Keeping a foundry clean is a challenge in itself and with the new silica dust permissible exposure limits (PEL) defined by OSHA, it may be even more difficult to keep them “dust free." Due to the nature of a foundry's work environment, it is common for most employees to be subjected to working conditions that are noisy, dusty, and extremely hot. This is especially true in steel and iron foundries where employees are often exposed to extremely high temperatures and harsh working conditions due to the casting methods that are performed with molten metal.
Cleaning rooms are the biggest contributor to silica dust production in foundries. Unsurprisingly, this is because the abrasive cleaning methods used in cleaning rooms increases the possibility of silica dust becoming airborne and entering the employee’s breathing zone.
The Process of Shake-Out
The largest generator of respirable silica dust comes from the shakeout and sand carryover processes that occur in the foundries cleaning room. Once metal has been formed and has had time to cool there is still a significant amount of dusty residue attached to each casting. This sand must be removed before the material is passed on for inspection by shaking or tumbling the piece until it is free of excess sand. When a conventional vibrating shakeout is used there is nothing surrounding or enclosing the machine to trap the excess dust. This increases the potential that a large volume of silica dust will escape and dirty a majority of the surface area in the cleaning room.
According to the American Foundry Society (AFS), in incidences of airborne-silica exposure, 25% can be attributed to the material handling of silica-bearing castings prior to being cleaned or “shook out”. Silica dust becomes much more hazardous when it is airborne and the abrasive processes that are completed in a foundries cleaning room often generate respirable dust at rapid rates. Silica dust can also occur when employees handle, cool, or transport materials that contain even slight traces of silica dust residue.
As such, cleaning rooms are the areas in need of the most attention.
With a June 2018 compliance date, foundries have already begun considering how to address the issue of reducing silica dust exposure in cleaning rooms. With limited budgets, existing installations, and building layouts as major constraints, it may be far more difficult to quickly and easily implement new and safer casting cleaning procedures. Essentially, these rooms need to be built and used in a way that makes them more efficient and less labor-intensive for employees without harming production.
Improving Shakeout Methods to Control Silica Dust
One of the “easiest” ways to make cleaning rooms safer is by implementing equipment such as enclosed sand-casting conditioners and cooling conveyors. These systems are often automated and closed-off, allowing the castings to remain contained during shakeout and carryover. Essentially this eliminates the possibility of silica dust particles becoming airborne.
Implementing these new machines during the cleaning process allows for less silica dust to reach employees during the inspection and material handling phases that follow casting cleaning. The end result of implementing these systems is that casting production levels are maintained and workers are far less likely to be exposed to silica dust hazards.
With new Permissible Exposure Limits on the horizon, foundries will be held responsible for providing safer working environments and procedures that protect employees from the dangers of silica dust. Contact Industrial Vacuum today to see how we can help you meet compliance by keeping your foundry clean and dust free!