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| FA key aim of Newton’s recent project with an insulation board manufacturer was to increase the plant capacity in line with the increase in demand created by tightening Government Regulations. An assessment indicated that there was potential increase production by raising line speeds. |
What was known about the production line speeds was that the packaging line seemed to be the bottleneck a lot of the time, especially on thicker products. There was no clearer understanding or analysis of the line speeds than this: the part of the production line that was the bottleneck could not be identified. |
The first step to improving the production rates was to measure the speed of each part of the process and build up a Speed Profile of the line. From this the bottleneck could be identified. It then became clear that the bottleneck moved around the process depending on the thickness of the product being made. For thin products the bottleneck was the Saw; for thick products the bottleneck moved to the Bander. |
A detailed study of the two bottlenecks followed, building up a Gantt Time Map of the machine cycles. This was used to identify potential improvements to the cycle. |
The Saw was an old hydraulic unit. The product is moved past the blade by a chain with pushing dogs on it. The drive starts when product hits a contact switch on a backstop, but there was a 0.9 second pause while the hydraulics started up. The Gantt of the Saw showed that this pause was on the critical path and therefore slowing down the Saw. This pause was removed by fitting a non-contact sensor halfway along the infeed and attaching it to a on delay timer. The hydraulics could then be sent a signal to start 0.9 seconds earlier, increasing the speed of the Saw by 15%. The Saw was now no longer the bottleneck since it now exceeded the line drive’s capability. |
This same rigorous process highlighted a 10 second chunk of time in the Bander cycle - the load and unload - that could be removed with some intelligent resequencing. By adding a sensor to the line and by reprogramming the machine, this chunk of time was reduced to 1.5 seconds. The Bander speed increased by over 50% and did not limit the line speeds on the thicker products. The new bottleneck for thick products was the pumping capacity. |
Combined, the effect of these changes was to increase the maximum line speeds by 36%. On a weekly basis, the average line speeds increased from a historic 99.7% of standard to over 115%. |
This 15% increase in production rate was possible with no increase in reject rate or downtime; the cost of the 2 new sensors and timer was less than £200; the changes made to the machines did not involve increasing the speed of any movements. |
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