Page 283 - DMGT206_PRODUCTION_AND_OPERATIONS_MANAGEMENT

Production and Operations Management

Notes

Notes The operations schedule is that part of the planning system designed to implement
the MPS by focusing on how best to use existing capacity, taking into account technical
production constraints. The output plan of either of these systems needs to be translated
into operations, timing and schedule on the shop floor. This involves loading, sequencing,
and detailed scheduling expediting and input/output control. In intermittent or job shop
operations, sequencing is critical to the efficiency and effectiveness of the system.

14.1.4 Sequencing

When numbers of jobs are waiting in queue before an operational facility (such as, a milling
machine or assembly-line), there is a need to decide the sequence of processing the waiting jobs.
Sequencing is basically an order in which the jobs, waiting before an operational facility, are
processed. It specifies the order required for the adoption of priority sequencing. In addition, it
also requires an in-depth knowledge of processing time, etc.

14.1.5 Detailed Scheduling

Detailed times and dates are specified once the priority rule of job and/or operations sequencing
is known. Calendar times are specified to sequence the job orders, employees, inputs as well as
outputs. This order determines which job is done first, which is the next one’s and so on. In
detailed scheduling, estimates are prepared regarding set up and processing time at which a job
is due to start and finish.

14.1.6 Expediting

A job’s progress needs monitoring. The job has to keep moving through the facility on time to
avoid a deviation from the schedule. In case of deviation from the schedule, the causes of
deviation are immediately attended to. Manufacturing or service operations inventory disruption,

Example: Due to machine breakdown, non-availability of a tool, unavailable materials,
etc., and, sometimes last minute priority changes, all require last minute deviations from plans
and schedules. In order to minimize disruptions in schedules, continuous follow up or expediting
is needed.

Figure 14.1: ‘Thrashing’ – Impact on Lead Time and Capacity

When lead times are not managed, overloads will occur. What happens is illustrated in the
following diagram. This shows that as capacity is reached, the manufacturing system starts to

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