Industrial Engineering and Ergonomics

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1 Industrial Engineering and Ergonomics Exercise Unit 2 Work organization Fall Winter 207/208 Dr.-Ing. Dr. rer. medic. Dipl.-Inform. Alexander Mertens Chair and Institute of Industrial Engineering and Ergonomics Instructor: M.Sc. Christina Bröhl c.broehl@iaw.rwth-aachen.de

Network Analysis Definition (I) DIN 69900 Definition: Network Analysis is a method based on workflow structures for analysis, characterization, design, regulation, control of activities, where time,

2 Network Analysis Definition (I) DIN Definition: Network Analysis is a method based on workflow structures for analysis, characterization, design, regulation, control of activities, where time, money, resources and other parameters have to be considered. A network plan is the graphical or tabularly illustration of a workflow structure, which consist of processes resp. events and s. Network elements structural elements descriptive elements activities events s nodes directed edges (arrow) activity event activity/ (Source: Landau 2005) 2-2

3 Network Analysis Definition (II) Activity (synonymical job, action, work step, work process) is a workflow element to describe a particular activity with a defined beginning and ending has a defined duration Event is a workflow element which describes the occurance of a particular condition occurs to a particular point in time but has no duration special events are called key-events or milestones Precedence Relation is a quantifiable dependence between events or activities defines the technical context activity event Node is an element to describe a mixing point symbolizes an event or activity depending on the character of the network Arrow is an element to describe the cirumstance between two nodes symbolizes an activity or ship depending on the character of the network activity/ (Source: DIN 69900) 2-3

4 Network plans Network plans Arrow Diagramming Method Precedence Diagram Method Event Node Method event activity and activity event activity arrow activity node activity arrow arrow arrow event node event event node 0 0 Critical Path Method (CPM) construc- 2 tion prefab.. comp Metra Potential Method (MPM) Construction Prefabrication Components Program Evaluation Review Technique (PERT) Construction finished Components completed

5 Precedence Diagram Method Metra Potential Method (MPM) Node number of Earliest start time of Latest start time of i activity description EST(i) D(i) EET(i) LST(i) BT(i) LET(i) Duration of Earliest end time of Latest end time of Buffer time of (Source: Landau 2005) 2-5

6 MPM Rules for modelling Nr. Ground rules Illustration in the Precedence Diagram Are two activities following each other, there is a sequential without aborization between them. A 2 A 2 2 Does one activity has several followers, there is an ANDaborization between the antecessor and the followers. B C Do several antecessors have one follower, there is an AND-consolidation between the antecessors and the follower. 2 A B 3 4 If there are parallel activities, an AND-aborization is followed by an AND-consolidation. A B C D 4 E (Source: Landau 2005) 2-6

7 MPM Example 2 Acquisition External units Pre-assembly unit A Pre-assembly unit C Final assembly Final inspection Construction Fabrication own units Pre-assembly unit B Assembly unit A+B Adjustment unit A Protective coating Node number of Activity description Earliest start time of activityi Latest start time of i EST(i) D(i) EET(i) LST(i) BT(i) LET(i) Buffer time of Duration of Earliest end time of Latest end time of 2-7

8 MPM Buffer and Critical Path 2 Acquisition External units Pre-assembly unit A Pre-assembly unit C Final assembly Final inspection Construction Fabrication own units Pre-assembly unit B Assembly unit A+B Adjustment unit A Prtotective coating Buffer Time (BT) = Period of time between earliest and latest start or end time. BT(i) = LST(i) EST(i) or BT(i) = LET(i) EET(i) Along the critical path no difference between EST und LST resp. EET und LET Deceleration leads to extension of the total time Example activity 4 ( Pre-assembly unit A ): BT(4) = LST(4) EST(4) = = 4 There is a time tolerance of four time units with reference to the start of activity 9 ( Final assembly ) 2-8

9 Network Analysis Pros and Cons The portrayal (...) in form of a network plan is not a schematic transformation of the real scheduled activities into a graphical illustration, but planning in its classical meaning. (Schwarze 200,S. 4) + The design of a network plan forces one to think the workflow through properly and explicitly + From the point of view of the designer the network plan contains the complete and consistent workflow with activities, realtions and milestones + The graphical illustration makes the control of the workflow and the correct classification easier A network plan can be illustrated in different ways. The variety of methods and the inconsistent choice of terms ( activity / action / job ) sometimes lead to misunderstandings activity activity action event event (Source: Schwarze 200) 2-9

