While EDMs offer the benefits of holding tight tolerances, working on nearly any metal, and being well suited for delicate or fragile parts, knowledgeable operators for the machines are increasingly hard to find and robots can’t always fill the gap. Automated processes in the machines, newer designs and features of Industry 4.0 are helping to solve the problem.
Eric Ostini, product manager for GF Machining Solutions (Lincolnshire, IL), whose father and grandfather both worked with EDM, said: “After I graduated and thought I knew everything about EDM, my father told me that after a few years in the trade I would realize I didn’t know anything about EDM, because back in the day they would actually be able to listen to the generator and know what to adjust on the machine. Today, everything is automated. You don’t know what you had to do in the past to make these machines work. You’re just pushing a button and they work.”
Machine makers have made it unnecessary for operators to understand the “what” and “why” of what’s going on internally, thereby making up for their lack of knowledge and experience.
“We’re making things more automated not only because technology is going in that direction, but also because of the knowledge of the people who are using the equipment,” Ostini added. “It’s very hard to find good operators. If you can make the machine more automated, to where it can do a lot of things a good operator can do, then even a mediocre operator can shine.”
At Belmont Equipment and Technologies (Madison Heights, MI), a proprietary circuit developed in-house for multi-lead part sensing on a customer workpiece fixture verifies parts are loaded correctly by touching sensors, eliminating the mis-loading of a part and the time-consuming operator intervention in the setup process.
Also, the company has developed machining software to utilize on board technology with the ability to edit it to create custom settings for specific applications. “Depending on the operator’s abilities or knowledge, the machines are made to allow the novice to operate the machine with presets and the journeyman to customize settings for job-specific applications, which can then be run by anyone following,” said Tony Tyll, vice president of operations for Belmont.
Pallets for Parts and Electrodes
Like other types of machine tools, EDMs can use pallet changers to automate the production process, according to Greg Langenhorst, technical marketing manager for MC Machinery Systems Inc. (Elk Grove Village, IL), a full-line distributor of machine tools, including Mitsubishi EDMs. “When you’re using any kind of automated setups for wire or sinker EDMs, workpieces—both for sinker electrodes and parts—are typically set up on a tooling base with references. As an example, a sinker electrode could be set up on a tooling pallet. The graphite would go into the graphite mill for machining, then be automatically moved and set in a chuck for inspection by a CMM.”
For automated wire EDM production of smaller parts, Mitsubishi EDMs use a Mitsubishi six-axis robot to exchange workpieces in and out of the EDM. In this articulated system, the workpiece can be vertical or horizontal, right side up or upside down or at an angle because the robot can handle that type of articulation.
“For larger workpieces, we use System 3R or Erowa robots. Generally those units have a fixed plane gripper that grabs the workpiece out of the tooling rack and sets it on the machine table exactly in the same orientation. A robot would require a flip-type or rotary gripper to load the head and table on a sinker or invert hanging electrode blanks onto the table of a graphite mill,” said Langenhorst.
The Erowa Compact 80 is a relatively new robot that can exchange electrodes and workpieces on a sinker EDM in the Z axis. It handles pallets up to 11.8 × 11.8″ (300 × 300 mm) with parts up to 176 lb (80 kg). “It can be used to create a workcell when you put it between a graphite mill and a sinker,” said Langenhorst. “It can be loading graphite blanks into the mill and pulling finished electrodes out, and then loading the workpieces on the sinker and grabbing the electrodes fresh out of the mill and putting them to use right away.”
He noted that one of MC Machinery’s EDM customers is a mold shop that uses large, rectangular frame-type fixtures. “They can load one big part or multiple workpieces on that frame/table, just like you normally would on the EDM if you wanted to run it overnight or over a weekend. It will take one frame with four or five different finished pieces off and put a different loaded frame back in. The workpieces are preset off the machine on the frame/table so they are all square and true. Next, all the zero points can be located by CMM and sent to the machine to be loaded with the part program to save machine time, or measured once loaded on the machine with the wire before running the program.”
To improve the capabilities of even nonexperts, Makino Inc. (Auburn Hills, MI) recently released a suite of remote monitoring functions called HyperConnect, and has developed several features in its existing Hyper-i control system to improve operator capability, including the E-Tech Doctor function that captures the knowledge and experience of an advanced operator, and transforms them into an easily used function for operators of all skill levels.
“Elevating the intelligence and capability of our adaptive power technologies helps to reduce the operator skill level required to achieve high-performance results,” said Brian Pfluger, Makino EDM product manager. “The machine is capable of doing more on its own by having a more robust, self-adapting capability, and this frees up the operators to divert their time to other shop activities.”
If a manufacturer employs robots, some wire and sinker EDM machine series from Sodick Inc. (Schaumburg, IL) are equipped with segmented drop tank doors to make the inside of the machines accessible for robotic arms. “The more you can automate some of these processes, [operators] can work on more important things or work on more things at once,” said Evan Syverson, additive business development manager at Sodick.
To make its EDMs simpler and easier to operate, MC Machinery Systems has created a knowledge-based system. For example, a wire EDM uses different wire diameters and machines different workpiece material types and thicknesses. “For each type of job, we have what we call E-Packs, which are power settings, feed rate values and cutter offset values related to specific jobs. A data table in the machine control has all that information, so the operator needs only to answer questions on the machine control to choose the type of wire, the workpiece material and thickness, and the desired accuracy and surface finish. The machine figures it all out for them. If it’s going to take one pass or five passes, the machine does that all on its own.
