Manufacturing Processes Chapter 39

Fixed routing is associated with which of the following types of manufacturing systems (two best answers): (a) automated production lines, (b) automated storage systems, (c) cellular manufacturing systems, (d) flexible manufacturing systems, (e) job shops, and (f) manual assembly lines?

(a) and (f).

Material handling is usually not associated with transportation between facilities that involves rail, truck, air, or waterway delivery of goods: (a) true or (b) false?

(a).

Which of the following types of material handling equipment are typically used in a process type layout (two best answers): (a) conveyors, (b) cranes and hoists, (c) fork lift trucks, and (d) railguided vehicles?

(b) and (c).

The physical layout of a flexible manufacturing system is determined principally by which one of the following: (a) computer system, (b) material handling system, (c) part family, (d) processing equipment, or (e) weight of parts processed?

(b).

What is the dividing line between a manufacturing cell and a flexible manufacturing system: (a) two machines, (b) four machines, or (c) six machines?

(b).

A machine capable of producing different part styles in a batch mode of operation qualifies as a flexible manufacturing system: (a) true or (b) false?

(b). A flexible manufacturing system does not normally operate in a batch mode.

Most parts classification and coding systems are based on which of the following types of part attributes (two best answers): (a) annual production rate, (b) date of design, (c) design, (d) manufacturing, and (e) weight?

(c) and (d).

Which of the following phrases are most appropriate to describe the characteristics of tasks that are performed at automated workstations (three best answers): (a) complex, (b) consists of multiple work elements, (c) involves a single work element, (d) involves straight-line motions, (e) requires sensory capability, and (f) simple?

(c), (d), and (f).

Batch model production lines are most suited to which one of the following production situations: (a) job shop, (b) mass production, or (c) medium production?

(c).

The transfer line is most closely associated with which one of the following types of production operations: (a) assembly, (b) automotive chassis fabrication, (c) machining, (d) pressworking, or (e) spot welding?

(c).

A dial indexing machine uses which one of the following types of workpart transfer: (a) asynchronous, (b) continuous, (c) parts passed by hand, or (d) synchronous?

(d).

Precedence constraints are best described by which one of the following: (a) launching sequence in a mixed model line, (b) limiting value of the sum of element times that can be assigned to a worker or station, (c) order of workstations along the line, or (d) sequence in which the work elements must be done?

(d).

Which one of the following technologies is most closely associated with flexible machining systems: (a) lasers, (b) machine vision, (c) manual assembly lines, (d) numerical control, or (f) transfer lines?

(d).

Flexible manufacturing systems and cells are generally applied in which one of the following areas: (a) high-variety, low-volume production, (b) low variety, (c) low volume, (d) mass production, (e) medium-volume, medium-variety production?

(e).

Industrial robots can, in general, most easily handle which one of the following part types in a flexible machining system: (a) heavy parts, (b) metal parts, (c) nonrotational parts, (d) plastic parts, or (e) rotational parts?

(e).

Production flow analysis is a method of identifying part families that uses data from which one of the following sources: (a) bill of materials, (b) engineering drawings, (c) master schedule, (d) production schedule, or (e) route sheets?

(e).

What is a flexible manufacturing system?

A flexible manufacturing system (FMS) is an automated group technology cell consisting of processing stations interconnected by an automated handling system and controlled by a computer.

What is a part family?

A part family is a collection of parts that share similar design and/or manufacturing attributes.

What is a production line?

A production line is a sequence of workstations at which individual tasks are accomplished on each work unit as it moves from one station to the next to progressively make the product.

What are the advantages of FMS technology, compared to conventional batch operations?

Advantages include (1) higher machine utilization, (2) reduced work-in-process, (3) lower manufacturing lead times, and (4) greater flexibility in production scheduling.

What are the advantages of a mixed model line over a batch model line for producing different product styles?

Advantages of the mixed model line include (1) no downtime between the different models due to line changeovers; (2) production rates can be matched to demand rates for the different models, and thus (3) inventory fluctuations can be avoided in which there are high inventories of some models while there are stock-outs of other models.

