Refer to documentation Implementation
The MRP processing function contains a single screen in which you select a processing date and one, or multiple storage sites (warehouses).
Presentation
You use this screen to specify what to include in the MRP processing run.
You can define a processing date in the past, or in the future.
You can run MRP for a single site, or multiple storage sites (warehouses). If running MRP for multiple sites, the position of a site in the selection table is important. In effect, MRP processes the sites successively, that is, if the selection order is site A, then site B, then site C, the calculation will be performed first for site A, then for site B, then for site C.
The processing order can be important if MRP calculations generate transfer (intersite) suggestions.
The MRP processing run analyzes the potential requirements (demand) and replenishments (supply) across the defined sites. The sites are processed in the order defined in the runtime table, and actual requirements established according to specified time buckets. MRP then uses a product-supplier selection hierarchy for suggestions created for purchase order suggestions, and subcontract order suggestions to determine the preferred (default) supplier by site, as follows:
If the MRP processing run fails to nominate a supplier the supplier must be selected manually when creating a purchase order, or subcontract order from the MRP results in an associated function. See MRP results below.
Where the potential material requirements includes a version-managed product, MRP will always issue a suggestion for the exact version of a product if components have been allocated (detailed allocation). If, however, a shortage of safety stock is found, MRP will always issue a suggestion for the latest active version.
MRP "manages" phantoms as subassemblies to consider the planned consumption of residual stock. Once the MRP results have been written to the Orders table (for use in workbenches and inquiries), the material in work order suggestion (MWS) and work order suggestion (WOS) for the phantom are removed from the Orders table (or the MWS reduced if stock is consumed), and the phantom component MWS demands are reattached to the WOS for the parent product. This ensures the correct relationship between the parent and the phantom components in the workbenches.
Stock management (GESITM): A product must have the Stock management field (STOMGTCOD) set to Managed, or have the Management mode as By order (STDFLG field).
Product-site (GESITF): The fields in the Management and Planning sections must be completed, noting the following:
The reorder policy provides selected information for a specific product during the MRP processing run, that is, the type of suggestion, the reorder quantity, the splitting, the safety stock, the use of the replanning analysis.
MRP generates three types of information:
Suggestion type (explanation of the triggered requirement, or trace)
Compared to a request, an order suggestion is generated for a BOM parent product. This suggestion, along with existing component resources (planned or firm orders), triggers a requirement that is in turn triggered from a component requirement. This is called a trace requirement. The order type will be MSS, MSP, MWS, MWP or MWF, depending on the status of the parent product resource.
Parent product | Generation of the parent product for the component | Suggestion for the component |
Requests => Order suggestions | MWS, MSS | Order suggestions |
Planned resources | MWP, MSP |
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Firm resources | MWF, MSF |
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The trace requirement has the same document number as the order at the origin of the requirement.
MRP handles supply and demand information for phantom products in the same way as for standard BOM components.
You use the Suggestion type field (SUGTYP) to control whether material requirement demand is displayed in the MRP results set. Available values are:
Reorder quantity
The Reorder quantity field determines the proposed reorder quantity with respect to the requirement. The possible options are:
Splitting
The Splitting field sets up quantity suggestions equal to the technical lot. These suggestions can run in parallel or sequentially.
Defining the requirements calculation parameters is mandatory in order for MRP to work properly.
Defining the ACH (Purchase) chapter, REF (Referencing) group parameters at the folder level to control the selection of the preferred supplier for purchase order suggestions and subcontract order suggestions.
You can view, and print the results of the MRP processing run in many associated functions:
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Fields
The following fields are present on this tab :
Block number 1
| This field displays the type of processing that will be carried out by this function. |
| This field displays today's date. Leave today's date as the calculation date for this processing run, or type in or select a reference date, either in the past or in the future. The calculation periods and start date for the processing run will be based on this date. |
| Select this check box to display the progress of the run. Details of the progress of each product and phase, or stage of the run is displayed. |
| Use this field to define the storage site (warehouse) at which Material Requirements Planning is required. A storage site has the check box Stock (Details section) selected. You can run MRP for multiple sites. The position of a site in the selection table is important. In effect, MRP processes the sites successively, that is if the selection order is site A, then site B, then site C the calculation will be performed first for site A, then for site B, then for site C. The processing order can be important if MRP calculations generate intersite suggestions. |
| The name of the storage site. |
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This function can be run in batch mode, but no dedicated standard task is delivered to run it.
