Üretim 8.2-MRP Structure

8/2/2019 retim 8.2-MRP Structure

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MRP Structure (Contd)


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Example 2 The Firm in Example 1 produces all

items in Product A.

Using Lead times and MPS, weconstruct the Gross MaterialRequirements Planas follows:


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Example 2


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Example 2 So far we assumed there is no

Inventory on hand.

If there is inventory on handfor aParent item, The requirements for theparent item and all its components will

decrease.


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Example 3

Given the

following on-handinventory, Weconstruct a Net

RequirementsPlan:


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Example 3 Net Requirements plan includes

following:

1) Gross Requirements, 2) On handinventory, 3) Net requirements, 4)Planned Order Receipt, and 5) Planned

Order Release for each item.


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Example 3 We now begin with A and work

backward through the components:


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Example 3A: We need 80 units of B at week 7

because we need 40 units of A at this

week, and one unit of A requires 2 unitsof B. Therefore 2 times 40 = 80.


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Example 3


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Example 3 Scheduled receipts are empty because

it is the products that we get from

Outside. In this example, we assume that we do

not buy any of the parts.


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Example 3


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Example 3


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Example 3


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Example 3


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Example 3

This example considered only product A.

Normally, there is demand for many

products. Scheduled program of each product

contributes to the Master Schedule ANDultimately to the Net Material RequirementsPlan(which includes all components for allproducts).


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Example

Lets combine several products into asingle plan.

Assume that product B is used inmaking products of A and S.

It is also sold directly to the market.


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Example

Now we will prepare a GrossRequirements Plan for B,

by combining the master schedules ofA,S, and B

Master schedules for A, S, and B are as

follows:


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Example


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Example

Now we will combine all three schedules ANDcreate Gross Requirements for B:

At period 1: we sell 10 units of B directly,therefore we should produce 10 units B.

At period 2: we sell 10 units of B directly.Plus, We also need 40 units of B forproducing A at period 6. Because lead timefor A is 4 periods.


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Example

At period 3: we need 40 units of Bbecause we will use them to produce 40

units of S at period 9.

Therefore:

Gross Requirements for B is as follows:


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Example

Period 1 2 3 4 5 67 8

Gross Req. 10 50 40 50 2045


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Example

In this example, we calculated only thegross requirements for B.

However, Remember that:

Net Requirements = (Gross Req.) -[(On hand) + (Scheduled Receipts)]


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Example

Therefore, we should also consider theInventory on hand for B AND also

Scheduled Receipts for B (if we buysome of B from other suppliers).

Remember that, Scheduled receipts are

the ones we do not produce and buyfrom Outside.


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Example

Scrapped components, Missed receivingdates, and Machine breakdowns

May Cause changes in the MaterialRequirements Plan.

Similarly, changes occur in MRP When

MPS changes.


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Example

Computerized programs perform all thecalculations and such changes.

So far we assumed that we produceexactly What we Need. No more or No

less.


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Example

The objective in an MRP system is toproduce units only as needed, With no

safety stock AND no anticipation offurther orders.

Such a procedure is consistent with

small lot sizes, frequent orders, lowinventory, and dependent demand.


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Example

However, when independent demandexists, A lot sizing technique called

Economic Order Quantity ispreferable.

EOQ technique provides a formula that

averages (or smooths) demand over anextended time horizon.


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Example

Now we will compare the traditionalMRP technique (produce as needed)

with EOQ technique in the followingexample:


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Example 4

Suppose that for product B, lead time is1 week, and inventory on hand is 35

units. We will first apply the produce as

needed approach. (traditional MRP)


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Example 4


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Example 4

Now we will apply the EOQ formula:

Economic Order Quantity (Q*) = [(2 D

S) / H]


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Example 4

Here, D is annual demand for B = 1404units

S is annual Setup cost = $100

H is annual inventory Holding cost =$52


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Example 4

Therefore: Q* = [(2 (1404) (100)) /52] = 73 units per order.

This means that, every time we give aproduction order, it should be 73 units.

In this case, Order releases for product

B will be as follows:


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Example 4


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Closed-Loop MRP

This implies an MRP system thatprovides Feedback to scheduling from

the Inventory Control System.All new and sophisticated computerized

MRP systems are now closed-loop

systems.


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Closed-Loop MRP

A closed-loop MRP system also providesfeedback to the 1) Capacity Plan, 2)

Master Production Schedule, andultimately 3) to the Production Plan.

In the Capacity Planning, For each work

center, Load reports are required.


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Closed-Loop MRP

Load reports show the ResourceRequirements (in hours) in a work

center For all work currently assigned tothat work center.

For example, suppose that initial load of

a work center exceeds the capacity ofthat work center (say 150hours/period).


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Closed-Loop MRP

Here, closed loop MRP systems allowproduction planners to Move the work

to other periods IN ORDER TO smooththe work load in each period.


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Closed-Loop MRP


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Closed-Loop MRP

Some tactics for Smoothing the workload are as follows:

1) Sending a lot to two differentmachines for the same operation. Thisis called splitting the lot. This process

involves additional setup for themachines, but results in a shorter time.


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Closed-Loop MRP

2) Moving the entire lot to anotherperiod which is near to the current

period. Today, the most sophisticated version

of Material Requirements Planning

(which is called MRP II) has substantialapplications beyond Scheduling andInventory Management.


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Closed-Loop MRP

Once a firm has MRP system, Inventorydata can be changed by Labor Hours,

by Material Costs, by Capital Cost, or byany Resource Variable.

When MRP is used in this manner, It is

usually referred as Material RESOURCEPlanning.


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Closed-Loop MRP

MRP II computer programs aregenerally tied into other computer

programs. It receives such data as Order Entry,

Inventory, Billing, Purchasing,

Scheduling, Capacity Planning,Accounting, Warehouse Management,etc.

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