What are the main components of an integrated manufacturing system?

As stated in the text, the main components of an integrated manufacturing system are (1) workstations and/or machines, (2) material handling equipment, and (3) computer control. In addition, human workers are required to manage the system, and workers may be used to operate the individual workstations and machines.

Why must a production line be paced at a rate higher than that required to satisfy the demand for the product?

Because all production lines suffer a certain amount of nonproductive time due to reliability problems.

Why are parts sometimes fixed to the conveyor in a continuous transfer system in manual assembly?

Because the parts are big and/or heavy and cannot be conveniently removed from the transfer system by a human worker.

Define cellular manufacturing.

Cellular manufacturing involves the production of part families using groups of machines (generally manually operated) to produce a certain part family or a limited set of part families.

Define computer integrated manufacturing.

Computer integrated manufacturing (CIM) refers to the pervasive use of computer systems throughout a manufacturing organization, not only to monitor and control the operations, but also to design the product, plan the manufacturing processes, and accomplish the business functions related to production.

Name some of the FMS software and control functions.

FMS software and control functions include (1) NC part programming, (2) NC part program download, (3) production control, (4) machine control, (5) workpart control, (6) tool management, (7) work transport control, and (8) general system management.

Define group technology.

GT is a general approach in which similarities among parts are identified and exploited in design and manufacturing.

What is the composite part concept in group technology?

In GT, a composite part is a hypothetical part that includes all of the design and/or manufacturing attributes of a given part family. The concept is useful in designing cells to produce the part family.

What is the difference between fixed routing and variable routing in material transport systems?

In fixed routing, all of the work units are moved through the same sequence of stations, which means that the processing sequence required on all work units is either identical or very similar. In variable routing, different work units are moved through different workstation sequences, meaning that the manufacturing system processes or assembles different types of parts or products.

What are some of the limitations of a mixed model line compared to a batch model line?

Limitations of a mixed model line include (1) the line balancing problem is more complex, (2) scheduling the models is more difficult, and (3) getting the right parts to each workstation is more complicated because more parts are involved.

What are some of the reasons for downtime on a machining transfer line?

Reasons for downtime on a machining transfer line include tool changes, unpredictable mechanical and electrical failures, and normal wear and tear on the equipment.

Why are single station assembly cells generally not suited to high-production jobs?

The entire work cycle is performed at one station, so single station cells usually operate at relatively slow production rates.

Name the five main types of material transport equipment.

The five main types of material transport equipment are (1) industrial trucks, which includes fork lift trucks, (2) automated guided vehicles, (3) rail-guided vehicles, (4) conveyors, and (5) hoists and cranes.

What are the criteria that should be satisfied to make an automated manufacturing system flexible?

The flexibility criteria for an FMS are (1) the system must process different part styles in non-batch mode; (2) the system must be able to accept changes in the production schedule, (3) the system must deal gracefully with equipment breakdowns, and (4) the system must be able to accommodate new part style introductions.

Describe how manual methods are used to move parts between workstations on a production line.

The manual methods include (1) work units are simply passed by hand along a flat worktable from one station to the next, (2) work units are collected in boxes and then passed between stations, and (3) work units are pushed along a non-powered conveyor between stations.

What are the principal material handling functions in manufacturing?

The principal material handling functions in manufacturing are (1) loading and positioning work units at each workstation, (2) unloading work units from the station, and (3) transporting work units between workstations.

Repositioning time on a synchronous transfer line is known by a different name; what is that name?

The repositioning time is called the transfer time; it is the time to move parts from one station to the next.

Briefly define the three types of mechanized workpart transfer systems used in production lines.

The three work transfer systems are (1) continuous transfer, in which parts move on a conveyor at a steady speed; (2) synchronous transfer, in which parts all move simultaneously from station-to-station with a stop-and-go action; and (3) asynchronous transfer, in which parts move independently between stations with a stop-and-go action.