metalworking – AUTOMATION INSIGHTS

The Evolution of RFID in Metalworking

RFID – A key technology in modern production

It’s not just IIoT that has focused attention on RFID as a central component of automation. As a key technology, radio frequency identification has been long established in production. The inductive operating principle guarantees ruggedness and resistance to environmental stress factors. This makes the system highly reliable in function and operation. With unlimited read/write cycles and real-time communication, RFID has become indispensable. The beginnings for the industrial use of RFID go far back. RFID was first successfully used on machine tools in the mid-1980’s. Since the usage of RFID tags on cutting tool holders has been internationally standardized (ISO 7388 for SK shanks, ISO12164 for HSK shanks), there has been strong growth of RFID usage in cutting tool management.

Cutting tool in tool taper with RFID chip

Track-and-trace of workpieces

Modern manufacturing with a wide bandwidth of batch sizes and ever compressed production times demands maximum transparency. This is the only way to meet the high requirements for flexibility and quality, and to minimize costs. Not only do the tools need to be optimally managed, but also the finished parts and materials used must be unambiguously recognized and assigned.

Workpiece tracking with RFID on pallet system

RFID frequencies LF and HF – both RFID worlds come together

In terms of data transmission for cutting tool identification, established systems have settled on LF (Low Frequency), as this band has proven to be especially robust and reliable in metal surroundings. Data is read with LF at a frequency of 455 kHz and written at 70 kHz.

When it comes to intralogistics and tracking of workpieces, HF (High Frequency) has become the standard in recent years. This is because HF systems with a working frequency of 13.56 MHz offer greater traverse speeds and a more generous read/write distance.

As a result, RFID processor units have been introduced that offer frequency-independent application. By using two different read-/write heads (one for tool identification and one for track-and-trace of workpieces) that each interface to a single processor unit, the communication to the control system is achieved in an economical manner.

RFID processor for both tool identification and workpiece tracking

New Hybrid Read-Write Head

Industrial equipment is designed for a working life of 20 years or even more. Therefore, in production you often find machines which were designed in the last century next to new machines that were installed when the production capacity was enlarged. In such a brown field factory you have the coexistence of proven technology and modern innovative equipment. For the topic of industrial RFID, it means that both low frequency and high frequency RFID tags are used. To use both the existing infrastructure and to introduce modern and innovative equipment, RFID read/write heads have been recently developed with LF and HF technology in one housing. It does not matter whether a LF RFID tag or a HF RFID tag approaches the RFID head. The system will automatically detect whether the tag uses LF or HF technology and will start to communicate in the right frequency.

This hybrid read-write head adds flexibility to the machine tools and tool setters as you can use the entire inventory of your cutting tools and tool holders.

RFID Tool ID tag ready for the Cloud

The classical concept of data storage in Tool ID is a decentralized data storage, which means that all relevant data (tool dimensions, tool usage time, machining data, etc.) of a tool/tool holder is stored on the RFID tag which is mounted on the single tool holder. The reliability and availability of this concept data has been proven for more than 25 years now.

With the Internet of Things IIOT, the concept of cloud computing is trendy. All — tool setter, machine tool and tool stock systems — are connected to the cloud and exchange data. In this case only an identifier is needed to move and receive the data to and from the cloud. For this type of data management Tool ID tags with the standard (DIN 69873) size diameter 10 x 4,5 mm are available now in a cost effective version with a 32 Byte memory.

Evergreen – more modern than ever: RFID Tool ID in Metalworking

Learn more about the Evolution of RFID in Metalworking from true experts at www.balluff.com or at Balluff events worldwide

Magnetic Encoders in Metalworking

When thinking about position sensing in machine tool applications typically glass scale systems for the CNC axis control come to your mind. These sensor principles are the most used ones in modern machine tools and are applied to requirements with resolutions to even submicrometer resolutions. Yet there are many other applications in metalworking which do not need these high end but also high priced measuring systems.

