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Closing the Gap on Data Transmission in Workholding

Jim Lorincz
By Jim Lorincz Contributing Editor, SME Media

The use of electronics, sensors and other advanced technologies in workholding is providing manufacturers with a whole range of options for data transfer via sensor-based clamping and measurement systems, custom software and innovative non-contact technologies, including direct-to-machine controller transmission of data.

Following are some of the ways workholding manufacturers are integrating these technologies in their products to maximize data collection, create real-time histories of processes, manage machining performance on the fly and establish a history-based platform for predictive maintenance.

ESA 120/70 UNILOCK chucks have a built-in air chuck circuit mechanically linked to the clamping mechanism. When air pressure is applied to unclamp the receiver, the air circuit is completed internally. (Provided by BIG Daishowa)

Future Is Now for Contactless Data Transmission

SMW-Autoblok’s new division, SMW-Electronics, is developing non-contact inductive transmission of energy and data; smart sensor and measuring systems; mechatronic clamping systems; and software based on inductive coupler technology. The SMW-Electronics systems can transmit energy and data, contact-free, between stationary and moving components via an air gap, according to Larry Robbins, president, commercial division, SMW-Autoblok North America, Wheeling, Ill.

“Contactless inductive transmission technology replaces traditional methods using cables or connectors and is completely wear and maintenance free,” he explained. “These wireless technologies are designed to optimize all aspects of manufacturing and supply chain operations that are revolutionizing the way we engineer and manufacture in smart factories according to Industry 4.0 principles.”

SMW-Electronics’ products feature non-contact inductive coupler systems that transfer energy and data (up to 1,500 W) via an air gap with a maximum of 20 mm. The new F180 Ethernet remote axial coupler provides wireless transmission between moving and stationary components with a high-speed power transmission of up to 400 W, and 20-mm transfer distance. A line of intelligent sensor systems, including the LPS 4.0 position sensor, identifies the exact position of a sensor element wirelessly with maximum repeatability. The LPS 4.0 is also protected to IP67 and offers outstanding EMC properties, according to the company.

SMW-Electronics’ contact-free digital clamping line, like this MM e-motion power chuck, offers a complete range of couplers and software to work with a wide range of downline systems to handle part holding, workholding actuation, systems controls, actuators and robotics. (Provided by SMW-Autoblok)

“Mechatronic and mechanical clamping systems for workpiece clamping include the e-motion product line that offers a complete range of couplers and software to work with a wide range of downline systems to handle part holding, workholding actuation, systems controls, actuators, and robotics. All e-motion products are based on the same concept of a contact-free inductive coupler system for signal and power transmission,” said Robbins.

He believes that the first industries to widely adopt this technology will be aerospace, automotive and defense, followed by general engineering and other sectors once the capabilities of the technology are fully understood. For example, the technology will monitor manufacture of critical defense components where workpieces can have hundreds of hours of machining time invested in them.

In addition, he believes that the technology will virtually do away with rework because you’ll be able to monitor for out-of-spec conditions during operations. Manufacturers will be able to make changes without having to take the part out of the chuck or whatever workholding devices are being used. Data generation is a powerful feature of the systems.

“With current technology, we can print out a report after every shift of the number of parts made over what time period and the clamping forces that were encountered. This information will also allow setting a baseline for process improvement by maximizing performance by operating within the mechanical limitations of the chuck,” Robbins said.

Sensors Reveal Hidden Machining Data

According to Allan Dopf, national sales manager, Hainbuch America Corp., Germantown, Wis., the company’s advanced IQ System can measure everything related to workholding.

“Our clamping devices, the IQ Chuck and IQ Mandrel with embedded sensor technology, enable monitoring on the fly for contactless transmission of data directly to the machine controller for analysis and correction if needed.” With the Hainbuch IQ system, the basic clamping device remains mounted on the machine and simultaneously relays information to the machine controller.

According to Dopf, the IQ system is recommended especially where non-productive time can be minimized through continuous, permanent monitoring and measuring right from the chuck in real-time rather than from outside of the machine.

“For example, complex and fragile measuring stations can be replaced by IQ clamping for applications where a very thin wall part requires that the clamping pressure be monitored on the fly to keep the part from deforming,” he said. “Sensors enable using robots and allow verifying that tight tolerances are held. Measurements go right to the controller, confirming the chuck is right and we don’t have to indicate it. We can also put sensors into our end stops for electronic part confirmation rather than air part confirmation.”

