Regional spotlights machinability VOCs for foundrymen.

At the base of the Smoky Mountains in Gatlinburg, Tennessee, more than 350 foundrymen convened February 3-6 for the AFS Southeast Regional. Hosted by the Tennessee Chapter, the conference featured 36 technical presentations and a product/literature exhibition that showcased 52 companies.

The conference's keynote speaker, Gordon Street, president and CEO of NAR Wheland Foundry, Chattanooga, Tennessee, discussed what he called the key ingredient to present and future manufacturing success.

"People are our most important advantage," said Street. "We must retain the employees who understand the importance of good work habits. We must go beyond our plant walls and embrace our schools. If we are to succeed in manufacturing, we must embrace our most important asset - the human being."

Machinability of Iron

Charles Bates, Univ. of Alabama-Birmingham, provided an update of his AFS research, "Effects of Inoculation on Machinability of Gray and Ductile Iron."

The bulk of his presentation focused on the completed first phase of the research to determine the major causes of defects in castings and the properties that increase the rate of machining tool wear. Bates said pearlite and hardness do not always tell the whole story for tool wear. The abrasives in the microstructure - the microcarbides and imbedded sand - are major causes of wear.

Other causes of wear include trace element nitrides, diffusion inhibitors, cell-growth restrictions, cleaning room practice and a cooling rate through the eutectoid range.

The second phase of research involves working with foundries and their metal handling practices to analyze machining rejects. Bates provided an initial conclusion with respect to inoculation and machinability, revealing that a 0.2% addition of 75% ferrosilicate (FeSi) resulted in the most easily machinable ductile iron.

VOC Data Collection

The focus of the conference's environmental sessions was the reduction of volatile organic compounds (VOC). Several presenters discussed VOCs, detailing proper testing, EPA enforcement and reduction strategies. Skip Markham, environmental manager of Wheland's Warrenton, Georgia plant, spoke on "Process Data Collection."

According to Markham, many foundries do not devote enough resources to the collection of their VOC data for self-testing, resulting in inaccurate and costly results.

"The investment of time and money in extensive process data collection during source testing is justified when consideration is given to the opportunity to develop air pollution emission factors that represent the processing areas in your facility," Markham said.

Four major benefits to proper process data collection of VOCs are:

* easier determination of emission profile changes, as related to process changes in the foundry;

* greater confidence in compliance certification;

* extended shelf lives of collected emission data;

* lower emission fees.

Variation Reduction

"The ultimate variation reduction in manufacturing is the production of parts that have zero tolerances," said Mike Thornbury, industry consultant. "This sounds impossible, but it isn't. Variation reduction is all about controlling the process."

Thornbury's presentation, "Variation Reduction in the Foundry," detailed his attempts at Chrysler Corp. to reduce tolerances and variation in the manufacturing process.

He described a situation in which Chrysler had three different suppliers for the same brake part. Despite the fact that all three foundries started with the same designs and dimensions, the parts they supplied the automaker were all different. Some were +0.02 mm on the tolerances, while others were -0.02 mm, creating problems for Chrysler. This lack of stability forced the automaker to adjust to each of its suppliers.

"If we can pull the constant variations from our systems, we can improve our product and reduce our scrap," he said.

From Thornbury's perspective, the answer is simple consistency of process equals consistency of product. If foundries, machining shops, etc. eliminate tolerances at every level and work toward a goal of perfection, then the result will be castings of the same design and dimension regardless of the source.