Manufacturing Processes and Facility Layout

1
Manufacturing Processes and Facility Layout

• Selected Slides from Jacobs et al, 9th Edition
• Operations and Supply Management
• Chapter 7 and 7A
• Edited, Annotated and Supplemented by
• Peter Jurkat

2
Process Flow Structures
7-2

• Job shop (ex. Copy center making a single copy of
  a student term paper)
• Batch shop (ex. Copy center making 10,000 copies
  of an ad piece for a business)
• Assembly Line (ex. Automobile manufacturer)
• Continuous Flow (ex. Petroleum manufacturer)

3
Product-Process Matrix
7-3
Variety - high
Mass Customization
Project fixed location Work center job
shop Continuous glass, paper, steel
Assembly Line automobile manufacturer
Variety - low
4
Break-Even Analysis
7-4

• A standard approach to choosing among alternative
  processes or equipment
• Model seeks to determine the point in units
  produced (and sold) where total revenue and total
  cost are equal, or
• Model seeks to determine the point in units
  produced (and sold) where we will start making
  profit on the process or equipment

5
Break-Even Analysis (Continued)
7-5
Solution to Revenue Cost DemandPrice Fixed
Cost DemandVariable Cost
Break-even Demand
Purchase cost of process or equipment
Price per unit - Cost per unit
or Total fixed costs of process
or equipment Unit price to customer -
Variable costs per unit

• This formula can be used to find any of its
  components algebraically if the other parameters
  are known

See Ch07_BreakEvenAnalysis.xls now you do
Problem 7.9 and then Example 7.1 - try to match
display on next page
6
7-6
Example 7.1 page 207
7
Manufacturing Process Flow Design
7-7

• A process flow design can be defined as a mapping
  of the specific processes that raw materials,
  parts, and subassemblies follow as they move
  through a plant
• The most common tools to conduct a process flow
  design include assembly drawings, assembly
  charts, process flow diagrams (operations), and
  route sheets

8
7-8
Assembly Drawing
9
Example Assembly Chart (Gozinto)
7-9
From Exhibit 5.14
10
Example Process Flow Chart
7-10
No, Continue
Material Received from Supplier
Inspect Material for Defects
Defects found?
Yes
Return to Supplier for Credit
11
Facility Layout
7A-11

• Facility layout can be defined as the process by
  which the placement of departments, workgroups
  within departments, workstations, machines, and
  stock-holding points within a facility are
  determined
• This process requires the following inputs
• Specification of objectives of the system in
  terms of output and flexibility
• Estimation of product or service demand on the
  system
• Processing requirements in terms of number of
  operations and amount of flow between departments
  and work centers
• Space requirements for the elements in the layout
• Space availability within the facility itself
• Each process type (project, job shop, cell,
  assembly line, continuous) has it corresponding
  basic layout
• Determine the best layout (one that minimizes
  flowdistance, or flowunit flow cost, ,
  maximizes throughput, )

12
7A-12
The Assignment Problem

• Assign each departments to one of the 8 rooms so
  as to minimize the cost of required flows
• Cost measured in (number of moves)(distance
  and/or time and/or cost of move)
• Can be done by exhaustive enumeration
  prohibitive for large problems
• All commercial software uses heuristics
• See Ch07A_Process_Layout.xls

13
Process Layout Systematic Layout Planning
7A-13

• Minimizing cost of numerical flow of items
  between work centers
• Can be impractical to obtain - cannot guarantee
  mathematical optimum
• Does not account for the qualitative factors that
  may be crucial to the placement decision
• Systematic Layout Planning
• Accounts for the importance of having each
  department located next to every other department
  rating factors
• Is also guided by trial and error
• Switching work centers then checking the results
  of the closeness score

14
Example of Systematic Layout Planning Reasons
for Closeness
7A-14
15
Example of Systematic Layout PlanningImportance
of ClosenessRating scale, symbols, and weights
7A-15
16
Example of Systematic Layout PlanningInitial
Relationship Diagram
7A-16
The number of lines here represent paths required
to be taken in transactions between the
departments. The more lines, the more the
interaction between departments.
Note here again, Depts. (1) and (2) are linked
together, and Depts. (2) and (5) are linked
together by multiple lines or required
transactions.
17
Example of Systematic Layout Planning Initial
and Final Layouts
7A-17
Note in the Final Layout that Depts. (1) and (5)
are both placed directly next to Dept. (2).
Now you do 7A.8
18
Assembly Line

• Layout not a problem its obviously a line with
  sequential work stations can be straight,
  curved, double back, ..
• Tasks along line and at each station must satisfy
  precedence relationships
• A line is balanced if the entire line moves at
  same speed and all tasks at all stations get done
  with no slack not only nearly impossible but
  not completely desirable
• Time at each station is workstation cycle time
• Assembly line balancing is to arrange tasks at
  each station so they can be done during the cycle
  time with minimum idle time
• Work time at each station is sum of task times
  (or longest sequence of task times at station if
  parallel tasks)

19
Example of Line Balancing Precedence and Task
Times Diagram
7A-19
Total task times 11.35 Task C determines cycle
time
Parallel work can be done on one line
20
Example of Line Balancing Determine Cycle Time
7A-20

• Question Suppose we want to assemble 100 fans
  per day. What would our cycle time and number of
  workstations have to be?

21
Example of Line Balancing Rules To Follow for
Loading Workstations
7A-21

• Assign tasks to station 1, then 2, etc. in
  sequence. Keep assigning to a workstation
  ensuring that precedence is maintained and total
  work is less than or equal to the cycle time.
  Use the following rules to select tasks for
  assignment.
• Primary Assign tasks in order of the largest
  number of following tasks
• Secondary (tie-breaking) Assign tasks in order
  of the longest operating time

22
7A-22
Sort table by number of followers
Cycle time 4.2
23
7A-23
Cycle time 4.2
Station 3
C (4.2-3.25).95 Idle .95
A (4.2-22.2) B (2.2-11.2) G (1.2-1 .2) Idle
.2
24
7A-24
Cycle time 4.2
Which station is the bottleneck? What is the
effective cycle time?
Now you do 7A.4
25
Example of Line Balancing Determine the
Efficiency of the Assembly Line
7A-25
Actually efficiency 11.35/(34.1) .923 but
may not want to run this tight.
26
Manufacturing CellTransition from Process Layout
7A-26

• 1. Grouping parts into families that follow a
  common sequence of steps
• 2. Identifying dominant flow patterns of parts
  families as a basis for location or relocation of
  processes
• 3. Physically grouping machines and processes
  into cells

27
7A-27
28
Project Layout
7A-28

• Question What are our primary considerations for
  a project layout?

Answer Arranging materials and equipment
concentrically around the production point in
their order of use.
29
Retail Service Layout
7A-29

• Goal--maximize net profit per square foot of
  floor space
• Servicescapes
• Ambient Conditions
• Spatial Layout and Functionality
• Signs, Symbols, and Artifacts

30
7A-30
Retail Layout for Visibility
Customer never sees less than four aisles and can
see as many as six in some locations
Customer never sees more than four aisles
Enhanced by having low counters in center and
high along walls