There was a time when EDM machine maker Chmer (Taichung City, Taiwan) might have expected high speed milling to take the place of a significant amount of die sinker EDM work. The company developed a line of high speed milling machines to complement its sinker, wire and holemaking EDM machines in anticipation of this change. But things didn’t work out that way—illustrating, among other things, how difficult it is to predict technology adoption. On a recent trip to Taiwan, I had a chance to speak about this with Chmer Marketing Director Brad Wang.
While the ability to take fast, accurate cuts at high feed rates potentially makes milling a contender for certain complex die/mold forms that sinker EDM is used to produce, EDM is still more efficient for features such as deep cavities, fins and many thin walls. These features occur just often enough that high speed milling has not been able to unseat the established technology to any considerable extent. However, high speed milling has proven popular among Chmer’s customers nevertheless, not as a replacement for EDM but as a complement. The fast, accurate cutting is efficient for roughing complex mold forms before the sinker EDM is used to complete those features that EDM is still the best at finishing.
The technology needs and preferences of customers reveal themselves over time, Mr. Wang says. His hope is for Chmer to continue to adapt. Here are the EDM features and capabilities right now that he sees as becoming increasingly important:
1. Linear Motors. Among each of the company’s EDM types (and its milling machines) are models equipped with linear motors for axis motion. Linear motor machines cost more than machines driven by ballscrews, Mr. Wang says, but these motors save cost through reduced maintenance while improving the accuracy of the machine. Compared to conventional drives, a wire EDM machine with linear motors can generate sharper corners on precise components such as die punches. More, linear motors maintain their accuracy over time. This is not the case with ballscrews, which wear and become less precise over time due to the ongoing surface-to-surface contact.
2. Machine Monitoring. Applications of EDM often involve rows of machines all running largely unattended because the cycles are so long. The unattended nature of the process makes the machines ideal for monitoring systems permitting remote viewing of the current status of the machine as well its performance history over time. Chmer’s in-house control has enabled the company to develop its own remote monitoring system, among other special features. (Read on.)
3. Ease of Use. The in-house control has also enabled Chmer to develop a programming system enabling inexperienced users to employ EDM effectively. An operator can enter the workpiece material and diameter of the wire along with the desired roughness of the machined surface to let the control automatically set the cutting conditions and parameters required.
4. Hole Making. Among the three EDM types, holemaking looks to offer the most potential for future growth, says Mr. Wang, thanks to the long-term likely demand for cooling hole machining in turbine components by the aerospace sector. Key capabilities here include precise CNC interpolation to give small holes with a diffuser (open funnel) form at the mouth, as well as integration with B-axis indexing for the array of angles characteristic of the set of holes in a typical blade.
Chmer’s AD4L is a linear-motor equipped holemaking EDM.
For this demonstration, the robot performed both workpiece pallet changeout and simulated polishing operations of machined parts.
I’ve been aware of the Run MyRobot capability available with Siemens Sinumerik controls for a little while, but I believe the cell below that was in Handtmann’s EMO Milan booth represents the first time I’ve seen a demonstration of the concept using an actual machine tool.
The idea is to provide intuitive robot programming capability at a machine’s CNC via the Sinumerik Operate GUI. In the case of this cell, the execution of the movements of the six-axis Kuka KR 600 Fortec robot (with 600-kg load capacity), provision of robot safety functions and other robot-specific functions are performed by the Kuka KR C4 robot control. However, that control is connected to the Handtmann five-axis HBZ Trunnion 80 machine’s Sinumerik 840D sl CNC. Therefore, the machine tool operations and robot program can be tracked and controlled on one screen via parallel channels.
The machine tool operations and robot program can be tracked and controlled on one CNC screen via parallel channels (the robot channel is shown here).
For this demonstration, the robot performed both workpiece pallet changeout (using Schunk clamping systems) and simulated polishing operations of machined parts. Of course, the robot can be used to perform a range of secondary operations, including drilling, brushing and deburring, depending on a manufacturer’s needs.
Check out this video that shows the cell at the show.
Amanda Raney joined Whelen Engineering after working in administration at a local hospital. Less than a year later she is already in charge of managing the company’s tool crib, which is a sophisticated and critical operation. Workers with backgrounds outside of manufacturing can provide fresh and interesting perspectives.