Hainbuch IQ chucks measure workpiece diameter, temperature, rpm and clamping force on machine. Data are processed in the controller or in the master computer and displayed on the machine panel. (Provided by Hainbuch America)

Hainbuch’s new IQ Intelligent System features embedded electronic sensors to measure temperature, clamping pressure and part diameter as clamped, among other parameters. “We’ve always had mechanical repeatability, but now we have a way of getting a history by measuring the rpms at the spindle, the clamping force, workpiece confirmation and thickness of the workpiece in case some foreign objects get in there,” said Dopf.

“With sensors embedded right in the chucks and end stops, we can measure and monitor in real time,” he continued. “Information can be saved for monitoring maintenance of the chuck and comparing actual values with target values. Changes can be made if actual values are heading in the wrong direction. In machining, because the workholding and the cutting tool are the only tools that actually touch the workpiece, sensors can help you see situations that can be complex and hidden. Data becomes accessible because it can be measured during the machining process, whereas you couldn’t see it in the past during the machining process.”

Part-Positioning Information After Loading

Carr Lane Manufacturing Co., St. Louis, has added a compact version of its line of Pivoting Edge Clamps for robust edge clamping. The new compact version allows more access to the workpiece than is currently available, according to COO Colin Frost. “In addition, while it is a manual clamp, a customer, after validating a design or determining that they would like to automate the tool, can replace the manual Ball-Ended Thrust Screw with a Roemheld Hydraulic Cylinder that can then be integrated into an automated load/unload system,” Frost said.

Carr Lane has also been extending its line of position sensors. “We have two versions, the non-contact Through-Hole Rest Button and the modular Air Rest Button,” said Frost. “Both are designed to provide part positioning information after loading but prior to clamping. Non-contact sensors have been available for some time, but many applications may require a contact sensor. Our contact sensor is designed to also function as a rest button [critical locating surface] rather than a secondary sensor point. Lastly, the Air Rest Button is modular so customers can choose from a variety of standard Rest Buttons or design a special rest button for the tool while using the same sensor.

Using non-contact position sensors and Air Gap Measurement tools from companies like Festo, it is possible to provide workpiece inspection within the tool, according to Frost. “Our partner, Roemheld, has just begun providing solutions like this in Europe,” he said. “Performing the inspection in the tool not only reduces costs and tools, but it also reduces scrap as the part can be inspected prior to and after machining.”

Frost explained that the Air Rest Button has a modular design in which any of its standard rest buttons can be installed. This eliminates the need to have a custom rest pad manufactured, potentially saving money. The Air Rest Buttons also allow the installation of a swivel pad, allowing more flexibility.

Upgrading to Automation

In addition to the traditional workholding challenges of making the workpiece as securely as possible and changing it faster, the newest challenge is upgrading for automation, according to John Zaya, product manager, BIG Daishowa Inc. (formerly BIG Kaiser Precision Tooling Inc.), Hoffman Estates, Ill. Specifically, there are a lot of options for what happens when an upgrade is desired from a traditional system to an automated application—whether changing actual parts in and out of the vise or workholding or changing the entire system.

For micromachining operations, especially those used by the microelectronics industry, System 3R has introduced the Nano Chuck for submicron accuracy machining. (Provided by System 3R)

“Proximity sensors or switches have been used for a long time to confirm that an item is physically where it should be before and after clamping,” said Zaya. “New software and controller capabilities are available to track data within the controller. For example, what is the repeatability? How well are the systems calibrated? And, how is the process performing? Performance data on part wear, for example, can influence a decision about changing from soft jaws to steel jaws to maintain system accuracy over a longer period of time and over more workpieces, justifying the cost of the change.

“With zero-point clamping systems, the workpiece and the fixtured part are typically going to be loaded and unloaded by a person,” he continued. “Adding a layer of control or safety controlled by the machine means that the machine can determine whether the fixture is loaded correctly and in the right position. You can track how many cycles the fixture comes in and out for, and see if at any point the fixture is not seated correctly or completely. You can build in a safety warning that indicates that the fixture is not loaded correctly.”

Sensors can do this by monitoring the proximity of things, but there are different ways to approach this if you want to build in fail-safe confirmation of clamping and unclamping of the mechanism, according to Zaya. “One way is by employing a secondary air circuit. ESA 120/70 UNILOCK chucks have a built-in air chuck circuit that is mechanically linked to the clamping mechanism so that when air pressure is applied to unclamp the receiver, the air circuit is then completed internally. It is a separate air circuit from the chuck’s clamping and unclamping. By monitoring that secondary circuit, you receive an actual confirmation that the chuck has opened all the way and it is safe to load or unload a fixture, which typically is going to be done by a robot.”

