3299710
Description
Flashcards by Vincent Bergeron, updated more than 1 year ago
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Created by Vincent Bergeron
over 8 years ago
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| Question | Answer |
| Name three materials used to manufacture drills and state the advantage of any two. | carbon tool steel - hobby shops HSS steel - twice as fast as carbon steel cemented carbides - for hard material. three times as fast as HSS |
| Define the body, web, and point of a twist drill. | BODY: portion of drill between the point and the shank WEB: Thin partition in the center of the drill that extends the full length of the flutes POINT: The tip of the drill, consists of the chisel edge, cutting edge, heel and body clearance |
| State the purpose of this part: Tang | On the end of a tapered shank to prevent the drill from slipping while it is cutting and allows the drill to be removed without the shank being damaged |
| State the purpose of: Flutes | They form the cutting edges, admit cutting fluid and allow the chips to escape from the hole |
| State the purpose of: Margin | it is the narrow raised section on the body of the drill. its purpose is to provide a full size to the dill body and cutting edges |
| State the purpose of: Body clearance | it is the undercut portion of the body between the margin and the flutes. it is made smaller to reduce friction between the drill and the hole. |
| Why are various drill points and clearances used for drilling operations? | to suit the wide variety of materials drilled |
| Describe and state the purpose of the following drill points: Conventional | 118 degrees general purpose drilling |
| Describe and state the purpose of the following drill points: long angle | 60 to 90 degrees used for drilling non ferrous materials |
| Describe and state the purpose of the following drill points:: flat angle | 135 to 150 degrees used to drill hard and tough material |
| Why is it necessary to thin the web of a drill? | to reduce pressure and heat while drilling |
| List four systems of drill sizes and give the range of each. | Fractional drill sizes Number drill sizes Letter drill sizes Millimeter (metric) drill sizes |
| State the purpose of the high-helix drill | for drilling deep holes in aluminum, copper, die cast material and other material where the chips have a tendancy to jam in a hole |
| State the purpose of the Core drill | has three or four flutes. used to enlarge cored, drilled or punched holes. |
| State the purpose of the Oil hole drill? | has one or two oil holes to force oil to the cutting edge cooling the drill and forcing chips out |
| State the purpose of the Straight-fluted drill | for drilling soft materials like brass copper or plastic. straight flutes prevent the drill from drawing itself into the material while cutting |
| State the purpose of the gun drill. | used for producing holes as deep as 20ft |
| State the purpose of the hard-steel drill | used for drilling hardened steel |
| What problems generally result from the use excessive speed and excessive feed? | excessive speed = wear at corners of drill excessive feed = breakdown of chisel point and cutting edges/lips |
| Discuss excessive lip clearance and insufficient lip clearance. | excessive clearance = lack of support behind cutting edge insufficient clearance = causes drill to rub behind the cutting edge |
| What is the effect of drills with unequal angles on the cutting lips? | one cutting edge works harder than the other causing bellmouth holes and poor tool life |
| What is the effect of drills with cutting lips unequal length? | produces oversize holes |
| What are the characteristics of a properly ground drill? | both cutting lips should be same length both cutting lips should be same angle lips free from wear or nicks no sign of wear on the margin |
| Unit 41: Why is it important that a drill be operated at the correct speed? | Placeholder |
| explain the difference between cutting speed and r/min. | Placeholder |
| What factors determine the most economical drilling speed? | Placeholder |
| Calculate the r/min required to drill the following holes using a high-speed drill: A 3/8 in diameter hole in tool steel | placeholder |
| Calculate the r/min required to drill the following holes using a high-speed drill: A 1-inch diameter hole in aluminium | placeholder |
| Calculate the r/min required to drill the following holes using a high-speed drill: a 9 mm hole in steel casing | placeholder |
| Calculate the r/min required to drill the following holes using a high-speed drill: a 20 mm hole in cast iron | placeholder |
| What is the purpose of a cutting fluid | Placeholder |
| Name four important qualities that a cutting fluid should have? | Placeholder |
| Select three of the most important safety suggestions and explain why they should be observed? | Placeholder |
| What result might be expected from too high a drill speed? | Placeholder |
| What results might be expected from too low a drill speed? | Placeholder |
| Why is it good practise to start each hole with a center drill? | Placeholder |
| State three reasons a center drill should be removed from the work frequently. | Placeholder |
| Why should center holes not be drilled too shallow? | Placeholder |
| Why should center holes not be drilled too deep? | Placeholder |
| What is the purpose of spotting a hole before drilling? | Placeholder |
| How deep should each hole be spotted? | Placeholder |
| What is the purpose of fastening a clamp or table stop to the left side of the drill press table? | Placeholder |
| When should drilling pressure be eased? | Placeholder |
| List the procedure for laying out a hole before drilling to a layout? | Placeholder |
| How deep should the hole be drilled before the drill point indentation is examined? | Placeholder |
| Explain how a drill may be drawn over to a layout. | Placeholder |
| List three disadvantages of a thick web found on large drills. | Placeholder |
| What are pilot holes and why are they necessary? | Placeholder |
| Why should pilot holes not be drilled any larger than necessary? | Placeholder |
| How high should the drill press table be adjusted when drilling large holes? | Placeholder |
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