Many engineering/manufacturing companies would love to be able to achieve all their delivery dates either on-time or early. But juggling multiple resources and dozens - if not hundreds – of jobs concurrently with machine down-time and changing priorities make the task virtually impossible.
Many Production Planners resort to complex spreadsheets to manage jobs as they flow through the workshop. Preparing the machine loading and priorities at the start of the week with the best of intentions, within the first few hours the chances are that a re-plan is required. An urgent job has arrived; expected raw materials have not been delivered; a machine malfunctions; all these factors can throw a well-structured plan into immediate disarray.
In addition, communication between the shop floor and the Production Planner needs to be timely and accurate. It’s no good developing a plan if the shop floor operators are not prepared to record where they are on each operation – e.g. operation started, operation paused (and why), operation completed (and how many parts finished?)
A typical routing in an engineering workshop could be:
Job No: 680: No. of parts: 300
|Work Centre||Setting Time HH:MM||Cycle Time HH:MM||Total Time HH:MM|
|Cut to size||0:30||0:01||5:30|
|Subcon heat treatment||7 days offsite|
|Pack & despatch||1:00||1:00||1:00|
The workflow for a routing like this could be:
This leaves a buffer of just one day before the requested delivery date. So, what could be done to increase the buffer period? Could the sub-contract heat treatment operation be done in less than seven days? Could we overlap operations? If so, what impact would that have? And this just shows one job! What if another job on the Lathe runs late? If I make changes, what will be the impact on other jobs?
Just a simple routing like this can throw up complex issues that are extremely difficult to resolve using just a spreadsheet – it’s very much “finger in the air”.
With dozens of work centres and many jobs being processed each month maintaining control of the schedule becomes a very daunting task!
Many engineering companies have multiple machines that can perform the same task. Can you group your similar machines and then later decide which machine it will run on? Could you split a single job over multiple machines and maintain traceability? If your machine group can process many of the same jobs, but if a part is of a certain size then only one of the machines can do it can that machine be selected automatically or does the planner need to know before assigning the job?
For a scheduling system to work effectively communication is required between the shop floor and the scheduling/planning system. Preferably this would be in real-time with some form of barcode or touch-screen data capture solution. In this way the scheduling system is always kept abreast of operator activities.
Recording when an operation is started can then instantly inform the scheduler, which would immediately move the operation forward and set the status to “WIP”. Recording when an operation is paused and how many parts were completed can indicate to the scheduler how much additional time will be required to complete the operation. If the actual cycle time is different to the estimate, an advanced scheduling system should be able to re-calculate the projected end time – either bringing it forward or moving it out.
When you have an urgent job it may well make sense to run it on many machines concurrently if you can do so. An advanced scheduling system should be able to manage this easily and effectively, whilst maintaining traceability of which machine the parts were produced on.
Being able to apply an efficiency rating to a machine would be beneficial. We’d all love our machines to run consistently at 100% but this virtually never happens. Building in a buffer for short down-time periods and clean up would provide a more realistic projection of job/operation end time.
No scheduling/planning system will be effective without process adherence.
If operation setting & cycle times are either not set or set inaccurately, the system won’t work.
If operators don’t logon/logoff operations and communicate with the scheduler, the system won’t work.
If delivery/target completion dates are not realistic, the system won’t work.
If capacity/shift patterns are not set correctly, the system won’t work.
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