MRP processing determines the end date and the start date, and positions the orders over time with respect to the requirement date.
WOS end date = requirement date - quality control lead time (on the product-site record)
WOS start date = WOS end date - production lead time (on the product-site record)
Production lead time: 5 days
Quality control lead time: 2 days
POS end date = Requirement date - quality control lead time (on the product-site record)
POS start date = POS end date - order lead time (on the product-site record)
Purchasing lead time: 7 days
Quality control lead time: 2 days
WOS end date = requirement date - quality control lead time (on the product-site record)
WOS start date = end date - routing time
The quality control lead time should not be defined on the product-site record, if quality control is included in the routing.
The start date is the processing date by default, if the calculated start date is earlier than the processing date.
Impact of the division on suggestions
Firm production (PF): 5 production lead time days
Sales order firm (SOF) 1: 50 parts; Work order firm (WOF) 1: 50 parts
SOF 2: 75 parts; WOF 2: 75 parts
Division in days
Division in weeks
SOF 1: 50 parts; WOF 1: 1,125 parts
SOF 2: 75 pieces
Division in days
Firm horizon: 1 week
Demand horizon: 2 weeks
PF product: 5 production days
SOF 1: 50 parts; Date of requirement: Monday, week 1 (WOF no. 1)
This order generates a WOF that will take place after the firm horizon.
SOF 2: 75 parts; Date of requirement: Wednesday, week 2 (WOF no. 2)
Sales order suggestion (SOS) forecast no. 3: 100 parts; Date of requirement: Friday, week 2
This forecast does not generate any work order suggestions (WOS), in effect the requirement date is located within the demand horizon.
SOS no. 4: 125 parts; Date of requirement: Friday, week 3
The Management mode (STDFLG) for this product in the following examples is Available stock.
Result of a simple net requirement calculation
Product A
Start stock: 0
Safety stock: 0
Production lead time: 5 calendar days
Period: week
| W0 | W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 |
SOF |
| 50 | 250 | 100 | 50 | 105 | 105 |
| 250 | 125 | 125 |
WOF |
|
|
| 100 |
|
|
|
| 100 |
|
|
WOS | 50 | 250 | 100 |
| 55 | 105 |
| 250 | 25 | 125 |
|
Projected stock | 50 | 250 | 100 | 100 | 105 | 105 | 0 | 250 | 125 | 125 | 0 |
Result of a simple net requirement calculation
Product A
Start stock: 125
Safety stock: 0
Production lead time: 5 calendar days
Period: week
| W0 | W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 |
SOF |
| 50 | 250 | 100 | 50 | 105 | 105 |
| 250 | 125 | 125 |
WOF |
|
|
| 100 |
|
|
|
| 100 |
|
|
WOS | 175 | 100 |
| 55 | 105 |
| 250 | 25 | 125 |
| |
Projected stock | 125 | 250 | 100 | 100 | 105 | 105 | 0 | 250 | 125 | 125 | 0 |
The MRP results for a product are dependent on the MRP parameters, the product-site record, the scheduling, the reorder policy associated with the product and the start stock.
Reminder: Parameters that impact MRP
Product-site data
Fields in the Management and Planning sections of the product-site record.
Maximum stock
Maximum stock is included if defined in the MRP Requirements parameters (Maximum stock analysis field).
Analysis of the product's maximum stock level is carried out at the end of each period. When the maximum stock level is exceeded, a warning message is generated and displayed in the MRP results inquiry. At the end of the period a VRS ("overstock" warning) is generated for the excess stock quantity. This VRS "warning" is only for information purposes and cannot be converted to a transaction.
Safety stock
Safety stock is included if it is included in the reorder policy associated with the product (the Safety stock field is selected), and if the Ignore safety stock check box in the MRP Requirements parameters is clear.
MRP checks the stock level at the end of the period and issues a suggestion if a shortage of safety stock is found.
