1 DELIVERABLES OF DESIGN REVIEW 1 Statement of problem/need Customer needs Product Design Specifications (PDS) Design targets Project plan TOOLS USED TO PRODUCE THOSE DELIVERABLES Customers research QFD Gantt’s chart CPM (if applicable)

2 PLANNING THE DESIGN PROJECT IN MME259a Design review 1 Design review 2 Design review 3 Final report Gantt’s chart should be updated by actual project progress (here in red)

3 CRITICAL PATH METHOD (CPM) Complex projects tasks require a series of activities, some of which must be performed sequentially and other can be performed in parallel with other activities. The collection of series and parallel tasks can be modeled as a network. The Critical Path Method (CPM) was developed in 1957 as a network model for project managements. CPS is a deterministic method using a fixed time estimate for each activity. The Critical Path Method - is a project planning technique used to determine the most efficient sequence of tasks. A modification of CPM is PERT (Program Evaluation and Review Technique) which takes into consideration that tasks duration may vary.

4 In a project, an activity is a task that must be performed and an event is a milestone marking the completion of one or more activities. Before an activity can begin, all of its predecessor activities must be completed. The milestone can be numbered so that the ending node of an activity has a higher number the beginning node. It is convenient to increment the numbers by 10 so that new nodes may be easily inserted. The activities are labeled with letters along with the expected time required to complete the activity. MILESTONE Node 40 (labeled as number) event marking completion of an activity TASK Activity E (labeled as letter) Duration 3 weeks CRITICAL PATH METHOD (CPM)

5 A 3 Primary elements of a CPM diagram : Activity - is a time consuming effort that is required to perform part of the project (a task). An activity is represented by an arrow. Event - is a point of accomplishment and/or decision (i.e. a milestone). It marks the end of one activity and the beginning of another. An event is represented by a circle.

6 RULE 2. An event cannot be reached (a task can not be completed) until all activities leading to it are complete. Activities F and G must both be completed before activity H can begin. Logic restrictions to constructing CPM diagrams: RULE 1. An activity cannot be started until its tail event is reached Activities D and E cannot begin until activity C has been completed. C D E 1 H F G 2 CRITICAL PATH METHOD (CPM)

7 Activity A must precede both B and C –B must precede D and E –C must precede E –D and E must precede F –Note: Dummy activities show a sequential connection but no expenditure of time. RULE 3.Sometimes an event is dependent on another event preceding it, even though the two events are not linked together by an activity A D E F B C CRITICAL PATH METHOD (CPM) Logic restrictions to constructing CPM diagrams:

8 Example: The CPM network shown below for constructing a building implies that the window frames can be installed before the walls are built (an illogical situation). By adding a dummy activity, the network now indicates that the installation of window frames has to await both the fabrication of the window frames and the building of the walls Build Walls Construct Roof Make Window FramesInstall Window Frames Build Walls Construct Roof Make Window FramesInstall Window Frames CRITICAL PATH METHOD (CPM)

9 Basic parameters for time estimates : ES - Earliest Start Time The earliest time that an activity can begin when all preceding activities are completed as rapidly as possible. LS - Latest Start Time The latest time that an activity can be initiated without delaying the minimum completion time for the project. EF - Earliest Finish Time EF = ES + Dwhere D is the duration of each activity. LF - Latest Finish Time LF = LS + D.TF - Total Float Time (slack) TF = LS – ES Note: An activity on the critical path has zero total float TF = 0 CRITICAL PATH METHOD (CPM)

10 ES = 4 node 50: B, EES = 6 A, D ES = 5 A, C, FES = 7 ES = 3 ES = 4 Calculation of early start times ES based on CPM diagram. ES times are determined by starting at the first event (node) and making a forward pass through the network while adding each activity duration to the ES of the preceding activity. CRITICAL PATH METHOD (CPM) ES for the last activity actually means the end of project

11 ES = 4 ES = 3 ES = 4 CRITICAL PATH METHOD (CPM) Calculation of late start LS times based on CPM diagram. LS times are calculated by starting at the last event (node) and a backward pass is made through the network while subtracting the activity duration from the limiting LS at each event LS = 5 LS = 3 LS = 4 ES = 7

12 ES = 4 ES = 7 ES = 3 ES = 4 CRITICAL PATH METHOD (CPM) An activity on the critical path has zero total float (slack) TF = LS – ES = 0 LS = 5 LS = 3 LS = 4 SLACK = 1 SLACK = 0 CRITICAL PATH

13 Gantt chart for testing a heat exchanger. Activities for testing a heat exchanger. Example: Prototype testing of heat exchanger. CRITICAL PATH METHOD (CPM) – EXAMPLE 1

14 STEP 1 Perform forward pass to determine ES for each activity ES times are determined by starting at the first event (node) and making a forward pass through the network while adding each activity duration in turn to the ES of the preceding activity Example: Prototype testing of heat exchanger. CRITICAL PATH METHOD (CPM) – EXAMPLE 1

15 STEP 2 Perform backward pass to determine LS for each activity LS times are calculated by starting at the last event (node) and a backward pass is made through the network while subtracting the activity duration from the limiting LS at each event – 2 = – 2 = = – 3 = 13 Example: Prototype testing of heat exchanger – 5 = 8 13 – 6 = = = 3 LIMITING LS I CRITICAL PATH METHOD (CPM) – EXAMPLE 1