10 Exercise : Creation of an activity network diagram (MPM) A company manufactures customer-specific desktop PCs and notebook computers. The whole process, starts with the costumer contact and ends with the packaging, is represented in this activity list. Task: Process number Create an activity network diagram (MPM) by using the following activity list. Process / Task name Predecessor Downstream Operaitons Duration () determine customer requirements (2) prepare an estimate 3, 4, 9 2 (3) procure hardware components (4) procure software (5) mount hardware (6) test hardware 5 7, 0 (7) software update 4, (8) test software 7 0 (9) create documentation (0) packaging and dispatchment 6, 8,

11 Process number Exercise 2: Process representation with bar chart Task: Transform the network plan into a bar chart (Gantt Chart). () (2) (3) (4) (5) (6) (7) (8) (9) (0) t 2 -

12 Exercise 3: Creation of an activity network diagram (MPM) Task: a.) Build a process network plan based on the list of processes shown in the following table. Include all of the predecessor and successor ships. b.) Indentify the critical path of the network plan. Process number Predecessor Successor Duration () - 2, 4 4 (2) 3 2 (3) (4), 3 5, 6, 7 4 (5) (6) 4 7, 8 (7) 4, (8) 5, 6,

13 Exercise 4: Creation of an activity network diagram (MPM) Task: a.) Build a process network plan based on the list of processes shown in the following table. Include all of the predecessor and successor ships. b.) Indentify the critical path of the network plan. Process number Process / Task name Duration [weeks] Predecessor () Kick-off meeting - (2) Formation of groups 2 (3) Taking up the production processes 5 2 (4) Taking up the maintenance processes 3 2 (5) Analyse the assembly processes 3 3 (6) Analyse the packaging processes 2 3 (7) Modelling 3 4, 5, 6 (8) Preparing a presentation 2 7 (9) Performing plausibility checks 7 (0) Presentation 8, 9 2-3

14 Exercise 4: Creation of an activity network diagram (MPM): a.) () Kick-off meeting (3) Taking up the production processes (6) Analyse the packaging processes (9) Performing plausibility checks (2) Formation of groups (4) Taking up the maintenance processes (7) Modelling (0) Presentation (5) Analyse the assembly processes (8) Preparing a presentation 2-4

15 Exercise 5: Task Analysis According to Performance The company s management decides on an extensive re-organization of the assembly department (assembling PCs and notebooks). The department Assembly includes the functional areas of Production planning, Casing preparation, Components in casing assembly and Software installation. PC Quantity Components Casing Power supply Motherboard CPU Memory (RAM) Graphics card -2 DVD drive -2 Hard disk various cable types Remark (PC): CPU, RAM and Graphics card have to be mounted on motherboard. Task: A task analysis according to performance must be performed for the assembly of the PCs. 2-5

16 Exercise 6: Task Analysis According to Objects PCs and notebooks are mounted in the functional area of Components in casing assembly. PC Quantity Components Notebook Quantity Components Casing Power supply Motherboard CPU Memory (RAM) Graphics card -2 DVD drive -2 Hard disk various cable types Notebook casing Motherboard CPU or CPU 2 Memory (RAM) -2 DVD drive -2 Hard disk various cable types Remark (PC): CPU, RAM and Graphics card have to be mounted on motherboard. Remark (Notebook): CPU or CPU 2 and RAM have to be mounted on motherboard. Task: A task analysis according to objects must be performed for the assembly of the PCs and notebooks. 2-6

17 Exercise 7: Task Analysis According to Rank A new assembly line for notebooks and desktop PCs shall be built up. It includes the execution and decision regarding to: a) Factory layout b) Division of work c) Production planning After the production planning is completed, the assembly of desktop PCs and notebooks starts. The assembly of desktop PCs and notebooks takes place by: a) Picking of components b) Component assembly Task: A task analysis according to rank must be performed. 2-7

Dependency Table Example. Task ID Name Predecessors 1 A 2 B 3 C 4 D 1 5 E 1;2 6 F 1;2 7 G 5;6 8 H 4;5

Dependency Table Example. Task ID Name Predecessors 1 A 2 B 3 C 4 D 1 5 E 1;2 6 F 1;2 7 G 5;6 8 H 4;5 Dependency Table Example Task ID Name Predecessors 1 A 2 B 3 C 4 D 1 5 E 1;2 6 F 1;2 7 G 5;6 8 H 4;5 Dependent tasks Dependency Matrix 1 2 3 4 5 6 7 8 9 10 1 x 2 x x 3 x x 4 x 5 x x 6 x 7 x 8 x 9 x x 10