Version-managed products: MRP will always issue a suggestion for the exact version of a product if components have been allocated (detailed allocation). If, however, a shortage of safety stock is found, MRP will always issue a suggestion for the latest active version.
Trend safety stock
Safety stock can also be used for trend safety stock if the MRPDYNSAF-MRP seasonalized safety stock parameter (STO chapter, REA group) is set to Yes, the forecast box of the product record is selected, and a trend curve is associated with the product.
Trend safety stock is calculated in proportion with the weight of the processing day in the curve.
Trend safety stock formula: Safety stock * (Period allocation key / Total allocation key) * (Period total weight in months / Period weight in months)
Example 1: Trend safety stock calculation
Product A
Start stock: 0
Safety stock: 350
Number of periods: 12
Period start | Period end | Allocation key | Coefficient | Trend safety stock |
01/01 | 31/01 | 100 | 0.33 | 117 |
01/02 | 28/02 | 200 | 0.67 | 233 |
01/03 | 31/03 | 300 | 1 | 350 |
01/04 | 30/04 | 400 | 1.33 | 467 |
01/05 | 31/05 | 500 | 1.67 | 583 |
01/06 | 30/06 | 600 | 2.00 | 700 |
01/07 | 31/07 | 500 | 1.67 | 583 |
01/08 | 31/08 | 400 | 1.33 | 467 |
01/09 | 30/09 | 300 | 1.00 | 350 |
01/10 | 31/10 | 200 | 0.67 | 233 |
01/11 | 30/11 | 100 | 0.33 | 117 |
01/12 | 31/12 | 0 | 0 | 0 |
Total allocation key |
| 3600 |
|
|
Example 2: MRP processing run including safety stock
Product A
Start stock: 0
Safety stock: 350
| W0 | W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 |
SOF |
| 50 | 250 | 100 | 50 | 105 | 105 |
| 250 | 125 | 125 |
WOF |
|
|
| 100 |
|
|
|
| 100 |
|
|
WOS | 400 | 250 | 100 |
| 55 | 105 |
| 250 | 25 | 125 |
|
Projected stock | 400 | 600 | 450 | 450 | 455 | 455 | 350 | 600 | 475 | 475 | 350 |
Technical lot
The technical lot is used in the reorder quantity and the division of the reorder policy.
Example 1
Product A
Start stock: 0
Technical lot: 60 parts
Safety stock: 350 parts
Reorder policy: Minimum quantity with rounding
| W0 | W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 |
SOF |
| 50 | 250 | 100 | 50 | 105 | 105 |
| 250 | 125 | 125 |
WOF |
|
|
| 100 |
|
|
|
| 100 |
|
|
WOS | 420 | 240 | 120 |
| 120 | 120 |
| 180 | 120 |
| |
Projected stock | 420 | 610 | 480 | 480 | 550 | 565 | 460 | 640 | 490 | 485 | 360 |
Example 2
Product A
Start stock: 0
Technical lot: 60 parts
Safety stock: 350 parts
Reorder policy: Minimum quantity without rounding
| W0 | W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 |
SOF |
| 50 | 250 | 100 | 50 | 105 | 105 |
| 250 | 125 | 125 |
WOF |
|
|
| 100 |
|
|
|
| 100 |
|
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WOS | 400 | 250 | 120 |
| 120 | 120 |
| 150 | 60 | 90 |
|
Projected stock | 400 | 600 | 470 | 470 | 540 | 555 | 450 | 600 | 510 | 475 | 350 |
Reduction factor
The reduction factor of the reorder lead time (reorder lead time = production lead time or purchase lead time) is used to correct the reorder lead time in proportion with the replenishment when the planned or suggested quantity is higher than the economic order quantity.
Corrected lead time = RL * [1 + (quantity/lot - 1) * factor / 100] where RL = Reorder Lead time
This factor is generally used for manufactured products. The supplier lead time is an average lead time, rarely in proportion with the size of a lot.
