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Insert tooling carves its own niche.

Helping increase productivity while holding down resharpening costs has helped carbide insert tooling become more attractive to woodworking tool buyers.

According to insert tooling manufacturers, wood products makers are more concerned than ever about manufacturing products that feature clean, tight fits and leave little margin for error. Just as equipment manufacturers have been pressed to engineer products that meet stricter tolerance requirements, cutting tool manufacturers have also been pressured to produce affordable cutting tools that not only produce precise cuts, but that also offer longer cutting life.

Enter insert cutting tools. Unlike conventional cutting heads that are welded to the body, these very hard, sub-micro grain carbide knives are clamped onto the bodies of cutterheads, router bits, grinders and even rosette cutters. When a tool change is necessary, a new cutting head can be substituted, usually without having to remove the tool's body from the machine.

Like standard cutting tools, inserts are made with a variety of materials, from high-speed steel to very hard C-4 grade carbide. Although not as hard as polycrystalline diamond (PCD) tools, inserts made with C-4 grade carbide have the ability to perform longer production runs than standard carbide tools. Traditional carbide-tipped bits feature hardness ratings of C-1 and C-2 and require brazing to fuse the carbide cutting edge to the tool body, according to Terry Jacks, vice president of Leitz Tooling Systems Inc.

The harder grade carbide is not used with conventional carbide tools because fusing C-4 carbide to the tool body can cause it to crack. Manufacturing insert tooling requires no heating because the cutting edge is the knife and the tool body mechanically holds the knife in place with clamping wedges and screws. The knives are either discarded, rotated or resharpened when they become dull.

"For the woodworking manufacturer, insert tools are a very convenient, accurate cutting tool because once the woodworker has the cutterhead, all he has to buy are the replacement knives instead of new cutterheads," said Richard Riggins, sales manager with Wisconsin Knife Works. "The entire cutterhead assembly doesn't have to be removed from the machine when the edge becomes dull, and that can decrease downtime."

Making the switch

Carbide inserts have three major benefits that make them attractive to end-users and well suited for today's CNC machinery. These benefits include longer production runs, elimination of machine adjustment after new cutting tool installation and less tool change downtime.

Many woodworking operations, including cabinet shops and millwork manufacturers, are finding that insert tooling can offer longer production runs than carbide-tipped tooling in many instances. Insert tools can be especially effective for smaller shops that work with plastic laminate because users don't have to wait for bits to come back from a resharpening service.

Ashley Furniture of Arcadia, Wis., uses insert tooling on its Weinig Hydromat 22 moulders to manufacture MDF dresser drawer fronts, according to Dave Piechowski, plant engineer. "We're able to cut 16,000 linear feet of edges with inserts before they need to be replaced, instead of 12,000 to 15,000 linear feet with carbide-tipped knives," said Piechowski. "And the quality of the cut is pretty good."

Picking the right carbide hardness grade of insert for the proper job is important to get maximum performance from the cutting edge.

"Hard, C-4 carbide insert tools shouldn't be used on materials like knotty pine or else you'll get broken knives from striking foreign materials like knots," said Jacks. "Try using a softer C-3 or C-2 insert and make sure the knife does not protrude out too far from the cutterhead. That protrusion will also cause knife breakage."

Insert bits should also not be used for serious plunging work, because that type of machining puts more stress on the end of the knife and can cause the knife to snap, according to Brian Corbley, marketing and technical director with Amana Tool Co.

For the CNC machine user, insert tooling has become popular because cutter edge patterns offer identical patterns and cutting circles, which helps eliminate the need to make machine readjustments when a new cutting edge is installed into the cutterhead. A resharpened head will lose its original edge and cutting diameter; with precision CNC machinery, such as a router, that recalibration can mean longer downtime.

In addition, many insert tools, such as those used on router bits and grinder heads, feature more than one cutting edge on each knife. When an edge wears out, the operator needs only to loosen the holding screw and rotate the knife to its new cutting edge.

"With insert tooling, when a cutting edge wears out, you can just pop in a new one or rotate to a new cutting edge and go," said Gary Metzgar, national products manager of North American Products.

Less machine downtime has allowed South Oak Creek, Wis.-based Bay View Industries, a manufacturer of office furniture tabletops and restaurant tabletops, to get more productivity from its cutting operation.

