Toolholders that Grip, Lock and Raise the Bar
By Sarah A. Webster
Editor in Chief
At first blush, the goal in designing and building toolholders is simple: Design a device that can hold a tool with enough rigidity for its particular application and so that it can maintain accuracy in a wide variety of machining conditions.
Oh, and make it easy to use so change-outs are quick and accurate. And help it extend tool life and improve finish quality if you can.
Increasingly, the industry is meeting those challenges and solving other problems, too, with patented new systems for gripping, clamping and locking, as well as deadening vibrations.
Generally speaking, the industry is also expanding its toolholder lineup, going ever bigger for applications in the energy, machinery and heavy-duty transportation markets and ever smaller for medical and aerospace parts.
The End of the Weldon Holder Era?
Haimer-USA (Villa Park, IL), for example, is proposing a whole new approach that it believes can eliminate Weldon side locks. It stems from a challenge proposed to the company five years ago by Boeing and GKN. The companies were increasingly working with blocks of lightweight, high-strength, corrosion-resistant materials that are difficult to machine, such as titanium.
“They would be roughing the material and the cutting tool would pull out of the toolholder, even with milling chucks, press-fit systems, hydraulic chucks, precision collets, or shrink-fit holders,” said Brendt Holden, president, Haimer-USA. This led to unnecessary scrappage of materials and excessive tool wear and breakage, not to mention wasted time. “They wanted assurance from a system that wouldn’t allow the cutting tool to be pulled out,” Holden said.
At the time, the companies were forced to go back to a Weldon-type side lock system, which has its drawbacks, such as pushing the tool off center, requiring the materials to be machined at relatively low rpms and the generation of high torques that can cause the cutter to break.
By 2008, Haimer’s patented Safe-Lock system was ready for testing. Here’s how it works: spiral-shaped grooves are ground into the cutting tool shank. In combination with corresponding carbide drive pins in the toolholder (available in shrink-fit, collet or hydraulic chucks), the specially shaped grooves unite frictional clamping force and positive locking. That prevents the tool from twisting or even being pulled out of the chuck during extreme machining. The interplay of pullout protection and runout accuracy leads to low vibration, less tool wear and efficient machining at higher speeds. The system also allows for adjustable tool length. In testing and in the field, the Safe-Lock system “never had pullout, could go faster and improved metal removal rates,” Holden said.
Originally designed for aerospace and defense, Holden said Haimer now envisions setting a new holding standard, eventually eliminating side Weldon holders altogether. The company has an ambitious plan to roll out its holders and license toolmakers to grind Safe-Lock grooves into its tools. Haimer is unique as a toolholder maker in that it doesn’t also make cutting tools, so it has licensed the specifications on its spiral groove to an increasing number of cutting tool makers, such as Sandvik Coromant, Kennametal, Widia and Walter.
“We’re just at the beginning of getting people to realize they should throw away the side locks once and for all,” Holden said. “They are wasting money.”
Haimer is offering Safe-Lock holders in its Power Shrink, Power Collet, Heavy Duty Collet and Heavy Duty Shrink Fit Chucks. In general, Safe-Lock can be added from tool diameter ½ up to 2" (12.7–50.1 mm).
Toolholding Innovations at Iscar
As part of a post-recession marketing campaign, cutting tool maker Iscar (Arlington, TX) at IMTS unveiled the biggest new product onslaught in its 60-year history—a wide range of innovative and problem-solving products across its lineup.
A highlight of those introductions is the Dove IQ Turn heavy-duty clamping toolholder system, part of a line of new products dubbed “Dove IQ” because of what Iscar calls a high-tech dovetail gripping system.e Dove IQ Turn aims to solve several problems. One is to immobilize the cutting insert in the pocket, preventing it from lifting during high-stress turning. Also, the current method of using single-sided inserts and top-clamp holders has the disadvantage of a fewer number of cutting edges and interrupted chip flow due to the obstruction of the top clamp.
With Dove IQ Turn, Iscar has developed a dovetail pocket, which helps to prevent lifting, combined with a lever clamping system, which eliminates the need for a top clamp.
“It’s a totally new design for heavy turning,” said Randy Hudgins, national turning and threading product manager, Iscar. What’s more, he noted, it can also hold double-sided inserts: “So you can use four corners instead of two."
