Solved problems
Chapter 4 Structured Analysis and Functional Architecture Design
Solved Problem # 4.1: Study the following Preventive Maintenance program at ACME
MACHINE SHOP, then solve the problem requirements:
•
Small job shop is doing machining services. It has 10 computer numerical control (CNC).
15 workers in the shop; 8 tool designers and machine tool operators. Customer’s orders
require highly trained tools designers and machinists, in order to obtain high precision
and special purpose machine parts (small lots).
•
The objective of the owner of the shop is to prevent idle times and waiting times due to
machines breakdowns to avoid losing money. He decided to use preventive maintenance
(PM) programs to avoid downtimes. In PM program, certain PM tasks are regularly
performed based on the number of operation of the machine. This information is given by
the machines’ vendors as in the following table:
•
The maintenance program is managed by maintenance supervisor and assists him
maintenance technician.
• Machines have meters to keep recording operating hours. The manufacturing department
collects the meter readings of machines operating hours and sends them to the
maintenance supervisor. After receiving the machines operating hours, maintenance
supervisor adds those hours to the record, as in the following table:
•
Then, the maintenance supervisor looks up the preventive maintenance schedule for each
machine and compares it to the sum of the hours of operation in the kept record. When
the number of operating hours from last time of PM (known from the completed
maintenance records) of a machine reaches the PM frequency, a request for PM task is
made through a work order. Work orders being performed is called open, until they
finished called completed work order that stored in the completed maintenance records.
The maintenance technician performs the PM task. The PM work order appears as
follows:
•
The work order number is a unique number. The machine ID is used to identify the
specific machine. The machine hours, which show how many total hours were on the
machine when the new maintenance.
Other data requirements are as follows:
Machine data table:
Requested summary reports:
Problem requirements:
1. Design a functional model using the IDEF0 methodology that shows how the preventive
maintenance function is done.
2. Design a data flow diagram of the processes and information flows involved in the preventive
maintenance process.
3.Design a data model using the ERD for the information requirement of the preventive
maintenance program.
Problem requirements Solution:
Summary of the PM function tasks:
IDEF0 activities (Physical & Informational):
1. Record machines operations hours.
2. Monitor machine PM hours
3. Produce PM workorder.
4. Perform Maintenance
5. Prepare/print completed PM & machine summary report .
The fifth activity could be further decomposed into two sub-activies:
1. Produce machine warranty expiration report
2. Produce PM history report
Maintenance
supervisor
Maintenance
devices
Maintenance
technician
Maintenance
personnel
A functional model using the IDEF0 methodology that shows how the preventive
maintenance function:
IDEF0 Decomposition of PM function into level-one:
Manufacturer’s PM
Schledule
Record
machine
operation
hours
Machine daily hours
A1
Machine total
hours (DB)
Monitor
Machine
hours
PM tasks frequencies (DB)
A2
Produce
Workorder
A3
Machine total
hours (DB)
Perform
Maintenance
A4
Maintenance
service
Closed workorder
(DB)
Complete
workorder
Maintenance supervisor
Machine data (DB)
PM tasks data (DB)
Produce
maintenance
report
Maintenance
technician
Maintenance reports
A5
:NODE First Level Decomposition
0A
:.NO
Machine data
Produce
machine
warranty
expiration report
Machine warranty expiration report
A5.1
PM tasks data (DB)
Produce
preventive
maintenance
history report
Complete
workorder
:NODE
5A
Preventive maintenance history report
A5.2
Produce PM reports
:TITLE
5 :.NO
3. A data flow diagram (DFD) of the processes and information flows involved in the preventive
maintenance process:
DFD activities (Informational (Only)):
1. Add machines operations hours.
2. Compare machine hours to PM schedule
3. Prepare PM workorder.
4. Close workorder
5. Prepare/print completed PM & machine summary report .
The DFD context diagram of PM function:
Decomposition of DFD context diagram into level-1 DFD:
Solved Problem # 4.2: Study the following shipping department activities at University Food
Company case, and then solve the problem requirements:
The University Food Company wants to use more information technology into its organization,
particularly its shipping department. The shipping department currently uses information from
sales and production planning departments in the course of doing its daily tasks. The shipping
supervisor wants to let someone study the activities in the department and to recommend an
information system design to support the operation.
What follows is a description of the tasks performed by the shipping clerk and support personnel
during a typical day:
•
At the beginning of each day, the sales department prints a report and sends it to the
shipping department. This report, called the “Open Orders Report,” is a list of orders
taken by sales that have not been closed out. Orders are not closed out until the final
shipment has been made against the order. An example of a typical open orders report is
shown in the following figure. Open orders are listed in the ascending order of their
promised delivery date (e.g., earliest first).