"We've got five NC routers and we used to use PCD bits to manufacture our tabletops but the PCD bits got to be pretty expensive," said Tom Schumacher, manufacturing manager at Bay View Ind. "We needed a cutter that could keep up with the NC machinery and offer less downtime. Insert tooling meets that demand."

One item about insert tools that should be noted is that the up-front cost to convert over to them can be expensive. But insert tooling manufacturers say that over a reasonable period of time, that initial expense can be quickly recovered.

"An insert tooling head can cost three to four times as much as a brazed head in the beginning, but after a few weeks, you only wind up paying for less expensive knives instead of brazed head resharpenings," Corbley said.

The resharpening question

With its harder cutting surface, insert tooling can offer longer run times. Although an insert tool can be resharpened, the cost to replace one prompts end users to decide whether it is cost-efficient to resharpen a dulled insert or just throw it away.

On one hand, insert tools are relatively easy to resharpen because its tool geometry is not that complex.

"Sometimes we can get as many as seven resharpenings on some insert bits," Piechowski said. "Since we're only performing a face grind on these bits, the integrity of the insert isn't being compromised. With resharpening, we've experienced 35 to 40 percent longer tool life with insert tooling over brazed carbide tools when we're cutting edges on our furniture."

But resharpening inserts can also have drawbacks. The cost of finding a grinding service or affording expensive grinding machinery, as well as safety concerns, are factors to consider when looking at resharpening insert tooling.

"We haven't been able to find an affordable service that does quality sharpenings, and we don't have the expensive grinding equipment either," Schumacher said. "But when you buy the inserts in volume, especially with more than one cutting edge on each knife, it's cheaper that way." He added that his company throws knives away when they become dull instead of resharpening them.

If improper grinding angles are used during resharpening, not only can the knife offer poor performance, it can create a safety hazard.

"A lot of people are resharpening insert bits, but we don't condone it because improper grinding could result in a weakened bit and cause breakage and possible injury to the operator," Jacks said.

The future of inserts

The demand for insert tools has been brisk, according to insert tool manufacturers. Many cutting tool manufacturing companies are adding insert tooling to their product lines. But with selling points like affordability and consistent performance records, does this mean the future of carbide-tipped tools is in jeopardy? According to Jacks, the answer is no.

"Carbide-tipped tools will always be around because they are inexpensive to manufacture," said Jacks. "But for long runs, you can get unbelievably affordable run times with insert tooling."

Available insert tools

The following roundup contains some of the insert tooling available on the marketplace. For further information on these products, circle the corresponding number(s) on the Reader's Service Card or consult the Red Book Buyer's Specification Guide.

Leiser USA Inc. offers carbide insert cutterheads for all types of machines, including CNC moulders, single- and double-end tenoners and routers. Features include constant diameter, constant profile, long cutting life and elimination of sharpening.

Tri-State Tooling Technologies manufactures custom insert tooling. The company can design and engineer special cutters for all types of woodworking applications.

Guhdo USA Inc. offers a universal safety cutterhead for shapers which allows changing a profile by simply changing the knives. This cutterhead is an insert-type head with profile knives made of tool steel. Knives are also available in HSS and carbide. In addition to a selection of 97 standard profiles, which include stile and rail, panel raising profiles, various ogee styles and radius profiles, knives can be ground to customer specifications.

Markay Cutting Tools has expanded its full service cutting tool capabilities. Custom tools, including replaceable inserts, are available, as are brazed cutters, router bits, saw blades and diamond tooling.

Esta-USA Inc. offers the Quick Set Cutterhead which the company says features 30% noise reduction because the gap between the cutterhead body and gibs has been eliminated. It is constructed from a lightweight tensile, wear-resistant alloy and incorporates Esta Dispoz-A-Blade knife inserts for fast change without the use of special jigs or gauges.

Leuco Tool Corp. offers Super Profiler cutterheads to fit CNC and conventional shapers, moulders and double-end machines. Advantages include: one body but many profiles, constant profiles for finer finishes and fast changeover because the solid carbide knives are replaceable.
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Copyright 1993, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:use of insert tools in the woodworking industry
Author:Derning, Sean
Publication:Wood & Wood Products
Date:Jan 1, 1993
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