Example: Lead time correction
Product A
Production lead time: 10 days
Technical lot: 50
Suggestions | Factor 50% | Factor 100% |
40 | 10 days | 10 days |
100 | 15 days | 20 days |
150 | 20 days | 30 days |
Coverage
Coverage is used for stock managed products. When MRP is run with coverage, this means that the process analyzes the requirements inside the coverage period in order to issue a global suggestion. This coverage can slide; the suggestion is placed at the beginning of the coverage period, that is at the earliest one coverage period before the requirement date.
Example
Product A
Coverage: 5 weeks
Start stock: 0; Safety stock: 0
Production lead time: 1 week
Requirements expressed per week
Table of requirements expressed over 10 weeks
| W0 | W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 |
SOF |
| 50 | 250 | 100 | 50 | 105 | 105 | 150 | 250 | 125 | 125 |
WOF |
|
|
| 100 |
|
|
|
| 100 |
|
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WOS | 350 | 105 | 105 | 150 | 150 | 125 | 125 |
| |||
Projected stock | 350 | 405 | 260 | 410 | 510 | 530 | 550 | 400 | 250 | 125 | 0 |
Coverage can be made to depend on the trend when the MRPDYNCOV - MRP seasonalized coverage parameter (STO chapter, REA group) is set to Yes and a trend curve is associated with the product.
Trend coverage is calculated in proportion with the weight of the day in the curve and with respect to the average weight of the applicable period.
Example
1 day: Factor of Day1
1 week: Average of the factors over Week1
1 month: Average of the factors over a month
Product record data: 5 weeks
MRP period (5 days / 3 weeks / 3 months)
Number of days in the year: 365
Period start | Period end | Allocation key | Coefficient |
01/01 | 31/01 | 100 | 0.2505 |
01/02 | 15/02 | 150 | 2.5887 |
16/02 | 28/02 | 500 | 1.1948 |
01/03 | 16/03 | 250 | 3.1064 |
16/03 | 31/03 | 600 | 1.4561 |
01/04 | 30/04 | 400 | 1.0355 |
01/05 | 31/05 | 500 | 1.2526 |
01/06 | 30/06 | 600 | 1.5532 |
01/07 | 31/07 | 500 | 1.2526 |
01/08 | 31/08 | 400 | 1.0021 |
01/09 | 30/09 | 300 | 0.7766 |
01/10 | 31/10 | 200 | 0.5010 |
01/11 | 30/11 | 100 | 0.2589 |
01/12 | 31/12 | 0 | 0.0000 |
Total allocation key | 4700 |
Processing date 02/01
Period start | Period end | Applied factor | Coverage |
02/01 | 02/01 | 0.2505 | 1 week |
03/01 | 03/01 | 0.2505 | 1 week |
04/01 | 04/01 | 0.2505 | 1 week |
05/01 | 05/01 | 0.2505 | 1 week |
06/01 | 06/01 | 0.2505 | 1 week |
09/01 | 13/01 | 0.2505 | 1 week |
16/01 | 20/01 | 0.2505 | 1 week |
23/01 | 27/01 | 0.2505 | 1 week |
30/01 | 30/01 | 0.2505 | 1 week |
31/01 | 31/01 | 0.2505 | 1 week |
01/02 | 28/02 | 1.8917 | 10 weeks |
01/03 | 31/03 | 2.2812 | 11 weeks |
Firm horizon
MRP generates suggestions and induced requirements after the firm horizon, it does not induce requirements or generate suggestions in the firm horizon. Dates are ignored during the firm horizon.
Example
Product A
Firm horizon: 3 weeks
Start stock: 0
Safety stock: 350
| W0 | W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 |
SOF |
| 50 | 250 | 100 | 50 | 105 | 105 |
| 250 | 125 | 125 |
WOF |
|
|
| 100 |
|
|
|
| 100 |
|
|
WOS | 50 | 55 | 105 |
| 250 | 25 | 125 |
| |||
Projected stock | 0 | -50 | -300 | 450 | 455 | 455 | 350 | 600 | 475 | 475 | 350 |
Request/Demand horizon
MRP ignores suggestions from customer orders during the request horizon, or "demand horizon".
Beyond the demand horizon, for each period, a suggestion is issued and MRP takes into account all the firm and planned customer orders as well as the variance between the forecasts and the firm and planned orders.
