Casting answers & advice.

Q: What are the choices available to replace leaded copper alloys for plumbing applications?

Background: Plumbing components in North America traditionally have been made from sand-cast leaded red and semi-red brasses (alloys C83600 and C84400). The lead content of these alloys varies between 4-8%. (Lead is added to sand cast copper alloys to improve machinability and achieve pressure tight castings.)

In Europe, plumbing components are produced by methods other than sand casting and the materials may have a lower copper or lead content (alloy C85800, for example). The U.S. EPA established the Lead and Copper Rule in 1991 setting the potable water action limits for lead at 0.015 mg/L and copper at 1.3 mg/L.

In conjunction with the Lead and Copper Rule, the EPA commissioned NSF International to develop standards for measuring, approving and monitoring lead, copper and many other metals and chemicals that come in contact with potable water. In response, NSF has developed several standards addressing these requirements, most notably Standard 61. NSF also has established the lead action limit for point-of-use products (faucets) and in-line mechanical devices at 15 ppb.

Recommendations: Extensive research and development work through AFS has introduced three Bi/Se-modified alloys know as EnviroBrasses (earlier known as SeBiLOYs). These new alloys have machining characteristics similar to the leaded brasses but require machining fluids for optimum machining performance.

* EnviroBrass I and II (C89510 and C89520) were developed to replace C83600 leaded red brass and C84400 semi-red brass. They have received ASTM accreditation and are listed in ASTM B584;

* EnviroBrass III (C89550) is a substitute for C85800 leaded yellow brass. It is currently under evaluation for ASTM listing.

In addition to the EnviroBrasses, there are several other patented copper-based low-lead or lead-free alloys available.

Alternate techniques for controlling lead leaching include metal treatments and coatings. Metal treatments that remove the surface lead in contact with potable water while maintaining the existing base metal characteristics are commercially available. Coatings also are being applied to the water contact surfaces to secure lead from leaching into the drinking water. Many of these alternate treatment and coating methods have obtained NSF product approvals.

Information was supplied by the AFS Copper Alloy Div.

Q: We recently purchased casting simulation software for the first time. What are the keys to successfully implementing this new process, and what can we anticipate in terms of cost payback?

Background: The use of computerized casting solidification and process simulation software has increased dramatically in recent years, and many foundries spend a considerable amount of money to buy the software packages. How those tools are implemented into the existing foundry infrastructure and process will likely determine how quickly the foundry will begin to see financial results from the purchase.

The keys to successful implementation are related to personnel decisions, infrastructure and plant culture. Hiring and managing of simulation personnel isn't any different from other personnel decisions, and difficulty in software implementation can often be linked to poor hiring and training procedures.

Recommendations: The following recommendations will help foundries successfully implement and utilize simulation software:

Staffing--Don't cut corners when staffing the position. A new user may make the false assumption that simulation is a part time job and that this work can be offloaded onto someone who already has his hands full. A better approach is to assign the position to someone with an engineering background or equivalent foundry experience. Methoding experience is a benefit.

Provide adequate time to learn the program and gain the expertise required. (Plan to allow a full year of on the job training to become an expert.) The foundry should begin to see some positive financial impact in six months, after the simulation engineer has become comfortable with the program and has "calibrated" it to the specific foundry requirements.

Communication--The simulation engineer must form positive working relationships with foundry personnel, specifically in the methoding, molding and patternmaking areas. Shop personnel may initially have some skepticism related to the new technology. To succeed, the simulation engineer must be viewed as an important resource or tool to improve the casting process.

Good communication skills and a helpful attitude are beneficial. It is difficult to successfully implement a simulation program if the relationship with foundry personnel breaks down or the simulation engineer is viewed as arrogant, combative or irrelevant-just a "punk kid with a computer."

Teamwork--Get simulation and foundry personnel talking and organized so that there are incentives for the simulation engineer and the foundry engineer to succeed by working together. Show support at all levels of management. If the simulation engineer does not have practical foundry experience, it can be helpful for him to work in various parts of the foundry for a few weeks to help him appreciate and respect the expertise involved in making castings and improve his knowledge of the foundry process.

Information was supplied by the AFS Engineering Div. Process Modeling Committee (1-F)

Recommendations are the opinion of the AFS Technical Dept. based on referenced literature and experience. If you need assistance with a technical issue, fax or email your question to: Casting Answers & Advice, c/o MODERN CASTING, at 847/824-7848 or [e-mail].