Chapter 6: Knowledge Check

Check Your Knowledge: Chapter 6

Quiz yourself using the following chapter review questions to check how well you can recall the material.

Review Questions

1. Why Create a Job Plan?
   1. A job plan will help conserve material
   2. It will help you determine the tools needed
   3. A job plan will establish a sequence of steps in an efficient order 
   4. All of the above
2. What’s so important about holding? Accordian:
   1. How does the way a part is held relate to the size of material needed?
   2. How does holding the part influence the order of operations?
   3.  How can the way a part is held indicate if fixtureing will be needed?
3. True or false: Cutting the groove after the holes are drilled is a good decision.
4. Picture this…Accordian:
   1. Will this part be made from bar stock, or plate material?
   2. Considering material conservation, which material, bar or plate, would be more economical?
   3. Why would a round part be supplied in a square configuration?
5. True or false: Technical drawings are the primary means of communication between the designer, or customer, and the machinist.
6. Use the correct term to complete the sentence. When removing a small amount of material off of a large flat surface, a ______________ should be used.
7. To remove the least amount of material for the thickness, this process should be chosen.
   1. Have someone else show you how
   2. Use sandpaper, and a flat block
   3. Use a surface grinder
   4. Cut with a face mill
8. Choosing the material to make the bench block: Accordian:
   1. 12L14 mild steel
   2. Aluminum 6061
   3. Acetal plastic
9. True or false: The most efficient type of material removal is by sawing, or drilling.
10. What should be considered, regarding efficiency, when making a job plan?
    1. The shape of the stock compared to the finished part
    2. The number of parts
    3. The tolerance of the part
    4. All of the above
11. True or false: Using strap clamps or a vice are the two most common ways of holding parts on a mill.
12. Working on a lathe Accordian:
    1. Choose a three jaw chuck when…
    2. A four jaw chuck is a good choice when…
    3. Choose a collet chuck when…
13. True or false: When deciding on the sequence of steps to create the part and how to hold it at each stage, notes should be taken so that a step is not missed during production.
14. True or false: Time should be spent at the start of the job to become familiar with the part by reading the technical drawing.
15. True or false: Planning starts with what feature is being cut and how it is held while being cut.

Answer Key

1. All of the above – Correct!;
2. Accordian answer:
   1. If the material is significantly bigger than the finish size of the part, something simple like a vice can be used to hold it. With the bench block, minimal material is available in its height. Dovetail vice jaws can maximize grip with minimum surface contact.
   2. Choice 1, hold the bench block in a dovetailed vice. Cut the profile. Now the challenge is how to hold it to drill the holes.
      Choice 2, drill the holes while it is a square, then cut the profile.
      By choosing #2, and determining how the part is held, it has been established that the holes need to be drilled before the profile is cut.
   3. An option would be to use the holes to mount the bench block onto a fixture to enable a full length profile to be cut.
      Pro – profiling of the part only has to be done once
      Con – extra components need to be made to help complete the part
3. True – An end mill can cut through a part with holes without any problems.
4. Accordian answer:
   1. In Figure 6.3, the stock material is shown to be a square. Therefore, the material used will be plate steel.
   2. Bar stock would be more economical, but could require special tooling to hold it as it is worked on.
   3. The material for some jobs are “customer supplied”. This means that the customer gives the machinist the material for creating the parts. This is the only material allowed to be used for the customers parts.
5. True – Yes, The drawings act as a contract between the machinist and the designer. Instructions, and specifications are stated to achieve a desired result.
6. face mill / shell mill / fly mill / fly cutter – Yes, this will be the most efficient way of removing material from a large flat surface.
7. Use a surface grinder – This is the best choice. Creates a flat surface with minimal material removed
8. Accordian answer:
   1. Best choice for the bench block when frequently used
      Good strength, dimensional stability
      Excellent machinability
      Good wear resistance. The holes in the bench block will wear the least with this choice.
   2. Good choice for the bench block when use is moderate to low
      Excellent machinability, corrosion resistant.
      Preferably, use carbide tooling with a sharp edge and a high helical angle to improve chip evacuation.
      Good strength to weight ratio
      Use of coolant is recommended to help reduce heat. Heat can cause thermal expansion, and poor surface finish.
   3. Ok choice for the bench block. Use should be low to infrequent to reduce wear.
      Knowledge of speeds and feeds is critical for this material as it is susceptible to melting if excessive heat is encountered.
      Good wear resistance in general. The holes in the bench block may degrade with frequent use.
      Good dimensional stability.
      Not recommended if solvents such as ketones will be present.
      Water may also be absorbed and affect dimensional accuracy.
9. True – Yes, the nature of the cuts are continuous. This is the best way to rapidly remove significant material.
10. Yes, All the above. A machinist should always be looking at what is being worked on with an eye to “how can this be done better?”
11. True – Correct! Strap clamps and vices are the most common and versatile work holding tools found in machine shops. The jaws on the vice can be easily modified to dovetail jaws to allow even more clearance around the part with minimal engagement.
12. Accordian answer:
    1. The three jaw chuck is a good choice as a first operation, or when there is sufficient material to be removed. This is a quick, and easy setup.
    2. The parts are irregular, or existing features need to be dialed in to ensure that the part runs true.
    3. Concentricity needs to be maintained, with minimal runout. This is a quick setup, but can require a larger investment of tooling as the colletts have a narrow range of holding.
13. True – Yes, notes can be referenced when working on the part to ensure all of the features are made.
14. True – Determining where the critical areas, tight tolerances, of the part are will aid in the planning. For example; If a lathe part needed to retain concentricity, a collet chuck would be used.
15. True – Yes, this sequence repeats for each feature.