Palletized 3D Printing Platform

System 3R, Lincolnshire, Ill., a GF Machining Solutions company, has recently developed a tooling platform for the 3D metal printing industry. It is designed to keep track of the printed parts’ location when transferring them to other machines for secondary operations if required. System 3R is known for its tooling, palletization and automation products.

“Our automation products can interface with the majority of the CNC controls that are currently on the market,” said John Roskos, regional sales manager for System 3R. “The tooling platforms are capable of two-micron repeatability and provide feedback that the chucks are engaged and pallets are locked in place before any machining takes place. We have parts-sensing built into our chucks to give us feedback once the pallet is secured and clamped. We get feedback through the air supply that is used to clean the chucks. When the pallet is secured, it locks in and immediately raises the air pressure in the pneumatic cleaning line, which trips the sensor on the line, sending a 24-V signal to the CNC control or to the cell manager.”

System 3R recently introduced chucks that can operate in high-heat environments such as 446°F (230°C), which is typical for 3D printing, and 1,473°F (800°C) Inconel pallets for operating in aerospace manufacturing environments. “Currently, additive manufacturing applications are mostly loaded manually with long cycle times. We supply the palletization necessary to transfer parts for operations like milling, grinding and wire EDMing for higher accuracy workpieces.”

Other recent chuck developments from System 3R include a vibration-dampening system said to significantly reduce vibration in high-speed milling operations. “We have seen tool life skyrocket, reducing tool costs and improving surface finish and cutting time by 35 percent,” Roskos said. “The patented system uses a proprietary vibration-dampening material that is applied between the pallet and subplate. The chuck literally floats on the subplate.”

For micromachining, especially for the microelectronics industry, System 3R has introduced the Nano Chuck for submicron accuracy machining.

Work Support Solutions

There are a lot of challenges when it comes to fixture design, according to Braden Damman, applications engineer for Vektek, Emporia, Kan. “On the work support side, we’ve come up with a really small OD thread to minimize the size of our latest work support. It is able to account for part density and to add clamping elements on a fixture in a compact way.”

Vektek’s anti-rotational device for rotating unions keeps hydraulics securely attached to the fixture. (Provided by Vektek)

Vektek has developed several new products for CNC fixturing, including high-capacity work supports. “Our new high-capacity work supports are available with an air-sensing feature. This gives you the ability to plumb the hydraulic fixture and have an air circuit that can be used as feedback to indicate that the work support is clamped and has contacted the part, which is confirmed by the air pressure in that circuit,” he said.

Another new product release is Vektek’s screw-in, cartridge-mount single twin lever link clamps. When unclamped, they provide clearance for easy part loading when clamping through a part or more clearance for part loading between two parts. The swivel equalizing system applies equal clamping force through both levers on surfaces that are within 0.06" (1.524 mm).

“The cartridge mount allows you to thread into a cavity,” said Damman. “With our TuffLink 360 screw-in clamp, you can torque it into the cavity and position the levers where they need to be, lock the lug and you’re good to go.”

An automotive knuckle is an example of an application that would benefit from the cartridge-mount style twin lever. “The two levers come out and clamp on the casting surface,” Damman explained. “There’s a pivot mechanism that allows an offset between the two levers. Previous types of clamping mechanisms limit the size of the bore because of the required use of multiple clamping elements. We’ve combined that clamping need into just one device.”

Furthermore, Damman added, “we have come out with a rotary union arm design for twin-pallet horizontal machining centers where you have live overhead hydraulics going to the pallets. In the past, we’ve seen some arms that load a rotary union in a way that causes premature failure, so we came up with a solution that helps minimize the load on the rotary unions.

“The nice thing about our four-link system is that it allows the pallet to easily move where it needs to be, up and down during pallet changes,” he continued. “The arm doesn’t permit any side load on the rotary unions. There are roller taper bearings that produce a robust design that can handle the weight of several hydraulic lines loading the arm. The arm is customizable for different machine lengths and travels. It uses telescoping tubing, so when you need to retrofit a 400-mm pallet or a 630-mm one, you can subtract, extend it or add additional tubing lengths for extended reach machines.”

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