Loading and Unloading of Workpieces

In highly automated processes of loading and unloading workpieces the required repeatability of the motion axis positions is in hundreds of millimeters. This is accurate enough to achieve a reliable and accurate handling of the workpieces. Here magnetic linear encoder systems provide an optimum performance-to-cost-ratio. With significantly lower price levels compared to glass scale systems and much easier installation the total cost of ownership is much better compared to glass scale systems. These magnetic linear encoder systems are offered with both incremental and absolute output signals. Signal types for incremental outputs are quadrature or sinusoidal. Absolute outputs e.g. are used with the industrially standardized SSI and BISS interfaces. Now more and more popularity the recently also industrially standardized serial IO-Link interface has gained.

The non contact, wear free system is designed for a long lifetime and allows tolerances in alignment to a certain extent, which is especially relevant in applications of axis lengths of several meters.

Position sensing at rotating applications

The usage of CNC controls started with typically 3 axis (X-, Y, Z-). In the last years more and more 5 axis solutions have entered the market as they offer more flexibility in manufacturing. Additionaly the efficiency of these machines is higher as in many cases workpieces may be produced without the need of manually changing their orientation in the machining process.

Modular systems like rotary tables and swivel tables significantly increase the performance of machine tools. The highly compact design of magnetic rotary encoder systems supports the design of these mechatronic modular Systems.

Another advantage of the magnetic rotary encoder principle is the generous leeway in the center of the axis which allows more room for media such as coolants as well as the power supply and signal lines.

Summary

Besides the usage of glass scale systems for the classical 3-axis control of CNC machines the automation of Metalworking processes in machine tools more and more uses magnetic encoder systems thanks to their features like compact design, cost efficiency and easy installation. Drivers for the design of new machine tool concepts will be efficiency and flexibility. Definitely magnetic encoders support these demands.

More information about magnetic encoders is available here.

Tool Identification in Metalworking

With the start of industry 3.0 (the computer based automation of production) the users of machine tools began to avoid routine work like manually entering tool data into the HMI. Computerized Numerical Controlled CNC machine tools gained more and more market share in metalworking applications. These machines are quite often equipped with automatic tool change systems. For a correct production the real tool dimensions need to be entered into the CNC to define the tool path.

Tool ID for Automatic and Reliable Data Handling

Rather than entering the real tool diameter and tool length manually into the CNC, this data may be measured by a tool pre-setter and then stored in the RFID tool chip via an integrated RFID read-/write system. Typically when the tool is entered in the tool magazine the tool data are read by another read-/ write system which is integrated in the machine tool.

Globally in most cases the RFID tool chips are mounted in the tool holder (radially mounted eg. in SK or HSK holders).

In some applications the RFID tool chips are mounted in the pull stud (which holds the tool in the tool holder). Especially in Japan this tag position is used.

Tool Data for Different Levels of the Automation Pyramid

The tool data like tool diameters and tool lengths are relevant for the control level to guarantee a precise production of the workpieces. Other data like planned and real tool usage times are relevant for industrial engineering and quality control to e.g. secure a defined surface finish of the workpieces. Industrial engineers perform milling and optimization tests (with different rotational spindle speeds and tool feed rates) in order to find the perfect tool usage time as a balance between efficiency and quality. These engineering activities typically are on the supervision level. The procurement of new tools (when the existing tools are worn out after e.g. 5 to 10 grinding cycles) is conducted via the ERP System as a part of the asset management.

Coming back to the beginning of the 3rd industrial revolution the concept of CIM (Computer Integrated Manufacturing) was created, driven by the integration of computers and information technology (IT).

With the 4th industrial revolution, Industry 4.0, the success story of the Internet now adds cyber physical systems to industrial production. Cloud systems support and speed up the communication between customers and suppliers. Tool Management covers two areas of the Automation pyramid.

Machine Control: From sensor / actuator level up to the control level (real time )
Asset Management: Up to enterprise level and beyond (even to the “Cloud”)

To learn more about Tool ID visit www.balluff.com