Clothing in a can

Isn’t it amazing what a little bit of lateral thinking can achieve. Most people will be familiar with the story behind the development of 3M’s post-it, the initial developments of Nylon and many other polymers were the results of accidents but what is wonderful to see is how these innovations and discoveries are put to good use.

Sometimes its the coming together of two different minds which can bring the most brilliant of ideas together. For example Paul Luckham from Imperial College London wrote recently for the Institute of Chemical Engineers’s Journal, TCE about the novel new developments which have arisen as a result of being approached by Manel Torres a student from the Royal College of Art. The result was clothing in a can.

Manel sought out Luckham to assist him to develop the “silly string from a can” concept to be actually able to spray a T-shirt from an aerosol can. Ultimately this was achieved as the video’s show.

Luckham sees other major potential for the technology apart from making clothes (or hats) in the development of sprayable cleaning/shoe shine cloths and possibly more importantly in medical bandages and dressings which would be sterile.

References:

Composite Decking- Point’s to be aware of

I’ve just had a read of Aston dot’s Blog (http://www.astondot.com/aston-dot/the-reason-people-should-think-about-composite-plastic-decking/) on composite decking also known as Wood Plastic Composite (WPC) Decking.

It’s a good discussion on the advantages of Composite Decking over traditional timber decking. I worked with Earth-wood and the lower maintenance costs, non- slip and the quality of finish made it an attractive proposition to customers.

Unfortunately Aston Dot is wrong on a number of points that he makes.

Composite decking for structural components

I’m afraid as yet I wouldn’t recommend Composite materials for structural components. While a lot of research was going into their use, it’s something you’ll need to be very sure about. The problem with WPC as used in decking is that they use Thermoplastic materials such as High Density Polyethylene (HDPE), Polypropylene (PP) or Polyvinyl Chloride (PVC). From recollection Ecodeck referenced in the article use HDPE. These materials are susceptible to a phenomena known as creep where they distort over time when exposed to pressure (either constant or occasional).

Hence if WPC is used for load bearing applications they are susceptible to warp and distort which could be potentially dangerous.

Composite decking is NOT dimensionally stable

While timber decking will expand when wet, and will shrink again during a dry summer. WPC decking is the opposite; it will expand in warm weather and shrink during the colder winter. We had a customer who ignored our installation guidelines and did not leave a 5 mm gap at the either end of plank. After a few warm weeks 2 planks butted up against each other and created a ridge in the deck.

Composite decking is NOT 100% environmentally friendly

I’m afraid nothing man made is, from the energy required to make the plastic in the first place, the energy required to recycle it and the energy and additive required to manufacture the WPC decking. I don’t know if it is more environmentally friendly than timber sustainably managed forests, but then the life span is significantly better than the softwood timbers from these forests.

Final word

Don’t get me wrong, WPC decking is a great product, we had a really good business supplying into marinas and public walkways as well as for domestic & commercial decks. It is long lasting, easier to maintain and keep clean, will not splinter from drying out. It will crack due to “Stress Crack Propagation” over time, especially if poorly installed but it’s better than timber for crack resistance and you know nothing is completely perfect.

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.