“You could have standard catalog items delivered the next day,” Plummer said. “But instead of buying 20 new drills, you could have the tools resharpened for a lot less money. There is a wait time, so you have to make sure there are enough tools in the crib so it bridges the wait gap.”

Still, repairing standard tools can provide ample benefits. “A simple indexable tool that is in every shop in the country still costs $80 to $100 new, so repairing it for about $40 is worthwhile,” Klutke added.

Available in two major types: tungsten high-speed steels (designated by letter T having tungsten as the principal alloying element) and molybdenum high-speed steels (designated by letter M having molybdenum as the principal alloying element). The type T high-speed steels containing cobalt have higher wear resistance and greater red (hot) hardness, withstanding cutting temperature up to 1,100º F (590º C). The type T steels are used to fabricate metalcutting tools (milling cutters, drills, reamers and taps), woodworking tools, various types of punches and dies, ball and roller bearings. The type M steels are used for cutting tools and various types of dies.

“Heightened uncertainty also exists in automotive and commercial aerospace markets,” the expert noted.

“While 2024 started on a positive note, we have seen significant stagnation in several markets utilizing cutting tools,” offered Steve Boyer, president of USCTI. “Aerospace has seen many challenges this year, and while we expect to see that market improve in 2025, it has impacted growth for 2024. Modest gains have been realized with orders for the automotive markets but have not fully offset some of the slides attributable to the aerospace industry.

Before (above) and after (below) images show a worn solid-carbide drill resharpened by Specialty Tools.

“Many of our customers are larger manufacturers,” said Jamie Dunneback, product manager of solid-carbide tools and gundrills for Star SU LLC, Farmington Hills, Mich. “Many smaller shops handle tool resharpening on a small cutter grinder, although they might use a local source, depending on the complexity of the tool.”

Stark Industrial performs on-machine probing to find the proper helix angle for resharpening a tool.

Indexable tool repair services typically recommend three repairs for a tool before disposing of it. However, the number of repairs can vary depending on the tool, according to Reiling. It is important to evaluate the application of the tool, the extent of damage and other factors specific to the customer’s needs when determining the repair life a tool has, she said.

It is inevitable that resharpening reduces tool diameter and length. Resharpening a drill or other tool that cuts on its tip affects its diameter less than other tools because only the end is resharpened, so the drill essentially remains the same nominal size. All drills have back taper, meaning they are larger in diameter at the end, so only a minute amount of diameter is lost, Williams noted.

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Before (top) and after (above) images show a worn indexable gear cutter repaired by Carbide Tool Services.

Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

Although a tool resharpening house tends to resharpen all brands, most OEMs only accept their own and may even limit resharpening to certain product lines.

Most companies, large and small, have their cutting tools resharpened, whether they do it in-house or outsource it to the OEM or, more commonly, a tool resharpener.

The main reason tools are not resharpened is because they have been resharpened enough times that there is no more value in them, according to Williams. “Either they are too short or too small in diameter.”

Customers send in boxes of dull tools (above and below) and US Tool, after determining what is economical to resharpen and what is not, resharpens and packages them to be sent back. Customers ship from 30 lbs. up to 3,000 lbs. of tools per week to US Tool.

“Cutting tool demand is likely to show further softness in the second half of 2024, driven by widespread inventory liquidation in many industries,” explained Eli Lustgarten, president of ESL Consultants. “While there are pockets of strength in markets such as government-financed infrastructure and data centers, the farm equipment sector will show dramatically lower production in the second half of 2024. Energy, construction, and mining sector output will decline.

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Whether specials or standards, tool resharpening makes great economic sense. “The key is to get good- quality regrinds so you don’t have to adjust speeds and feeds or sacrifice part finishes or other part requirements because you are using a resharpened tool,” Plummer said, adding that receiving them back in a timely manner is also important. “If that is happening, it works for the whole industry. That is what makes it click.” CTE

All cutting tools eventually wear or break. It is up to end users as to how much tool life they are going to get before a cutter is gone for good. Resharpening cutting tools is a well-established practice, but when does it make sense to regrind instead of buying new? That’s a question any user of carbide and HSS rotary tools should consider. There are many variables in the equation: the tool’s geometry, substrate, coating, wear, damage and application all play a part in the decision to resharpen a tool.

Rush services are available and a tool can be rebuilt in a day or two, depending on the tool. “We receive projects daily that need to be turned around in 24 hours or less because the customer is shut down or running without backup tooling,” Reiling said.

“In the past 10 years there has been an explosion in tool geometries, with things like variable helixes and differential helixes,” he continued. “The first thing we do before resharpening is probe the helix to find the helix angle. We have to probe each flute because they are often different on some high-performance tools.”

After resharpening, coated tools are typically recoated, either in-house by the tool resharpener or outsourced.

