Mark of distinction: Inspection Efficiency

Advancements in marking technology can lead to lower integration costs and more benefits for the end user.

The marking process has its origins in the least complex of methods, such as simple inspection stamps applied with a steel die and hammer. Today, advances in marking and traceability technology enable sophisticated product identification and tracking solutions. However, these advances have also produced added costs.

The demand for more traceability, in particular, has led to higher integration costs when considering what marking equipment must be used. Simple, single-character approval stamps or symbols have given way to marking production date and time, serial number, part number and bar code all on a single part. The demand for this capability has posed a significant challenge to the marking industry: How to provide a marking and traceability solution at a price end users can justify.

Courtesy of All images: Columbia Marking Tools

Operating in a 600° F environment, a Square-Dot scribe system from Columbia Marking Tools marks an engine block at a foundry.

Many marking equipment manufacturers have answered the call from both a controls and hardware standpoint. They are taking advantage of the latest in motion-control technology by providing controls that allow them to drive not only stepper motors but also servos, which provide faster printing (marking) speeds and thus shorter cycle times. Hardware has become more robust and versatile, allowing users to apply the equipment in parts of the manufacturing process previously unusable for traceability. For example, marking systems are now integrated into robot-assisted machining cells, welding stations and at foundries.

Integration Issues

By far the largest obstacle to overcome is integration into a variety of control platforms. This is especially challenging when new marking technology must be integrated into older manufacturing lines and controls. With users and their customers demanding vital statistics about how, when and where parts were produced, process engineers are tasked with trying to mate new marking technology with old production equipment, and do so with minimal difficulty and cost. Marking technology suppliers have responded with systems that are versatile enough to integrate with most any programmable logic controller.

Systems now provide options for users to send marking data to the controller via serial port, Ethernet/IP, Profibus DP, Modbus TCP or other communication protocols. Of course, for less complex applications users can program a date stamp with serial number and the marking controller will do the rest.

When integrating into newer manufacturing lines, users can interface with the controller on various levels. Integration can be via 24v DC digital I/O, or, to save time and the added cost of wiring, the marking system can communicate with the production system via Ethernet, Modbus or Profibus.

Because marking companies recognize the need for value-added features on their equipment, many offer features that allow users to save money elsewhere. For example, some marking controllers have the ability to control ancillary devices such as shuttles, clamps or Z-axis positioning devices. This helps users save money by eliminating I/O in their PLC that would normally be dedicated to these devices. In some instances, the marking control can completely take the place of a PLC if one does not already exist.

A marking controller (left) can be programmed via LAN or Ethernet, enabling multiple marking systems (top) on the shop floor to be programmed simultaneously.

Many marking systems are being integrated side by side with vision systems. Thus, the need arises to communicate with the camera system and verify the marking data is correct and usable. With advances in communication to marking controls, some systems can communicate seamlessly with vision systems to simplify the entire process. In some cases, the marking system can even provide real-time camera data within its software interface.

Control Options

While PC-based controls for marking equipment allow programming for a variable mark, the PC interface has limitations in an automated environment. The most important is use of a keyboard entry for a cycle-start command. Also, the ability of operators to inadvertently or intentionally change the marking program may hinder efficient automation. Finally, users must consider the added expense of having a dedicated PC in the application.

On the plus side, marking systems requiring a PC can work well in low-volume applications where a graphical representation of the marking layout makes changes easy and straightforward.