Engineers at Rego-Fix agree that even with the highest clamping forces available, there are applications that require additional cutter retention measures. At IMTS 2012, Rego-Fix introduced the secuRgrip anti-pullout system, available for powRgrip, ER collet holders and milling chucks. A small, profiled steel locking key insert is installed in the ground flat of standard Weldon-shank cutting tools, locking the tool to the collet. A threaded friction bearing cap secures the collet in the holder and provides increased clamping force to prevent the collet from spinning.

For many generations, machining was a largely manual process with relatively slow speeds and shallow cutting depths. The most common toolholders were Weldon/sidelock chucks and ER collets, and, under these comparatively benign machining conditions, cutting tool slippage or pullout was not a serious issue.

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The aerospace sector is an important market for Kennametal and its tool development as the advanced engineering involved always poses new machining challenges. An example of this is the tooling specialist’s membership of the Advanced Manufacturing Research Centre (AMRC) in Sheffield, where along with aerospace OEMs and other industry stakeholders machining and materials research is carried out for aerospace and other high-value manufacturing sectors.

For maximum tool security, the Pin-Lock Collet system is available as an option. This feature works with any Weldon shank tool and guarantees pullout protection.

“We anticipate that composites will continue to grow in aerospace,” says Penkert. Kennametal has a number of products for composite machining. These include trimming tools, which mill the outside edge of a part or tools that drill and then mill from the inside of the part. We also have tools for contour milling of CFRP.

Rego-Fix Tool Corp. (Indianapolis) markets both a friction fit and a tool locking system. The powRgrip series includes holders, collets, and automatic or manual pressing systems. The collet is pressed into the holder with up to 9 tons (8.16 t) of pressure, which Rego-Fix claims to be the highest clamping force in the industry. The compression contacts the nose of the holder and not the taper.

