In-Depth Analysis of the Total Forming Process

By: Ed Evensen and Jerry McCabe, of Process Technologies Group, Inc., and Thomas Kopka and Anton Schwer, of Schwer + Kopka GmbH
Topics: Envelope Monitoring, Process Analysis, Fault Detection, IMPAX-SK

The IMPAX-SK 4 process monitor combines high-speed envelope monitoring techniques with the data storage capacity and computing power of a PC

IMPAX-SK Process Monitor

Traditionally, process monitors have fulfilled the task of monitoring production and switching off the machine when the defects were detected. Although limited in their capabilities, those systems have proven their worth in saving production cost, reducing scrap and protecting tooling and machines from damage. On the other hand, the older monitors were not designed to provide the relevant information needed today to really analyze and constantly improve the manufacturing process.

The new enhanced IMPAX-SK 4 process monitoring system combines high-speed "envelope" monitoring techniques with the data storage capacity and the computing power of a PC. The IMPAX-SK monitors were, in fact, the first monitoring systems for the cold forming machines to utilize this technology.

Envelope Monitoring

The envelope monitoring technique scans the entire forming force curve point for point. By computing an individual range for each of the more than 256 points scanned, upper and lower thresholds are established. This procedure ensures that phases of high process stability are monitored with very tight envelopes, while phases with standard fluctuation automatically lead to wider thresholds.

IMPAX-SK Profilemaster

In other words, the IMPAX-SK System continuously determines the limits that comply most precisely with the forming characteristics of the different phases. It would take hundreds of peak load monitors to match this coverage.

The new SKProfilemaster feature can focus in on a small window of the force curve to detect minor variances that do not exceed peak limits, but do give telltale signs of a quality problem. This magnifying utility can provide the in-depth analysis required to enhance quality troubleshooting and to eliminate the guesswork involved in setups.

The main advantages to be generated from this new technique are that just one button needs to be pushed to start monitoring, every forming phase relevant to defects is monitored (not just the peak value or area under the curve), memorized job waveforms speed setups, and adjustments and unwanted nuisance shutdowns are eliminated.

Fault and Process Analysis

Very often process monitoring systems tend to shut the machine down but leave the operator in the dark as to what the problem is. If the operator cannot identify the problem that has caused the shutdown, he will lose faith in the monitoring system. Eventually, the system is found running at very coarse monitoring limits, making it just an expensive crash detector.

IMPAX-SK Error Analysis

The IMPAX-SK system is designed to visually indicate exactly what happened. The precise reason for each machine shutdown will be stored for fault analysis and will be shown in detail including which station has caused the problem, high and low envelope curves, current stability factor, the defective force curve with the relevant envelopes, amount of deviation and explanation for the shutdown in English.

With one prompt, this cumulative information may be analyzed for frequency and type of all stop codes during the run, chronological listing of all stops, defective force curves for each stop and machine efficiency data.

Quality and Price Pressures

Increased quality and price pressures are forcing the fastener industry to improve the efficiency and quality of their production processes. Yesterday's tools are no longer good enough to keep up with today's demands. With the newer systems providing early detection of tool breakage, cracking and chipping, the first generation of electronic units introduced in the 1980's and early 1990's are becoming obsolete. New ideas and technologies such as the IMPAX-SK 4 system are now available to further the efficiencies gained from process monitoring.

Return on Investment

To determine the return on investment (Payback Schedule) for a new process monitoring system, several benefits should be considered: reductions in setup and adjustment time, machine damage costs, overruns, scrap, sorting and contamination costs, customer charge-backs, premium freight charges and customer returns. Others include improved man-to-machine ratio, the ability to run machines through break times and after shifts and reduced legal liability and FQA penalties for producing bad parts.

Payback Schedules will differ for each application, but even the most expensive 4-channel IMPAX-SK 4 system has been proven to bay back its cost in less than 115 working days. Other real-world cost justifications have shown IMPAX-SK systems to pay for themselves in less than 50 working days. Process Technologies Group, Inc. (PTG) has documentation analyzing actual Cost Savings Payback Schedules for a variety of applications.

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