LESSON 6 (Scheduling and Just-in-time Manufacturing Systems) Flashcards
can be defined as “ prescribing of when and where each operation necessary to manufacture the product is to be performed”.
SCHEDULING
Scheduling tends to achieve maximum efficiency when the task sizes are small, and all tasks of same order of magnitude.
The principle of optimum task size
also defined as “establishing of times at which to begin and complete each event or operation compromising a procedure”.
SCHEDULING
The planning should be such that it imposes an equal load on all plants.
Principle of optimum production plan
Scheduling tends to achieve the maximum efficiency when the work is planned so that work hours are normally used in the same sequence.
Principle of optimum sequence
for specific jobs that are arrived from customers is impracticable in actual manufacturing situation. Changes in orders, equipment breakdown, and unforeseen events
deviate the plans.
- Detailed Scheduling
vary widely among firms and range from ‘no scheduling’ to very sophisticated approaches. These strategies are grouped into four classes
Scheduling strategies
are scheduling guides that are used
independently and in conjunction with one of the above strategies, i.e., first come first serve. These are useful in reducing Work-In-Process (WIP) inventory.
Priority decision rules
of total work load is useful
especially for long range planning of capacity needs. This may load the current period excessively and under load future periods. It has
some means to control the jobs.
- Cumulative scheduling:
combination is both feasible and practical approach. If master schedule has fixed and flexible portions.
- Cumulative detailed
Scheduling Strategies
- Detailed Scheduling
- Cumulative scheduling:
- Cumulative detailed
- Priority decision rules
is to utilize the companys resources to maintain a consistent production flow. By doing so, downtime is reduced, and bottlenecks are mitigated to optimize production
- Planning
is done with the assumption that process steps will change. As a result, materials must be ready but actual production must wait until demand is determined
Dynamic Planning
is done with the assumption that all process steps will be completed on time and with no changes
Static Planning
In discreet manufacturing where final products are made from a lengthy and complex series of sub-processes, a bill of materials may be used to dictate what items are required and in what quantity.
- Routing
utilizes the established planning level to produce goods from components or raw materials. It is time based and must satisfy the demand established at the planning level.
- Scheduling
is the process of assigning the order of jobs to be done next from a sub-set of jobs in the production queue.
- Dispatching
requires informed management decisions, trained staff, accurate data as inputs into the
production plan and schedule and reliable sales figures and forecast numbers. All must be present for the organization to execute its production schedule and complete orders.
- Execution
Five Components of
Production Scheduling
- Planning
- Routing
- Scheduling
- Dispatching
- Execution
Types of Scheduling
Can be categorized as:
- Forward Scheduling
- Backward Scheduling
- is commonly used in job shops where customers place their orders on “needed as soon as possible” basis.
- determines start and finish times of next priority job by assigning it the earliest available time slot and from that time, determines when the job will be finished in that work centre.
- Forward scheduling
- is often used in assembly type industries and commit in advance to specific delivery dates.
- determines the start and finish times for waiting jobs by assigning them to the latest available time slot that will enable each job to be completed just when it is due, but done before.
- Backward scheduling
is a production and inventory control system in which materials are purchased and units are produced only as needed to meet actual customer demand.
Just-in-Time
helps organizations control variability in their processes, allowing them to increase productivity while lowering costs.
JIT manufacturing
is a workflow methodology aimed at reducing flow times within production systems, as well as response times from suppliers and to customers.
Just in time (JIT) manufacturing
