Production Schedule Planner (jobs on machines and Gantt)

About the Production Schedule Planner (jobs on machines and Gantt)

Schedules your jobs on your machines or work centres. Open a file of jobs — each with its quantity, due date and priority, and its operations in routing order, each on a machine with a setup time and a run time per unit — or paste it from your spreadsheet. Pick a sequencing rule (earliest due date, critical ratio, shortest processing time, priority, first come first served, or your own order) and the planner builds a finite-capacity schedule: one operation at a time on each machine, only in its shift calendar, never on a holiday, each operation after the one before it in the job.

You see a Gantt chart of every machine, each job's start and finish against its due date, the late jobs and their delay, and the load of every machine week by week. Drag a job up or down the list (or use its move buttons) to try another order: the schedule is worked out again at once. Your calendars and holidays are kept in this browser for next time.

Without a pass the schedule is a free preview: scheduling and re-sequencing work on all your jobs, the Gantt chart carries a watermark and the tables show their first rows; the schedule file, the workbook, the printable job tickets with a QR code and the copy unlock with a Premium pass. Your files are read in your browser and never uploaded.

Common uses

• The weekly plan of a job shop, a fabrication shop or a print shop.
• Checking whether a rush order can still be delivered on time, and which jobs it would delay.
• Finding the bottleneck machine and the weeks it is overloaded.
• Operations management coursework on dispatching rules.

How the schedule is built

The jobs are put in order by the rule, then scheduled one job at a time, each operation as early as it can go: not before the plan starts, the job’s release date or the end of the job’s previous operation (plus any move time you set); only in its machine’s working time, so an operation that does not finish in a shift goes on in the next one; and only where the machine is not already booked. An operation may use an earlier gap on its machine when the whole of it fits there, so a job scheduled later never delays one scheduled before it. Each operation takes its setup time plus its run time × the job’s quantity.

The sequencing rules

These are dispatching rules from Pinedo’s Scheduling: Theory, Algorithms, and Systems:

• Earliest due date (EDD): the job due first goes first. On a single machine it keeps the largest delay as small as it can be.
• Critical ratio (CR): working time left until the due date ÷ the job’s work. The job with the lowest ratio goes first; below 1 it cannot be finished in time even if it starts now.
• Shortest processing time (SPT): the job with the least work goes first. On a single machine it gives the shortest average time jobs wait and run, but long jobs may wait.
• Priority: your priority numbers, 1 first, then the due date.
• First come, first served: the order of the file.

With several machines no simple rule is best every time: try them on your own jobs and compare the late jobs and the delay.

Calendars, holidays and load

Each calendar is a set of working days and shifts; a shift that ends after midnight belongs to the day it starts. A holiday stops every calendar for that day. The first calendar is every machine’s calendar until you give a machine another. The load of a machine in a week is the working time booked on it ÷ the working time its calendar has that week: above 100% cannot happen in a finite-capacity schedule, so a machine near 100% week after week is the bottleneck to add a shift to.

Job tickets

The printable job tickets give each job a ticket for the shop floor: the item, quantity, customer, due date and priority, each operation with its machine and planned start and finish, boxes to sign off each operation, and a QR code with the same job and operation times as text, which any phone camera reads.

Limitations

• A plan from your times: breakdowns, absent operators and late material are not known to it; schedule again when they happen.
• Each operation runs on one named machine; alternative machines, operations that overlap in time, batch splitting and sequence-dependent setups are not handled.
• At most 500 jobs, 3,000 operations and 400 days at a time.
• Critical ratio counts the working time of the first calendar; the schedule itself follows each machine’s own calendar.

Privacy

On this device; its files download once

Your jobs are read in this browser and never uploaded; your calendars, holidays and plan settings are kept on this device only.