The second reason a tool might not be resharpened is damage, such as broken edges, structural problems or extensive margin wear. However, many broken or excessively worn drills are salvaged. The damaged section is cut off and the drill point is reestablished.

Depending on the complexity of the tool geometries, Star SU works with customers to determine maximum tool life and when the tool should be taken out to maximize the number of regrinds and maintain part print tolerances, Dunneback noted.

“You can save from 35 to 80 percent on the cost of a new cutting tool by having it resharpened,” said Bruce Williams, president of US Tool Group, Farmington, Mo., with a savings of about 50 percent being the most common. With 400 employees, US Tool reconditions more than 500,000 cutting tools per week. Customers ship 30 lbs. to 3,000 lbs. of a variety of tools per week to US Tool.

In general, the bigger the tool, the more economical it is to resharpen. “For example, a ½ "-dia., through-coolant drill that goes 10 diameters deep might cost $170 and can be resharpened for $25 to $30,” said Jerry Plummer, president of Specialty Tools Inc., Beloit, Wis., which specializes in solid-carbide high-performance drills. But Specialty Tools generally draws the line at solid-carbide drills 1⁄4 " in diameter and smaller for sharpening because it is not as economical.

Milling cutter held by its shank that cuts on its periphery and, if so configured, on its free end. Takes a variety of shapes (single- and double-end, roughing, ballnose and cup-end) and sizes (stub, medium, long and extra-long). Also comes with differing numbers of flutes.

If a tool is “pulled” before there is any chipping or significant wear, only a minimal amount of material is removed during regrinding, enhancing the economic gain. “We spend a lot of time educating our customers about tool wear, and most are knowledgeable, but we still get tools in all the time that are too far gone and not economical to resharpen,” Wilkof said.

Gear hobs and cutters, because of their high cost, are almost universally reconditioned. “Most gear cutters are designed for resharpening and reconditioning, where the tool user has an expectation of how much life the tool can provide and, therefore, has a systematic method of running the tool, pulling it out to resharpen and recoat, and then reinstalling it,” said Tom Bell, vice president of sales for cutting tools at Star SU’s facility in Hoffman Estates, Ill.

Feature that allows the operator to compensate for tool diameter, length, deflection and radius during a programmed machining cycle.

The number of times a cutting tool can be resharpened depends on tool type and condition, but three to six times is typical. For instance, a general-purpose drill might be resharpened five or six times before being discarded, but a drill for making tight-tolerance holes might only be reground three times, according to cutting tool resharpeners.

Indexable tools are not repairable when damage negatively impacts overall tool integrity. “The issues that we see where the tool shouldn’t be repaired are a cracked or bent tool. If the damage affects the integrity of the original structure, we recommend replacing it,” Reiling said.

In GKI’s process, it removes the entire damaged section of the tool and material congruent with the original material is added. Insert pockets, coolant holes and screw holes are recut into the new material.

“All of the tools we resharpen are recoated,” Specialty Tools’ Plummer said. “We do not strip the existing coating because it is harmful to the carbide substrate. With the few main types of coatings that we use, we achieve good coating adhesion over the existing coating. Coating thickness is generally never an issue. Even if a tool is coated over and over and suffers some adhesion issues on the existing coating, the new, sharpened cutting edge is not affected by the multiple layers of coating.”

2-D or 3-D path generated by program code or a CAM system and followed by tool when machining a part.

“We are building on material, where they are taking it off,” said Julie Reiling, president of Carbide Tool Services Inc., Anoka, Minn., an ISO-certified company that specializes in indexable tool repair. “We pride ourselves on economically repairing damaged tools to their original specifications without compromising the integrity of the manufacturer’s original material.”

CNC machine tools have adjustable offsets, making it possible to apply resharpened tools. “CNC machines are programmed to compensate for the actual diameter and length of each tool and recalculate the toolpath to maintain the finished workpiece geometry,” Williams said. “More cost-effective and cost- conscious companies use cutter compensation effectively so they can use their tools multiple times.” (It is common practice for most tool sharpening services to label the tool package with the new diameter.)

“While tempering our enthusiasm for the second half of 2024, expectations for cutting tool order growth are still very positive for 2025,” Boyer added.

It helps if the customer practices preventative maintenance. “We have a customer that makes large diesel engines,” Klutke said. “Imagine a 48 " milling cutter that costs $60,000 to $70,000 new that is used to machine an engine. The customer sends that tool in even though there is no visible damage. We essentially give it a tune-up so the cutter continues performing like new.”

When resharpening an endmill, however, the material removed from the cutting edges does decrease the diameter.

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Typical turnaround time for repaired indexable tools is 3 weeks. The repair service is even more critical for delivery of custom tools, as new tools can take up to 16 weeks from the OEM.

