For shops that primarily machine ferrous materials, magnetic conveyors are commonly method of chip disposal. They use a series of rare earth or ceramic magnets mounted beneath a stainless steel conveyor belt to pull scrap up an incline. At the top, the magnets retract to release the scrap, which falls into a waste bin or another conveyor system.

Machine protection provider Hennig Inc., Machesney Park, Ill., also makes and sells conveyors. Scott Cooley, chip conveyor and filtration system business manager, said the company offers several flavors, including magnetic conveyors, scraper-type conveyors for cast iron, bronze and brass machining, and general-purpose, hinge-style ones. Of these, hinged conveyors account for 90 percent of Hennig’s conveyor sales.

Secures a cutting tool during a machining operation. Basic types include block, cartridge, chuck, collet, fixed, modular, quick-change and rotating.

Tangential velocity on the surface of the tool or workpiece at the cutting interface. The formula for cutting speed (sfm) is tool diameter 5 0.26 5 spindle speed (rpm). The formula for feed per tooth (fpt) is table feed (ipm)/number of flutes/spindle speed (rpm). The formula for spindle speed (rpm) is cutting speed (sfm) 5 3.82/tool diameter. The formula for table feed (ipm) is feed per tooth (ftp) 5 number of tool flutes 5 spindle speed (rpm).

Carbide-USA quotes recycled carbide and accepts shipments of carbide scrap materials that weigh under 70 lbs. (31.8 kg). It also accepts carbide sludge from oil- and water-based coolant filtration systems, as well as cartridge-type filters. Carbide sludge is typically shipped to Carbide-USA in barrels.

There are many reasons to invest in a chip management system. The first is uptime. Every minute an operator spends with a shovel in his hand is a minute he isn’t checking tools or loading parts. The first line of defense in this case is a scrap conveyor, which removes machining waste from a machine tool to a drum or wheeled bin for transport, while giving the shovel an early retirement.

1. Permanently damaging a metal by heating to cause either incipient melting or intergranular oxidation. 2. In grinding, getting the workpiece hot enough to cause discoloration or to change the microstructure by tempering or hardening.

That’s not to say chip management is a lost cause for smaller shops. Chip conveyors are still a good investment, reducing the time needed to shovel out the chip pan, improving efficiency and worker disposition. Clever job scheduling and dedicating machines to certain materials minimizes contamination, thus increasing the price received from the scrap man. And medium-size shops with a dozen or so machines running common materials may benefit from centrifuges and briquetting systems. Whatever the solution, it’s time to get rid of those shovels. They’re a real backbreaker. CTE

Instead, many shops opt for vacuuming chips to a central location or “pump backs” that use coolant to flush the chips to a holding tank for processing. Whichever way you go, stringy chips can create problems. Applying cutting tools with chipbreakers help, but some chips still don’t behave. For this situation, shredders are needed. “Auto-makers use these on their crank and camshaft lines,” Zeitz said. “The other option is a cutter pump, which breaks up small strings and allows them to be move through the recycling system.”

The sawtooth edge on a hinged-belt conveyor helps grab stringy chips and pull them out of a machine. Image courtesy Hennig.

Kip Hanson is a contributing editor for Cutting Tool Engineering magazine. Contact him by phone at (520) 548-7328 or via e-mail at kip@kahmco.net.

WS40PM was designed to meet the needs of the aerospace, defense, and medical industries, where titanium is used for everything from landing gear and seat tracks to lifesaving implants and surgical instruments. As the testing results show, however, WS40PM is suitable for far more than titanium. High-temp steel alloys, austenitic and PH stainless steels, nickel-based superalloys such as Hastelloy and Nitronic—these materials cause tool failure due to built-up edge (BUE), notching at the depth of cut line, cratering, chipping and extreme heat generation, which in the case of wet-cutting operations lead to cracking.

Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.

Success with superalloys takes more than a good carbide grade, however. Sperhake also recommends increasing the cutting fluid concentration, and using a high-pressure coolant pump wherever possible. Selecting the right cutter body for the application is likewise important. WIDIA’s VSM490 shoulder mill offers a state of the art insert and cutter design, one that supports WS40PM and other high-performance grades.

In each instance, WS40PM competed with the test subject’s legacy carbide grade. Speeds and feeds were kept the same or in some cases increased to take advantage of WS40PM’s exceptional toughness, wear-resistance and ability to resist thermal cracking.

“We have a customer in Iowa that machines a lot of aluminum,” Zeitz said. “Due to their large chip volumes, and because the scrap hauler was charging a fee for every pickup, the company invested in a system that shreds and compacts the material into briquettes.”

