Title: Session 11 Multi-Level Bill of Material Explosion http://www.pom.edu/mpc/lectures_in_manufacturing_planning.htm lecture session 11
1Session 11Multi-Level Bill of Material
Explosionhttp//www.pom.edu/mpc/lectures_in_manuf
acturing_planning.htmlecture session 11
- Product Structure Diagrams
- Multi-Level Bill of Material Explosion Linking
MRP Records - Front and Back Loaded Schedules
- Lead Time Offsetting
- Technical Issues
2Product Structure Example P301 Computer
- Memory board (M)
- Assemble 4 RAM chips and 1 switch (S) onto a
board type (X). - Arithmetic board (A)
- Assemble 1 integrated microprocessor (Z) with 2
ROM chips and 1 switch (S) onto a board type (Y).
M
A
3Product Structure Example P301 Computer
(Continued)
- Processor unit (P)
- Working from back to front of the box casing (B),
assemble one switch (S) to the inside of each of
the 4 plug connections at the back of the box.
Then fit 4 memory boards (M) into the 4 identical
rows of connectors. Finally, fit the arithmetic
board (A) into the front connector row.
4Product Structure Example P301 Computer
(Continued)
- Final Assembly
- The video unit (V) and the keyboard unit (K) have
been preassembled (with connecting cables).
Simply connect the sockets on the end of their
cables to the corresponding plugs at the rear of
the processor unit (P). The computer is now ready
to use.
P
5Product Structure Example P301 Computer
(Continued)
- Draw the product structure tree according to the
assembly directions. - Determine low-level codes for each product.
- Assume no inventory of any item. How many of each
part should be available to assemble one
completed unit?
6Product Structure DiagramP301 Computer
-
7Product Structure DiagramP301 Computer
(Continued)
Item Low-Level Code Quantity Required for One Unit
A Arithmetic Board 2 1
B Box Casing 2 1
C Ram Chip 3 16
K Keyboard Unit 1 1
M Memory Board 2 4
P Processor Unit 1 1
R ROM Chip 3 2
S Switch 3 9
V Video Unit 1 1
X Board Type X 3 4
Y Board Type Y 3 1
Z - Microprocessor 3 1
Assuming no inventory for any item Assuming no inventory for any item Assuming no inventory for any item
8Product Structure DiagramP301 Computer
-
9Linking MRP Records Examples
- The Big B Bike and Trike Shop produces two basic
bikes called A and B. Each period, Paul, the
owner. plans to assemble 10 A bikes and 5 B
bikes. Given this information and the following
product structure diagrams for A and B, fill out
the MRP records for component parts G and Y for
the next seven periods.
10Linking MRP Records Examples (Continued)
11Linking MRP Records Examples (Continued)
MPS Bike B 5 u/period
Bike A 10 u/period
12Linking MRP Records Problem 8 Part a
13Linking MRP Records Problem 8 Part b
- Suppose 10 units of safety stock are required for
part Y. What changes would result in the records?
Would the MRP system produce any exception
messages? - Exception message period 2 below safety stock.
- There will be an increase in the order in period
1 from 18 to 28 units.
14Front and Back Scheduling Example
- Peters Power Tools (PPT) has
- just received an order for 50
- PPT band saws, to be shipped at
- the beginning of period 9.
- Information concerning the saw
- assembly is given in this table.
- Draw the product structure diagram
PPT band saw PPT band saw PPT band saw
Item Lead time (periods) Components
Saw 2 A(2), B, C(3)
A 1 E(3), D
B 2 D(2), F(3)
C 2 E(2), D(2)
D 1
E 1
F 3
Number of parts required to make one parent. Number of parts required to make one parent. Number of parts required to make one parent.
15PPT Product Structure Diagram
- Draw the product structure diagram
16PPT Front Loaded Schedule
- Construct a Gantt chart for the new order using
front scheduling logic.
E
D
F F F
A
C C
B B
SAW SAW
1 2 3 4 5 6 7 8 9
Period Number Period Number Period Number Period Number Period Number Period Number Period Number Period Number Period Number
17PPT Back Loaded Schedule
- Construct a Gantt chart for the new order using
back scheduling logic.
F F F
D
E
B B
C C
A
SAW SAW
1 2 3 4 5 6 7 8 9
Period Number Period Number Period Number Period Number Period Number Period Number Period Number Period Number Period Number
18Scheduling Explanation
- The front scheduling logic causes all the work to
be done ahead of schedule which creates
additional inventory and occupies resources that
could be used on other orders. MRP applies back
scheduling logic so that parts and components are
completed when they are needed to fill customer
orders.
19Lead Time Offsetting
- Precedent Relationship
- Components of Lead Time
- Set-up Time
- Run Time
- Material Handling Time
- Queue Time
- Staging Time
- Cumulative Lead Time
- Advantage of Back Loaded Schedules
20Technical Issues
- Low Level Coding
- Indented Bill of Materials
- Pegging
- Cumulative Lead Time
- Planning Horizon
- Processing Frequency
- Regeneration
- Net Change