Mechanical paint removal

A mechanical paint-removal process is also used by American Commodities Inc., based in Flint, MI, and it is reported to be the largest recoverer of post-consumer automotive plastics in North America. The company has capacity to recycle 40.5 million pounds of TPO a year. One user of the American Commodities process is Visteon, which recycles 1 million pounds of painted TPO parts each year, using about 15 percent recycled old TPO bumpers in manufacture of new bumpers. Even higher amounts of scrap can be used when available, as the company is approved to use 100 percent scrap. Visteon s Milan plant increased scrap use to 60,000 lb per week of recycled TPO in 2000. ... 

The mechanical methods and low-temperature paint removal are restricted to a few special areas of application. Chemical and thermal methods have their specific advantages and disadvantages, not only as regards paint removal but also with respect to environmental pollution by paint slurry, rinse water, effluent, and waste air. 

One of the problems with recychng automotive plastics is paint removal. This applies not only to end-of-life vehicles but also to thermoplastic olefin (TPO) painted parts, which have a high scrap rate. Polymer Sciences Inc. announced plans in late 1999 to build recycling facilities in Duncan, SC, and somewhere in Europe, using the company s mechanical process for stripping paint from TPO parts before they are gronnd and pelletized. However, the plant was not built, and the company now fists paint removal as a technology that it has available for sale or license. ... 

Mechanical-based paint removal methods involve machineiy and/or manual labor. Two acceptable methods on exterior surfaces are contained water blasting (Hydrosander, 1990) and abrasive blasting with a vacuum arrangement (LTC, 1990 Vacublast, 1990 Zero, 1985). Table 11.3 lists examples ofvacuum abrasive media-cleaning units. Water blasting requires a containment system, which is very difficult to maintain. In addition, clean-up costs are significant, and water damage to interior structures is a possibility. 

Therefore, with this robot it is possible to carry a variety of non-destructive testing equipment, de-riveting devices, and paint removal systems. In addition, this robot or a variation of it can be used in many other applications such as the inspection of hazardous areas in nuclear power plants, ship maintenance, cleaning windows of sky scrapers, painting storage tanks, etc. It is clear that a robotic system can be used for aircraft inspection and maintenance. The work which has been done to this point is an introduction to prove the feasibility of such a robotic system. Further work needs to be done to optimize the mechanical design or to develop a faster system with more intelligence. 

The characteristics of interior paints that require testing and analysis include hiding and appearance, package stabiHty, adhesion, spatter resistance, flow and leveling, color and sheen uniformity, touch-up, stain removal, burnish resistance, and block and print resistance. A popular test that assesses the wet abrasion resistance of an interior paint is to measure its scmb resistance. A mechanical device is used to scmb a paint film of a specified thickness with a standard bmsh and abrasive cleanser suspension. The number of scmb cycles (back and forth movements of the weighted bmsh) at various end points (first cut through, or 50% removal of the film) is then recorded. Scmb resistance usually holds steady or decreases slightly as PVC is increased, but drops quickly once the CPVC is exceeded in a paint formulation. 

TechXtract has several potential limitations. The technology is limited by the depth it can remove contaminants, which is related to the porousness of the contaminated surface. The technology may be less effective on painted or sealed surfaces. Process chemicals will remove certain types of coatings, but mechanical methods may be needed in some cases. H signihcant cracks are present in concrete or masonry, pockets of contaminants can form that are not readily extracted. Cracked areas may require sealing, or the area surrounding the crack may have to be chipped out. The environment must have a temperature above 32°F. In addition, the contaminated surface must be accessible to the process chemicals. 

Steels and stainless steels develop oxides scales during hotworking, annealing, or welding that lower corrosion resistance or paint adhesion. Scales are removed using chemical means, mechanical means, or combinations of both. Within the trade, chemical descaling is often referred to as pickling. In the case of stainless... 

Completion of all outstanding mechanical work such as insulation and painting and removal of scaffolds, etc., that cannot be completed during operation. 

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