'Chromalloy Case Study
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CHROMALLOY JETTING AHEAD WITH OPENBATCH
The Company
Chromalloy is a division of Chromalloy Gas Turbine Corporation, and is based in Phoenix, Arizona. Founded in 1986, Chromalloy Arizona is an authorized FAA repair station. Its customers include major airlines along with original engine manufacturers. The company has been using Sequencia's OpenBatch™ software for the last year and a half to control coating as well as fluoride ion cleaning operations for turbine engine components.
The Situation
Prior to the installation of the current control system, Chromalloy was only able to fluoride ion clean. "The original control system had never been fully operational," explained Rick Alexander, metallurgical engineer overseeing CVD (chemical vapor deposition) operations. The original system did not have the capability to run coating recipes. Troubleshooting was a complete nightmare and there was no recipe system. In early 1996, the company sought a fully integrated batch control system that would allow them to better control the process with improved safety and flexibility. They chose systems integrator Topro (now Tava Technology) to perform the integration.
The Solution
The installation process took approximately six months. During the process, Rick Alexander was closely involved. "I wouldn't let them use any of the previous system – we started from scratch. It's a very complex system consisting of an Allen-Bradley 540 PLC and 520 I/O, half of that being analog. Chromalloy is using Intellution's FIX 32 version 6.2 as an MMI and Sequencia's OpenBatch version 3.0 for recipe management."
The FIX32 software shows what is happening in the PLC, displays digital positions such as valves and analog values such as temperatures, and allows manual control of specific devices (such as valves). OpenBatch stores and executes the recipes, which includes downloading of parameters to the PLC along with the sequence of operation.
The Process
This equipment has two functions:
To fluoride ion clean repair components prior to braze operations. The fluoride ion cleaning process removes any remaining surface oxides along with oxides and sulfides which are in tight cracks. It is important to remove these oxides so the braze alloys will flow into the cracks, thus mending them.
To apply an aluminide coating to both new and repair components. This alumnide coating protects the surface of turbine components from corrosion at high temperatures.
The big advantage that Chromalloy has seen using the OpenBatch software, according to Alexander, is the versatility it provides. OpenBatch allows any possible recipe configuration without complicated PLC logic. It also makes recipe building easy using the SFC (sequential function chart) configuration. All that is required is to just put the necessary steps together and connect them. A typical cycle will run 9 to 24 hours, during which the operator monitors the MMI for alarm conditions and determines what is happening in the PLC. The operator also monitors OpenBatch to determine where in the recipe the cycle is. FIX32 and OpenBatch communicate via DDE, thus allowing reports to be generated from the MMI which contain recipe information.
The Benefits
According to Alexander, the benefits to the control system include better control of the system, increased reliability, increased flexibility and easier troubleshooting. When the system was first installed it was in the experimental stages and the final plumbing configuration which would be needed to produce the coatings was not known. OpenBatch allows recipes for all possible plumbing configurations to be made easily. OpenBatch communicates to FIX32 which configuration will be used and the screens are displayed with the proper plumbing going to the correct devices, and which devices are active.
The number of aborted runs has decreased 90% in the last 2 years. Based on the flexibility of the OpenBatch system, Chromalloy is able to bypass non-essential pieces of equipment and continue the run. Before the run had to be aborted in order to find out what and where the problem was. Previously, the company aborted runs 5-6 times a year. In the last two years, they have only aborted one run.
Troubleshooting has decreased to one tenth of the time previously required. Tags are tied to a phase, so that when an error comes in, they can tell instantly what piece of equipment is having a problem. The errors are now specific. Previously, it took over an hour to find the erro when they got an alarm, based on the information they were receiving from the previous system. Now they can find them instantly.
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