A 'bit' of good advice: Wood & Wood Products talks to industry experts about new developments and suggested practices for optimizing router bit usage.

Imagine this: You are an expert woodworker with a top-of-the line router, preparing to add a decorative edge to your masterpiece, when you realize you are missing a crucial component of your system. You run circles around the shop, kicking up sawdust and screaming, "No! This can't be happening to me!" You wake in a cold sweat from this horrible nightmare and thank the stars above that you have a vast collection of router bits at the shop, waiting to be utilized.

Although this is an overly dramatic scenario, quality router bits are an important accessory, helping to ensure a clean cut and a superior finish to any woodworking project. Recently, Wood & Wood Products sought the knowledge and experience of industry leaders to learn about suggested practices, as well as new developments, in the exciting and expansive world of router bits.

Diamonds Are a Router's Best Friend

When asked of new developments in router bit technology, the majority of those questioned mentioned the advances made in polycrystalline diamond (PCD) tooting. "We believe there are very few applications where properly engineered PCD routers will not improve quality, eliminate downtime and reduce tooling cost," says Scott Burton, regional sates representative of Royce//Ayr Cutting Tools Inc. Burton lists technological advancements, such as new state-of-the-art machinery for reducing PCD erosion, resulting in finer cutting edges. He also feels versatile design capabilities, which allow for hook and shear configuration specific to wood species or composite panel density, have aided in the improvement of PCD tools and helped to make them the best option when profiting solid wood.

"PCD-tipped tooling generally will provide an acceptable finish and provide the longest tool life," says Mike Serwa, vice president of sales and engineering for Vortex Tool Co., "but will do it at about half the feed rate of solid carbide."

"The material grades, cutting geometries and applications keep adapting in order to rout abrasive or specialized materials," adds Bill Kochan, product manager for Onsrud Cutter LP. "This technology will keep advancing and growing in order to meet customers' needs."

Some new developments in router technology are linked to the need for smaller diameters and faster feed rates desired in nested-based applications, according to Karin Deutschler, president of GUHDO USA Inc. She says that in a fast-paced CNC production facility, carbide-tipped tooling is a thing of the past. "The choices today are either solid carbide spirals, carbide-inserts or diamond tipped, depending on application and volume."

Kochan agrees. "CNC machines offer a high, consistent feed rate, allowing solid carbide or diamond tools to be utilized to their fullest."

The Right Tool Matters

Choosing the correct tool material for a specific application is important for many reasons, including a longer tool life and a quality finish. "The way to analyze and characterize the correct tools for each material is not an exact science," says Marco Camilli, mechanical engineer and plant manager at CMT Utensili S.p.A. "Carbide type, helix angle, rake angle, core diameter and the speed of the woodworking machine must all be considered."

"The best rule is that the harder and more abrasive the material to be cut, the harder the cutting edge must be," adds Ron Migedt, president and CEO of Riverside Tool Corp.

"Typically, man-made materials will require either carbide or PCD," says Serwa. "High-speed steel and carbide-tipped tooling, although sometimes used for solid wood, plastics and metal-cutting applications, are precluded from a majority of today's CNC applications. Solid carbide will provide the best finish cut quality and the fastest feed rates, which can save significant machine time."

However, high-speed steel and carbide-tipped tooling do offer advantages in some instances, such as manual- or hand-feeding operations. "High-speed steel tools offer a sharp cutting edge, and the core is tough, allowing it to absorb the shock of inconsistent feed rates," says Kochan. "Carbide-tipped tools have the same characteristics of high-speed steel, but the carbide cutting edges allow for longer tool life."

"There are some applications, where extreme vibration is present that high-speed steel is the only thing that will hold up and not break or chip," adds Chuck Hicks, president of Southeast Tool. "But the life is still not great."

'Configure' It Out

Tool configuration also has an impact. Burton says factors such as material and machine type, part size, number of tool paths to be programmed, the application itself, and desired feed rate and cut quality all should be considered.

According to Hicks, it is hard to determine which configuration works best for an operator, as many people are running different tools and getting mostly the same results. "It depends a lot on the feeds and speeds, and the condition of the machine and collets if running on a CNC router," he says.

"The harder and denser the material, the lower the hook and shear required," adds Migedt.

Serwa stresses the importance of the Helix direction. "Helix direction can influence dramatically the performance of the cutting tool," he says. "Finish on the part will be best when the Helix direction is pushing into the part--upcut flutes on the bottom, downcut flutes on the top, and compressions on both top and bottom. Helix direction also will have an influence on part hold down and chip flow. All three factors should be considered when making tool selection."

The Quest for Optimum Chip Load

When asked for the optimum chip load for achieving the best finish, most of those interviewed remarked that it is difficult to determine, citing variables such as diameter and type of tool, type of flute, machine, hold down, and material variations.

"What is optimum for one customer may be unachievable by another," says Migedt.

"One cannot run all tools at the same chip load and expect a good edge finish," says Kochan. "Different types of wood tools have specific chip load ranges which are based on their cutting geometry. A large diameter can take a heavier chip load than a small tool."

"Solid carbide tooling can generally handle the largest chip loads, while PCD tooling will require the smallest chip loads," adds Serwa. "The more dense the material the smaller the chip load needs to be. The softer or less dense materials can be cut with the largest chip loads."

Deutschler says that most users will not have to worry about calculating chip loads, as it is inherently part of the tool design itself. "A standard off-the-shelf tool will be designed to run in a specific RPM range with a feed-rate range that will encompass the desired chip load, and custom tooling, of course, is designed around the specifics of the application."