“We also have a slide bar on the machine control that offers a choice between speed on the left side and accuracy on the right side,” Langenhorst continued. “As you push the slide to the right, it slows the machine down and makes the corners more accurate. If you don’t need as much accuracy and you want speed, you push it all the way to the left. If you want something in between, you can choose that.”
Making Controls for Robots
When GFMS’ Ostini said an operator equipped with a basic knowledge of EDMing need only to push a button to make the machine work, he meant that literally. Thanks to software changes, an operator can adjust the power setting by pushing one button, depending on what he wants to do.
If the operator wants to cut 10–15% faster than standard, he can push a button and software adjusts all the generator settings. Conversely, Ostini said, let’s say it’s Friday and time to go home. The operator can push a button and the machine will go into conservative or eco mode. In this instance, the wire slows down drastically.
In the past, that would create inaccuracies in the part, said Ostini. “But because we’ve developed the technology around this setting, we’ve adjusted the generator so that we still maintain the same accuracy but he’s saving 30–35% on his wire usage.” GFMS added similar, one-button automation on the diesinker side.
GFMS has also added measurement and validation functions to EDMs using scopes and Renishaw probes to make sure the operator has set up a job correctly. After the cutting, the probe and scope can be used again to validate the job before the workpiece is removed.
“For example, in our CUT 1000 machines we have a system called IVU [integrated vision unit], which measures what’s been cut and tells you before you remove the part from the machine whether the part was cut correctly,” Ostini said. “If not, you either fix it right there or scrap it.”
Belmont Equipment and Technologies offers different models designed around levels of automation the customer may want to do now or in the future. “This could entail solutions ranging from a complete robotic turnkey system, to a pre-wired design with mechanical changes that could allow for an easy add-on later,” said Tyll.
Industry 4.0 and Data Analysis
While qualified operators are hard to come by, some elements of Industry 4.0 are helping to make up the difference by creating efficiency in operations. Among the objectives of Industry 4.0 is creating the ability to collect machine data that can be analyzed to identify problems.
“Many customers are looking for the data feedback that will give them the knowledge of the process to analyze how to operate their machines in the most efficient manner,” said Tyll. “Along with this, it allows them to identify problems before they start. With several offline software packages out there that handle the analytical side, we work with our customers to establish the connections needed for the feedback.”
Troubleshooting is a key part of Industry 4.0, agreed Ostini. “Once you see something, then you want to know why,” he said. “And that’s where the analytics need to be more intuitive.” He offered an example of a shop owner looking at how long a machine has been cutting vs. not cutting. He notices in the data that at 4 pm it seems to be more off than on, and wonders why that is.
“That’s when you need to be able to look at other data,” Ostini said. “It could be maintenance, or down due to alarm, or down because the operator is setting up a part.” A company in Indiana did that and noticed a consistent hiccup during the week. So, they looked at the data, and noted it was at change of shift. There was a dip in production because the operator going off had a job in the machine and the operator coming on didn’t know what it was, so he had to figure it out. As a result, the company added 15 minutes to each shift to create an overlap so the two operators could do a handoff. The company cost-estimated the change after one year and realized they saved $100,000, even accounting for the extra operator pay.
Float Sensors Prevent Spills
Sodick has made its EDMs accessible for robots, and made access for humans more convenient with its drop tank doors. The feature is on its ALN series of wire EDMs and AG series of sinker machines.
“It’s particularly useful automation-wise because rather than having someone physically open the door, the door is low enough that a robot can come in and change out your tool or change out your workpiece,” said Syverson.
Due to the door’s multi-segmented walls that lower into each other, a tank can be opened partway. This allows operators to access the workpiece without fully draining the tank and opening the door all the way. Also, the door has a float sensor, Syverson said. “So that tank fills up with dielectric during machining, and you obviously don’t want to lower the door with a tank full of fluid. If the water level is too high, it’ll actually stop at the water level rather than continuing to go down, preventing an accidental spill.”
The AG sinker series features cooled linear motors and a C-axis option that can rotate at speeds up to 2000 rpm.
At Makino, newer machines are capable of doing more on their own. Options can include automated toolchangers for sinker EDMs, and an automatic wire threading system for wire EDMs, both of which extend the untended operation of the machine. Higher-level automation typically includes the use of robotics to exchange the workpiece to improve machine utilization, and can include the servicing of multiple machines by one robot.
The new HyperConnect provides four functions to improve remote access and networked communication when the machines are connected to an internal network. With EDM Mail, the machine has the ability to send e-mail updates on machine status, including machine stoppage, an effort to minimize machine downtime and lost production. With EDM Viewer, the operator can monitor and access the machine control remotely on a PC or smart device. This allows an operator to “see” exactly where and what the machine is doing during untended operation. With Machine-to-Machine Viewing, the operator can view any other networked Hyper-i control directly from the machine control without having to leave his work area. And with PC Viewer, the operator can access and display any program and data from a networked PC on the machine’s 24″ (610-mm) display. This function allows the operator to perform every task needed to operate the machine from the Hyper-i control, including other specialized software such as Microsoft Office or specialized CAD/CAM software.
In addition to E-Tech Doctor mentioned previously, Makino has developed several other Hyper-i control system features, including multiple canned pick-up cycles (including leveling of a workpiece without the need for internal probes), measurement verification, and machine utilization tracking and reporting.
“The idea of the utilization tracking feature is to provide a shop with the necessary tools to monitor the effectiveness and efficiency of their current processes, which is a common area of deficiency for most shops,” said Pfluger. “This new tracking tool provides the means to measure machine utilization 24/7 and identify areas for improvement.”