•
University Food plans its production in two ways: produce to order and produce to
inventory. In the first case, production is scheduled for a specific order. In the second
case, production is done in the absence of a specific order. The second case occurs
because a specific order is small and it is desirable to have a longer production run before
changing over to another product. Changeovers ‫التبديل أو اإلنتقال إلى و اإلعداد لمنتج غذائي مختلف‬
require that the machinery is thoroughly cleaned before the next product can be made,
and is costly. The excess production is placed in inventory and is available for shipment
the next time a customer orders the product
•
The shipping clerk receives a report (printout) of the finished goods inventory from the
production planning department, showing the location of the finished goods inventory by
inventory lot. The report is ordered by material ID in the ascending order ً‫تصاعديا‬.
•
The shipping clerk examines each of the open orders and determines whether or not there
exists a matching product inventory lot. If the match occurs, a shipment can be made. A
typical finished product inventory report is shown in the following table:
•
After identifying an inventory lot that can be shipped, the shipping clerk dispatches ‫يرسل‬
the forklift truck operator to the warehouse to fetch (palletts) ‫ يجلب أو يحضر‬items to be
shipped. He does this by giving instructions to the driver (forklift truck operator)
concerning the lot number and location of the product.
•
The forklift truck operator collects the items and brings them on pallets (‫ )األرفف الحاملة‬to
the shipping dock. He informs the shipping clerk that the pallets have been retrieved and
gets his next assignment.
•
It is the responsibility of the shipping clerk to keep a daily record (DB) of everything that
is transferred out of the warehouse for shipping and to indicate on the record the
customer order against which it is shipped. The shipping clerk completes this record
when pallets are brought to the loading dock. This document is transferred at the end of
the day to the sales department where it is used as the source of information to close out
sales orders.
The warehouse transfer report, shown in the following figure:
•
After completing an entry on the warehouse transfer report, the shipping clerk directs his
shipping personnel to load the cases of product on to a truck. As cases are being loaded,
he fills out another important report maintained by the shipping clerk, the shipping
summary report.
•
This report is kept daily and held in a file (DB summary report) in the shipping
department. It describes the quantity of cases that are shipped, the customers to whom
they are shipped, and the truck number on which they are shipped. A typical shipping
summary report is shown as follows:
Shipping Summary, 11/01/03
•
University Food maintains its own fleet of trucks ‫أسطول سيارات‬, which is managed by the
company’s transportation department. The shipping department is only responsible for
tracking the shipment to the truck on which it is dispatched. The transportation
department is responsible for tracking deliveries to the final customer.
•
For each customer shipment on a truck, the shipping clerk prepares a bill of laden ‫فاتورة‬
‫ الشحن‬for the truck driver after the cases of product are loaded on the truck. Most of the
information for the bill of laden is taken off the shipping summary and open orders
reports. A copy of the bill of laden is sent to the transportation department at this time,
and the other copies are given to the truck driver. No copies are kept in shipping (i.e., no
kept in a database…no data store).
•
This bill of laden is presented to the customer when the driver arrives at the customer’s
receiving location. A signed copy of the bill of laden is turned in to the transportation
department when the driver returns from a delivery. The transportation department
matches this copy to the one sent by the shipping department and closes out the delivery
in its records. A typical bill of laden is shown as follows:
Problem Requirements:
1. Using the description presented earlier, develop a functional architecture based on the IDEF0
method. The context diagram should be labeled “Operate Shipping Department.”
2. Draw a corresponding data flow diagram.
Problem Solution
Tasks summary of shipping department:
IDEF0 activities (Physical & Informational):
1. Match orders with
2. Dispatch forklift driver
3. Transfer orders to the dock
4. Load orders to trucks
5. Prepare Bill of Laden
1. The IDEF0 context diagram:
The DFD context diagram:
IDEF0 Decomposition of Shipping department operation into level-one:
Decomposition of DFD context diagram of the shipping process into level-1 DFD:
Loaded shipment
information
Bill of Laden
data model (ERD) of the MRP system, given the following details:
Inputs to the MRP are:
•
The Master Production Schedule (MPS) through (sales order or warehouse stock replenishment
request). MPS contains how much and when (gross requirements) of finished product units
•
The Item Master File is organized by part number and contains, at a minimum, a description of
the part, bill-of-material (BOM) information, lot-size information, and ordering/manufacturing
lead times (‫)فترة إنجازالطلبيه أوزمن اإلنتاج‬. Item master file is kept.
•
The inventory information (stock onhand (OH)) comes from inventory control department and
that are kept in the MRP system in inventory file.
Warehouse transfer
report
Identified
inventory lot
Solved Problem # 4.3: Draw the functional model both context and decomposed level 0 (DFD) & the
•
The status of purchased or/and manufacturing orders known as scheduled receipts (SR). ‫الطلبيات‬
‫ المتوقع إستالمھا‬. SR can be planned order release that has actually been released. When the job (or
orders arrived) is completed, the scheduled receipt is deleted from the database and the on-hand
inventory is updated. The SR are sent either from purchasing department or the shop-floor
department.
The output of an MRP are:
•
Planned order releases (POR): POR becomes the jobs processed in the plant
•
Change notices indicate change of existing jobs (expediting/deferring ‫)تأجيل أو إرجاء‬, such as
changes in due dates or priorities
•
Exceptions report indicates job or inventory count differences, or tardy jobs ‫أعمال متأخره‬.