Problems and Prevention

Of course, nothing in life, including router bits, is perfect. Problems can and will arise. Common issues with router bits include: breaking, heat, bad collets, and improper feed rates and tool speeds. Fortunately, there are many possible solutions to be found when troubleshooting these problems. (See chart, page 73.)

"The most common problem while routing is the creation of heat, which reduces tool life," says Kochan. "To achieve maximum tool life, a router bit needs to be fed at an aggressive feed rate in order for the heat to go into the chip and not the tool. Increasing the feed rate will improve productivity as well."

Serwa says the number one problem he sees with router bits in CNC applications is running the tools at an improper combination of feed rate and RPM. "Most machine tool spindles operate at higher RPMs. At these high rates, it is very important to select the proper feed rates. If the tool is run at too high of an RPM and too low of a feed rate, premature wear or tool breakage can result."

When it comes to many of these problems, prevention starts with proper maintenance. Numerous issues are not with the router bit itsetf and can be attributed to other factors.

"A common problem that occurs is with the tool holding system," says Serwa. "If there is a defect or wear in a collet or tool holder, it may appear that there is a problem with the router bit. Collets need to be replaced on a regular basis (about every 600 hours) and collet nuts should always be tightened to the proper torque settings."

"One of the biggest problems with router bits is breaking," says Hicks. "This is almost always caused by bad collets. The collet is more important than the tool."

Kochan also stresses collet maintenance. "Collets have a four-month lifespan if used eight hours a day, five days a week. The reasoning is that collets are made out of spring steel and they loose their ability to properly grip a tool over time. This results in the operator having to over-tighten the collet nut, ultimately leading the tool to break. Collets should be cleaned every time the tool is changed."

"Proper part fixturing, timely collet replacement, and regular machine cleaning and maintenance are all critical factors which promote premium cut quality and increased tool life," says Burton. "Even minimal vibration in either the part or tool can dramatically affect the performance of a router bit. For pod systems, always ensure that pod gaskets are not worn or damaged. Spoilboard systems can be improved by creating dedicated spoilboards using gaskets."

Kochan, as well, says fixturing is a critical part of the manufacturing process. "The best tool in the world will not work if you can't hold the part," he says, recommending flow-through and dedicated vacuum methods.

Deutschler strongly suggests that machinery manual recommendations for maintenance be taken seriously and followed. "A well-cared-for machine will last many years longer than a machine with a neglected maintenance schedule," she says.

Looking Forward

Router bit technology will continue to evolve as better machining and grinding capabilities are developed, as new and improved cutting materials are introduced, and as superior and more complex composite materials are engineered. "The last 20 years have seen a snowball effect in cutting technology," says Deutschler, "and in order for any wood industry manufacturer to remain on the leading edge of the competition, it is essential to be able to produce faster, better and at a lower per-piece cost. The ultimate challenge for all leading tooling suppliers is to be able to meet this demand."

"The day of using one tool to cut all materials is over," Kochan says. "Router bit technology keeps advancing and many unique cutting geometries are being created for specific materials."

"Router tooling, in general, has been improved to meet the demands of new high rate machinery," says Burton. "The extremely accurate engineering and balancing required for production of large moulder heads has had a positive effect on router tooling as well. Extreme accuracy and precision of router tooling will give a competitive advantage in the marketplace."

Camilli says that technology and materials are important, but that in the end it is the person using the machine that matters most. "Every process hinges on the 'know-how' and the expertise of every operator in the factory," he says. "I think the 'human factor' and the research are, overall, the secrets of router bit production."

ROUTER BITS: COMMON PROBLEMS AND SOLUTIONS

Problems             Possible Causes           Solutions

1) VIBRATION

                     Dirty collets             Clean collets
                     Worn collets              Recommended collet life
                                               = 800 to 1000 hrs.
                                               Replace collets.
                     Improper collet diameter  Use exact diameter
                     Unbalanced tool or tool   Consult tooling/holder
                     holder                    supplier
                     Worn (eccentric) spindle  Consult machinery dealer

2) BURNING OR
MELTING MATERIAL

                     Improper chip load        Chip load = Feed rate/
                                               (RPM x number of cutting
                                               edges)
                     Improper tool selection   Consult tooling
                     for material or           representative
                     application
                     Inadequate chip removal   Improve dust collection

3) PART MOVEMENT

                     Improper vacuum           Improve vacuum system
                     Improper tool selection   Use down shear for small
                                               parts
                     Improper chip load        Chip load = Feed rate/
                                               (RPM x number of cutting
                                               edges)
                     Parts too small           Use gasket seals
                                               (dedicated to part)
                                               Leave thin skin on part
                                               and send through
                                               thickness sander

4) POOR TOOL LIFE

                     Improper chip load        Chip load = Feed rate/
                                               (RPM x number of cutting
                                               edges)
                     Vibration                 See #1 under Problems
                     Poor chip removal         Improve dust collection
                     Improper tool selection   Consult tooling
                                               representative
                     Eccentric spindle         Consult machinery dealer

5) POOR CUT QUALITY

                     Improper chip load        Chip load = Feed rate/
                                               (RPM x number of cutting
                                               edges)
                     Tool running out          Consult tooling
                                               representative
                     Part movement             See #3 under Problems
                     Vibration                 See #1 under Problems
                     Damaged tool              Inspect cutting edge
                     Dull tool                 Service tool

6) TOOL BREAKAGE

                     Vibration                 See #1 under Problems
                     Dirty/worn collets        See #1 under Problems
                     Improper chip load        Chip load = Feed rate/
                                               (RPM x number of cutting
                                               edges)

* Chart and information courtesy of Royce//Ayr Cutting Tools Inc.