Example
Product A
Demand horizon: 4 weeks
Start stock: 0
Safety stock: 350
W0 | W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 | |
SOF |
| 50 | 250 | 100 | 50 | 105 | 105 |
| 250 | 125 | 125 |
SOS | 100 | 100 | 100 | 250 | 100 | 100 | 100 | 360 | 100 | 100 | 100 |
WOF |
|
|
| 100 |
|
|
|
| 100 |
|
|
WOS | 400 | 250 | 100 |
| 105 | 105 | 360 | 250 | 125 | 125 |
|
Projected stock | 400 | 600 | 450 | 450 | 455 | 455 | 710 | 590 | 475 | 475 | 350 |
MRP and replanning
Replanning analysis allows the MRP process to tackle the following questions for a second positioned resource: What is it used for? Should it be moved forward? Should it be postponed? Should the quantity for it be increased? Should the quantity be reduced?
Replanning is not compatible with products managed By order (Management mode field (STDFLG)).
MRP analyzes the first actual requirement during the replanning period around the resource date.
Replanning analysis requires a replanning time period, a replanning rule for each resource (MRP parameter) and a replanning policy (Replanning analysis check box is selected).
The analysis used for each resource is one of the following:
Example
Replanning analysis: 5 weeks
Rule to be applied to firm work orders only
Lead time: 7 calendar days
Ignore reorder policy in replanning: Selected (ticked)
A WOF resource of 100 parts in W3
A resource of 100 parts in W8
Table of the requirements expressed over 10 weeks
W1 | W2 | W3 | W4 | W5 | W6 | W7 | W8 | W9 | W10 | |
SOF | 50 | 250 |
|
| 105 | 105 | 150 | 250 | 125 | 125 |
WOF |
|
| 100 |
|
|
|
| 100 |
|
|
MRP results, in simulation mode | ||||||||||
WOS | 50 |
|
| 105 | 105 | 150 | 150 | 125 | 125 | |
WOF | 100 |
| 100 | |||||||
WOS |
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WOF |
| 250 |
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The process will suggest to increase and bring forward the initial WOF from 100 parts to 250 parts. | ||||||||||
Results in message only | ||||||||||
WOS | 50 | 250 |
|
| 105 | 105 | 150 | 150 | 125 | 125 |
WOF |
|
| 100 |
|
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|
| 100 |
|
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WOS |
|
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|
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| ||
WOF |
| 250 |
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|
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The process will suggest to increase and bring forward the initial WOF from 100 parts to 250 parts, but the dates and quantities will not be modified. |
MRP and expiration
MRP processing integrates expiration dates.
When a lot reaches its expiration date MRP generates a VDS ("trace" warning) to be found in the MRP journal and in the MRP inquiry. The VDS "warning" corresponds to the quantity of the expired lot. It is generated depending on the status assumed by the expired lot and the MRP setup (start stock).
Table of the warnings as based on the MRP setup and the product expiration status.
Expiration status | ||
Start stock | Q | R |
A | VDS | VDS |
A+Q |
| VDS |
A+Q+R |
|
|
MRP and load calculation
An appropriate MRP setup is used, in parallel with the MRP process, to generate a workload.
The workload is generated according to the routing times over the course of the workload calculation horizon. The division of the MRP periods should be identical to the division of the scheduling periods (see the Scheduling documentation).
The scheduling of dates uses the data from the routing. If the start date is prior to the processing date the system recalculates the end date using backward scheduling (following the scheduling setup) in order for the start date and processing date to be on a par.
After backward scheduling:
When the setup specifies "no backward scheduling", if the start date is prior to the processing date the system modifies the start date (start date = processing date) and displays the message "Delay firm horizon".
Backward scheduling only concerns the released product which can result in a bottleneck at the component level.
Workload display
You can view the workload suggestions using the WIP and Graphical loads inquiries.
MRP and transfer option
Transfers are used to place an order with another site in the same company. This relationship is based on a sales and purchase contract between the two sites when generated orders for the requesting site are of type TRx and type TPx for the supplying site.
Successive MRP processes can be interesting when there are regular transfer orders:
In addition to the generic error messages, the following messages can appear during the entry :
This message is displayed when the calculated start date is earlier than the processing date.