Filtering device that uses a spinning bowl and the differences in specific gravities of materials to separate one from another. A centrifuge can be used to separate loosely emulsified and free oils from water-diluted metalworking fluid mixes and to remove metalworking fluids from chips.

Ability of a tool or component to be flexed repeatedly without cracking. Important for bandsaw-blade backing.

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.

1. Permanently damaging a metal by heating to cause either incipient melting or intergranular oxidation. 2. In grinding, getting the workpiece hot enough to cause discoloration or to change the microstructure by tempering or hardening.

That may seem like a lot of money, but without clean cutting fluid, tool life and part quality suffer. Mike Hook, responsible for North American sales at chip and fluid management systems manufacturer PRAB Inc., Kalamazoo, Mich., said the cutting fluid aspect of chip management is frequently overlooked. “Before you send a dumpster full of wet or oily chips down the road, consider the cost of those cutting fluids, as well as the environmental impact of not recycling them.”

Don Suderman, material handling product manager for Bunting Magnetics Co., Newton, Kan., said scrap conveyors aren’t optional. “Unless you need the exercise or have the extra manpower, there are easier and more economical ways of handling scrap steel than moving it with a shovel.”

My first shop job was shoveling brass chips from the tail end of an Acme Gridley screw machine. Each afternoon I went home with my pants reeking of sulfur-based oil, my legs covered in rashes and my 16-year old back afire from hauling 55-gal. drums of oily swarf. I lasted 2 weeks.

Stainless steels possess high strength, heat resistance, excellent workability and erosion resistance. Four general classes have been developed to cover a range of mechanical and physical properties for particular applications. The four classes are: the austenitic types of the chromium-nickel-manganese 200 series and the chromium-nickel 300 series; the martensitic types of the chromium, hardenable 400 series; the chromium, nonhardenable 400-series ferritic types; and the precipitation-hardening type of chromium-nickel alloys with additional elements that are hardenable by solution treating and aging.

All of this is good news for the shop making lots of aluminum aircraft components annually or the Tier 2 automotive supplier cutting trainloads of engine blocks. But for the typical job shop, there’s less joy here. High-tech automated systems are designed to efficiently process a single material. Switching a chip management system from one material to another means extensive cleaning to prevent cross-contamination. Yet many mom-and-pop shops machine dozens of different materials every week, and no one has yet invented a cost-effective way to separate, for example, stainless steel chips from brass ones.

Sperhake recommends a balanced approach to cutting parameter selection. “As radial engagement increases, cutting speeds should be reduced proportionately,” he says. “That’s because the amount of heat entering the insert goes up substantially on heavy cuts. At around 90 percent engagement, for instance, you’ll probably want to reduce the RPM by 25 percent or so, depending on the material. Feed rates may also have to be lessened somewhat, depending on setup and machine rigidity. And smaller cut widths, of course, spindle speed and feed rates should be kicked up substantially.” “Going too easy” is a common mistake when machining titanium and other difficult materials, Sperhake says, leading to poor productivity levels and shortened tool life. For example, problems such as BUE and edge wear can often be eliminated by pushing the tool harder. “Tool life, especially in superalloys, is a three-legged stool of feed, speed and cutter engagement. Each has a direct impact on the others.”

It’s much easier to design a shop for an automated scrap handling system than it is to retrofit one. Trough-style conveyors are an effective way to transport chips for processing, but may require extensive concrete cutting and remodeling. And environmental concerns over leaks and groundwater contamination are making some companies look towards the ceiling, with overhead conveyors, rather than down at the floor for chip management. “In-floor systems seem to be getting fewer and farther between,” said Ed Zeitz, sales engineer at Mayfran International Inc., Cleveland.

Depressions formed on the face of a cutting tool caused by heat, pressure and the motion of chips moving across the tool’s surface.

WS40PM’s cobalt-rich substrate provides robust fatigue resistance and edge integrity, while the multiphase AlTiN-TiN PVD coating reduces tool wear, making it suitable for a range of high-temp steel alloys, austenitic and PH stainless steels, nickel-based superalloys such as Hastelloy and Nitronic, and titanium.

Liquid used to improve workpiece machinability, enhance tool life, flush out chips and machining debris, and cool the workpiece and tool. Three basic types are: straight oils; soluble oils, which emulsify in water; and synthetic fluids, which are water-based chemical solutions having no oil. See coolant; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

Tough, difficult-to-machine alloys; includes Hastelloy, Inconel and Monel. Many are nickel-base metals.

