Routing & Scheduling of a Fabrication Company using Simulation Software
Routing
It is defined as the selection of path which each part of the product will follow while being transformed from raw materials to finished products. Path of the product will also give sequence of operation to be adopted while being manufactured.
In involves the following steps:
1. Type of work to be done on product or its parts.
2. Operation required to do the work.
3. Sequence of operation required.
4. Where the work will be done.
5. A proper description of the personnel required and the machine for doing the work.
Techniques of Routing
while converting raw material into required goods different operations are to be performed and the selection of a particular path of operations for each piece is termed as ‘Routing’. This selection of a particular path, i.e. sequence of operations must be the best and cheapest to have the lowest cost of the final product. The various routing techniques are:
Route card: This card always accompanies with the job throughout all operations. This indicates the material used during manufacturing and their progress from one operation to another. In addition to this the details of scrap and good work produced are also recorded Work sheet: It contains
Specifications to be followed while manufacturing.
Instructions regarding routing of every part with identification number of machines and this sheet are made for manufacturing as well as for maintenance.
Route sheet: It deals with specific production order. Generally made from operation sheets.
One sheet is required for each part or component of the order.
Move order: It is prepared for each operation as per operation sheet. On this the quantity
passed forward, scrapped and to be rectified are recorded.
Scheduling
Scheduling can be defined as “prescribing of when and where each operation necessary to
manufacture the product is to be performed.” It is also defined as “establishing of times at
which to begin and complete each event or operation comprising a procedure”. The principle
aim of scheduling is to plan the sequence of work so that production can be systematically
arranged towards the end of completion of all products by due date.
Inputs to Scheduling
1. Performance standards: The information regarding the performance standards helps to know the capacity in order to assign required machine hours to the facility.
2. Units in which loading and scheduling is to be expressed.
3. Effective capacity of the work centre.
4. Demand pattern and extent of flexibility to be provided for rush orders.
5. Overlapping of operations.
6. Individual job schedules.
Types of Scheduling
Types of scheduling can be categorized as forward scheduling and backward scheduling. Forward scheduling is commonly used in job shops where customers place their orders on “needed as soon as possible” basis. Forward scheduling 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. The forward method generates in the process inventory that are needed at subsequent work centers and higher inventory cost. Forward scheduling is simple to use and it gets jobs done in shorter lead times, compared to backward scheduling.
Backward scheduling is often used in assembly type industries and commit in advance to specific delivery dates. Backward scheduling 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. By assigning jobs as late as possible, backward scheduling minimizes inventories since a job is not completed until it must go directly to the next work center on its routing.
The scheduling methodology depends upon the type of industry, organization, product, and level of sophistication required. They are:
1. Gantt charts and boards,
2. Priority decision rules.
3. Mathematical programming methods.
Gantt Charts
Gantt charts and associated scheduling boards have been extensively used scheduling devices in the past, although many of the charts are now drawn by computer. Gantt charts are extremely easy to understand and can quickly reveal the current or planned situation to all concerned.
They are used in several forms, namely
1. Scheduling or progress charts, which depicts the sequential schedule.
2. Load charts, which show the work assigned to a group of workers or machines; and
3. Record chart, which are used to record the actual operating times and delays of workers and machines.