Update on Router Bit Technology
August 14, 2011 | 6:08 pm CDT

Industry experts share their insight on changes in tool geometry and other recent innovations in router bit technology.

The growing popularity of lightweight panels is driving the need for longer router bits, as well as other changes in tool geometry. Photo courtesy of Onsrud Cutter.

The evolution of router bit technology is moving swiftly ahead as changes in the composition and geometry of these cutting tool workhorses continue to keep pace with developments in substrates and the ever-increasing need for faster-paced production in the plant.

“The change in [substrate] materials has inspired tool manufacturers to develop new [composition] materials and configurations of tools to hold up to the challenges the new substrates have on the machining process,” says Ron Migedt, president and CEO of Riverside Tool Corp.

Perhaps most notable has been the influence of lightweight panels on tooling technology, particularly as the substrate’s popularity and applications continue to grow.

“Lightweight panels have created several new challenge for tooling engineers,” says Gene Veening, president of Royce//Ayr Cutting Tools Inc. “The porous core structures of the panels make tool geometry a very important consideration. Unique hook and shear must be added to the tools to reduce chipping or delamination on the top and bottom of panels. [Also,] the number of flutes must be increased, to decrease chip loads and further prevent cut quality problems within the panels core,” Veening says.

“Lightweight panels, as well as other compound substrates, have added to the complexity of shank type cutting tools,” adds John Michel, director of sales and technical services for Leuco Tool Corp. “Take for example, lightweight panels made up of sandwiching honeycomb paper between HDF or particleboard. The demands on the cutting tool are to provide a long life and good finish on the HDF, as well as cutting of unsupported paper without ripping or pulling out. These demands require cutting tools to have a combination of geometries as well as in some cases, a combination of cutting materials within the same tool body,” he says, citing the successful combination, in some applications, of carbide and diamond.

Corresponding to that demand is need for longer tool lengths in order to process the lightweight material, says Ansgar Uhl, application engineer for Leitz. “Lightweight panels are generally thicker than conventional panel products. Tool design must also permit clean cutting of the top and bottom surface material, while gently trimming or recessing the softer core material,” Uhl says.

“As materials evolve so will cutting tools,” says Leslie Banduch, senior vice president of marketing for Onsrud Cutter LP. “Lightweight panels are one example, but more and more natural materials will be replaced by man-made ones. You just have to look at aircraft or even automotive construction to see the growth of lightweight and strong composite materials, or a combination of composite and natural materials. These materials present new challenges as they are more abrasive than natural materials, and the combination of these materials will drive new geometries that have to produce a good edge on all the layered edges,“ he adds.

Instead of simply single- and two-flute designs, router bits offer three- and four-flute designs, thereby meeting the needs of all solid wood and panel production. Photo courtesy of Delmac Machinery Group

Changing Composition and Geometry

Those tooling manufacturers interviewed say they are responding to these new demands in a number of ways, including retooling the geometry and refining the composition of the bit.

“Just as the development of composite materials resulted in the expansion of alternative carbide grades and even polycrystalline diamond for cutting tools, lightweight panels and other alternative materials will without doubt drive a further evolution in cutting tools,” Michel says. “Material developments, as well as machine and customer demands, will likely involve ever-more complex cutting geometries combining varying hook, shear, helix, and even tooth pitch on the same tool, to address these challenging applications.”

“We continue to respond to new materials by adjusting tool geometry and configurations,” says Mike Serwa, vice president of sales/engineering at Vortex Tool Co. Inc. “In a recent instance a customer had switched to a new backer material. Although it looked identical to the original material, it frayed badly when cut with the same tooling the customer had always used. We experimented with tool geometry and found that we needed to provide a tool with variable helix angles in order to cut the new backer material cleanly.”

Other items to consider include the binder used in the substrate, which, says Chuck Hicks, president of Southeast Tool, “[could] mean a lot more wear and tear on cutting tools. Because of this, we are having to make tools with a less percentage of cobalt. This means the tool will wear longer because it is actually harder, but the increased hardness makes tools that are more brittle and more prone to breaking.”

