Impact on production line speeds and OEE

Of utmost concern to production/operations teams is the impact serialization will have on production line speeds.

If you’re installing a brand new line, this is less of a concern. But likely the overwhelming majority of lines will be retrofit.
But one of the elephants in the room is line downtime itself. A packaging line may be out of service for at least a month, and possibly up to six months, to allow for line retrofits, new equipment implementation, controls integration, testing, and validation. Plus a big chunk of packaging lines simply don’t have the room for additional inspection and reject stations on the line. It’s not uncommon for facilities to be altered to accommodate these new stations.

With the addition of codes that take longer to print, along with multiple inspection and rejection stations, there’s no question that performance will take a hit. Estimates vary for how much of a speed loss to expect once the line is back in operation. Many experts believe an initial loss of 8% to 10% in Overall Equipment Effectiveness (OEE) should be expected when a line is restarted. With ongoing efforts at line optimization (which needs to be built into the schedule, by the way), some have seen the drop in OEE stabilize at around 4%. If the engineering team is being evaluated on the basis of OEE, this may have to be examined and adjusted in light of serialization’s impact on line performance.

(There is another view. Some experts say using the serialization project as a catalyst to change out older machines may in fact lead to greater productivity.)

One technique is to create parallel conveyers to manage serialization on two tracks.  This helps maintain line speed and provides redundancy should something fail on one track.  Electronic batch records and integration with enterprise systems help to reduce the impact of having to configure systems for two tracks, but the payback in speed and redundancy may be worth it.

One item that often gets overlooked as a source of problems with regard to productivity is the automating of the serialization system with the MES and ERP system for master material data. For facilities that choose not to automate the integration with these systems, they are looking at additional line start-up time, changeovers, and reconciliation of loose product at the end of a lot. Efforts to streamline or automate such reconciliation procedures can help reduce downtime between changeovers.

Of course, aggregation itself can slow down a line, particularly on a line with manual case packing.  One pilot test revealed that the act of picking up each bottle, manually scanning the barcode, and then placing the bottle into the case took double the time of the previous process of simply placing the bottle into the case. This is another area where using two tracks may balance the effects of serialization on OEE.

Scheduling will be affected too. It’s important to get a handle on the estimated reduction in throughput in order to rethink all of your scheduling. If you’re running single or double shifts, you may need to periodically schedule an extra shift on a night or Saturday to make up for the lost output.

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