16 18 – 2 = – 2 = = – 3 = 13 Example: Prototype testing of heat exchanger – 5 = 8 13 – 6 = = = 3 LIMITING LS I STEP 3 Find critical path Critical path is where TF = 0 CRITICAL PATH METHOD (CPM) – EXAMPLE 1

17 Example: Prototype testing of heat exchanger. Summary of boundary timetable. CRITICAL PATH METHOD (CPM) – EXAMPLE 1

18 CRITICAL PATH METHOD (CPM) ES is determined by forward pass through network LS is determined by backward pass through network Time float TF = LS – ES Path where TF = 0 is the CRITICAL PATH

CRITICAL PATH METHOD (CPM) – EXAMPLE 2

?3? 5?5? 8 ?8 ? 5?5? 9 ? 1?1? 3?3? 5 ?5 ? Forward pass to determine ES 7?7? CRITICAL PATH METHOD (CPM) – EXAMPLE 2

= = – 2 = – 4 = – 2 = – 2 = 7 5 Backward pass to determine LS 7 9 – 1 = 8 CRITICAL PATH METHOD (CPM) – EXAMPLE 2

= = – 2 = – 4 = – 2 = – 2 = 7 5 The critical path where we must not allow any delay or else the final event will not be reached in 9 weeks 7 9 – 1 = CRITICAL PATH METHOD (CPM) – EXAMPLE 2

23 ActivityDescriptionTime estimate, weeks Preceded by AProduct design5none BMarket research1none CProduction analysis2A DProduct model3A ESales brochure2A FCost analysis3C GProduct testing4D HSales training2B, E IPricing1H JProject report3F, G, I EX 1.The various activities associated with developing a new product are summarized below. (i)Draw a CPM network diagram for completing the above activities in the proper sequence (ii)Determine the critical path by calculating ES, LS, EF, LF and TF CRITICAL PATH METHOD (CPM) – EXAMPLE 3

A(5) B(1) E(2) H(2) I(1) F(3) C(2) D(3) G(4) J(3) Product design A5 Market Research B1 Production Analysis C2 Product Model D3 Cost Analysis F3 Product testing G4 Sales brochure E2 Sales training H2 Pricing I1 Project report J3 CRITICAL PATH METHOD (CPM) – EXAMPLE 3

A(5) B(1) E(2) H(2) I(1) F(3) C(2) D(3) G(4) J(3) Forward pass to determine ES CRITICAL PATH METHOD (CPM) – EXAMPLE 3

A(5) B(1) E(2) H(2) I(1) F(3) C(2) D(3) G(4) J(3) = = =9 12-3=9 12-4=8 8-3= Backward pass to determine LS CRITICAL PATH METHOD (CPM) – EXAMPLE 3

27 ActivityDescriptionDESLSEFLFTF A Product design B Market research C Production analysis D Product model E Sales brochure F Cost analysis G Product testing H Sales training I Pricing J Project report D = Duration (weeks) ES = Earliest Start LS = Latest Start EF = Earliest finish (ES + D) LF = Latest finish (LS + D) TF = Total float time (LS-ES) CRITICAL PATH METHOD (CPM) – EXAMPLE 3

A(5) B(1) E(2) H(2) I(1) F(3) C(2) D(3) G(4) J(3) Total Project duration = 15 weeks CRITICAL PATH METHOD (CPM) – EXAMPLE 3

29 ActivityDescriptionTime estimate, weeks Preceded by AInvestigation and planning5none BCustomer feedback2none CDefine the market1none DInitial concept design4A EConcept Selection3B FSystem modeling2B, C, E GDetail Design3B, C, E HInitial Prototype3B ITesting3A, D JFinal Prototype2A, D KProduction1G, H, I LEstablish product cost2F CRITICAL PATH METHOD (CPM) – EXAMPLE 4

CRITICAL PATH METHOD (CPM) – EXAMPLE 4 Investigation and planning A5 Customer feedback B2 Define the market C1 Initial concept Design D4 Concept Selection E3 System modeling F2 Detail Design H3 Detail Design G3 Testing I3 Final Prototype J2 Production K1 Establish product cost L2

A(5) B(2) E(3) H(3) I(3) F(2) D(4) G(3) J(2) C(1) 6 2 K(1) L(2) CRITICAL PATH METHOD (CPM) – EXAMPLE 4 Forward pass to determine ES

A(5) B(2) E(3) H(3) I(3) F(2) D(4) G(3) J(2) C(1) 6 2 K(1) L(2) LS=9 12 CRITICAL PATH METHOD (CPM) – EXAMPLE 4 Backward pass to determine LS

33 ActivityDescriptionDESLSEFLFTF AInvestigation and planning BCustomer feedback CDefine the market DInitial concept design EConcept Selection FSystem modeling GDetail Design HInitial Prototype ITesting JFinal Prototype KProduction LEstablish product cost CRITICAL PATH METHOD (CPM) – EXAMPLE 4

A(5) B(2) E(3) H(3) I(3) F(2) D(4) G(3) J(2) C(1) 6 2 K(1) L(2) Total Project duration = 13 weeks