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Manufacturing systems > Production systems > Flashcards

Production systems Flashcards

1
Q

What are the types of production?

A

Job Shop production
• Batch production
• Mass production

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2
Q

Explain batch production

A

Involves manufacture of medium-sized batches of the same product
• Batches may be produced once, or on regular intervals
• Used to meet continuous customer demand for a product
• The plant is normally capable of production rates that exceed the demand
• General purpose manufacturing equipment is used but are designed for higher production rates
• Product examples: furniture, books, shoes, clothes

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3
Q

What are some of the functions of manufacturing?

A 
– Processing
– Materials handling and storage
– Assembly
– Inspection and testing
– Control
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4
Q

What is processing?

A
  • Processing operations transform the product from one state of operation into another more advanced stare of completion.
  • This could involve changing the shape of parts, remove material from it, alter its physical properties, or accomplish other forms of work to change it.
  • Processing operations are categorised as follows:
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5
Q

What are the different types of processing operations?

A

Basic processes

  1. Secondary processes
  2. Operations to enhance physical properties
  3. Finishing operations
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6
Q

Basic processes

A

• Basic processes are those which give the work
material its initial form
• The raw material is concerted into the basic
geometry of the desired product
• Normally additional processing would be
required to complete the production
• Examples: Casting, moulding

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7
Q

Secondary processes

A

• This follows the basic process
• These are operations that give the final
desired geometry shape of the product
• Examples: Machining, drilling, milling

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8
Q

Operations to enhance physical properties

A

They don’t necessarily change shape of the product

• For example Heat-treating operations are used to strengthen metal parts

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9
Q

Finishing operations

A

• These are the final operations on the product
• They help improve appearance of the product
or provide protective coating
• Examples include polishing, painting, chrome
plating

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10
Q

Material Handling and Storage

A
  • A means of moving and storing materials between the processing and assembly operations
  • In most cases materials spend more time being moved from one place to another than being processed
  • Sometimes majority of labour costs is spent on moving materials
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11
Q

Assembly

A

• Assembly and joining operations constitute the second major type of manufacturing
• Two or more separate components are joined together
• Mechanical fastening operation includes screws, nuts,
rivets, etc.
• Other joining processes include welding, brazing,
soldering
• Adhesive joining is also being widely used

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12
Q

Inspection and Testing

A

• Inspection and testing are normally considered as part of quality control
• The purpose is to determine whether the manufactured product meets the design standards and specifications
• Examples are tolerance checking of diameters, etc.
• Testing is to establish the functional and operational
specification of the overall final product

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13
Q

Control

A

• Control function includes regulation of individual processing and assembly functions
• The manufacturing control function at the plant level
represents the major point of intersection between the
physical operations in the factory and the information
processing activities that occur in the production

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14
Q

Plant layout

A

• This is the arrangement of physical facilities in a
production plant
• Different types of production require their own plant layout
• Three principal plant layout types are:
– Fixed position layout
– Process layout
– Product-flow layout

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15
Q

Automation

A

A technology concerned with the application
of mechanical, electronic and computer based
systems to operate and control production.

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16
Q

Types of Automation

A
  1. Fixed Automation
  2. Programmable Automation
  3. Flexible Automation
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17
Q

Fixed Automation:

A

a system in which the sequence of processing, or
assembly, operations is fixed by the equipment
configuration. The operation in the sequence are
usually simple. It is the integration and co-ordination
of many such operations into one piece of equipment
that makes the system complex.

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18
Q

Features and applications of fixed automation

A

Features: •High investment for custom-engineered equipment.
•High production rates.
•Relatively inflexible in accommodating product changes.
Applications: •Mechanized assembly lines (1913)
•Machine transfer lines (1924)

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19
Q

Programmable Automation:

A

The production equipment is designed with the capability to change the sequence of operations to accommodate different product configurations. The operation sequence is controlled by a program and can be changed to produce new product.

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20
Q

Features of programmable automation?

