But Ispat Inland--one of the largest steel companies in the United States--has never been content to simply match such requirements. The company's mill in East Chicago typically produces its steels and steel-alloy products to more stringent standards imposed by its own quality design engineers.
Before the flat rolled coils and bar products are released for shipment, samples from each lot are tensile tested at the company's on-site Quality Control Center. To accommodate the large number of samples that arrive daily from the mill, the QC Center uses a fully automated, mechanical horizontal testing system (MHT) provided by Tinius Olsen Testing Machine Co. Inc. (Willow Grove, PA).
One key feature of the system, in use since 1998, is its robotic handling system. By enabling full automation of the testing process, the robotic system has produced big savings in time and labor, compared to the nonrobotic test systems previously used by the company.
"When you use manually operated machines, you have to do a lot of handling and measuring by hand before you actually pull the specimen apart," notes Roger D. Mikuly, project engineer who oversees materials testing operations at the QC center. "Using manual machines for tensile testing is very labor intensive, and if you are testing for r and n values, it takes a lot of time to calculate the results by hand with paper and pencil."
The automated MHT has a 30,000 pounds of force (150,000 newton) capacity and provides high-resolution, high-elongation testing with a longitudinal extensometer and a transverse extensometer. System components include a laser bar code scanner for specimen identification, a specimen measuring station, and a PC-based data acquisition and control system.
The Tinius Olsen system is itself "put to the test" by the combination of the 400 to 900 samples sent daily from the mill to the QC center, the varieties of steel and the range of testing standards for Ispat Inland's breadth of global customers. Products range from a soft, drawing quality steel up to martensitic 220 kilopounds per square inch (ksi) tensile strength steel. System capabilities include testing according to ASTM, EN, DIN, ISO and JIS test methods, variously required across the mix of customers worldwide.
In operation, the robotic handler moves each specimen, typi-cally 1 by 9 inches with its simple or special test requirements indicated in its barcoding, into the automated MHT for testing against a confirmed standard. The MHT's grips securely hold both ends of the specimen during the two minutes or longer for the sample to be pulled apart. The robotic handler removes the broken pieces and inserts another specimen--while the MHT transmits the test results via local area network to Ispat Inland's mainframe computer for fast analysis and instant release of the product. "The mill knows within a minute after we test a specimen whether it's okay to ship the product," Mikuly points out.
Once the system operator has separated and loaded the specimens into the racks and set the automated MHT into motion, the operator is free to perform other duties. This characteristic lets the mill tap even greater value in the testing system: the MHT is used 24 hours a day, seven days a week.
"The robotic system has, in effect, opened up another 'seven-day testing week' for us," Mikuly observes. "Before the second shift is over at 11 p.m., we'll load specimens into the system and let it run tensile tests overnight, without the presence of an operator."
Tinius Olsen Testing Machine Co.