Supply chain Dynamics in Indian Apparel Export Manufacturing Submitted by: Shikha Aggarwal Vikas Punia

What is Critical path The longest chain of activities considering task dependencies (A-B-D is the critical Path) A = 2, B = 3, C = 1 and D = 2 man-days

Why Critical Path Critical path based time action calendar concepts have been used for scheduling pre-production activities with a goal to deliver order within the original delivery date.

Lead-time reduction in the existing network Elimination (Remove a process) Compression (Remove time within a process) Integration (Re-engineering interfaces between successive processes) Concurrence (Operate processes in parallel)

Need for Critical Chain ( A Time compression technique) To explore a generalized or standardized solutions/techniques that can be applied across the industry. Critical Chain characteristics have commonalties with garment pre-production activities like Reverse scheduling, Multitasking and Resource dependencies.

Let’s first understand how generally human being works….

Task Estimating While estimating task duration, hidden safety factor is being added against the effect of unplanned work interruptions

Student Syndrome General human nature is to put off starting of any task until the last minute, thus eating away the safety buffer in the beginning.

Parkinson’s Law If a task is estimated at 10 days, it usually doesn’t take less, people will simply adjust the level of effort to keep busy for the entire task schedule.

Multi-tasking We all have experiences of having to stop working on one task so that progress can be accomplished on another task in another project. It comes with the penalties of reduced focus and loss of efficiency.

No Early Finishes! Tasks seem to either finish on time, or late, but rarely early. Early finishers often being accused of sandbagging their estimates instead of being rewarded for completing ahead of schedule.

Traditional work environments Stress not being late, but they do not even promote being early. Which encourages hidden safety, the student syndrome, and Parkinson’s Law effects.

Traditional Critical Path Concept Tasks are scheduled as-soon-as-possible (ASAP) from the project start date. Every task has a published start and finish date. It does not promote speed-to-market driven performance. It ensures that early finishes are lost, and only late finishes accumulate in the schedule.

Critical Chain Concept

Task Estimating Task is estimated at per actual working days (without buffer). The buffer days are then accumulated and added at the end of network or at important milestones. As pooled buffers are known to everyone (unlike hidden) time management is transparent.

As-Late-As-Possible Scheduling Tasks are scheduled as-late-as-possible (ALAP) based upon the target end date. Benefits: Work-in-progress (WIP) are minimized and not incurring costs earlier than necessary. Better focus at the critical start of the project Drawback: An increase in duration of any task will push out the project end date by the increased amount.

Relay Race Approach When one task is getting close to completion, next task’s resource should be on the track and ready to go as-soon-as- possible after the preceding task completes. De-emphasizing the task scheduled start and finish dates and concentrate, instead, on triggering their preparation and start on the preceding task’s progress

Resource Constraint & Allocation Critical Chain is defined as the longest chain of tasks that consider both task dependencies and resource dependencies. Critical Path is defined as the longest chain of tasks based upon only task dependencies

Critical Path Concept Critical Chain Concept Time estimates for each tasks are A = 2, B = 3, C = 1 and D = 2 man-days. Assumption: Resources are freely available 4 different persons are available then the project would take 7 man- days to complete, A-B-D being the critical path. Actually resources are not aplenty. Imagine task B & C have to be done by same person. So with resource dependencies (i.e. only 3 different persons available) the same project would take 8 man-days to complete.

Critical Chain Application in Pre production process Set Up Mode 1)Select orders and team of people 2)Briefing 3)Reverse Scheduling 4)Duration Estimates 5)ALAP Scheduling 6)Pooled Buffers

Contd. All the interdependent activities are plotted in PERT network The activities (tasks) are classified based on internal dependent, transportation or external dependent. Then the duration of each activity are estimated and put into PERT network.

Supply Network

Critical chain network 0,0 4,4 9,9 6,8 4 5 Project Buffer

Follow Up Mode No due dates for individual tasks, but finish as early as possible and handover to next person for next tasks. As the order activities moved forward respective executives were pre-informed and prepared for tasks to arrive, thus ensuring prioritization and speedy execution of tasks. Actual performance i.e. no. of working days to complete the order was compared with scheduled no. of days as per critical path and as per critical chain. It was observed that order was completed as per critical chain schedule and well before time as per critical path. Note: It is important to note that critical chain completion date is always followed by project buffer, and even the order overshoots the critical chain timing the order was very much completed within buffer dates.

Multitasking in Pre production process Three activities namely CAD (CAD operator), sampling (sampling tailor) and patternmaking (Pattern master) were selected where multitasking is frequent The loudest and nosiest customer is catered first. The day-to-day activities of all the three departments was collected including the lunch breaks, the standard time for similar activities was noted. Data was collected for 1 month involving 2-pattern master, one CAD operator and 3 sampling tailors.

Summarized findings are: 1)Multitasking induces start up loss (due to lack of focus) measured at average 43%. 2)The increase in lead-time of a particular task can be as much as three days instead of two hours. 3)For pattern master the time lost on multitasking was 32.85%. 4)The time lost on multitasking by CAD department was 38.80%.s

Pattern making activity in multitasking environment

Pattern making activity in without any multitasking

Conclusion While traditional “time-action-plan” concept application in pre-production activities tries to control lateness critical chain approach actually induces team-working spirit and have potential to compress the time further. Promises huge benefit by planning schedule and prioritize tasks is a common-resource but multi- style environment, thus minimizing or eliminating multitasking can result considerable gain in internal activities.

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