Kennametal has launched a new insert grade named KCSM40, targeted to machine high temperature titanium alloys widely used for aerospace applications. Ed Hill spoke to the cutting tool specialist about its products designed for difficult-to-machine materials. Due to production rates ramping up for new aircraft, particularly in the commercial market, developers of cutting tools are constantly under pressure to deliver faster and more efficient metal removal rates. In an industry that often uses difficult to machine materials such as titanium this throws up some demanding challenges. Kennametal has developed a new carbide grade, KCSM40, said to greatly enhance cutting of titanium Ti6Al4V and other high tensile strength alloys. Werner Penkert, Kennametal, manager aerospace solutions engineering EMEA, says: This new grade is a development from our carbide grades, KC725M and X500 which are well-known for their reliable performance and long tool life. It increases speed by around 30% but still with excellent tool life.” The KCSM40 grade has an advance cobalt binder that provides very high thermal fatigue resistance. In addition to the new material substrate Kennametal’s proprietary AlTiN/TiN coating enhances wear resistance at the cutting edge. Cutting edges still performing well after 100 minutes of machining Ti6Al4V at 47m/minute with a .0067ipt chip load More speed In trials, the target cutting speed for KCSM40 in titanium Ti6Al4V was 175 SFM (53m/min) while achieving greater than 20 cubic inches per minute (327cm³/min) metal removal rate for 60 minutes. Not only has KCSM40 achieved this, but results of milling titanium at speeds up to 270 SFM (85m/min) at a lower radial depth of cut have been achieved. Scott Etling, director of global product management, for indexable milling at Kennametal, explains the radial engagement of the milling cutter to the workpiece is one key component when optimising the cutting speed. “At higher radial engagements, the insert is cutting the material for a longer time which creates more heat at the cutting zone,” He says. “The heat will not transfer into the titanium chips as is the case when milling steels so controlling the heat is critical. Lower cutter speeds at higher radial engagements is good practice. At lower radial engagements, higher cutting speeds can be achieved.” Kennametal has carried out extensive trials using a new HARVI Ultra helical milling platform to mount the new inserts. It achieved over 100 minutes of tool life running at 155 SFM (47m/min) with a 0.0067ipt (0.12mm/tooth) chip load. The radial depth of cut was 25mm and the axial depth of cut was 76mm. “The edge condition on the KCSM40 grade insert still looked great,” states Etling. “And we are getting many other fantastic results. In one face milling operation on a hardened steel wear plate the number of passes was reduced from 234 to just 22. I am very excited how KCSM40 will benefit our customers.” Demand for higher metal removal rates was the main driver for Kennametal to develop the new grade. “Cycle time is very important because all aircraft builders are under pressure to deliver higher volumes,” notes Penkert. “When companies invest in new machine tools, they want to process the parts much faster. However, customers also require secure processes with other developments such as increased automation. “These days it is rare that a machine operator will be constantly monitoring a machine. Machine tools also use high pressure coolant so it’s very difficult to see what is happening at the cutting edge. A secure manufacturing process is essential because of the value of the parts being produced and the value of the machines they are being made on.” Kennametal has carried out extensive trials using a new Harvi Ultra helical milling platform Heat and steam Titanium poses particular challenges when being cut because of the high temperatures generated at the shear zone. Coolant can vaporise even before it makes contact with the workpiece. “You need high pressure coolant because of the super-heated steam in the shear zone,” Penkert explains. “It’s very important to protect the carbide tools from heat because there can be a softening effect where the cobalt binder weakens and your cutting process is no longer secure.” Kennametal carries out many trials with it customers to help them come up with efficient cutting strategies. “We have good data about our cutters’ tool life but you always have to judge what is happening with an application in the real world,” Penkert continues. “We have to consider what material is being cut, the stability of the machine tool, the clamping, the lubricant etc. All these variations have to be taken into account including the part being made itself. Is it thick and stable or thin and instable? “Our data is a starting point but then we have to prove out strategies in a manufacturing cell. Here we can monitor the wear, so after a number of minutes of cutting we have an accurate idea of the wear rate which occurs in that application.” Along with its metalcutting products used for machining high grade alloys, Kennametal has also developed a range of cutting tools for the increasing amounts of composite materials used in aerospace. “We anticipate that composites will continue to grow in aerospace,” says Penkert. Kennametal has a number of products for composite machining. These include trimming tools, which mill the outside edge of a part or tools that drill and then mill from the inside of the part. We also have tools for contour milling of CFRP. “We are also involved in the assembly of the aircraft with hole drilling. This can involve drilling through CFRP/aluminium or CFRP/titanium stacks. This can be difficult because you have to prevent burrs on the entry and exit of holes, avoid delamination and fibre breakout and we have to provide a geometry that can deal with these different materials in one operation. Another factor is composite materials are highly abrasive. In these circumstances we find PCD is a very good cutting grade or diamond film coated drills.” More Kennametal tools used for aerospace applications such as turbines Adding advances The aerospace sector is an important market for Kennametal and its tool development as the advanced engineering involved always poses new machining challenges. An example of this is the tooling specialist’s membership of the Advanced Manufacturing Research Centre (AMRC) in Sheffield, where along with aerospace OEMs and other industry stakeholders machining and materials research is carried out for aerospace and other high-value manufacturing sectors. Werner Penkert, Kennametal, manager aerospace and defence solutions EMEA “We work very intensely with the OEMs and tier 1 companies on projects, along with our application engineers who help all our customers in the industry. Also, there is always the demand created by new and improved machine tools. Manufacturers and their customers want turnkey projects which includes us providing solutions. In these situations, there is a lot of collaboration between the cutting tool supplier, the machine tool builder, the fixture manufacturer and the end user. Our specialists work with all involved to support each other.” And Penkert believes there are still possibilities for cutting tool performance to be enhanced. “Improvements can be made to the carbide grade, the substrate and the coatings. And there are ongoing developments with machine tools which means there is always a research partnership needed between us and the manufacturers. When a machine tool comes along with new performance capabilities, this allows the cutting tool developers to create products that match the improved performance of the machine tool.” www.kennametal.com

An exclusive Key Grip locking mechanism provides anti-pullout protection. It is placed into the Weldon flat of the end mill shank, which is then inserted into one of the three Key Grip grooves inside the chuck. A spring functions to remove the gap between the Key Grip and the wall of the groove. Tightening a clamping nut secures the Key Grip in place, achieving dual contact between the nut and chuck body for rigidity close to that of an integral cutter.

Drew Strauchen, vice president, marketing and business development, Haimer USA LLC (Villa Park, IL), cautioned against total reliance on the ability of friction-fit holders to provide maximum tool security. “High gripping torque by itself does not equal guaranteed pullout protection,” he said. “The incredible cutting forces generated by faster machine spindles and more aggressive toolpath strategies [like full radial engagement trochoidal milling] have exposed the limitations of even the best friction-fit clamping systems.”

