Introduction To Prent Malaysia

Dispatching : Function of selecting and sequencing available jobs to be run at individual work centers. It normally includes the following information and is updated and published at least daily :

• Plant, department and work center.
• Part number, shop order number, operation number and operation description of jobs at the work center.
• Standard hours.
• Priority information.
• Jobs coming to the work center.

Dispatching Rules : There are are many rules, some attempting to reduce working process inventory, others attempting to minimize the number of late orders or maximize the output of the work center. Some commonly used rules are :

• First come first served (FCFS). Jobs are performed in the sequence in which they are received. This rules ignores due dates and processing time.
• Earliest job due date (EDD). Jobs are performed according to their due dates. Due dates are considered, but processing time is not.
• Earliest operation due date (ODD). Jobs are performed according to their operation due dates. Due dates and processing time are taken into account.
• Shortest process time (SPT). Jobs are sequenced according to their process time. This rule ignores due dates, but it maximizes the number of jobs processed. Orders with long process times tend to be delayed.
• Critical Ratio (CR). This is an index of the relative priority of an order to other orders at a work center. It is based on the ratio of time remaining to work remaining and is usually expressed as:

CR = (due date - present date ) / lead time remaining

= actual time remaining / lead time remaining

CR less than 1 (actual time l less than lead time ) *Order is behind schedule.

CR equal to 1 ( actual time to equal to lead time ) *Order is on schedule.

CR greater than 1 ( actual time greater than lead time ) *Order is ahead of schedule.

CR zero or less (today's date greater than due date ) *Order is already late.