The functions performed by the MRP system:
1. Compute gross requirements (BOM explosion) (GR): Use the MPS and Bill of Material
(BOM) to generate gross requirements of any required components at the next level(s).
2. Compute net requirements (Netting) (NR): Determine net requirements by subtracting on-hand
(OH) inventory and any scheduled receipts from the gross requirements. NR = GR – (OH + SR)
3. Lot sizing: Divide the netted demand into appropriate lot sizes to form jobs. The lot sizes
information comes from item master file
4. Time phasing: Offset ‫ ترحيل‬the due dates ‫ أزمنة التسليم‬of the jobs with lead times to determine start
times. The outputs of time phasing are the planned order release (POR) jobs. The POR are sent to
the shop-floor department.
‫‪Figure Summary of MRP detailed inputs, outputs, and main core operations.‬‬
‫توضيح‪ :‬مدخالت و مخرجات نظام تخطيط إحتياجات المواد من المعلومات كما ھو موضح بالشكل السابق‬
‫المدخالت )البيانات المتدفقة الداخله( ھي‪:‬‬
‫)‪ : Item mater file (BOM‬ملف الجزء الميكانيكي األساسي و به مكوناته من األجزاء األخرى وأزمنه اإلنجاز لعمليات تجميعه من‬‫األجزاء المكونه‪ ،‬و حجم الدفعة )‪ (lot size‬و يأتي من قسم التصنيع أو تخطيط اإلنتاج‬
‫‪ : Onhand inventory‬المتوفر من المخزون لكل جزء‪ ،‬و يأتي من المخازن أو قسم المخزون‬‫ ‪ : (MPS) Master production schedule‬جدول اإلنتاج الرئيسي )الكميه و الوقت للمنتجات الرئيسيه( يأتي من تخطيط اإلنتاج‬‫أو المبيعات‬
‫ ‪ : Scheduled receipts‬الطلبيات المتوقع إستالمھا )من اإلنتاج أو الموردين( يأتي من قسم المشتريات أو من قسم الورش )‪Shop-‬‬‫‪(floor‬‬
‫المخرجات )البيانات المتدفقة الخارجه( ھي‪:‬‬
‫)‪ : Planned order release (POR‬طلبيات العمل الموجھه للورشه لإلنتاج بعد تصفية المخزون المتوفر و االطلبيات المتوقعه و‬‫أخذ زمن اإلنجاز في اإلعتبار‪ .‬و يذھب لمدير الورشة أو قسم الورش )‪(Shop-floor‬‬
‫‪ : Change notice‬مالحظات التغير في تشھيل أو إرجاء العمل أو تغير أولوية اإلنجاز لألعمال أو ميعاد التسليم‬‫‪ : Exceptions reports -‬توضح اإلختالفات في العدد أو المخزن لألعمال عن المتوقع نتيجة ألي سبب ‪ ،‬و كذلك األعمال المتأخره‬
‫األنشطة أو العمليات أو الوظائف ھي‪:‬‬
‫‬‫‪-‬‬
‫الوظيفه الرئيسيه‪Operate MRP system :‬‬
‫الوظائف أو العمليات الفرعيه ھي‪:‬‬
‫التصفيه )‪ : (Netting‬تقوم بطرح المتوفر من المخزون )‪ (Onhand‬و الكمية المتوقع وصولھا )‪ (Scheduled receipts‬من‬‫القيمه اإلجماليه )‪ (Gross Requirements‬للمنتج الرئيسي الموجود بجدول اإلنتاج الرئيسي للحصول على المتطلبات الصافيه‬
‫)‪ (Product net requirements‬لكل من المنتج الرئيسي بطلب العميل‪.‬‬
‫ تحديد حجم دفعة الإلنتاج )‪ :(Lot-sizing‬يتم تقسيم الطلب الصافي المحسوب في الخطوه السابقه على دفعات يتم تحديدھا مسبقا ً‬‫ حساب كمية المكونات )‪ :(BOM explosion‬تقوم بحساب الكميه الصافيه )‪ (Parts net requirements‬لألجزاء المكونه‬‫بمعلوميه الكميه الصافيه للمنتج الرئيسي )‪(Product net requirements‬‬
‫ الترحيل )تحديد بدء األعمال( حسب )‪ :(Time phasing/offsetting‬ترحيل زمن تسليم كافة األعمال )منتج و جزء( للوراء‬‫حسب زمن اإلنجاز لكل منتج و جزء‪.‬‬
‫المطلوب تصميم مخطط تدفق البيانات )‪ (DFD‬للمخطط الرئيسي و مخطط التحليل للمستوي األول ) ‪First level‬‬
‫‪ (decomposition‬باإلضافه لنموذج قاعدة البيانات )‪.(ERD‬‬
‫‪Solution of the MRP problem‬‬
‫;‪The DFD Context diagram‬‬
The DFD first level Decomposition: