Whether captive or commercial, the heat-treat operation faces a tougher challenge for productivity/profitability than other departments of manufacturing.
Computerized Maintenance Management Systems
Remote Diagnostics™ (or RDX) is one of the computerized maintenance management systems designed to increase furnace uptime and productivity through analysis of and reaction to equipment performance data. Data is gathered from the furnace PLC, allowing the customer and AFC-Holcroft to interrogate the furnace data via web conference.
By examining the data, a team of furnace experts can diagnose potential recurring issues and recommend corrective actions. Through this process, the equipment OEM can help customers target the most common causes of unplanned downtime and take steps to remedy them. Real, data-driven reliability and maintainability information gathered supports continuous improvement efforts, which can lead to both process and product advancements.
Remote Diagnostics™ – How It Works
Remote Diagnostics™ (RDX) starts with the acquisition of the furnace’s operational and historical data as stored in the HMI from the PLC or else transferred from the PLC to an RDX unit. The data can be collected manually by the customer, by the OEM through remote login or by automating the transfer of data through nightly transmission. Once the data is acquired, it can be filtered by date, time, occurrence, alarm ID, events, and whether these events occurred “in auto,” “in manual” or “in burnout” mode.
Charts and graphs are developed to help visualize and Pareto the data, displaying occurrences with blue bars that show their frequency and red lines that denote the length of time over which the occurrence transpired. Various items can be excluded in order to filter out unwanted noise.
This allows the team of furnace experts to drill down into certain occurrences, such as an alarm for “Tray too long in furnace after recipe complete.” This leads to dialogue with the customer, usually via web conference, which allows the OEM to reconstruct the cause and effect of a particular event. This can then lead to the diagnosis of recurring problems or alarms, the need for targeted maintenance, and/or action items to improve the efficiency and productivity of the customer’s furnace.
Consider a typical fastener manufacturing plant, where heading and threading machines can be turned off for the weekend or for a long holiday, thus saving energy. Not so for the heat-treat operation, where energy is required constantly to keep the furnace hot. Add to this scenario the time and money associated with maintenance and repair.
If a heading or threading machine goes down, it can be worked on immediately provided the necessary spare parts are available. Again, not so for the heat-treat operation, where furnaces can run at temperatures in excess of 1600°F and do not cool down quickly in order to be accessible for immediate inspection and repair. For these reasons, most heat-treat operations prefer to run 24/7 with only minimal, annual downtime planned for in the production schedule. Therefore, downtime is expensive, uptime is optimal and integrated software solutions can help.
Improving Uptime by Targeting Downtime – Some Examples
RDX Saves Commercial Heat Treaters More Than $100,000 per Year
Mike Coburn, sales engineer at AFC-Holcroft, details one customer’s experience. “Our customer, a commercial heat-treat operation, was running parts through a two-row pusher furnace (Fig. 1), and they kept experiencing regular crashes because the trays were jamming up in the furnace. The operators felt that since it was an older furnace, the crash was just a part of the regular day-to-day business. They knew that the root cause was that the trays had grown out of spec and beyond the usable life expectancy. Prior to purchasing new trays, the customer asked us for a review and for some assistance.”
Upon examination, the RDX data revealed the extent of the crash and recovery impact on the operation’s productivity and helped the customer to quantify this loss of time. Recovery costs were estimated to run over $20,000 per quarter/per pusher row. As a solution, the customer chose to invest in new tray positioners, which not only extended the useful life of the existing trays but also eliminated the costly downtime.
“The ROI for this customer was less than three months,” Coburn said. “The customer knew that they had periodic problems, but they had not realized the magnitude of the problem in dollars and time until they saw the RDX data summarized.
“AFC-Holcroft has a history of success stories working with customers through Remote Diagnostics where those customers have realized significant savings and improvements to both their production time and profitability.”
RDX Data Revealed the Absence of a “Handler Load Advance” Fault
“The prox sensor was proven true,” said Coburn. “The hardware was OK. The fault was triggered in manual mode. The absence of the expected ‘Handler Load Advance’ fault lead to a much faster diagnosis of the problem. The PLC was evaluating the prox’s ‘true’ position instead of a value stored in the managed bit. The managed bit preserved status between scans, so the PLC program was changed back to the original standard and the tray stoppage problem was eliminated. Without seeing the RDX data, troubleshooting for this customer would have taken a lot longer than turned out to be the case.”
RDX Team Gets at the Root Cause after Months of Guessing
“A commercial heat-treat customer found that the transfer car (Fig. 3) on their batch equipment line was stopping for unknown reasons,” Coburn said. “We made multiple visits to the customer to inspect the equipment and even brought in a sub-supplier to diagnose the controls. Our team suspected at least one of the following as the culprit: PC fault, bad OPC I/O signals and/or even potential network issues.”
When the RDX data was obtained, the RDX team analyzed the offending alarms. There were high-alarm occurrences for both “Car has tray, no data” and “Car has data, no tray.” So the team reasoned through the conditions for both alarms.
The root cause turned out to be that when the mechanical plunger on the transfer car jiggled, it intermittently failed to make prox switch “true.” Identifying the plunger as the root cause, it was reinforced to correct the issue. The collective team’s review of the RDX data succeeded where prior efforts had failed.
Supplier as Doctor/Consultant
Remote Diagnostics is a mutually beneficial process between the equipment OEM and the customer that promotes the continuous improvement of product and operational process. In some cases, a customer may not even know that their furnace is not operating at peak performance levels and that they have become “accustomed” to the way their equipment functions. Like a doctor or a consultant, the OEM can identify and evaluate the events or “symptoms” and then recommend remedies or “cures.”
Other Computerized Maintenance Management Systems developed by AFC-Holcroft include:
- Maintenance Module™
- Calibration Mode ™
- Engineering Optimization Program™
Calibration Mode will assist with a more in-depth analysis of the machine by collecting information on the different mechanisms and devices to ensure a proper functionality of the furnace. Calibration Mode is a set of diagnostics based on a thumbprint taken when the equipment or software is first commissioned. It takes approximately 60-90 minutes to run the Calibration Mode recipe, and it will display every completion of the steps through the recipe with a “done” message on the screen or leave a blank/fail indicator displayed.
Calibration Mode also offers the ability to change the original setpoints upon determination of the system’s needs (Fig. 4). This means that all information setpoints are available to be changed through a password-protection screen for the benchmark (original) values to be set based on the behavior of the machine components. In addition, the information from the last run of Calibration Mode will be left on the screen until the next test is performed so one can go back and look at the information to reference the machine’s condition at the time of the previous test. These are just a few reasons why running Calibration Mode while on a shutdown is a good idea.
AFC-Holcroft strongly recommends that a furnace and quench be shut down completely at least once a year for a complete system inspection. This practice has the potential to catch problems before they cause costly downtime. A yearly shutdown is the ideal time to run AFC-Holcroft’s Calibration Mode to obtain current annual readings to compare with the benchmark values.
All graphics were submitted by AFC-Holcroft.