When you evaluate essential team members in mechatronics applications for the automation field, don’t overlook sensor specialists.
That’s the word from TURCK, a Minnesota-based sensor company that works with engineering teams in some of the industrial world’s most demanding applications.
Stamping presses are a very good example, notes Brian Tarbox, a TURCK business development manager. Progressive stamping presses typically operate at speeds of 30 to 400 strokes a minute, he points out, and some can reach up 1600 strokes in the manufacture of tiny electronics parts. In this environment, it is extremely important to protect the die and press from damage due to a host of problems that can crop up as the metal blank moves down the line for processing.
“Because dies are so expensive and eliminating down time is critical to production and quality, many stamping companies employ a sensor specialist,” says Tarbox. “A sensor specialist’s role is to help the toolmakers integrate sensors onto the die to protect it from pulled slugs, jammed material strip and broken punches, and to detect material that has not fed properly and did not eject out of the die.”
Among other concerns, die sizes in many applications are shrinking and require smaller sensor packages that are still durable enough to withstand the shock, vibration, oils and cutting fluids found these applications. However, mounting sensors in small dies can be challenging, since there is limited space for troughs to run sensor cables back to the controls or junction box. This is especially true when more than one sensor is needed in a smaller die, and bundled cables may be too large for the cable troughs that are machined into the die.
In one recent example, the sensor specialist experienced this space problem first-hand when he tried to install a machined cap over a sensor and its 5.2 mm diameter cable to protect the assembly against damage during operation. However, the bend radius of the cable was very tight, making it difficult to fasten the cap on the sensor/cable assembly.
When approached with this problem, TURCK modified the barrel sensor with a smaller diameter cable. The result: an 8 mm sensor with a 3 mm diameter cable. “The smaller cable can withstand tighter bends without strain, and is much more suitable for the smaller dies,” says Tarbox.
For added protection in this application, where the assembly needed to stand up to oil and coolant exposure, TURCK chose a polyurethane jacket for the cable.
“The stamping market requires much more precise sensing than most of the other markets TURCK serves,” says Tarbox, “so we have helped engineers in this field by giving them charts and graphs that define the characteristics on our sensors. It is vital for the sensor specialist to select the proper sensor to be used in the dies to accurately sense parts at the correct position every time.”
In looking at the contributions that sensor experts make to a mechatronics design team, Tarbox notes that these specialists must interface as early as possible with the engineers who design the dies and presses to determine how many sensors are needed and where they should be placed on the die. That decision is often made with input from manufacturing engineers who must program and maintain the stamping machines.
Finally, says Tarbox, the sensor specialist needs to have a thorough knowledge of the control system used in the application, whether it is a PLC, industrial computer or other solution.
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