To stop the assembly line or not to stop the assembly line?
Particularly a batch process synchronous manufacturing assembly line where the movements of the jobs are coordinated, and workers adhere to a set time to complete their job. Stopping a synchronous line impacts the performance of the entire assembly line because each job has a predetermined TAKT time and Goals Planned Actual (GPA) target to achieve. If a job is delayed or a problem arises that requires a line stop, then TAKT time over-clocks and these event can potentially be a factor in whether the manufactured products goal is met or not for the scheduled shift.
Inevitably a reason for a line stoppage will arise and require the worker (or system) to stop the manufacturing process. ANDON is a system which is able to notify management, maintenance, and other workers of a quality or process problem. The most advanced and effective ANDON systems are controlled by Manufacturing Execution System (MES) Software and can feature over sized signboards which graphically display the status of each work station and the individual worker by name. It shows which station/worker is having the problem, or requires attention in an intuitive way with graphics. For example, if the worker needs materials replenished to continue her job then she presses a button and a visual alert is displayed on the big screen for the Line Supervisor to see (in the example screenshot shown below it is a ‘blue dot’). The ANDON system being a website based software is easily configurable to show the essential information needed to ensure productivity; when goals are being achieved the screen displays green and the progress for each member is shown in a bar graph below their name.
ANDON system alerts are typically activated manually by a worker using a pull cord or button, or may be activated automatically by the production equipment itself. The MES software includes the feature to stop production so the issue can be corrected. MES based ANDON alert systems also incorporate audio alarms, stack lights, mobile text/email, and video messages or other animated graphics such as an ‘OEE’ performance gauge for all to see. It is up to the Manufacturing Engineer or Production Team to determine which of the alerts constitute a line stoppage, or the interjection of a Line Supervisor who has the access to remedy/bypass the situation. Keeping that in mind, whether the Manufacturing Engineer or the Line Supervisor are faced with a delay or line stoppage for “whatever” reason, the MES is capturing each and every input by the individual users and storing those events and notes in a database (as well as machine events); valuable data which can be accessed right away or analyzed later in easy to interpret manufacturing reports.
It would be interesting to receive comments pertaining to whether it is a good idea to stop the manufacturing line to remedy situations as they happen? To correct the actions that led to the problem on the spot; and to nearly deny all failed parts from proceeding? Of course for issues such as materials replenishing, or the replacement of a broken tool, the raising of an alert in advance or as soon as problems start is fundamental and encourages preventative actions to ensure the line does not stop in the first place. In the cases where the manufacturing stoppage happens due to a worker not completing their job quickly enough, or is due to a quality issue, the power of how the assembly line should react is up to the strategy the manufacturer implements, i.e. there are pros and cons to consider: stopping the line will consume TAKT time and adversely affect GPA, although on the other hand the quality issue is sorted, the bad part is repaired or quarantined; and in the cases that the reason for the stoppage is due to worker errors, then that situation itself can be addressed by Line Supervisor interaction, such as recommending additional training for the worker. Or perhaps it is revealed the TAKT time is too short for that particular operation, meaning scheduling adjustments need to be made, e.g. jobs reallocated or TAKT time increased.
Whether the line is stopped or not, the ANDON alert will lead to a response action anyway, to encourage the line keeps moving or starts up again quickly if it stopped. If the line is set up to only stop for major issues then yes it forces production to keep moving, and yes you do have the data recorded for the days’ manufacturing events to consider; BUT are you guaranteeing bad parts did not ship, and are you guaranteeing your manufacturing assembly line is optimized as much as it could be? Both scenarios fit a certain manufacturing strategy – it becomes a question of how quickly the manufacturer wants to deal with problems and learn from those mistakes.
Manufacturers have the choice since MES is configurable to their needs. You have the option to remedy the issues as they arise, even if it takes more time and less products are made each day. One can think of it as short term pain for long term gain because yes stopping the line may adversely affect the goal, although at days end a lesson is learned, the problem is addressed and should not happen again; and ultimately a bad part’s chance of being shipped to the customer is more diminished. That is truly continuous improvement on-the-fly. For more information on website based configurable plant floor management please see www.pinpointinfo.com and please do not hesitate to contact us.