The Dove IQ Turn is expected to find its market in the growth of heavy-duty turning in the oil and mining sectors.
Deep, Vibration-Free Cutting
When tools get long, they tend to vibrate—especially as cutting speeds increase. The cutting force tries to bend the tool, causing a harmonic, self-exciting vibration and, eventually, accuracy robbing runout.
Introduced at IMTS in September, the Smart Damper from BIG Kaiser (Hoffman Estates, IL), a toolholder with an integrated damping system for deep-hole finish boring and extended reach milling, aims to solve these cascading problems.
The 16" (406-mm) Smart Damper, which has a 6:1 L/D ratio, eliminates the vibrations that force machinists to curtail speeds and output. The Smart Damper can handle cutting speeds up to 325 sfm (99.1 m/min).
By correcting the vibration, manufacturers can maintain high speeds, throughput and fine finishes.
Jack Burley, VP of sales and engineering, BIG Kaiser, said he cannot discuss the technology used to deaden vibrations in the Smart Damper, except to say that it does not use fluid as similar products do and it builds upon D-Vibe Bar technology.
“It’s unique,” Burley said. “Our product is developed by BIG Daishowa in Japan, and it was developed with finish boring in mind first.”
And although you can’t completely cheat physics, BIG Kaiser does offer a 4" (100-mm) extension on the Smart Damper.
Upgraded Collet Chuck
Meanwhile, Seco Tools (Troy, MI), in February will launch an upgraded collet chuck suitable for all kinds of machining operations, including high speed.
The high-precision EPB 5672, shown at IMTS in September, boasts a longer tool life, better surface finish due to a maximum runout of 3 microns at 3xD and higher transmittable torque and rigidity. Tool clamping force is nearly double that of existing collet chucks. What’s more, the 5672 collect chucks provide better gripping for smaller diameter tools as compared with shrink-fit holders that excel when cutter shank diameters are over 16-mm diameter.
The new collet chuck also has reliable axial and radial positioning of the tool with accurate repeatability.
Mike Smith, product manager, Tooling Systems, Seco, said that there are plans to come out with an even slimmer line in the second quarter of this year.
And while Smith said Seco “believes in shrink fit,” he said there are cost benefits with the EPB 5672. While the 5672 is about one-and-a-half times more expensive to buy than a shrink-fit toolholder, the collet chuck doesn’t require the initial capital investment of a shrink-fit machine. Although he acknowledged that the tool exchange time with shrink fit could be as fast as three seconds with the right machine, such as a Seco model, versus two minutes with the collet chuck, saving time that could ultimately pay for the machine.
The EPB 5672 was also designed with chrome coating to protect against oxidation, the highest grinding quality on the front of the taper and a stop screw with taper front with through coolant available as accessories.
Toolholding for Tapping
Still using a collet chuck to tap threads?
If so, you might be missing out on some important advances in tapping holders that don’t just improve the life of the tap but the quality of the threads, too.
“Most companies would tell you it’s accurate enough to hold the tap in a collet chuck in a machine that is brand new, but over time, the ballscrews get a little end play in them so there’s not as much accuracy,” BIG Kaiser’s Burley said.
In rigid tapping, one should feed the exact pitch per revolution of the tap. Going in isn’t so much the problem as reversing and getting the tap out of the hole exactly the way it went in. Complete synchronization is a must to get a clean thread and protect the integrity of the tap.
Axial mismatch between the feed of the machine and the feed of the tap can leave behind threads with burrs and wear the taps unnecessarily because of extra load on them.
A collet chuck is not designed to compensate for the misfeed the way a tapping holder is with built-in elastic components that compensate with tension and compression. “It’s an overlooked process improvement and most customers don’t know what they could be missing,” Burley said.
In fact, the tap holding area has been rife with competition in recent years, with a lot of new offerings and designs.
BIG Kaiser has expanded its Mega Synchro line of tapping holders with the MGT36 at the larger end and MGT3 on the smaller end of its lineup. “Most of our customers see a huge increase in tap life,”Burley said.
A Growing Range of Tap Holders
Meanwhile, Emuge (West Boylston, MA), a leader in thread cutting technology, which also says it was the first to offer SSY tap holders, reports that it has the widest range of tap holders and continues to expand its lineup.