However, Hicks is quick to add, “If the user stays on top of his feed rates and keeps the collets changed, this is usually not a problem.”

While feed speed, in general, does not affect the basic geometry of the tool, Uhl says, “a tool may have to have additional cutting teeth to maintain the correct chip-load at higher feed rates.”

“The demand for faster production rates has also caused a need for greater number of flutes on the tool,” adds Veening. “The use of ‘chip breakers’ or staggered wing tools allow feed rates to be increased without sacrificing cut quality.”

According to Migedt, tool geometry now includes higher shears, more wings and smaller diameters. “This has all been able to be done through the new technology of machines and software on the tool design and manufacturing side,” he says.

“With today’s sophisticated CAD/CAM systems just about any geometry can be ground into a solid carbide tool,” Banduch adds. He cites an example of a compression, dual-grade carbide tool that incorporates a smaller diameter, which in turn exerts less lateral forces on the part, thereby preventing part movement while enabling faster feed rates.

“In recent years we have responded to the industry’s need to run faster by providing small diameter routing tools with increasing numbers of cutting edges,” adds Serwa. “However, there is a limit to the effectiveness of wood cutting router bits with an increased number of cutting edges. In other words, at some point, an increased number of cutting edges does not allow the tool to be fed faster.”

Experiments using “air through tool” technology are being conducted in an effort to overcome this issue, Serwa says. “What we have done is moulded a large diameter hole through the center of the tool where pressurized air can ‘blast’ into the cutting sight of the router bit. This reduces tool cutting temperatures and removes chips more effectively, increasing tool life and allowing the tool to feed faster,” he adds.

Manufacturers also are focusing on improvements in the tool body for dust extraction efficiency. FS Tool/FS Cruing won a Challenger’s Award at the 2008 International Woodworking Fair for its dust extraction system which generates a vortex to pick up dust generated during nested-based manufacturing.

“Dust extraction is always an important part of cutting tool design. If the dust cannot be removed quickly and efficiently during the cut, heat is generated which contributes to premature tool wear and even breakage,” says Karin Deutschler, vice president of GUHDO-USA Inc.

“Over the last few years we have witnessed the evolution of solid carbide spirals from single- and two- flute designs to three- and four-flute designs to accommodate faster feed rates,” says Deutschler. “Similarly, diamond tooling has also evolved to special tool bodies greatly reducing flexing, breakage and improving dust extraction. With faster feed rates, hydro tool holders are finding their place for precision machining… a small investment up front which pays off in both improved tool life and finish,” she adds.

Still, she and others agree, even the best cutting tool is only as good as the machine used. “Synergy between the material being machined, tooling and router/machining center is necessary for optimum results,” says Deutschler. “The best designed router bit cannot compensate for a bad machine application.

“Often,” she adds, “too much attention is paid to tooling and not enough to clamping. With HSK and ISO tool holders, collet type is important. Depending on what is used, the tolerance changes considerably. Since many people shop on cost alone, not knowing the difference, they end up with collets that have considerable runout, contributing to poor tool life and poor finish. The old adage ‘you get what you pay for’ is so true here.”

Hold-down systems also play an important role in achieving a good cut, Deutschler adds. “Lightweight panels, such as Trespa, honeycomb and sandwich panels, sometimes present a challenge, particularly if the machinery is older and the vacuum hold-down is not efficient.”

Hicks agrees. “We have added the 4 + 4 compression bits, but most machines cannot run the feed rates needed to benefit from this tool,” he says. “The size of the part being cut and the hold-down systems simply
cannot hold the workpiece.”

Correct grinding of the tool is also critical, says Michel. “Grinding technology in recent years has significantly helped tool builders to design steeper cutting angles, more aggressive shears and complex fluting...all of which reduce cutting forces, allowing tools to run faster, longer and cleaner.” However, he cautions, “It must be noted that the grinding machine alone does not make the difference. The tool builder needs to know how to use it.”

