This blog post will discuss the new technology of rail car window recycling. We will also discuss why refurbishment of old windows has not found a place in the market.
Transit system operators often use hard coated Polycarbonate windows for their rail cars, trams and buses. During operation these windows can become dirty and therefore require frequent cleaning. The cleaning process as well as in service damage can cause the windows to deteriorate over time. With the volumes of windows used in these applications, replacement of the windows can become a significant operating expense. Disposal of the old windows also is not environmentally friendly as most old windows go to landfill. Disposal also involves a significant cost.
On a number of occasions, HighLine has been asked whether it is possible to refurbish these windows. This blog post briefly looks at why refurbishing has not been a viable option to date and discusses an alternative environmentally friendly way forward – rail car window recycling.
Refurbishment of existing windows.
It is not the purpose of this blog post to go into large technical detail of how windows might be refurbished. However, we will briefly discuss the main steps to illustrate why it has been prohibitive due to cost and technical difficulty.
Removal of the hard coat
In many cases the old windows have a hard coat that is either scratched or worn away on areas of the window. Some of these scratches go too deep into the window and would prevent refurbishment of a certain percentage of the windows. The remaining windows would need to have this coating removed. This process would typically be done by abrasion. The abrasion process could either be manual or could be done by specially designed machinery. In either case there is going to be significant cost in terms of labor or capital. There would also be an environmental issue to contend with as a lot of dust would be generated.
With the abrasion, not only would the coating be removed, but some of the Polycarbonate itself would be removed. This process would result in the thinning of the window which would require retesting of the window to the various mechanical tests required by law. It may also require the modification of the window gasket or assembly to accommodate the thinner window.
Polishing the window
After the coating is removed the polycarbonate window surface would be extremely scratched. This scratching would need to be removed by polishing the surface. The polishing could potentially be accomplished either mechanically or chemically. We do not want to go into details of how this polishing could be done as it would require development as a process. Suffice it to say it would require either high labor costs or high equipment costs. There would also be environmental and safety issues to address. Some of the safety issues, particularly with the chemical polishing, would be significant.
Adding a hard coat to the window
A new hard coat would need to be applied to the window. Not only would this be required to protect the refurbished window against scratches, but it would be required to protect the window against UV damage. The UV protection is accomplished by the coating primer.
In the fabrication of new windows a sheet is coated before the window is cut out. In the refurbishment of windows it would not be possible to coat windows in the same way (a flow coating method) as the window would need to be supported differently. There would be development required to coat the windows using possibly a spray coating system. Again this process would require labor or capital expenditure.
Refurbishment summary
The three main steps of the refurbishment process described above are not established processes. They would each require development and capital expenditure. There would also be no guarantee of success. Even if they were successful the refurbishment cost per window would be high and may even be close to, or exceed the cost of a new window. The refurbished windows may not be comparable to the quality of a new window.
With these significant barriers, it is not surprising that refurbishment of windows has not been commercialized.
Rail car window recycling.
HighLine has been working with a major Polycarbonate resin producer who has developed a process to take old hard coated car headlights and recycle them to make high quality extruded sheet. We believe that we can use this process for rail car window recycling. HighLine is the only company that has access to this technology for producing extruded sheet. We have already produced sheet with this material and have samples available for evaluation by customers.
HighLine is now looking for rail and transit operators to partner with us to recycle old coated rail car windows. We would take the old windows, grind them up (with the coating still on) and then put them through the process to make new polycarbonate pellets. These pellets would be extruded into new sheets, then coated and then cut into new rail car or bus windows. These windows would be as new with no drop off in either mechanical or optical properties compared to new windows.
As the transit operator is providing the old windows as a raw material, we expect to be able to provide the recycled windows at a reasonable discount to new windows. The process would also eliminate the cost and environmental impact of sending the old windows to landfill.
We are confident that we can recycle clear windows in this way. We are also in the initial discussion phase with a major transit company about evaluating the recycle of heavily tinted windows. We expect to be able recycle these tinted windows but we need to verify in our process.
If you are a major transit company that has a significant quantity of windows that need to be replaced, please contact us to discuss the possibility of recycling your old windows into new windows. This process would both save money on new windows and have environmental benefits. We believe that rail car window recycling offers numerous benefits to transit companies.