Haimer is best known for its extensive line of shrink-fit toolholding. This system is a simple one-piece, highly rigid design with no moving or wearable parts. Benefits include runout accuracy up to 0.00012″ (0.00305 mm), superior repeatability, minimum vibration and chatter and excellent balance, according to the company.

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Hydraulic expansion toolholders were developed by Schunk more than 35 years ago and have been continually improved to keep pace with advancements in machine technology and carbide tooling, Krolak said. The Tendo line features a high concentric clamping force, excellent vibration dampening and runout of less than 3 µm @ 2.5×D. All commercially available tools, with Weldon, Whistle notch or cylindrical shanks, can be clamped. Micron-accurate tool changes can be made in seconds.

There are secure toolholders for a variety of cutting operations, including milling, drilling and tapping. For example, Emuge Corp. (West Boylston, MA) offers its highly rigid FPC Mill/Drill Chuck with three tons of traction force to hold a tool securely. This is the world’s only chuck with a 1:16 wormgear, according to Emuge. The collet-cone assembly absorbs virtually all vibration, for maximum vibration dampening. With a 3×D tool length, variation in concentricity is less than 3 µm, which extends tool life and substantially improves workpiece surface finishes. All models are balanced to G2.5, 20,000 rpm. In a speed comparison with four competing chuck designs, the FPC chuck enabled the feed rate to be increased by 30% with no loss in performance.

Werner Penkert, Kennametal, manager aerospace solutions engineering EMEA, says: This new grade is a development from our carbide grades, KC725M and X500 which are well-known for their reliable performance and long tool life. It increases speed by around 30% but still with excellent tool life.”

TIR is less than 0.0001″ (0.0025 mm) even after thousands of tool changes, and powRgrip’s rigidity and high mass minimizes harmonics, extending tool life and reducing consumable costs, according to the company. The system has five sizes, resulting in only five machine inserts the operator would ever need to use every holder, and eliminating the need to purchase machine taper mounts.

One of BIG Kaiser’s newest products, the Mega Perfect Grip milling chuck, is designed specifically to prevent cutter failure. The high-accuracy milling chuck has fully concentric clamping and runout of less than 0.0004″ (0.0102 mm) @ 4×D. It accepts standard Weldon flat end mills and requires no special grinding of the milling cutter.

In trials, the target cutting speed for KCSM40 in titanium Ti6Al4V was 175 SFM (53m/min) while achieving greater than 20 cubic inches per minute (327cm³/min) metal removal rate for 60 minutes. Not only has KCSM40 achieved this, but results of milling titanium at speeds up to 270 SFM (85m/min) at a lower radial depth of cut have been achieved.

Emuge also produces an extensive line of tapping toolholders. The Softsynchro rigid tap holder, with minimal length compensation, is said to reduce axial force to a fraction of that required in typical tapping applications, improving thread quality and extending tool life by up to 300%. Patented elastomer springs separate the spindle from the tap, absorbing excessive axial forces and providing the tap with a significant boost in tool life and performance. Torque from the spindle is transferred to the tap via ball bearings in precision-ground grooves, promoting precision micro-correction of lead errors in a rigid tapping cycle. The modular system is adaptable to any application requiring a length adjustment screw and interchangeability for different size taps.

Shops should be aware that heavy-duty machining is not the only cause of tool pullout, said Ryan Krolak, technical sales specialist for Schunk Inc. (Morrisville, NC): “It can also be the result of toolholders that do not offer concentric clamping,” Krolak said. “This often causes excessive runout, creating an uneven chip load on the cutter and premature tool failure. This shouldn’t have to be said, but it is important to make sure that all the running parameters are within the range of the material and the cutting tool being used.”'

“Our data is a starting point but then we have to prove out strategies in a manufacturing cell. Here we can monitor the wear, so after a number of minutes of cutting we have an accurate idea of the wear rate which occurs in that application.”

That was yesterday. Today, the productivity needed to be globally competitive requires ever increasing metal-removal rates during operations such as roughing and high-speed slotting. Process reliability is paramount, especially when working with difficult-to-machine materials. Conventional toolholders typically do not cope well with the high axial forces generated by aggressive machining, and cutter pullout can occur.

