Latex Foam International (LFI) produces mattress cores in seven firmness grades, ranging from “pillow soft” to “super firm.” The firmness grade is determined, among other things, by the amount of latex foam compound poured into the mattress core molding press—the more foam injected, the firmer the mattress core.
“There are very small differences between those seven ranges, and our ability to target and hit those ranges has been significantly improved by an added weighing system that’s controlled by our Siemens automation system,” says John Coffey, an LFI executive.
The weighing system is more accurate than using flowmeters to measure the amount of foam injected into the presses, says Bob Godard, president of NIC Systems Corp., the integrator who installed the system. In the LFI press room, robots are used to inject the latex material. “The accumulator tank that holds the compound that gets pumped by the robot into the presses sits on load cells, and we monitor to within a tenth of a pound exactly how much goes into the press,” Godard explains.
Near the end of its production process, LFI performs a quality control check on each core using what’s call an Indentation Load Deflection (ILD) test. The automated ILD process performs a pressure test at nine points on each core to determine that the cores uniformly meet the target firmness grade, measured by the amount of pressure required to compress the material by 25 percent, Coffey says. “The ILD system confirms that the amount of material we put into the press did, in fact, give us the firmness range we wanted.”
Coffey notes that improved consistency and uniformity in mattress core firmness made possible by the automation system has paid dividends in the field. “Our return rates are extremely low,” he says.
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