16-17#05 Air Sampling Method for OSHA Silica Compliance
Principal Investigator: Robert Scholz, TRC Solutions
Steering Committee Chair: Tom Slavin, Slavin OSH Group
OSHA’s new worker exposure standard for respirable, crystalline silica requires that foundries limit exposure during work shifts to about one-half the concentration level of the previous Permissible Exposure Limit (PEL). Meeting this strict standard will necessitate that foundries refine their ability to identify and address root causes of exposure. Unfortunately, the method of averaging silica exposure over the work shift does not provide a basis for pinpointing those activities that have the greatest impact on overall average exposure levels. Real-time monitoring of silica concentrations could provide the needed diagnostic capability. However, this method is only in the developmental stage at this time. Instruments are commercially available to measure the concentration of silica-bearing respirable particulate matter (RPM). If real-time RPM measurements can be correlated to its silica content in a foundry situation, the needed capability for diagnosing the root causes of exposure could be made available to foundries.
The goal of the project was to develop a procedure for providing the needed correlation in a wide variety of foundry process operations.
Library Paper Number: 16-17#05
16-17#06 Quantifying Casting Quality Through Filling Conditions
Principal Investigator: Dan Hoefert, Eck Industries
Steering Committee Chair: Adam Kopper, Mercury Marine
Today, predicting the actual filling damage that oxides may cause to a casting remains largely based on theory, experience and speculation. In the past decade, great strides have been made in simulation capabilities. Heat transfer data and computational fluid flow have been combined to do a wonderful job of predicting porosity and mechanical properties. Filling concerns such as excessive filling velocity, eddies and other turbulent conditions can also be noted with simulation software. However, simulation software does not take the chemical reaction of oxide formation into account. Filling results only offer an indirect indication of the potential oxide damage, with no effect to the predicted porosity or mechanical results. As such, serious pitfalls can exist when it comes to interpreting simulation results.
Without correlating filling concerns related to oxide-damage, misleading simulation results can be predicted. If a gating design includes well-placed feeders and chills, but includes turbulent filling conditions, simulation can falsely predict excellent soundness and mechanical properties; despite the filling damage noted indirectly by viewing the filling results. As foundries look for competitive ways to tool and fill castings, this confusion can tempt a foundry to choose a more turbulent-fill gating design if the simulation results predict quality advantages over a more tranquil-fill gating design.
This project was intended to help answer these difficult questions with meaningful data that can be used to quantify these concerns.
Library Paper Number: 20-051 Webinar Link: Click Here
16-17#10 Evaluation of Alternate Aggregates for Use in Green Sand Systems
Principal Investigator: Sairam Ravi, University of Northern Iowa
Steering Committee Chair: Vic Lafay, Imerys
The lower cost of silica sand and its relatively high refractoriness makes it a viable and economical choice for green sand systems, with millions of tons of silica sand used every year. However, a new rule by Occupational Safety and Health Administration (OSHA) considerably toughens the use of silica sand in a foundry. The regulation will require foundries to implement extensive engineering controls, which will be cost prohibitive for small to medium-sized metalcasting facilities. One possible solution for foundries will be to utilize a non-silica aggregate in their green sand systems. This will minimize or eliminate the respirable crystalline silica, in addition to the large capital cost associated with engineering controls mandated in the new regulations. Little research has been conducted in the use of alternate non-silica aggregates in a green sand system and these materials need to be characterized and tested for ensuring good results when bonded with a bentonite clay.
It is the intent of the project was to determine what limitations non-silica aggregates have in the replacement of silica sand and then to educate the industry in these areas.
Library Paper Number: 20-058