Data Collection Goes Wireless
Data Collection Goes Wireless
About 25 years ago, the concept of data collection for process control took a major leap forward. This was about the time that a combination of electronic technology and economics allowed gauging to become digital. With a digital signal available, it became possible to transfer information via cable directly from a gauge or digital indicator to the data collector. This made it much more practical to make process control decisions based on statistical analysis.
Electronic data collection also occasioned a major improvement in data quality. Prior to this leap, data is either hand written on a sheet of paper and then logged into a computer directly at the point of gauging. You can easily understand how an operator, sitting at a bench measuring hundreds of parts, could transpose numbers, skip digits or just enter wrong numbers. These problems are virtually all eliminated as data went directly into the data analysis software and electronic data collection strategies where first implemented. It was normal to see collection efficiencies and errors in manual collection methods reduce by 10-fold.
These days, checking parts at a gauging station with a hand-tool or a dedicated fixture gauge connected to a computer via a cable for data collection is the norm. Today’s hand-tools and digital indicators have data output built-in and collecting data is easy and cost effective. It is fast, reliable, inexpensive and provides a great solution for many process or quality control applications.
Nonetheless, when the part cannot reach to the bench. What happens? Maybe it is still in the machine or it is simply just too large to bring to the gauging station. Running a long cable from the gauge to the computer can be a hazard especially if with different gauges multiple dimensions are checked. A collection of long cables can quickly become a snarled mess.
Technology is ready to take another leap. Just as mobile phones and wireless computer peripherals have become common, wireless technology is moving out onto the shop floor. Small transmitters are now available for most hand-tools, digital indicators and gauges, which allow them to transmit data hundreds of feet to the gauging computer. Each transmitter uses a slightly different signal coding that allows many gauging stations to communicate to a single computer simultaneously. Of course, these transmitters are more expensive than data cable, typically, five to ten times as much but the cost is more than justified when cabling will not get the job done.
Therefore, now with these transmitters, very large parts are measurable where they sit or in the machine tool, without having cables caught in the tooling. In addition, many transmitters provide feedback by generating a signal to the operator than the computer receives and acknowledges the transmission. This is virtually instantaneous so as not to slow the operator down and most transmitters configure to provide a go or no-go signal to the user depending if the part is within tolerance.
Eliminating cables is great but probably the best application for this technology is right at the machine tool. By transmitting wirelessly into the machine tool’s controller. The data is uses as part of the calculation for offsetting. Thus, as the operator measures the parts, the data is uses to assign the proper offsets, greatly improving the quality and throughput of the machine tool. Out-of-spec parts get virtually eliminate and it improves the machines ability to make parts to the desired dimension.
At the same time, the data can be stored for long-term archiving, it records when the part is measured and by whom. Additionally, it is uses for tracking and improving operator throughput.
Today the triangle is becoming complete, with a combination of digital gauging for accurate shop floor measurement, unrestricted wireless transmission of reliable data, and statistics for process control. These three tools allow for truly effective use of measurement data.
By transmitting wirelessly into the machine tool’s controller, data is use as part of the calculation for offsetting. Thus, as the operator measures a part, the data is use to assign the proper offsets, greatly improving the quality and throughput of the machine tool.
George Schuetz, Mahr Federal Inc.