Options for Removing Paint from Part Racks

Q:We are a paint applicator currently outsourcing our rack cleaning, but we are not satisfied with the high cost and poor quality and are considering a possible in-house solution. What options are available for our paint-removal needs?

A necessary evil of all paint applications is the eventual requirement to remove the cured paint from part racks, hooks and fixtures. Ensuring proper contact between the part and its fixture is paramount in achieving a quality paint finish, and as cured paint builds up on fixtures, the area of contact becomes narrower and proper part racking becomes more difficult. The only way to continuously ensure the highest paint transfer efficiency and minimal part defects is to remove the cured paint.

Traditionally, this paint removal is achieved by one of three methods: mechanical, thermal and chemical. There are many companies today that will contract the paint removal process, typically by one of the three methods mentioned, however, there are some key disadvantages to outsourcing your paint removal needs, and we will get into those disadvantages below.

Mechanical  

Mechanical paint removal refers to any process that uses mechanical action to physically remove paint from a substrate’s surface. In this instance, we’re talking about fixtures coated in cured paint. The most common mechanical methods are media blasting and high-pressure spray/hydro-jet. Although mechanical methods are free of significant environmental restrictions, they do have some associated disadvantages, including:

• Substrate damage, resulting in costly fixture replacement.
• Line-of-sight inefficiencies.
• High noise pollution.
• They are slow, labor-intensive processes that poses a significant safety hazard to employees.

Thermal

Thermal paint removal refers to any process that uses high temperatures to break down the organic paint coating. Often referred to as pyrolysis, high-temperature paint removal processes often include burn-off ovens and fluidized sand beds, which typically operate at temperatures greater than 750°F (400°C). The disadvantages of thermal paint-removal methods include:

• Substrate fatigue and damage due to repeated exposure to high temperatures.
• High capital investment and finite life of equipment.
• Significant energy demand.
• A secondary cleaning step often is required for ash removal.
• They are not suitable for light metals (aluminum, zinc, magnesium).
• Necessity of fire-suppression equipment.

Chemical

Due to their low cost and ease of accessibility, commodity chemicals such as methylene chloride, concentrated alkali and sulfuric acid are often compelling options for paint-removal applications. However, as with the other methods, there are some key underlying factors that make these commodity chemistries hazardous to work with:

• There are significant regulations on their use, especially in California.
• High evaporation rates result in short solution life and poor efficiency.
• Significant capital investment is required for air scrubbing to minimize emissions.
• Elevated temperatures and simplistic equipment design expose employees to unsafe work environments.
• There is risk of employee exposure to hot concentrated acid or alkali solutions.
• The cost is high for needed hazardous waste disposal.

Outsourcing

Many paint applicators in all industries elect to outsource their fixture cleaning due to the many disadvantages associated with the conventional paint-removal methods listed above. However, they may not be taking into consideration many key cost drivers, such as the fact that contract paint-removal companies often charge a price per unit. Additional costs that should be considered before outsourcing paint removal include:

• Having an extra set of fixtures to rotate in as paint builds up on the other set as well as while they are with the contract paint-removal company.
• The high cost per unit.
• Damage through transportation, handling or processing that requires re-work or repairs.
• Lengthy lead time, resulting in decreased operating efficiency.

Many paint applicators today are actively seeking ways to avoid outsourcing their paint-removal requirements but are unwilling to utilize traditional in-house solutions due to the associated disadvantages. Fortunately, chemical processes are now available that allow paint applicators to safely and economically conduct these activities in their own facilities. Modern chemical processes are free of halogenated solvents as well as strong acids and alkalis, and they offer an alternative capable of eliminating the lengthy lead times and high capital requirements of outsourced options.These processes offer the highest level of process versatility, capable of operation in spray or immersion mode as well as inline or offline, and can easily be coupled with simple yet sophisticated equipment designs to create a long life and sustainable process.Implementing these safe and highly efficient processes can significantly reduce the cost per unit, resulting in a sustainable and cost-effective solution with an attractive return on investment. 

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Sylvain Masson is global product manager PST for Paint Removal Technologies at Atotech. Stephen Taylor, North American product marketing manager PST, also contributed. Visit atotech.com.