Chapter 41
41-1. What are the major functional elements or departmental areas of the production system?
- Marketing and sales department
- Finance and accounting
- Manufacturing system
- Manufacturing engineering
- Personnel or human resources
- Research and development
- Design engineering
- Purchasing and procurement
- Production planning and control
- Inventory control
- Quality control
- Plant engineering or maintenance
41-12. If the supermarket were a factory, which kind of manufacturing system design would you say it was: job shop, flow shop, lean shop, project shop? Explain your answer.
A supermarket most closely resembles a flow shop because customers and products move through a standardized sequence of steps, especially at checkout (scan, bag, pay). Each transaction follows the same general process, which is characteristic of a flow shop system.
1-17. List three purposes of packaging operations.
1. Product design (styling) - a customer's first impression
2. Quality control - maintains the product's quality between completion and use
3. Material handling - prepares the product for delivery to the user
2-11. What are static properties?
Static properties are characteristics of a material under constant, non-moving, or slowly applied loads/forces.
3-1. What enables us to control the properties and performance of engineering materials?
We can manipulate material structure and composition through processing
41-2a. What is the function of a route sheet?
The route sheet is a document that lists the processes that must be performed to produce a part, in their sequential order, and the machines or workstations and tooling that will be required for each operation.
41-17. Now you have all your groceries at home and you want to prepare a meal - do you use a route sheet or an operations sheet? What's your operations sheet called?
When preparing a meal, you'd use an operations sheet, called a recipe.
1-25. If the rolls for the cold-rolling mill that produces the sheet metal used in your car cost $300,000 to $400,000, how is it that your car can still cost less than $20,000?
Although the rolls are expensive, they can create a high volume of cars, which allows companies to easily recuperate their costs.
2-21. What are two tensile test properties that can be used to describe the ductility of a material?
Percent elongation and percent reduction in area
3-25. What is a grain? A grain boundary?
41-3. What is a process flow chart? How is it related to the bill of materials?
- A process flow chart is an overview of the product, showing various levels of the product, subassemblies, and components.
- The bill of materials is the record of the relationship between the independent demand item (ex. car) and its dependent components (ex. tires, horn, windows). While the process flow chart describes HOW the product is built, the bill of materials defines WHAT goes into it.
1-3. The Subway sandwich shop is an example of a job shop, a flow shop, or a project shop, which?
A Subway sandwich shop is a FLOW SHOP because it uses a standardized assembly line where the sandwich moves through fixed workstations in a specific sequence. While you can customize your toppings, the linear "Bread → Meat → Veggies → Pay" process remains identical for every customer.
1-30. In view of Figure 1.2 (page 2), who really determines the selling price per unit?
The selling price is determined by multiple people/factors:
1. Manufacturing & engineering costs (how the product is designed and built) - 55%
2. Marketing & admin ("cost of doing business") - 25%
3. Profit (return on investment) - 20%
4. The market (demand for the product and how much customers are willing to pay)
2-53. Describe the growth of a fatigue crack.
Fatigue cracks happen as a result of repeated or cyclic loadings. First, there is fracture initiation, which often corresponds to discontinuities in the form of surface cracks, sharp corners, machining marks, or even "metallurgical notches," such as an abrupt change in metal structure. When the load is applied, the stress at the tip of the crack exceeds the strength of the material, and the crack grows a very small amount. Crack growth continues with each successive application of load until the remaining cross section is no longer sufficient to withstand the peak stresses. Sudden overload fracture occurs without warning through the remainder of the material.
3-28. How does a metallic crystal respond to low applied loads?
If the applied loads are relatively low, the crystals respond by simply stretching or compressing the distance between adjacent atoms (elastic deformation).
41-4. What is an operations sheet? How is it related to the route sheet?
An operations sheet is a document that lists, in sequence, the operations required for machining a part. The operations sheet and route sheet are closely related. The route sheet explains WHERE and WHAT order the operations should take place, whereas the operations sheet defines HOW the operations should take place.
1-4. How does a system differ from a process? From a machine tool? From a job? From an operation?
- A system (the highest-ranking term in the hierarchy) is the collection of people, money, equipment, materials and supplies, markets, management, and the manufacturing system.
- A process converts unfinished materials to finished products, often using machines or machine tools.
- A machine tool is an assembly of related mechanisms on a frame or bed that together produce a desired result.
- A job is the total of the work or duties that a worker performs.
- An operation is a distinct action performed to produce a desired result or effect.
2-3. Knowledge of what four aspects and their interrelations are critical to the successful application of a material in an engineering design?
1. STRUCTURE of materials
2. PROPERTIES of materials
3. PROCESSING of materials
4. PERFORMANCE of materials
These four aspects have an interdependent relationship.
2-58. What mechanical property changes are typically observed when temperature is increased?
An increase in temperature will typically induce a decrease in strength and hardness and an increase in elongation. The material is now both weaker and more ductile.
3-43. What is the difference between brittle fracture and ductile fracture?
When metals are deformed, strength and hardness increase and ductility decreases. If too much plastic deformation is attempted, fracture may occur. If plastic deformation precedes the break, the fracture is known as a ductile fracture. Fractures can also occur when the load is below that required for plastic deformation, which are sudden, catastrophic failures known as brittle fractures.
41-7. What is the functional objective of production control?
Production control personnel try to determine where the parts need to go, when they need to go, and how many need to go (lot size), so they develop a schedule to ensure that delivery of the final product meets the customer demand.
1-12. What forming processes are used to make a paper clip?
Cold forming / cold working
Bending
2-7. What are some of the more common nonmetallic engineering materials?
Wood, brick, concrete, glass, rubber, and plastics
2-72. Describe an engineering application where the density of the selected material would be an important material consideration.
In aerospace engineering, selecting materials with low density is crucial because they can reduce overall weight, enabling higher fuel efficiency, greater payload capacity, and improved flight performance, as density directly impacts the total mass.
3-50. How can deformation and recrystallization improve the grain structure of a metal?
When metals are plastically deformed at temperatures below their recrystallization temperature, the process is called cold working. The metal strengthens by strain hardening, and the resulting structure consists of distorted grains. As deformation continues, the metal decreases in ductility and may ultimately fracture. It is a common practice, therefore, to recrystallize the material after a certain amount of cold work. Through this recrystallization anneal, the structure is replaced by one of new crystals that have never experienced deformation. All strain hardening is lost, but ductility is restored, and the material is now capable of further deformation without the danger of fracture.