Only 5 percent of the world’s reserves of tungsten ore−the primary ingredient of cemented carbide cutting tools−are in the U.S. Some reserves are located in Russia, Canada and other countries, but China holds 60 percent of the planet’s tungsten reserves, according to the U.S. Geological Survey. Bill Walter, president of carbide recovery firm Carbide-USA, Elmira, N.Y., said this is a darned good reason to recycle carbide in the U.S. “The Chinese already have most of the ore. Domestic recycling gives us more raw material to work with at home.”

Cemented carbide is tough stuff. For those wondering about the monstrously powerful process used to mash scrap inserts and endmills into tungsten powder, it’s not that exciting. It 's called zinc processing and works when graphite “boats” are loaded with scrap carbide, then filled with molten zinc. The carbide gradually swells like a marshmallow over a campfire, leaving a porous cake that is ground into tungsten-cobalt powder, suitable for blending with virgin tungsten.

Conveyors can be equipped to do more than move chips. Small metal fines can plug high-pressure coolant systems and damage pumps, while tramp oil eventually turns even the most pristine machine sump into a swampy mess. To combat these problems, Cooley recommends a chip disc-filtration system, an integrated hinged or scraper belt conveyor that includes disc-style permanent media filters, high- and low-pressure pumps and an inline oil skimmer. System cost ranges from $15,000 to $35,000, depending on the configuration.

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The other recycling process is electrochemical and breaks cemented carbide into its constituent components. It’s a bit more complex, but yields tungsten powder indistinguishable from its original form. “It becomes virgin material again,” Walter said. “You can use it to create anything−endmills, drills, inserts, whatever. It’s more expensive than zinc recycling, but gives you greater flexibility with the product.”

Of course, that wasn’t the last time I shoveled out a chip pan. In a machine shop, dealing with chips is part of the job. But chip management shouldn’t mean oily clothes, skin rashes and cut fingers. Manufacturers of material handling equipment offer many different solutions to tame pesky chips, preserve the environment and improve profitability.

While costly, payback for a shop with a few dozen machines running 24/7 can be relatively quick—6 months—or much longer—up to 6 years—depending on the materials being recovered, the volumes and the initial investment. The payback comes from significantly reducing coolant loss and generating clean, dry chips that bring a premium price.

Depending on the briquetter, compacted aluminum briquettes weigh around 125 lbs./cu. ft. and are nearly 10 times denser than loose chips, saving considerable storage space. And scrap dealers sometimes pay two to three times as much for briquettes compared to noncompacted material.

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.

A MagSlide conveyor can carry more than chips. In this application, fasteners are removed from a cold heading machine. Image courtesy Bunting Magnetics.

About the Author: Kip Hanson is contributing editor for CTE. Contact him at (520) 548-7328 or khanson@jwr.com.

Another consideration is volume, especially for light, fluffy chips, such as aluminum and zinc ones, or for shops in rural areas where the scrap man might have to drive long distances. For these chip producers, minimizing the size of their machining waste brings maximum value.

Josef Fellner, WIDIA Products Group’s manager portfolio management for turning and indexable milling, says the company recently took its newest advanced milling grade, WS40PM, on a world-wide testing tour. The results have been quite impressive: ♦ An aircraft manufacturer enjoyed a 90 percent reduction in machining time per piece and increased tool life by 50 percent during Ti-6Al-4V face milling operations. ♦ Insert flank wear decreased by more than 90 percent at a UK shop cutting Inconel 625, resulting in a 70 percent reduction in tooling costs. ♦ At a turbocharger producer in China, tool life increased 80 percent while machining an austenitic stainless steel component using WS40PM, with improved part surface quality, reduced cutting forces and better chip flow. ♦ In another titanium component, the WS40PM/VSM490-15 platform doubled metal-removal rates and delivered 80 percent longer tool life through increased depth of cut and feed per tooth in face and shoulder milling operations. ♦ The testing laboratory for a well-known brand of machine tools reports metal-removal rates 49 percent greater when shoulder milling Ti-6Al-4V.

Runs endmills and arbor-mounted milling cutters. Features include a head with a spindle that drives the cutters; a column, knee and table that provide motion in the three Cartesian axes; and a base that supports the components and houses the cutting-fluid pump and reservoir. The work is mounted on the table and fed into the rotating cutter or endmill to accomplish the milling steps; vertical milling machines also feed endmills into the work by means of a spindle-mounted quill. Models range from small manual machines to big bed-type and duplex mills. All take one of three basic forms: vertical, horizontal or convertible horizontal/vertical. Vertical machines may be knee-type (the table is mounted on a knee that can be elevated) or bed-type (the table is securely supported and only moves horizontally). In general, horizontal machines are bigger and more powerful, while vertical machines are lighter but more versatile and easier to set up and operate.

