for manufacturability (DFM) - ANS consciously trying to design parts that can be manufactured for the lowest cost while meeting the required design intent and safety factors what is the typical tolerance range associated with free hand flame/ plasma cutting - ANS +- 0.050-0.100 what is the typical tolerance range associated with free hand grinding - ANS +- 0.020-0.050 what is the typical tolerance range associated with turning, milling - ANS +-.002-0.010 what is the typical tolerance range associated with drilling - ANS +-0.002-0.010 what is the typical tolerance range associated with boring - ANS +-0.001-0.005 what is the typical tolerance range associated with reaming - ANS +-0.0005-0.002 what is the typical tolerance range associated with bandsaw cutting, sheetmetal shearing, and sheetmetal bending - ANS +- 1/16- 1/8 in if a material's machinability refers to its ability to be easily machine to final shape, would stronger materials possess higher or lower machinability? - ANS lower how should engineers select materials to meet strength and manufacturability requirements? - ANS always select the weakest material that meets the strength requirement summarize the relationship between (minimum) achievable dimensional tolerance and part size - ANS as part/ feature size increases, so does the minimum achievable part/ feature tolerance summarize the relationship between relative production time and feature surface finish - ANS relative production time increases exponentially in relationship to desired surface finish list 8 design mistakes which can cause us to look like we dont know what were doing - ANS 1. designing clearance holes as line fits 2. specifying incorrect threads for the material type 3. specifying tapped holes with less than 5 threads of engagement 4. drawing unnecessary fillets and curves which cause an otherwise simple part to require a CNC 5. designing square of "D" shaped holes to be made using traditional processes 6. finishing all part surfaces 7. failing to consider room for assembly tools 8. designing a part which can be purchased OTS list 15 dimensioning mistakes that cause us to look like we dont know what were doing - ANS 1. omitting necessary dimensions 2. omitting tolerances for ANY dim (or assigning one tolerance for all dims) 3. dimensioning to hidden lines 4. showing hidden lines or dimensions in iso views 5. duplicating dimensions in multiple part views 6. dimensioning which requires the manufacturer to perform calculations to make the aprt 7. dimensioning a hole by its radius or an arc by its diameter 8. specifying metric thread callouts as UNC/ UNF 9. specifying metric thread lengths in inches 10. poor print quality 11. dimensions placed carelessly over part views 12. shading in isometric or orthographic views 13. inconsistent line weights across dimensions 14. disproportionately scaled dimensions 15. too many views on one page define the casting process and explain when it would be used - ANS pouring molten metal into a mold and allowing it to cool and solidify to produce a part that is near net shape list the two types of parts casting is good for - ANS complex or hollow parts mass production T/ F the suitability of parts for the casting process is independent of desired quantity - ANS TRUE Define the forging process and explain when it would be used - ANS deforming heated SOLID metal using hammers or dies to increase material STRENGTH while maintaining good TOUGHNESS List the type of parts forging is good for - ANS high strength parts requiring high toughness T/ F the suitability of parts for the forging process is independent on desired quantity - ANS TRUE rank the following materials by assigning score between 4 (weakest) and 10 (strongest) based on their relative strengths (4, 7, 10): billet metal cast metal forged metal - ANS billet: 7 cast: 4 forged: 10 when working in industry what happens if we cant communicate effectively, design simple parts that can be easily manufactured, create decent part drawings, or read measuring instruments correctly? - ANS we look ignorant and lose credibility with our coworkers, bosses, and customers T/ F There is no such thing as a dumb question in this course - ANS TRUE T/ F There is no such thing as a dumb question once you are hired and start working for a company - ANS FALSE T/ F Every part you design or drawing you make from this point forward is a reflection of your intelligence and design capability - ANS TRUE T/ F A vital part of your success as a design engineer is to realize what an enormous resource those with more design and manufacturing experience can be to your professional development - ANS TRUE T/F The best manufacturing shops do not need your work, so you have to convince them your parts will be easier to make than your competitors by using proven DFM techniques, clear, complete and concise drawings, and by listening to their feedback on how to simplify your parts while achieving the desired function - ANS TRUE use larger/ smaller part tolerances - ANS larger use coarser/ finer surface finishes - ANS coarser use tapped/ thru- bolted clearance holes - ANS thru- bolted clearance use screw/ bolt holes - ANS bolt use blind/ thru holes - ANS thru specify cone- bottomed/ flat- bottomed holes - ANS cone- bottomed make the part larger/ smaller - ANS smaller design parts for min/ max raw- stock removal - ANS min design parts to use larger / smaller cutting tools - ANS larger design parts to use cutting tools with larger/ smaller L:D ratios - ANS smaller design parts around custom/ standard cutting tool sizes - ANS standard design parts with / without chamfers and fillets - ANS without avoid/ use mirror image parts - ANS avoid use clearance/ line fits for fasteners holes - ANS clearance always/ never design parts that can be purchased OTS - ANS never specify slots or pockets with round/ square corners when using traditional mfg. equipment - ANS round consider/ ignore room for assembly tool - ANS consider always place fastener threads in shear / tension - ANS tension use fasteners/ pins for locating parts with respect to each other - ANS pins specify (8) 1/4- 20 UNC threads in aluminum/ (8) 1/4-28 UNF threads in steel/ either - ANS (8) 1/4- 20 UNC threads in aluminum specify (8) 1/4-28UNF threads in steel/ (8) 1/4- 28 UNF threads in titanium/ either - ANS (8) 1/4-28UNF threads in steel specify (8) 1/4 -20 UNC threads in aluminum/ (8) 4-40 UNC threads in aluminum/ either - ANS (8) 1/4 -20 UNC threads in aluminum specify (8) 1/4-28 UNF threads in steel/ (4) 2-64 UNF threads in steel/ either - ANS (8) 1/4-28 UNF threads in steel specify (8) 1/4 -20 threads in aluminum/ (8) M6x1.0 threads in aluminum/ either - ANS either specify (8) 1/4-20 UNC threads in aluminum/ (8) 1/2 -13 UNC threads in aluminum/ either - ANS (8) 1/4-20 UNC threads in aluminum which of the following is not a common component of an engine lathe: A. headstock B. cross slide C. tool post D. tailstock E. ram - ANS E what rotates on a lathe: A. cutting tool B. chuck C. material/ workpiece D. B&C E. none of the above - ANS D T/ F turning is a metal cutting process used mainly for the generation of rectangular surfaces - ANS FALSE which of the following is not a common workholding method on a lathe: A. holdng in a chuck B. holding between centers C. holding in the tailstock D. holding in a collet - ANS C when operating a lathe the tool bit should typically be positioned: A. above center to obtain better surface finish B. below center to enhance chip evacuation C. directly on the spindle centerline D. none of the above - ANS C list three required items you must bring every week to your lab and TA office hours - ANS safety sheets, pants, proper shoes T/ F Milling is a metal cutting process used primarily for the generation of cylindrical surfaces - ANS FALSE what rotates on a milling machine A. material/ workpiece B. cutting tool C. spindle D. B&C E. none of the above - ANS D common types of milling machines include: A. knee and column mills B. bed mills C. turret mills D. drill mills E. A&B - ANS E which of the following is the most common workholding method on a milling machine: A. holding in a chuck B. holding between centers C. holding in a vise D. holding in a collet E. holding in your hands - ANS C Explain the difference between relay and proportional control - ANS relay- on and off proportional - can alter how much voltage list 5 benefits of using 80/20 - ANS easy to assemble common tools low density reusable relatively strong the following are dangerous to wear when operating powered equipment: A. shorts or open toed shoes B. long hair not tied back C. jewelry on your hands or wrists