Serwa agrees. “By utilizing the latest advancements in grinding machine technology, we are able to produce better and more viable cutting tools out of harder carbides and even other types of cutting tool materials.”

According to Deutschler, many of the changes taking place in the cutting tool industry are being driven by educated end users, “trying to maximize their investment in both machinery and tooling, who will continue to challenge tooling manufacturers to develop longer lasting and better performing tools.”

Banduch cites some examples. “Many of the tools developed for lightweight panels used in aircraft construction are now finding their way to the other areas, including cabinets used in the RV, boating, along with RTA furniture and other areas where weight is an issue or where solid materials are too costly,” he says.

“As the use of lightweight panels becomes more common, the demand for effective tooling solutions will obviously be increased,” Veening adds. “Increased global shipping costs also will continue to drive demand for lighter weight materials, resulting in more standard lines of tooling that are readily available to the consumer.

Diamond Continues Rise in Popularity

With regards to material composition, many of those interviewed say they see continued growth in the popularity of diamond tooling for router bits. “Diamond (PCD) tooling and coated tools will continue to grow in popularity as customers recognize the positive financial impact of long tool life and reduced machine downtime,” Uhl says. “Diamond and coated tools are also essential when working with abrasive composite and certain plastic materials, which continue to gain popularity.”

According to Uhl and many others, tooling manufacturers are responding to market demand in a number of ways, including offering smaller diameter PCD tools for nesting applications. “We also currently supply 12mm diameter 3+3 wing diamond tooling, which is very popular in Europe and Asia,” Uhl says.

“Smaller diameter tools with longer cut lengths and maximum number of cutting edges will continue to be important as customers work to maximize raw material yields at optimized productivity levels,” Uhl adds.

“The use of PCD-tipped tools has increased dramatically due to the abrasive nature of the panel cores,” adds Veening. “The use of solid PCD tools is often more cost effective, especially when machining modern honeycomb or NOMAX cores that are common in the aircraft industry. There is no substitute for a properly designed custom diamond tool for a specific application.”

According to Migedt, other trends in tool composition include: “the development of a carbide rod that has the ability to handle greater tool pressure; thinner PCD tips allowing tools to be made with more geometry on small diameters; and true-thermal coatings on the bodies, which are helping to resist heat build-up and the transfer of the heat through the tool into the tips and spindle. This new coating also resists pitch build-up,” he says.

Coatings and Other Developments

Highlighting the growing interest in coatings is cutting tool manufacturer Super Thin Saws being awarded a Challenger’s Award for its heat dissipation coating on blades at IWF 2008. For many of those interviewed, further developments in coatings is definitely on the horizon.

“Tool coating technology is a relatively new concept in the woodworking tooling market, but is advancing very quickly,” Uhl says. Benefits include increased service life by reducing surface friction and the addition of a very strong wear layer for machining abrasive materials.

“Tool coatings have become more and more popular,” agrees Michel. “Currently, tool builders have several types from which to choose.” However, he adds, “While some coatings have proven success, users need to evaluate the performance in their specific application. What works for one may not for others.”

Deutschler concurs. “Although many coating technologies have been tried over the years, there has not been one that is proven to apply to woodworking tools in general,” she says, adding that, “Some tools undergoing cryogenic treatment have proven to extend tool life by multiples in some applications, while not at all in others.”

While there are benefits to coatings and other treatments, there is a downside in that the cost for the processes may prove prohibitive to end users. “Coatings are effective in some situations, but the need for re-coating after service is an added cost that must be incurred,” cautions Veening.

“Coatings seem to help some, but most are looking at the cost and lead time that is involved,” says Hicks. “The cryogenic, or deep freeze, treatment seems to help on steel items, but not carbide, as far as all the testing that we have done,” he adds.

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