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Steel foundries examine quality & waste control.

Steel Foundries Examine Quality & Waste Control

U.S. steel foundries, confronted with growing quality and cost demands, coupled with increased pressures for waste control, are examining a variety of techniques, processes and materials in their effort to remain on the cutting edge of foundry technology and operations. More than 190 steel casters were brought up to date on developments in these areas through the more than 30 papers presented during the 1990 National Technical & Operating Conference of the Steel Founders' Society of America, Nov 8-10 in Chicago, Illinois.

Quality Techniques

"Good quality has been a requirement for survival in the steel casting industry for the last decade and even though business conditions have improved overall, continuous quality improvement is still of paramount importance as it has the most significant potential for reducing costs and increasing profits," Rick Perry and Gary Ferguson stressed in their report on quality assurance programs at Texas Steel Foundry. They described some of the interesting efforts the foundry has made in pursuing its quality goals.

One result from their efforts was the development of a monthly cost of quality index which helps categorize and control quality-related expenses based on information obtained from the accounting and production control departments.

With this index, quality costs are broken out into four categories:

* Appraisal & Prevention Costs: QC and QA Costs--This is simply the total monthly expense to operate the quality control and quality assurance departments.

* External Failure Costs: Defective Castings and Repair/Return Costs--This includes the monthly cost of credits to sales revenue due to defective castings plus the portion of finishing and machine shop manufacturing cost attributed to processing of repair and return castings.

* Internal Failure Costs: Scrap Costs--This is the monthly portion of molding, core, melting, finishing and machine stop manufacturing costs associated with castings that are scrapped internally.

* Rework Costs: This is the monthly cost of labor and material associated with arc air (excluding riser removal) and welding.

"Since this program began in 1989 we feel that it is a much superior measure of how we are doing overall on quality than we have ever had before because it includes all aspects of quality," they explained.

Another quality tool being examined by steel foundries is the filtration of molten steel. In his report to the conference, Stephen Gear, Kubota Metal Corp./Fahramet Div. (KMF) described his foundry's work with filters to reduce scrap caused by exogenous inclusion defects. A study of the problem indicated that turbulence in the metal flow during pouring was a leading cause of the defect. According to Gear, during the last 2-1/2 years the foundry has experienced a sustained reduction of inclusion defects.

As-Cast Steels

R. C. Voigt, Pennsylvania State Univ, reported on work in progress to determine the mechanical properties of C-Mn as-cast steels. Other project members were C.H. Tu, Pennsylvania State Univ., and R.L. Rosmait, Pittsburg State Univ. The researchers showed that a "good combination of strength and ductility can be achieved for C-Mn steels in the as-cast condition. Alloys with less than 0.22% C can have as-cast strength levels greater than can be achieved by normalize or normalize and temper heat treatments. Carbon contents above 0.25% C lower the as-cast ductility."

Initial results of the research are encouraging as the as-cast steels showed the following properties: UTS--70-95 ksi; yield strength--40-75 ksi; and elongation 7-27%. "These properties," it was reported, "are similar to those that can be obtained for conventional C-Mn steels of the same composition in the heat treated condition...Elimination of heat treatment reduces both the cost and processing time for producing steel casting. This may permit low-cost, as-cast C-Mn steels to compete with the commonly specified grades of ductile iron for many applications."

Waste Control

Control of wastes of all types is rapidly becoming a major concern for foundries due to rising disposal costs and increasingly rigid regulations. Besides these considerations, Rockwell International's steel foundry operations in Atchison, Kansas were faced with rapidly escalating costs for zircon sand used in its molding operations. This made it necessary for the foundry to begin reclaiming the zircon in order to keep overall manufacturing costs under control. J.R. Kujawa, Rockwell International, summarized the foundry's successful efforts to reduce zircon use through reclamation and other methods. This was a report written by Kujawa, L. Heineken and C. Anderson or Rockwell. Utilizing a pneumatic and mechanical reclaimer the foundry was able to reduce zircon usage. With additional zircon reclamation capacity coming on-line in 1991, the foundry will be able to further reduce usage.

In addition to its reclamation efforts, Rockwell continues to pursue alternate methods to reduce zircon consumption. Among these are:

* testing zircon/silica blends to reduce zircon use;

* reduce waste zircon with better mixing control;

* continue to test synthetic materials (mulgrain) to seek a cost effective replacement for zircon.
COPYRIGHT 1991 American Foundry Society, Inc.
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Copyright 1991, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:Steel Founders' Society of America 1990 National Technical and Operating Conference
Author:Thomas, Susan P.
Publication:Modern Casting
Date:Jan 1, 1991
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