Last year, Emuge introduced new modular MQL Softsynchro tap holders for machines with synchronous spindles. The new Softsynchro MQL modular system makes it possible for the same toolholder body to be used for minimal quality lubricant or HSK coolant applications. Emuge MQL Softsynchro modular tools can also be custom-built from standard components, depending on the tap size, MQL configuration and application. The new MQL modular system features a pressurized MQL delivery system supplying a sealed air system that equalizes the pressure within the MQL tube and collet adaptation throughout the entire holder. With this system, pressure is the same on the inside of the tube and outside of the MQL delivery system preventing any leaks within the MQL holder.
The modular toolholder can also be supplied with a spring-loaded tube, the preferred method in MQL applications. The modular system for the HD units provides coolant-thru capability up to 50 bar in the high-pressure SSY units. And these SSY holders have the option of adding an adjusting screw, giving the ability to preset the length of the tap.
The modular system also employs a new Heli-Coil mechanism designed to reduce the force that occurs when tightening the collet nut. When tightening the collet nut with the tap fixed against the adjusting screw, there typically is some movement that can damage the tap or adjusting screw.
The axial movement of the collet can be 0.08 to 0.3 mm, with forces of 800–5000 N. The Heli-Coil mechanism compensates for this axial movement, preventing unwanted displacement and potential damage to the tap or MQL adjusting screw. "The Heli-Coil helps protect the components, especially carbide taps, from movement after setting length and then tightening the collet nut,” said David Ridenour, OEM sales and tool holder product manager for Emuge. The new modular bodies are available in KSN1 ER20 and KSN3 ER32.
In recent years, Emuge also has added the KSN5 and KSN6 Softsynchro tap holders, which it says are the largest in the industry. Ridenour said those have filled an increasingly important need for larger taps in the oil industry, power generation and wind turbine applications, as well as in the production of large diesel, locomotive and ship engines.
The KSN5 series is for tap sizes M16 to M56 and ANSI sizes to 1 ¾" (45 mm). The KSN6 series is for sizes M24 to M76, and will accommodate tap sizes 1 through 2 ½" (25.4–63.5 mm) with adaptors.
On the Smaller Side
Meanwhile, Rego-Fix (Indianapolis, IN) is taking its Swiss precision toolholding to new levels of small with its slimmest toolholder in its popular powRgrip press-fit system, the slim-nose powRgrip 6 toolholder, or PG6.
Launched last year, the PG6 is especially well suited for the aerospace, automotive, medical and watch industries. It has a minimal outside diameter of 0.4" (10 mm), as well as a clamping diameter ranging from 0.008 to 0.125" (0.2–3.175 mm). Because of its slim design, the PG6 provides less tool interference, easily machines tight pockets and delivers high levels of productivity.
When paired with the expanded line of HSK 40 E holders, the PG6 enhances the capabilities of the company’s existing powRgrip toolholding system, which offers better TIR, improved tool dampening, easy presetting, longer tool life and unparalleled clamping forces.
Along with PG 6, REGO-FIX has introduced secuRgrip to deal with the most demanding cutting applications. Most importantly, said Dave McHenry, Technical Product Engineer, Rego-Fix, “Everybody who uses a Weldon flat cutting tool can use the new secuRgrip holder. There’s no proprietary cutting tool necessary. We’re taking an old standard and we’re giving it new life.” The grip, McHenry said, is tighter and more secure than that achieved with methods such as heat shrink.
So while shrink-fit toolholders achieve 3 microns of accuracy, McHenry said, that grip often isn’t maintained. The secuRgrip and all other PG holders will not lose accuracy or clamping force and it comes with a five-year or 20,000-cycle warranty.
Rego-Fix achieves this grip with the secuRgrip holder by locking the cutting tool to the collet with threading. And as with all other PG holders, the connection of holder components is also naturally damping because the various components are made from different types of steel, which result in improved harmonics that eliminate self-exciting vibrations.
Once that assembly is pressed in, a special cap nut covers over the collet, further locking the cutter in place.
“There’s nowhere for anything to move, and the cutter itself will break first—that’s the only form of failure that’s possible,” McHenry said. ME
This article originally appeared in the January 2013 issue of Manufacturing Engineering. A PDF of the original article can be found here.