Process Control System Hones Job Shop's Competitive Edge

Shops without zero defects programs or that cannot comply with customers’ Cpk demands probably won’t survive the heightened competitiveness of today’s metalworking scene. Gormac Products (Racine, Wisconsin), a job shop that produces small precision parts for the hydraulic, aerospace, medical, automotive and other markets, is determined to be a survivor and has acquired the appropriate survival tools.

Gormac has more than 90 machines, including Swiss screw machines, CNC lathes, machining centers and small-bore diamond tool, single-pass finishing equipment. The company wanted/needed a data collection and process control system that was suited to its job shop operations. Specifically, the company wanted a system that would satisfy its machine operators, who will not waste any time on data collection if they do not benefit from it; its engineers and supervisors, who will not waste time on process redesign if data is not reliable; and its management team, which will not waste time on problems that are not fully defined.

After researching the available systems, Gormac chose Micronite, a knowledge-based, process control software developed for metalworking operations by High-Tech Research (Deerfield, Illinois). HTR’s Web site describes Micronite as a new category of software known as intelligent process-adaptive control technology (iPACT) that provides next-generation capabilities beyond traditional Statistical Process Control. “There is a limit to an operator’s ability to run jobs at maximum efficiency, and [there is] a limit to an engineer’s ability to make optimal process and tool design for difficult-to-control processes,” explains Dr. Stephen Birman, HTR’s president and the developer of Micronite. “To improve efficiency, the operators need meaningful data analysis performed by an artificial process manager in real-time.”

“For easy-to-control jobs, real-time data analysis should lead to efficient inspection sampling and process changes (adjustments and tool change-overs),” he continues. “For operations with high tool-wear rate, timely warnings and messages for adjustment are crucial. Far-reaching system adaptability means that each job will be precisely controlled by the system to achieve maximum process efficiency and zero-defect quality.”

Val Gray was one of the first Swiss CNC operators at Gormac to work with Micronite. “Right now, I’m running a part with a couple of dimensions with a tolerance of 0.0006,” she explains. “Before we installed the new system, we could not run a part like this without producing some defects. Now, I don’t see how we can run without it. It tells me exactly when I need to inspect parts, stop the machine, make an adjustment or a tool change and even how much to offset my tools. The system decisions have always been accurate, and I can’t think of a time when it let me get too close to a tolerance limit or stopped me when everything was fine. The system’s color coding is easy to understand, the action charts help us learn more about our processes, and it makes us better and more skillful operators.”

Micronite does not require statistical literacy of its users. “We learned that in our diversified job shop environment, a standard SPC system cannot be maintained without coordinators and that statistical errors are costly,” adds Mark Sommer, president of Gormac Products. “Our new system removes much of the burden for statistical decisions from the supervisors and operators. Some of our jobs require Cpk over 1.67. In the past, we had problems maintaining required Cpk for some close tolerances. Even when capability studies confirmed our ability to produce parts with a specified Cpk, process data showed lower Cpk values. With our new system, we now find actual process performance to be much closer to the short-term process potential. The system provides in-process capability control messages to the operator. They advise the operator when and how to sample and how to adjust a process in order to achieve required process control. And by efficient control of the process, productivity is increased.”

As for reliability, the new system has reportedly made no errors in permitting a machine to run or in requesting a tool change. The system enforces inspection discipline and demands inspection of all related characteristics after each tool change.

Before the new system was implemented at Gormac, John Reidenbach, the quality assurance supervisor for the company, had to frequently visit the shop floor to see if anyone needed assistance with the SPC data collection. Now, he can monitor those activities from the system’s server station to view any problems with process, quality or tooling. “Where traditional SPC produces numerous false alarms, our expert system is very accurate and timely,” he notes.

The system is also easy to learn. It takes about 15 to 20 minutes on average to train a new operator on data collection, decision making, process event monitoring and other basic procedures. The operator gradually moves on to other parts of the system until he or she becomes a process analyst.