A
  • High investment in general-purpose equipment.
  • Low production rates relative to fixed automation.
  • Flexibility to deal with changes in product design.
  • Most suitable for batch production.
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21
Q

Flexible Automation:

A

This is an extension of programmable automation. A
flexible system is one that is capable of producing a
variety of products with virtually no time lost for
changeover. Consequently, the system can produce
various combinations of scheduled products, instead of
producing them in separate batches.

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22
Q

Features of flexible automation

A
  • High investment for a custom-engineered system.
  • Continuous production of variable mixtures of products.
  • Medium production rates.
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23
Q

Reasons of automation

A 
 Increased productivity
 High cost of labor
 Labor shortage
 Trends of labour towards the service sector
 Health and Safety
 High cost of raw materials
 Improved product quality
 Reduced manufacturing lead time
 Reduction in process inventory
 High cost of not automating
24
Q

Reasons against automating

A 
 Risk associated with change
 Cost of change
 Disruption to production
 Employee consequences
 Inadequate skills to support the change
25
Q

Types of assembly systems

A

 Manual single-stations assembly
 Manual assembly lines
 Automated assembly system

26
Q

Manual single-stations assembly

A

 Manual single-stations assembly method consists
of a single workplace in which the assembly work
is accomplished on the product or some major
subassembly of the product.
 Normally the product is complex and very small
in quantity.
 Custom-engineered products such as machine
tools, ships, aircraft, are examples that use this
type of assembly.

27
Q

Manual assembly lines

A

 Manual assembly lines consist of multiple
workstations in which the assembly work is
accomplished as the product (or subassembly) is
passed from station to station along the line.
 At each station one or more human workers
perform a portion of the total assembly work on
the product, by adding one or more components
to the existing subassembly.

28
Q

Design for automated assembly
The following are some of the recommendations
and principles that can be applied in product
design to facilitate automated assembly:

A

 Reduce the amount of assembly required
 Use modular design
 Reduce the number of fasteners required
 Reduce the need for multiple components
to be handled at once
 Limit the required directions of access
 Require high quality in components
 Implement hopperability

29
Q

Automated assembly system

A

 Automated assembly system makes use of
automated methods at the workstations rather
than human beings.

30
Q

 Automated assembly can be classified as follows:

A

 Continuous transfer system
 Synchronous transfer system
 Asynchronous transfer system
 Stationary base part system

31
Q

Continuous transfer system

A

 With continuous transfer system, the workparts
are moved continuously at constant speed.
 Workparts are moved during processing as well.
 Examples: beverage bottling and packaging
operations.
 Continuous transfer system is relatively simple to
design and fabricate, and can achieve high
production rate.

32
Q

Synchronous transfer system

A

 In synchronous transfer system, the workparts are
transported with an intermittent or discontinuous motion.
 The workstations are fixed in positions and the parts are moved between stations.
 All workparts are transported at the same time, and hence the word “synchronous”.
 Examples: machining operations and pressworking.

33
Q

Asynchronous transfer system

A

 Asynchronous transfer system (also known as power-and-free system) allows each workpart to move to the next station when processing at the current station has been completed.
 Each part moves independently of other parts. Hence some parts are being processed on the line at he same time that others are being transported between stations.
 Asynchronous transfer system gives greater flexibility that other systems.
 In-process storage of workparts can be incorporated
 Parallel stations can be used for the longer operations.

34
Q

What are some parts feed devices?

A 
Elements of parts feed delivery system:
 Hopper
 Parts feeder
 Selector / Orientor
 Feed track
 Escapement and placement device
35
Q

Why do we need flexibility in manufacturing systems?

A

 Variety in products thus options for the consumers.
 Optimizing the manufacturing cycle time.
 Reduced production costs.
 Overcoming internal changes like failure,
breakdowns, limited sources, etc.
 External changes such as change in
product design and production system.

