Ductile Iron Castings: How State Line Restored an OEM’s Confidence

The Foundry Finds Answers – In a Hurry

There are bad days, and then there are days that shake a business to its core.

This story started with a phone call to a Tier 1 supplier (referred to as Supplier X going forward). An OEM customer – a big OEM customer – had experienced an engine failure in the field.

And another. And another.

A cursory review pointed to a specific part: a support casting provided by a Tier 2 supplier. But responsibility ultimately fell on the Tier 1 suppler. That meant the OEM was very unhappy with Supplier X.

More investigation determined that defective castings were the cause of the field failures. Making matters worse, the castings were part of the current product build for the OEMs. More than 50 castings awaiting installation had to be scrapped. Production came to a halt.

First, failures in the field? And now, a defective part on the production line? It was time for answers.

There were phone calls and Zoom meetings – including one that was attended by about 20 representatives of the OEM and Supplier X.

Quick action was needed. Supplier X called State Line Foundries for help, which includes Winnebago and State Line Foundry.

Supplier X had worked with State Line previously – and even had some other projects currently with the foundry. There was a great deal of trust between the supplier and State Line.

More Than a Speed Problem

Supplier X needed to/promised to provide the OEM with new, correct castings – and fast. So it reached out to Jesse Milks, president of State Line.

Both Supplier X and Milks’ team knew that speed alone would not solve the problem. The OEM was gun-shy and wanted proof that the replacement castings would perform as intended.

The project started with an analysis of the failed castings.  The microstructure and tensile analysis showed subpar ductile iron.  The failed castings had internal porosity at the failure points.  The OEM’s trust had been shaken. Fortunately, State Line had the processes, expertise and capacity to respond.

Engineering for Success

Time was critical given the OEM’s production line was down. Yet State Line could not simply use the same pattern and processes that were proven ineffective. Adjustments to tooling, gating, risers and other processes were needed.

State Line’s Winnebago facility immediately prioritized the project, dedicating engineering, quality and production resources to the effort.

Solidification analysis was a key step. Fortunately, State Line’s solidification modeling systems accelerated the process and gained confidence. Before a single casting was poured, it allowed engineers to simulate how molten ductile iron would flow and cool inside the mold. The technology identified potential issues such as shrinkage, hot spots, incomplete filling and gas entrapment. This was crucial when considering gating, risers and mold design before production began.

OEM Keeps Watchful Eye

The modeling provided valuable data that State Line’s advanced engineering team used to fine-tune processes and meet exacting specifications. When it was time for the first production pour, State Line invited representatives from the OEM to witness the process firsthand. State Line’s plant manager and quality manager walked the OEM through the controls, inspections and validation steps being used throughout production. Trust was returning as the OEM watched the first pour. 

After the castings were produced, X-ray inspections provided another layer of assurance. By examining the internal structure of each casting, inspectors could detect porosity, cracks and other hidden defects that might otherwise go unnoticed. Dimensional, tensile, and microstructure analyses were also performed by State Line and the OEM.

Together, these technologies helped prevent defects before production and then helped verify casting integrity afterward – a critical combination given the circumstances.

Confidence Restored

Castings shipped within two weeks of State Line receiving the pattern tool, allowing production to resume at the OEM. The OEM also regained faith in both the castings and the process behind them.

For State Line, the project demonstrated more than speed. It showcased the ability to solve problems and respond when customers face high-stakes challenges. The result was an ongoing production partnership with Supplier X and a stronger reputation for helping manufacturers overcome critical challenges when relationships are on the line.