Heat Treating for the Competitive Edge
In spite of their cutting-edge technologies, AST was just like everyone else in terms of their control and recording instrumentation. They had a variety of manufacturers and generations of instrumentation. The furnaces, both new and used, were bought at different times, and some of the furnaces had previous instrument upgrades.
HistoryAST had a sister company, Summit Heat Treating, located just two miles away. Management decided to merge AST into Summit since there was more land for expansion at the location. This move was to be accomplished by their maintenance department with the help of a local integrator, AQI Engineering Co. of Cuyahoga Falls, Ohio. Production impacts were to be minimal. Therefore, only one furnace at a time could be moved.
It was decided that the instrumentation on the integral-quench (IQ) furnace line would be upgraded during the move. Yokogawa Green Series was already in use on a few furnaces, so it became the instrument of choice. The decision to replace the failing paper chart recorders was also made at this time. Since AST already had SpecView (a computerized data-acquisition system) in place, it was expanded to work with the additional furnaces.
Instrumentation UpgradeThe line consists of three IQ furnaces and three companion temper furnaces. When this line was moved, the controls were upgraded. The original controls were on the shop floor by the furnaces. The new controllers were placed in a control room. The upgrade allowed for the control panels to be identical with the same controllers and operator-interface layout (Fig. 1). The controller used on the IQ furnaces was the Yokogawa UP750. The dual-loop model with “Custom Computation” allowed one controller to handle both temperature and carbon-control loops on the furnace (Fig. 2).
The UP controller allows the operators to store programs or recipes to ensure consistent heat-treat cycles. The recipes are created on a laptop with the controller software LL100 and the companion instrument interface. This allows the quality department to create the recipe once on the laptop and then download it to the three controllers. The software allows the quality department to verify the recipes in the controller against the “controlled” copy on the laptop. This follows their quality-assurance-program guidelines for ISO 9001:2000 and Nadcap.
The companion tempers were also upgraded with UT450 controllers, which are single-setpoint controllers (Fig. 3). These instruments have a timer feature for one of the alarms, which allows the operator to set a soak time in the unit. After reaching setpoint, the timer starts, and at the end of the soak an alarm sounds. This gives the operator a simple method of running a soak cycle without having to use a programmable controller.
For the remaining controllers that were not upgraded, data was obtained through modbus modules. These modules, by ModMux, accept eight thermocouple inputs. A twisted-pair communication wire back to the computer connects the modules. Although it does not have communication to the controller, it does allow the recording of data from the furnace. As existing controllers need to be replaced, the appropriate Green Series controller is installed. All new controllers have the digital communication capability to take advantage of the two-way communication with the controller. Standardizing with one brand of controller provides consistency for the operator, the quality-assurance department and the maintenance department.
Data-Acquisition SoftwareAs noted before, the data-acquisition software is SpecView. The local integrator who helped with the move also handled the customization of the SpecView software. The customers already had “Job Shoppe” software, which is a custom, Access-based, job-tracking software in use. The data-acquisition software had to pass heat-cycle data to the job-tracking software to satisfy the Nadcap and other certification requirements of AST customers. The data-acquisition software is designed to give the operator an overview of furnace groups such as vacuum, temper or integral quench. This overview gives a quick look at the process value for all furnaces and the setpoint on instruments with communications (Fig. 4). There is also an indication, by way of a color change on the detail button, that the heat-cycle data is being logged for a job.
The data-acquisition software logs data continuously in a “write-once, read-only” file. It is a copy of this data that is passed in a uniquely named file to the job-tracking software. When the operator is in the detail page for the furnace, there is a chart and instrument faceplate. These items are familiar to the operator. When the operator is ready to start logging data for a job, he presses the “start” button on the screen. The system then generates a unique number that is placed on the Job Shoppe router paperwork. This number is the file name that will be used by the job-tracking system to generate the required certification charts. The detail screen also tells the operator when the job was started.
On the furnaces with communication-equipped controllers, the software is programmed to allow the operator to access the controllers. Through the detail page, the recipe number can be chosen. The controller can also be placed in run, reset or local mode through the computer. Many other controller variables, such as PID values and alarm setpoints, are accessible through the software, which is used for maintenance and troubleshooting.
The heat-cycle data is backed up nightly on the central server and saved to satisfy the records-retention requirements. Data from jobs run two or three years ago can be retrieved just as easily as the data from yesterday. Since data from several years can be stored on a hard drive, charts can be printed and reprinted on demand.
SummaryBy upgrading their controllers and replacing their recording devices, AST is able to offer their customers “heat treating for the competitive edge.” This is accomplished by using state-of-the-art controllers and data-acquisition software that integrate seamlessly to their job-tracking and accounting software. All of this gives their customers complete documentation and traceability of the heat-treatment process. IH
For more information: Contact Rick Sabo of AQI Engineering Company, PO Box 911, Cuyahoga Falls, OH 44223; tel: 330-926-0861; fax: 330-926-0907; e-mail: rsabo@AQIEng.com; web: www.AQIEng.com
Additional related information may be found by searching for these (and other) key words/terms via BNP Media SEARCH at www.industrialheating.com: Intensiquench, integral quench, programmable controller, data-acquisition software, job-tracking software