36
Q

Define Flexibility in Manufacturing Systems

A

 Flexibility can be defined as collection of
properties of a manufacturing system that
support changes in production activities or
capabilities (Carter,1986).
 Ability of the manufacturing system to
respond effectively to both internal and
external changes by having built-in
redundancy of versatile equipments.

37
Q

What are the different types of machine flexibility?

A

 Product flexibility
Ability to change over to a new set of products
economically and quickly in response to markets.
 Production flexibility
Ability to produce a range of products without
adding capital equipment.
 Expansion flexibility
Ability to change a manufacturing system with a
view to accommodating a changed product
envelope.
 Machine flexibility
Capability of a machine to perform a variety of
operations on a variety of part types and sizes
 Routing flexibility
Alternative machines, sequences or resources
can be used for manufacturing a part for changes
resulting from equipment breakdowns, tool
breakages, controller failures, etc.
 Process flexibility
Ability to absorb changes in the product mix by
performing similar operations, producing similar
products or parts.

38
Q

What are the three basic ways flow line performance can be measured?

A

 Average production rates
 Production of the time the line is operating
(line efficiency)
 Cost per item produced on the line

39
Q

What is Tc?

A

 Tc is equal to the time required for parts to transfer plus the processing time at the longest workstation.
Workstations which take less time will have an amount of ideal time.

40
Q

What is Tp?

A

Due to breakdowns of line, the actual average

production time is Tp will be longer than Tc

41
Q

What is Td?

A

Average downtime of the line

42
Q

What is Fj and Tdj?

A

Fj is frequency of a particular event stopping production and Tdj is the average time it stops production for.
Thus Fj x Tdj gives the meantime the machine
will be down for reason j.

43
Q

What is the formula for average production time?

A

Tp = Tc + F*Td

44
Q

Average production rate

A

Rc= 1/ Tp
If the flow line produces less than 100% yield, this
production rate must be adjusted for the yield
For example if 2% of the work parts are scrapped during processing, the production rate would be 98% of that calculated by the above formula

45
Q

What is the theoretical production rate?

A

Theoretical production rate, rarely achieved in practice, is given by:
Rc = 1 / Tc

46
Q

What is line efficiency, E?

A

E = Tc / Tp

47
Q

The proportion of Downtime on the line, D, is given by:

A

D = FTd / Tp = FTd / (Tc + FTd )

E+D=1

48
Q

What are some of the gear equations?

A 
 N = Number of Teeth
 r = Gear radius
 T = Available torque
 Θ = Given angle of rotation
 ω = Angular velocity
 a = Angular acceleration
 (N1/ N2) = (r1/ r2) = (T1/ T2) = (Θ2/ Θ1) = (ω2/ ω1) = (a2/a1)
49
Q

What are the advantages of a harmonic drive?

A

No backlash - Loss of motion caused by clearance between the parts.
high compactness and light weight, high gear ratios

50
Q

name some Rotary to linear Conversion systems

A 
 Lead Screws
 Rack-and-pinion
 Belt and Pulley driving a Linear Load
 Slider Cranks
 Cams
51
Q

What are the different types of flexibility?

A

Machine, routing, process, product, production, expansion.

52
Q

Machine flexibility

A

Machine flexibility
 Capability of a machine to perform a variety of
operations on a variety of part types and sizes

53
Q

Routing flexibility

A

 Routing flexibility
 Alternative machines, sequences or resources can be
used for manufacturing a part for changes resulting from
equipment breakdowns, tool breakages, controller
failures, etc.

54
Q

Process flexibility

A

Process flexibility
 Ability to absorb changes in the product mix by
performing similar operations, producing similar
products or parts.

55
Q

Product flexibility

A

Product flexibility
 Ability to change over to a new set of products
economically and quickly in response to markets

56
Q

Production flexibility

A

Production flexibility
 Ability to produce a range of products without adding
capital equipment.

57
Q

Expansion flexibility

A

Expansion flexibility
 Ability to change a manufacturing system with a view to
accommodating a changed product envelope.

Manufacturing systems (3 decks)

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