HITACHI Carbide Insert – Page 2 - hitachi carbide insert

Like mechanical trepanning, laser trepanning produces a core when holemaking. To cut those holes, the laser is turned on and moves in a circular path until the hole is completed, explained Stuart Woods, director and general manager of direct diode and fiber systems for Coherent Inc., Santa Clara, Calif.

Another alternative, thermal drilling, offers the advantage of reducing cycle time compared to conventional drilling, according to Mitch Ray, president of Flowdrill Inc., St. Louis, a manufacturer of tool bits for thermal drilling and roll-form threading. Also known as friction or flow drilling, the process’ main cost-saving improvement comes from reducing the number of operational steps. For example, an end user may be placing a fastening device, such as a threaded insert or ribbed nut, into a drilled hole and can flow drill and thread the same features without having to pay for the fastening devices, and the labor to position them and remove the generated debris.

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The local extraction units are the key to the program. “We used to have to ship the entire drill bits to facilities around the world,” says Kangleas. “And the extraction of the cemented carbide then required a very unsafe and energy intensive process. By doing this in a safe and efficient way at the point of use we now only transport the material we need. This significantly reduces our transport emissions. We can also provide jobs on the local extraction units to people in the local communities.”

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

For example, compared to drilling with a solid or indexable-insert drill and circular interpolating with an endmill, trepanning requires less machine horsepower, produces a slug, or core, of material that can be used to make other parts and can create holes with a larger depth-to-diameter ratio. “If people are trying to produce large-diameter holes and their machines don’t necessarily have the horsepower to push a solid drill, a good alternative is a trepanning tool,” said Mark Sollich, president of BTA Heller Inc., Troy, Mich.

BTA Heller offers standard indexable-insert trepanning tools with replaceable carbide pads and cartridges from 2½ " to 30 " in diameter, with the majority from 3 " to 8 " in diameter, Sollich noted. The pads help guide the tool, maintain hole straightness and semiburnish the ID. The tools are rated to produce holes 100 diameters deep, “but it’s possible to go deeper,” Sollich said. “The main limitation is your machine tool and not necessarily the tooling.”

Woods noted that various types of lasers are available for producing holes in metal, including sealed CO2 and fiber lasers. “Typically, if you’re looking at metals, CO2 does a very good job,” he said. “It gives you the most functionality.”

It’s not enough to achieve a precise hole location and size tolerance at the start of a hole. “We look at the total quality of the hole though the bore,” Kinder said. “Otherwise a core pin will get canted or an ejector pin will wear and gall and finally seize up.”

He noted that end users can apply trepanning tools on standard machines, such as lathes with OD chip exhausts, as well as dedicated deep-hole drilling machines for performing BTA (named after the Boring and Trepanning Association) drilling, where coolant is introduced around the tool and chip evacuation occurs through the tool’s center and the tube drill that drives it.

Intensified, pulsed beams of light generated by lasers—typically carbon dioxide or neodium-doped yttrium aluminum garnet (Nd:YAG)—that drill, weld, engrave, mark, slit and caseharden. Usually under CNC, often at both high cutting rates (100 linear in./sec.) and high power (5kW or more). Lasers also are used in conjunction with in-process quality-control monitoring systems allowing measuring accuracies of 0.00001".

Cylindrical sleeve, typically made from high-grade tool steel, inserted into a jig fixture to guide cutting tools. There are three main types: renewable, used in liners that in turn are installed in the jig; press-fit, installed directly in the jig for short production runs; and liner (or master), installed permanently in a jig to receive renewable bushing.

Enlarging a hole that already has been drilled or cored. Generally, it is an operation of truing the previously drilled hole with a single-point, lathe-type tool. Boring is essentially internal turning, in that usually a single-point cutting tool forms the internal shape. Some tools are available with two cutting edges to balance cutting forces.

Cutting tool materials based on aluminum oxide and silicon nitride. Ceramic tools can withstand higher cutting speeds than cemented carbide tools when machining hardened steels, cast irons and high-temperature alloys.

A shorter bushing can be formed by using a pilot hole, with a larger pilot hole used for generating a shorter bushing length. Where there’s a need to reduce the amount of restriction for the flow of air, liquid or gas through a pipe, for example, a shorter bushing would be required. But that’s an exception.