Titanium poses particular challenges when being cut because of the high temperatures generated at the shear zone. Coolant can vaporise even before it makes contact with the workpiece.

In addition to the characteristics inherent the hydraulic expansion design, the Aviation toolholder employs a locking mechanism. A cutting tool with a standard Weldon shank is inserted into a special sleeve with a ball lock. The tool/sleeve assembly is then locked into place via set screws in the base of the toolholder. Finally, the holder is hydraulically actuated. As with other Tendo models, this process can be accomplished in seconds.

Along with its metalcutting products used for machining high grade alloys, Kennametal has also developed a range of cutting tools for the increasing amounts of composite materials used in aerospace.

“We have good data about our cutters’ tool life but you always have to judge what is happening with an application in the real world,” Penkert continues. “We have to consider what material is being cut, the stability of the machine tool, the clamping, the lubricant etc. All these variations have to be taken into account including the part being made itself. Is it thick and stable or thin and instable?

The KCSM40 grade has an advance cobalt binder that provides very high thermal fatigue resistance. In addition to the new material substrate Kennametal’s proprietary AlTiN/TiN coating enhances wear resistance at the cutting edge.

“We work very intensely with the OEMs and tier 1 companies on projects, along with our application engineers who help all our customers in the industry. Also, there is always the demand created by new and improved machine tools. Manufacturers and their customers want turnkey projects which includes us providing solutions. In these situations, there is a lot of collaboration between the cutting tool supplier, the machine tool builder, the fixture manufacturer and the end user. Our specialists work with all involved to support each other.”

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Shrink-fit is based on the thermal expansion and contraction of metal, and uses an induction heating unit for assembly. The bore of the holder is initially slightly smaller than the outside diameter of the tool shank. When heated, the holder expands sufficiently to allow tool insertion. After cooling, contraction of the holder grips the cutting tool with up to 10,000 lb (4536 kg) of force. Tools can be changed in seconds, and operator training is minimal. As noted above, the Safe-Lock feature can be incorporated into Haimer shrink-fit toolholders.

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Scott Etling, director of global product management, for indexable milling at Kennametal, explains the radial engagement of the milling cutter to the workpiece is one key component when optimising the cutting speed.

“Cycle time is very important because all aircraft builders are under pressure to deliver higher volumes,” notes Penkert. “When companies invest in new machine tools, they want to process the parts much faster. However, customers also require secure processes with other developments such as increased automation.

Cutting edges still performing well after 100 minutes of machining Ti6Al4V at 47m/minute with a .0067ipt chip load

Kennametal carries out many trials with it customers to help them come up with efficient cutting strategies.

Toolholder manufacturers have responded with a variety of rigid, highly secure systems offering anti-pullout protection. These include shrink-fit, hydraulic expansion and locking toolholders. Each features high gripping torque (clamping force) for a tight friction fit on the tool shank. Many offer proprietary locking mechanisms that can guarantee up to 100% tool retention.

“These days it is rare that a machine operator will be constantly monitoring a machine. Machine tools also use high pressure coolant so it’s very difficult to see what is happening at the cutting edge. A secure manufacturing process is essential because of the value of the parts being produced and the value of the machines they are being made on.”

Kennametal has launched a new insert grade named KCSM40, targeted to machine high temperature titanium alloys widely used for aerospace applications. Ed Hill spoke to the cutting tool specialist about its products designed for difficult-to-machine materials.

“At higher radial engagements, the insert is cutting the material for a longer time which creates more heat at the cutting zone,” He says. “The heat will not transfer into the titanium chips as is the case when milling steels so controlling the heat is critical. Lower cutter speeds at higher radial engagements is good practice. At lower radial engagements, higher cutting speeds can be achieved.”

“We are also involved in the assembly of the aircraft with hole drilling. This can involve drilling through CFRP/aluminium or CFRP/titanium stacks. This can be difficult because you have to prevent burrs on the entry and exit of holes, avoid delamination and fibre breakout and we have to provide a geometry that can deal with these different materials in one operation. Another factor is composite materials are highly abrasive. In these circumstances we find PCD is a very good cutting grade or diamond film coated drills.”