If you take a look at the resumes of those hired by Whelen Engineering—based in Chester, Connecticut, with an additional facility in Charlestown, New Hampshire—you’ll find they come from a wide variety of backgrounds. Some were teachers, while others worked in retail or stocking shelves at supermarkets. This can be seen in a number of ways. One is that manufacturing is an attractive alternative to many types of employment, paying good wages with benefits including health care and retirement plans and allowing workers to learn valuable skills. Another is in line with the philosophy of John Olson, former president of Whelen Engineering, who says “it’s not easy to find good employees, you have to grow them.” This is evident in the training provided to all of the company’s employees, which is conducted on-site by an instructor from a local community tech center. Topics include controls, programming, writing G code and metrology. At the same time, the company believes it’s best to provide hands-on learning activities from the very beginning.
“If someone was hired to become a machine operator and has no experience with CNC machining, we’ll start them off doing basic operations as simple as loading the machine, hitting the green button, and then unloading it at the end of the cycle,” says Jeff Kochis, production machine shop manager. “We believe that it’s important for them to be comfortable with the machine and not afraid of it. That way they’ll be eager to learn more.”
Whelen is also thinking strategically, offering an “Intro to Manufacturing” course to area middle-school students to give them a taste of everything from design manufacturing and machining to working with sheet metal and injection molding. By planting this seed of an idea early, the company hopes students will consider manufacturing as a career once they’ve graduated high school. “One of the reasons we keep the shop floor so clean is that we never know when there will be a tour coming through,” Mr. Kochis says with a laugh.
The new VL600Q offers more than just longer travels.
If you’re using EDM technology, chances are your competitors are, too.
That's one reason behind demand for larger machines like Sodick's new VL600Q wire machine, formally introduced in North America at the company's recent "Smart Technology" open house event. So says Alan Losch, applications engineer, who explained that the technology is more accessible than ever, and the days when simply having an EDM could differentiate a shop are long gone. Instead, many try to set themselves apart with larger standard models like the VL600Q, which offers longer travels in all three linear axes than the comparable VZ300L and VZ500L machines (the latter offers travels of 500 x 350 x 250 mm, compared to the VL600Q's 600 x 400 x 270).
Yet, the machine offers advantages beyond longer travels, and many extend throughout the company's entire line. Every machine on the floor at the October 21-22 event—both mills and EDMs alike—was driven by linear motors. According to the company, developing and manufacturing its own motors and accompanying motion control systems is one reason why they can achieve repeatable accuracy within 1 micron. "You can't do that with a ballscrew," Mr. Losch notes, adding that 2016 will be the 10th anniversary of the company's commitment to fully guarantee motion system accuracy for a decade after machine installation. Another feature common to all Sodick machines is a base construction incorporating a custom ceramic material that offers abrasion resistance and a low thermal expansion coefficient (less than one-third that of cast iron).
Displays certainly weren't limited to EDM. This demonstration involved machining highly contoured, gear-like geometry on a linear-motor-driven HS650 VMC.
The VL600Q also serves as a platform for technological advances that are far more recent than the company's longstanding use of linear motors and custom ceramics. For instance, the entire VL line features an updated version of the company’s SuperJet automatic wire threader (AWT). One new capability is the Pop-Up Search function. Previously available only on FixedJet AWTs, this feature uses a stream of air to push the guide—and the wire along with it—upward and away from the hole when threading fails. The process can then be repeated until the wire successfully threads the gap. According to the company, the feature is particularly useful for threading on curved or inclined surfaces and through multiple, in-line holes on stepped/hollow workpieces.
The SuperJet also employs a longer annealing cycle than previous versions, as well as an extra wire contact, to ensure straightness. For the user, this translates to less time spent spent returning to a zero/reference point to rethread, then working the wire back through the cut to pick up where it left off.
This demo of an older version of the wire-threader showcased automatically guiding 0.01-inch wire through holes measuring 0.06 inch in diameter. With an additional wire contact and longer annealing cycle, the new SuperJet is even more capable.
The new wire machine certainly wasn't the only highlight of the "Smart Technology" event, which also featured plenty of sinker and milling displays and presentations from participating partners, including Erowa and OSG USA. Nonetheless, as the company's latest model, it provides an informative look at the technology that's long characterized Sodick machines as well as newer developments.
A plastic part like this could be milled or 3D printed. How do you decide between processes? Image courtesy of Proto Labs.
Additive manufacturing is a good choice for functional prototypes. It’s often faster and cheaper than molding or machining the part, and flexible enough to quickly produce design iterations. But is it always the best choice?
Not necessarily. Depending on the material, geometry, tolerances and other requirements of a given prototype, machining is sometimes the better option. See how they match up and learn how to decide between 3D printing and machining in this short article based on information from Proto Labs.