Is Grinding E-Coated Parts Safe?

Q. Can you tell me if it is safe to rework electrocoated parts with grinding—using pads to remove the coating, and so on? M.D.

A. Due to the great number of variables involved in your question, I cannot give you a straight yes or no. However, let me give you several issues to consider.

Any process that uses a dry, mechanical, abrasive means for the removal of materials such as E-coat will create an airborne dust.

The first questions are: What is the chemical composition of the electrocoating material? Does it contain a regulated metal, such as lead or chrome? The best source of information will come from the E-coat’s Material Safety Data Sheet (MSDS). E-coat paint formulations have dramatically changed over the years to become more environmentally friendly, so I would be surprised if it contains heavy metals at concentrations that would cause concern.

The second set of questions are about the substrate. What is the metal composition of the substrate under the E-coat? Does it contain regulated metals such as chrome and nickel? Since you are using an abrasive technology to remove the E-coat, it is very likely that you will also, inadvertently, remove some of the substrate metal in the process.

Another set of questions to consider are: What ventilation is provided to carry particulates away from you, either to the outside or through a collection unit? Is the unit properly designed to capture a very high percentage of the resulting pollutants? If properly captured and collected, even toxic metals can be reworked safely.

Assuming there are no toxic materials contained within the E-coat and substrate, the most likely hazard will be airborne dust or particulate.
The U.S. Occupational Safety & Health Administration (OSHA) has established a list of known airborne hazardous air contaminants and has published them with an accompanying airborne concentration not to be exceeded without controls or personal protective equipment (PPE) in place. Table Z-1 - Limits for Air Contaminants can be found at short.pfonline.com/Z1.

For general particulates not otherwise regulated, the 8-hour Time Weighted Average (TWA) limits for total dust and respirable fraction are 15 and 5 mg/m3, respectively.

In order to answer your question in the most satisfactory manner, I recommend personal air sampling by a professional trained in this methodology and analysis for potential contaminants. With the resulting data, you will be able to determine if 1) more engineering controls are needed, 2) different work practices must be implemented, and, 3) personal protective equipment is still necessary.

Again, the safety professional who assists you with the personal air sampling should also be able to help you with these issues.

And if it is determined that your linishing operators will need respirators, remember that you will have to develop and implement a written respiratory protective program in conformance with OSHA regulations (29 CFR 1910.134). The written program must contain the following elements: procedures governing the selection and use of respirators, training, proper respirator cleaning and storage, inspection and repair of respirators, regular evaluation of program effectiveness, and initial and periodic medical examination of employees using respirators.

D.M., I hope this guidance will be of assistance toward helping you answer your question.