For high production tapping, the Speedsynchro tap holder features a programmable integrated transmission of 1:4.412 to optimize thread production on CNC machines with synchronous spindles. Combined with Softsynchro’s minimum length compensation, this allows high cutting speeds at a relatively low synchronous machine tool speed, compensating for synchronization errors during the threading process. Thread production cycle time is reduced by up to 40%, and the lower spindle speed can result in significant savings in energy costs.

”After more than four years, there have been no documented cases of a tool pullout with a secuRgrip holder,” said Chris Herdman, technical field support engineer for Rego-Fix. “The only mode of failure is that of the cutting tool itself.” Unlike other systems, secuRgrip does not require purchase of specially modified end mills, but rather can accept standard 0.5–1″ (12.7–25.4-mm) carbide or HSS end mills. The system maintains 0.0001″ runout and allows users to preset tool heights.

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As machining speeds increase and more difficult-to-machines alloys are introduced, machine shops need to continually re-evaluate their toolholding options. While highly secure toolholders typically cost more than their standard counterparts, the payback—in terms of the ability to machine at higher speeds and fewer scrapped parts and tools—can be substantial.

“The edge condition on the KCSM40 grade insert still looked great,” states Etling. “And we are getting many other fantastic results. In one face milling operation on a hardened steel wear plate the number of passes was reduced from 234 to just 22. I am very excited how KCSM40 will benefit our customers.”

The Tendo holder contains an internal clamping piston that compresses hydraulic fluid into the oil chamber. The piston is manually actuated by an external clamping screw turned to a dead stop by an Allen key. A flexible sleeve immediately expands evenly against the tool shank, first centering the tool, then powerfully gripping it on the full surface. A length-setting screw can be actuated radially or axially for tool presetting.

“Improvements can be made to the carbide grade, the substrate and the coatings. And there are ongoing developments with machine tools which means there is always a research partnership needed between us and the manufacturers. When a machine tool comes along with new performance capabilities, this allows the cutting tool developers to create products that match the improved performance of the machine tool.”

Due to production rates ramping up for new aircraft, particularly in the commercial market, developers of cutting tools are constantly under pressure to deliver faster and more efficient metal removal rates. In an industry that often uses difficult to machine materials such as titanium this throws up some demanding challenges.

ANT Industries, a leading manufacturer of aero engine and gas turbine components in Atherstone, Warwickshire, has announced a significant milestone in its commitment to quality and excellence.

Kennametal has carried out extensive trials using a new HARVI Ultra helical milling platform to mount the new inserts. It achieved over 100 minutes of tool life running at 155 SFM (47m/min) with a 0.0067ipt (0.12mm/tooth) chip load. The radial depth of cut was 25mm and the axial depth of cut was 76mm.

“You need high pressure coolant because of the super-heated steam in the shear zone,” Penkert explains. “It’s very important to protect the carbide tools from heat because there can be a softening effect where the cobalt binder weakens and your cutting process is no longer secure.”

Several years ago, Haimer developed and patented an anti-pullout system, Safe-Lock, as an optional feature on its shrink-fit holders and power collet chucks. Safe-Lock employs special drive keys in the holder and mating grooves in the tool shank, ensuring positive locking in place of the cutter and preventing spinning and pullout. Unlike Weldon flats, the mating ground grooves are perfectly symmetrical, thus eliminating issues associated with unbalance and uneven side loads. The system also provides users with the ability to adjust the axial position of the cutting tool in the holder. With 14 of the largest round tool companies as official licensed partners, tools from any number of global suppliers are readily available.

Krolak agreed that machining aerospace parts is particularly challenging. “Aircraft manufacturers have many applications with materials costing thousands of dollars and individual part cycle times exceeding 12 hours,” he said. “With this much invested in each machined component, tool failure is absolutely not an option.” To meet this need, Schunk recently introduced the Tendo Aviation toolholder for applications that require a secure tool that will not pull out.

The aerospace industry in particular has a big stake in secure toolholding, notes Jack Burley, vice president, sales and engineering for BIG Kaiser Precision Tooling Inc. (Hoffman Estates, IL). “A number of critical components are made from titanium, which is expensive and difficult to machine. If a cutting tool slips or pulls out, the results are extremely costly, in terms of both downtime and material loss,” Burley said.

Kennametal has developed a new carbide grade, KCSM40, said to greatly enhance cutting of titanium Ti6Al4V and other high tensile strength alloys.

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