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“If you look at what chip management costs in terms of labor and downtime, it doesn 't take long to justify some automation,” Hook said. “Every minute spent manually cleaning a chip tank or wrangling chips into a scrap bin costs money. Also, the cost of fluid handling can quickly add up. That’s why it’s important to select a chip management system that not only dries the chips but recovers and recycles cutting fluids to like-new condition.”

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.

“Job shops might cut Inconel one day, brass or aluminum the next,” Cooley said. “In this situation, a hinged conveyor works best. It can handle long, stringy chips from stainless steel machining, very fine chips from cast iron machining and anything in between.”

Phenomenon leading to fracture under repeated or fluctuating stresses having a maximum value less than the tensile strength of the material. Fatigue fractures are progressive, beginning as minute cracks that grow under the action of the fluctuating stress.

Liquid used to improve workpiece machinability, enhance tool life, flush out chips and machining debris, and cool the workpiece and tool. Three basic types are: straight oils; soluble oils, which emulsify in water; and synthetic fluids, which are water-based chemical solutions having no oil. See coolant; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

Tool-coating process performed at low temperature (500° C), compared to chemical vapor deposition (1,000° C). Employs electric field to generate necessary heat for depositing coating on a tool’s surface. See CVD, chemical vapor deposition.

As the name implies, hinged conveyors use a cleated steel belt that looks like the tread on a battle tank to grab chips and carry them out of the machining area. Like a tank, the belt is rugged and handles heavy loads.

Suderman said magnetic conveyors have no external moving parts, making them relatively jam-proof. By running the conveyor at a low speed, much of the cutting fluid that would otherwise be carried with the chips drains back into the machine. A basic system starts at around $10,000.

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“WS40PM’s advanced cobalt-rich substrate provides robust fatigue resistance and edge integrity, while the multiphase AlTiN-TiN PVD coating reduces wear,” says Mike Sperhake, EMEA-region product specialist for WIDIA. “Using an initial cutting speed of 175 ft/min (53 m/min) we’re seeing 25-35 percent productivity gains and consistent improvement in tool life, even when milling very tough materials like Ti-5553 and Super Duplex steels.”

This is especially true with cutting oils, which can run $20 or more per gallon—10 to 20 times the cost of water-soluble cutting fluids. For heavy users of cutting oil, such as Swiss-style CNC shops and screw machine houses, this can mean big bucks. Recycling a ton of brass chips contaminated with just 5 percent by weight of oil could mean a loss of $5,000. Likewise, shops that generate a dumpster’s worth of aluminum chips each week may lose comparable amounts of money in water-based cutting fluid.

Finally, consider the machine tool, toolholder and spindle interface. Rigidity across the board is needed for productive titanium machining. WIDIA offers the KM4X platform, which according to Global Product Manager Bill Redman is “the strongest connection available, period,” and is available on a wide variety of toolholders and machine tools alike. Says Sperhake, “From Tier 1 aerospace suppliers to the job shop on the corner, everyone wants the same things from a tooling solution: higher accuracy, better surface finish, reliability and productivity. All are critical factors to their success, and that’s what we intend to deliver. WS40PM is a big part of that.”

Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.

Whatever the extraction process, Walter said there needs to be greater effort towards recycling. “At current rates, shops can get around $8 per lb. or more for clean scrap carbide, but most figures show recycling rates at only 35 percent. It needs to be much higher. It’s good for the environment and, provided we keep it here, good for the U.S. as well.”

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.

But why bother? Scrap steel and iron isn’t worth very much—a pound of clean, dry chips fetches only 35 to 65 cents from a dealer. But in today’s green world, keeping waste out of the landfill is important. According to the American Iron and Steel Institute, steel is the world 's most recycled material and suffers no degradation with repeated processing.

Distance between the bottom of the cut and the uncut surface of the workpiece, measured in a direction at right angles to the machined surface of the workpiece.

Reduction in clearance on the tool’s flank caused by contact with the workpiece. Ultimately causes tool failure.

A complete, automated chip processing system from PRAB includes volume reduction, a shredder, a centrifuge and conveyors. Image courtesy PRAB.

Oil that is present in a metalworking fluid mix that is not from the product concentrate. The usual sources are machine tool lubrication system leaks.

One solution is spinning. Centrifuges are the metal equivalent of heavy-duty salad spinners; they quickly turn wet chips into dry ones. Some shops keep it simple: Fill the chip carts on a regular schedule, pull them to a central processing system, dump them in the hopper and push the button. “There’s some manual labor involved, but it’s minimal,” Hook said. The alternative is an automated system that conveys the chips to the processing unit. Depending on the shop, this can cost $100,000 to $1 million or more.