|BOM Web Example|
The BOM Web example includes reports on anticipated part shortages and analyzes the critical path for each planned order. The reports include a rough-cut shortage analysis, critical path identification, and material requirement/availability schedule. These reports are described in the following sections.
Figure A.12 shows a portion of the Rough-Cut Shortage Analysis report for the order of
40 5-Gal Carpet Cleaners that is due on September 27, 2001. The starting date of the
planning period is June 11, 2001. This figure shows only the first eight columns of the report;
the remaining columns include Lead Time, Total Lead Time, Type, Unit, Parent, Qty. Per Assembly,
Final Product, and Qty. Needed.
Figure A.12: Rough-Cut Shortage Analysis
Items with positive Variance will not be available in the desired quantity when needed, and hence will have shortage or schedule problems. There might be many items with such problems, but typically only a few affect the release dates for the planned orders.
You can evaluate the impact of the Variance value for an item by comparing it to the two reported slack values. If Variance does not exceed Slack to Next Assembly, availability for the item will not delay production of the listed parent component. If Variance does not exceed Slack to Final Product, availability for the item will not delay release of the order.
The items controlling their parent items' availability are those items with a zero value for Slack to Next Assembly; these are referred to as pacing items. Every subassembly has its own pacing item. Items with a zero value for Slack to Final Product are said to be critical. For example, Figure A.12 indicates that Part Numbers 0125, 6221-1, 2104, and 7350 are pacing items. In addition, Part Numbers 0125, 2104, and 7350 are critical.
The Rough-Cut Shortage Analysis report uses the CPM procedure to compute the promised date, the slack to next assembly, and the slack to final product, and backward scheduling to determine the need date. You can construct a similar report with a single call to PROC CPM, followed by one data step. Suppose the indented bill of materials for the 5-Gal Carpet Cleaner is stored in a data set named IndBOM_0125. The following code creates a Rough-Cut Shortage Analysis report for the product, which is saved in a data set named RoughCut0125. This data set contains the information listed in Figure A.12, along with some additional variables that will be used in the section "Material Requirement/Availability Schedule" to produce Gantt charts of the schedules.
proc cpm data=IndBOM_0125 out=RoughCut0125 date='11Jun2001'd addact; act Part_ID; succ Paren_ID; dur Leadtime; id _all_; run; data RoughCut0125; format PromDate NeedDate date9.; set RoughCut0125 (rename= (e_finish=PromDate f_float=Slack2NA t_float=Slack2FP)); NeedDate = '27Sep2001'd - (Tot_Lead-Leadtime) - 1; Variance = PromDate - NeedDate; QtyNeeded = 40*Qty_Prod; run;
Figure A.13 shows a portion of the Critical Paths report for the
order of 40 5-Gal Carpet Cleaners that is due on September 27, 2001.
The figure shows only the first nine columns of the report; the remaining
columns include Total Lead Time, Type, Unit, Parent, Qty. Per Assembly,
Final Product, and Qty. Needed. In this example, steel (Part 5640) is the
lowest level item and, therefore, is the most crucial of the critical items.
Figure A.13: Critical Path Identification Report
The Material Requirement/Availability Schedule for the order of 40 5-Gal Carpet Cleaners is shown in Figure A.14.
In the BOM Web example, the schedule bars are selectable and produce a ``Material Requirement
Implosion,'' which uses a Gantt chart to depict a full level pegging for the selected item.
This is a time-scaled Indented Where-Used report for the selected item in the
designated final product. Figure A.15 shows the Material Requirement
Implosion produced by selecting Steel (Part 5640) from
Figure A.15: Material Requirement Implosion
You can use PROC GANTT to produce Material Requirement/Availability Schedules similar to the Gantt chart shown in Figure A.14. The following code produces a Material Requirement/Availability Schedule for the 5-Gal Carpet Cleaner with an order quantity of 40, a starting date of June 11, 2001, and a due date of September 27, 2001. The code uses the RoughCut0125 data set created in the section "Rough-Cut Shortage Analysis Report".
title1 'Material Requirement / Availability Schedule'; title2 'Part: 0125 (5-Gal Carpet Cleaner) Order Quantity: 40'; title3 ' Start Date: 11JUN2001 Due Date: 27SEP2001'; pattern1 v=s c=green; pattern2 v=e c=green; pattern3 v=s c=red; pattern4 v=e c=red; symbol1 v="B" c=green f=ORFONT h=0.5; symbol2 v="D" c=blue f=ORFONT h=0.5; proc gantt data=RoughCut0125 logic=RoughCut0125; chart PromDate NeedDate / act=Part_ID succ=Paren_ID duration=Leadtime e_finish=PromDate ref='27SEP2001'd cref=red reflabel nojobnum noarrowhead compress; id Description Qty_Prod Variance; label Description = 'Part Description' Qty_Prod = 'Quantity Required'; run;