Detecting Fine Process Errors with IMPAX Performance Enhancements

By: Process Technologies Group, Inc.
Topics: Performance, Tool Damage, Cracked Heads, Short-feeds, IMPAX

Five simple upgrades to help IMPAX monitors detect tool fractures, die chipping, cracked heads, and short-feeds

The typical IMPAX installation and software settings provide basic force monitoring capabilities utilizing calculated control limits, a single timing window, a standard piezoelectric sensor, and limited control logic. Generally, this type of configuration is not well suited to detect tool fractures, die chipping, cracked heads, and slight short-feed conditions. The standard IMPAX installation makes it very difficult for an operator to tighten control limits without causing excessive nuisance shutdowns caused by material and machine inconsistencies. As a result, many operators open up the control limits, making it virtually impossible to detect certain key defects.

Solution:

Five independent upgrade strategies are available to address this problem. The upgrades can be added individually or as a single overall enhancement. Obviously, we feel that the overall enhancement strategy offers the greatest potential to improve the IMPAX unit's ability to detect problems. However, some of our clients have experienced success utilizing select upgrades.

Upgrades Available:

1. Using the Exceptions Logic available in all IMPAX units, a Parts Sorter can be added to divert "suspicious" product. A pre-set number of diverted parts will be allowed before the header is shut down. This enables the user to over-tighten the control limits without unnecessary nuisance shutdowns. There may be a fair number of "good" parts sorted with the bad, but most users feel this is an acceptable tradeoff in their efforts to prevent contamination. Parts sorters can be custom manufactured by PTG, Inc. or we can instruct you how to manufacture these devices.
2. PTG, Inc. now offers two types of "Directional" Sensors that are less prone to picking up machine noise. Our standard disk sensor is very dynamic in essentially all directions. This means that the sensor detects not only the direct forming forces but also machine vibration, transfer noise, etc. Since the IMPAX unit "tunes" to this signal, the less influence from unwanted noise, the better. The directional 8mm sensors can be aimed to react to forces coming from a specific direction, thus there is a much cleaner signal to work with. You also have the option to add sensors like our Short-feed Detector. This enables you to set up a specific channel sensitized to detect only short-feed conditions. This has proven to be a far more reliable means of detecting short feeds as compared to utilizing the upset blow channel.
3. Another innovation is the Timing Enhancement Kit. This involves adding another proximity sensor input to split the timing adjustment for each blow. Normally, one proximity switch is set up to read 90 degrees to 180 degrees for the finish blow and 180 degrees to 270 degrees for the upset blow. The addition of the second timing window allows the user to "trim" each timing signal to read only bottom dead center signals for each blow (i.e., 30 degrees to 60 degrees). By using smaller timing windows, we also eliminate machine and transfer noise, giving us a more accurate signal.
4. In every IMPAX system, you can set up each channel to evaluate a specific desired function. For example, if you set up the IMPAX unit to analyze blow one or blow two on the same channel (this is the normal procedure), both the low and high limits are recalculated with any force change. If nuisances only occur as high force errors, then it is desirable to want to adjust only the high limits. This can only be done if we split the channels and assign independent control for the high/low set points. In other words, keep the low limits very tight to detect cracked heads, and widen the high limits to detect critical smashups without causing nuisance shutdowns. Such control makes a significant impact on sensitivity and nuisance shutdown reduction.
5. IMPAX monitors can be upgraded to run our Version 58 enhanced software. This upgrade activates a real-time clock and enhances our Exceptions Control Logic. The system's Error Log will capture and timestamp every error, including exception errors that are used to control a sorter. This feedback will allow you to find the optimum setup for your sorting device and also determine the frequency of sorting. Version 58 also provides a specific control setting called Immediate Limits. When activated on a specific channel, the software will require the force values to match the previous control limits. This prevents a long re-learn process, since the Immediate Limits test must match within four cycles or there will be an error generated. This is a very important feature if sorting is set up on a specific channel.

Results

Many of our customers have had great success by applying one or more of these upgrades. By refining the monitoring process, we can detect tool damage with much finer resolution, which allows the IMPAX monitor to better ensure good production. We can also detect cracked heads and short-feeds that were previously undetectable, reducing the danger of contamination and the need for sorting.

Please contact us for more information about any of these upgrades. We'd be happy to help you improve your monitoring process.

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