Waste Minimisation at Start-Up

In every industry, workplace or environment there are levels of waste which are above what they need to be. Whilst I doubt that the elimination of all waste is economically viable, companies (and individuals) can save money by cutting their waste levels.

In the polymer sector the biggest single way of reducing your waste level on a daily basis is to not switch off. The reasons are easy to be seen, by not stopping;

  • Time isn’t lost waiting on machinery to warm up
  • Material isn’t lost trying to get the production running correctly and within spec
  • Material isn’t lost when shutting down.

This isn’t always an option for companies, for example in Earth-wood we didn’t have the orders to make it viable to run 24 hrs a day or 7 days a week. So initially we ran 8 hrs a day- 5 days a week and as production increased we worked overtime depending on orders.

If you don’t measure it, you can’t control it”

We kept daily production records and consistently had quite high waste levels; we could also see that we could do better. Looking at the production process and using a process flow diagram we highlighted areas where material waste could be formed.

The next stage we carried out was to monitor and record the waste levels from the different causes of waste.

This clarified what our major sources of waste were and we then used cause and effect analysis to identify the possible causes of these waste streams and identified what actions could be taken to reduce the waste levels.

One of the sources was an easy hit- Start up.

In the morning was taking up to 2 hrs, between getting the die up to temperature, and then getting some of the material in the die melted to enable us to get material flowing, and a large lump of un-melted material out before production could begin properly.

So our first remedial action was to change the shut down procedures for the line, instead of just shutting down the line, operators changed to continuing to pull material out of the die and then using a pry-bar ensure that it was fully cleaned out inside. This reduced the material waste from typically 150 kg down to 15kg during the production start up.

The time taken for the die to warm up still too high, around 90 min. We observed that in the morning the die was warming up from room temperature 15-20 oC. An investment in a specially designed insulation jacket to fit around the die and melt pump to keep reduce the heat loss from them over night. As a result the die was at 50oC in the morning and keeping the insulation jacket on while the die heated up meant that more of the heat from the heater bands went into the die rather than the air around it.

This simple action reduced warm up time to 30 minutes in the morning. Hence by the time woodflour was loaded, equipment checked, and everything else set up, there was no further waiting around for the line to get up to temperature. So operators would then remove the jackets and get production underway.

These few simple actions helped reduce a significant cause of waste, it hasn’t been entirely eliminated but a 90% reduction is a good start.

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