Lot-Sizing Techniques and Adjustments—Extended Exercises
IMPORTANT |
It is extremely important
that you set up and work within your own site to maintain your
data integrity. If you work within any other site, you will
compromise your own exercise data as well as the data of other
students. Predictable exercise results require that your data
be isolated in your own site. |
Basic Data Setup
MRP Extended Data Setup
Purpose: The purpose of this exercise is to set up the
required prerequisite data needed for the extended MRP exercises. You
must
do this exercise once to support the extended MRP exercises in the current
database. (If the database has been refreshed since the time you set up the data
for the MRP extended exercises, you will need to set up the data again.)
- If you haven't done so already, create your own site and set up the
extended MRP data (for extended exercises) in that site.
General exercise
for Overview of Extended MRP Data
Main Exercise
Purpose: The purpose of these exercises is to perform
MRP on the parts that you have already defined and evaluate the result.
Windows:
Perform MRP
Background Jobs
MRP Material Plan
MRP Part Information
- Open the Perform MRP window and start the MRP process on your
primary site.
- Check the process from the
Background Jobs window.
- Go to the next section when the process is done.
- Open
MRP Material Plan window and query for parts in your
primary site.
- When the query results display, notice that the 90-210, 90-272, 90-273,
and 90-274 parts are not listed because those parts are defined with
aplanning method of either B (order point planning), C (replenishment level), or N (next
level demand), and MRP does not handle parts with those planning methods.
- Select the 90-220 part from the Part Number list. This part is
defined with planning method D (fixed lot size) and has a multiple lot size of 5. In the product
structure, the quantity per assembly of this part is 2 because there is a customer order demand
of 3 pieces for the 90-200 parent part. This demand will require 6 pieces of
the 90-220 part. To supply this demand, MRP
will look at the multiple lot size setting and create a plan receipt of 10
pieces.
- Select the 90-230 part from the Part Number list. This part is defined with
planning method E (least unit cost) and has an ordering cost of 100, inventory interest of
3%, and a material cost of 200. The calculated stock-keeping cost per day will be 200
x 0.03 / 220 = 0.027.
Note: The calculation above assumes that the number of
stock keeping days per year is 220 days, which is the default value specified at
installation.
- MRP will look at the demands for 90-230 part as in the table below:
No |
Date |
Demand Qty |
Description |
1 |
today+1 month |
3 |
Demand from Customer Order |
2 |
today+1 month |
100 |
Demand from Material Requisition |
3 |
today+2 months |
100 |
Demand from Material Requisition |
4 |
today+3 months |
100 |
Demand from Material Requisition |
- On the first day, the system will see a demand of 103 pieces from the customer order(s) and the material requisition(s). At this point MRP will first determine whether it
should create supply for future demand so it can obtain least unit cost. As calculated, there are 32 days between demand
numbers 2 and 3, and 33 days between demands numbers 3 and 4. After comparing setup costs against
stock-keeping costs, MRP determines that it would be
best to create supply only for the future demands of demand numbers 2 and 3,
so a shop order requisition for 203 pieces is created. This shop order requisition will supply the demand number 1 (3 pieces), demand number 2 (100
pieces), and demand number 3 (100 pieces). Demand number 4 exists 3 months ahead
and will be supplied later because it will increase inventory
cost too much.
Note: You may find that your exact results differ from what is described above
because the number of days between each demand affects the inventory cost.
- Select the 90-231 part from the Part Number list. This part is defined with
a maximum lot size of 10 pieces. Demand from the parent part is 203 pieces and
the supply
cannot be ordered as one requisition because
that would exceed the maximum lot size. Instead MRP will break up
the order into twenty requisitions for 10 pieces each and one requisition
for 3 pieces. The same situation occurs with demand number 2, which is for 100
pieces. MRP will supply that demand by creating ten requisition with 10
pieces each.
- Select the 90-240 part from the Part Number list. This part is
defined with planning method F ( Part Period Balancing ), and has an ordering cost of
100,
inventory interest of 0.5%, and a material cost of 200. The calculated stock-keeping cost per day will be 200 x 0.005 / 220 = 1/220. This will obtain the optimal quotient: 100 /(1/ 220) = 22000.
Note: The calculation above assumes that number of stockkeeping days
per year is 220 days which is the default value specified at installation.
- Then MRP will look at the demands for 90-240 part as in the table below
No |
Date |
Demand Qty |
Description |
1 |
today+1 month |
6 |
Demand from Customer Order |
2 |
today+1 month |
100 |
Demand from Material Requisition |
3 |
today+2 months |
100 |
Demand from Material Requisition |
4 |
today+3 months |
100 |
Demand from Material Requisition |
- When demand number 1 for 6 pieces is processed, MRP
will first determine whether it needs to create supply for future demand to
find the optimal relationship between order overhead and stock-keeping costs
using the optimum quotient. MRP determines that it is best to supply the
future demands of numbers 2, 3, and 4 along with the demand of number 1.
Therefore as calculated, MRP creates supply
for 306 pieces on the demand number 1 date.
Note: You may find that your exact results differ from what is described above
because the number of days between each demand affects the inventory cost.
- Select the 90-250 part from the Part Number list. This part is defined with
planning method G (order cover time) and has the order cover time set to 5
days. With this setting, when MRP finds the first demand it also will look to
supply any other demand 5 days ahead. The first shop order requisition for this part is created
with a quantity of 56 pieces. This supplies the first demand of 6 pieces and the
material requisition of 50 pieces. The third demand for 5 pieces is supplied separately
because it is outside the order cover time.
No |
Date |
Demand Qty |
Description |
1 |
today+1 month |
6 |
Demand from Customer Order |
2 |
today+1 month + 3 days |
50 |
Demand from Material Requisition |
3 |
today+2 months |
5 |
Demand from Material Requisition |
- Select the 90-251 part from the Part Number list. This part is defined with
a Manufactured/Acquired Split percentage, indicating a percentage to
be manufactured within the site and the remainder to be purchased. The
part has a Manufactured Supply Type of Schedule, which means
the manufacturing portion of demands are supplied by creating production schedules instead of shop
order requisitions. The part has an Acquired Supply Type of Requisition,
which means the purchasing portion of demands are supplied via purchase
order requisitions.
- Select the 90-260 part from the Part Number list. This part is defined with
planning method K (blow through), which means that when MRP finds any demands for this part,
it will not create supply for them. Instead it will pass demand to its components.
Check the created demands for 90-261 part, which is a component part.
- Select the 90-270 part from the Part Number list. This part is defined with
planning method M (manufacturing cell), which means that MRP will create a requisition to supply demands but
it will not break down the demand for its components. Check to see if there
are any
demands created for 90-271 part,
which is the component. Demands for the component should not be
created.)
- Select the 90-280 part from the Part Number list. This part is defined with
planning method P (phantom), which means that the net
requirements will be passed to its components but no supply will be
created for
this part. The existing supplies and quantity on hand will be used to
calculate the net requirement.