Controlling sound levels in a foundry environment is an ongoing challenge. The processing of heavy industrial noise-transmitting material such as iron can contribute a lot of noise pollution to the surrounding area. This can cause long term health problems for the employees working in these environments.
According to the American Foundry Society, hearing loss has affected over 22 million people in the United States with industrial exposure leading the list of causes at 20%. Out of industrial exposure, the rate of hearing loss caused by foundry environments is roughly 3 times greater than in private manufacturing. Long term unprotected exposure to high levels of noise can lead to tinnitus and permanent hearing loss making it difficult to communicate and hear important safety signals.
What Causes Noise in a Foundry Environment?
In a foundry environment there are many factors that contribute to the creation of noise. Noise is rated as A-weighted decibels or dBA as perceived by the human ear. To list a few:
-Shakeouts (Vibratory or Rotary) (105-115 dBA)
-Shot Blast (100-110 dBA)
-Casting and sprue handling via conveyors and feeders (95-115 dBA)
-Cast Grinding (92-115 dBA)
Metal is an extremely effective noise transmitter so it should come as no surprise that the moving and transporting of this material is going to create noise. When working in a foundry environment it is important to remember these factors.
Permissible Exposure Limit
The permissible exposure limit (PEL) regulated by The United States Department of Labor is dependant upon the hours of exposure to noise. If working an 8 hour shift the PEL for that time is 90 dBA. The dBA PEL continues to gradually increase as the time spent exposed to noise decreases. See the chart below for different lengths and exposure limits.
If the action level of 85 dBA is met or exceeded, employees must take part in the Hearing Conservation Program which demands noise monitoring, audiometric testing, hearing protection devices, employee testing, and documentation.
Ways to Prevent Exposure
Personal Protective Equipment or PPE may seem like a decent solution to noise exposure, however, in a study by NIOSH, PPE has been found to be the least effective. Most reasons cited were that the PPE was uncomfortable, ill-fitted, or flat out neglected. Many claim that PPE interferes with the ability to hear communications from coworkers, however, it has been proven that vocal interpretation actually increases in loud environments with the use of PPE.
A more effective option is administrative controls as it includes completely relocating employees away from harmful noises or the less effective shortening of their shift to reduce exposure. This option is not always beneficial to production which leads many to resort to another effective option of engineering controls.
GK Engineering Controls
If these noise limits are not met, your company can be cited for violations and fined. There are ways to suppress noise however and General Kinematics can help!
Here are a few things we recommend to our customers to reduce foundry noise levels:
- Enclosures can be helpful for isolating noise away from operators. A popular option is hooded vibratory equipment and sound enclosures that are built directly around the equipment.
- Manipulators will remove operators from the source and let them work in an isolated cab.
- Liners provide iron handling equipment with sound deadening troughs to deaden some of the noise that is being projected. The choices of material for this solution are sound deadening sandwiched decks, aluminum liners, and external spray-on sound absorber. Rubber can be implemented if the castings are below 200°F.
- Keeping your equipment operating well and working within the proper stroke range reduces mechanical noise. Moving equipment further away from walls can also be helpful because it reduces deflection of sound waves.
- Last but not least, GK Flat-Stroke designed equipment eliminates the sound caused from large material impacts and keeps the castings in contact with the conveyor surface.
Have other ideas and ways you have reduced noise levels in your foundry? Mention them below. For more information on how General Kinematics can improve your foundry equipment and environment, please contact me!
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