Cutting tool purchases fell -2.9% in value from May to June 2024, totaling $208.1 million in the latest Cutting Tool Market Report issued by AMT - the Assn. for Manufacturing Technology and the U.S. Cutting Tool Institute. The June figure is also -4.2% lower than the June 2023 result, and it brings the January-June 2024 value for cutting tool purchases to $1.27 billion – which is still 2.6% higher than last year’s six-month total.

Loosely, any milling tool. Horizontal cutters take the form of plain milling cutters, plain spiral-tooth cutters, helical cutters, side-milling cutters, staggered-tooth side-milling cutters, facemilling cutters, angular cutters, double-angle cutters, convex and concave form-milling cutters, straddle-sprocket cutters, spur-gear cutters, corner-rounding cutters and slitting saws. Vertical cutters use shank-mounted cutting tools, including endmills, T-slot cutters, Woodruff keyseat cutters and dovetail cutters; these may also be used on horizontal mills. See milling.

Carbide and high-speed-steel tools coated with thin layers of aluminum oxide, titanium carbide, titanium nitride, hafnium nitride or other compounds. Coating improves a tool’s resistance to wear, allows higher machining speeds and imparts better finishes. See CVD, chemical vapor deposition; PVD, physical vapor deposition.

Space provided behind the cutting edges to prevent rubbing. Sometimes called primary relief. Secondary relief provides additional space behind primary relief. Relief on end teeth is axial relief; relief on side teeth is peripheral relief.

Any type of tool with an insert pocket can be considered for repair. “Savings on a repaired indexable tool can be from 50 to 85 percent over the purchase of a new tool,” said Olaf Klutke, president of GKI Cutting Tools, Crystal Lake, Ill., an indexable tool service that repairs about 30,000 different tools a year. “Savings on standard tools are typically lower, but savings for custom tools [which are usually costlier than standards] are more significant.”

However, for large manufacturers that consume hundreds if not thousands of cutting tools monthly, it can still be economical to sharpen tools no matter the size. “Because US Tool processes 500,000 cutting tools per week, setup and operational costs are amortized,” Williams said. “Even twist drills costing less than $1 can be economically resharpened for heavy users of twist drills.” Carbide drills down to 1⁄16 " in diameter are routinely resharpened, he added.

Most types of round cutting tools are resharpened, with the majority being specials. “About 70 percent of our work involves custom tools, meaning the customer has a specific print and we recondition to that print, and about 30 percent are standards,” US Tool’s Williams said.

Williams pointed out that even a 5 percent savings on some isolated cutting tools still makes resharpening worthwhile because the customer already owns the tools. “There is no procurement process, no purchase order needed for that specific tool,” he said.

Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

Customers generally let the tool resharpener determine what tools are cost-effective to resharpen. “The customer sends in a whole box of dull tools—drills, endmills, custom tools, everything—and asks us to evaluate what is economical to resharpen and what is not,” said Jonathan Wilkof, manufacturing engineer, Stark Industrial LLC, North Canton, Ohio. In addition to operating as a job shop, Stark makes and resharpens cutting tools.

Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.

When shipping a custom tool for repair, it helps to include components like setscrews and inserts in the package. In addition, the tool repairer should have a copy of the original blueprint for a special to ensure it is being repaired to original specifications. “Because of the very tight tolerances that are required on many indexable tools, it is important that we have accurate documentation and communication with the customer when rebuilding their tooling,” Reiling said.

Coated or not, typical lead times for resharpened tools range from 2 to 4 weeks, although rush service is available.

When Stark Industrial designs cutting tools, it prefers to use cam relief for its endmills, Wilkof noted. “The benefit of cam relief is that when you resharpen the tool, you only have to resharpen the flute face, right at the cutting edge. If you have a primary and secondary relief, then you have to essentially resharpen the form itself and add back the primary and secondary relief, which takes more time and costs more.

GKI’s repair process takes a damaged indexable drill through a process, from left to right, of cutting off the damaged end of the tool, adding new material and machining a new end on the tool, which results in a repaired tool with a new pocket, screw holes and coolant holes.

USCTI and AMT’s monthly Cutting Tool Market Report, summarizes shipments made by companies who comprise the majority of the U.S. market for cutting tools – whose customers are contract machine shops (job shops) and OEMs for whom cutting tools are significant consumable.

Manufacturers’ demand for cutting tools closely matches U.S. durable goods shipments as a measure of overall industrial activity, and according to an analyst cited by AMT the remainder of 2024 does not appear to result in increased manufacturing activity.

Tool damage is generally caused by routine wear and tear but could be the result of a crash. Carbide Tool Services removes the damaged area from the tool pocket, builds up the damaged area with proprietary welding rod that matches the original material and machines it to OEM specifications. “We control our welding process, and the material we use, to match the variety of materials used today,” Reiling said.