Drilling deep holes that are too large to be drilled by high-pressure coolant drills or gundrills. Trepanning generates a solid core and normally requires a big, powerful machine. Shallow trepanning operations can be performed on modified engine or turret lathes or on boring machines. See boring; drilling; spade drilling.

Even so, those machines primarily create holes from 0.025 " to 0.040 " in diameter and PDC often needs to rough sinker EDM 0.006 "- to 0.007 "-dia. start holes in 400 series stainless steel. The company then finish wire EDMs holes as small as 0.010 " in diameter with a wire as small as 0.002 " in diameter to eliminate bellmouthing and achieve the final size. “We don’t concern ourselves with the fine-hole recast finish due to the clean up with the wire EDM,” Kinder added.

BTA Heller offers indexable-insert trepanning tools with replaceable carbide pads and cartridges from 2½ " to 30 " in diameter.

Regardless of the type of application, Sollich recommends a load meter for monitoring down-hole conditions when trepanning. A rising load meter reading indicates tool wear and the onset of potential problems. “A load meter can be set to a level where if an insert wears out or potentially breaks, the machine will automatically shut down before a catastrophic failure occurs,” he said.

Conversion of an ingot or billet into lengths of uniform cross section by forcing metal to flow plastically through a die orifice.

Hole or cavity cut in a solid shape that connects with other holes or extends all the way through the workpiece.

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.

Many end users consider EDM holemaking to be the realm of fast-hole EDMs, or hole poppers, but that’s generally not the case for holes requiring precision because hole poppers use a higher input voltage than sinker EDMs and employ a water dielectric. “Those two in combination give you excellent machining speed, but inversely equate to less hole accuracy for straightness and roundness and a rougher surface finish,” Bradford said.

Minimum and maximum amount a workpiece dimension is allowed to vary from a set standard and still be acceptable.

When matching a type of laser with a work material, Woods noted that it’s important to know the material’s absorption profile so it will absorb the laser and have an interaction. Coherent’s applications laboratory regularly evaluates customers’ workpiece samples and provides feedback about the laser wavelength that will work best based on the application.

As the required hole diameter increases, the amount of coolant flow (in gpm) also increases. The rule of thumb is a machine needs to deliver 25 to 30 gpm per inch in diameter, meaning a 3 "-dia. hole requires 75 to 90 gpm to properly flush the chips, according to Sollich.

Conventional drilling is the most common metalworking operation, with 92 percent of CTE readers performing it, according to a recent survey by market researchers ReadexResearch. But conventional drilling isn’t the only way to make a hole. Depending on the application and a manufacturer’s available equipment, alternative holemaking methods may be a better choice. Presented here are the pros and cons of using trepanning tools, thermal drills, lasers, electron beams and EDMs when holemaking.

High-power CO2 lasers are suitable for drilling holes from about 100µm to millimeter size in metal foils, such as stainless steel, with a thickness down to 0.1mm, whereas fiber lasers are better suited for thicker materials, according to Woods. That’s because a CO2 laser tends to form a kerf when cutting thicker materials.

For the tightest tolerance holes, Bradford noted that an ultraprecision wire EDM tops a fine-hole sinker. For example, a user could feed a 15µm-dia. wire through a 30µm-dia. start hole to produce a hole with 500nm circularity. “But the wire’s primary advantage is you’re minimizing recast and also producing a surface finish that is two to three times better or more than what you could produce on our fine-hole sinkers,” he said. Bradford noted that the recast layer from a fine-hole sinker is about 2µm at a hole transition edge and in the double-digit nanometer range for a wire. A tungsten-carbide electrode could impart a 0.17µin. Ra finish.

Because the process is performed in a vacuum, it’s usually not economically feasible to electron beam drill a small number of holes. The process is also not suitable for workpieces with a low melting temperature, such as many plastics. Compared to conventional drilling, however, electron beam drilling quickly produces a large number of holes. “Try putting six million holes in a part with any other process,” Norsworthy boasted.

Off the EDM, PDC uses a Nikon VMR vision measurement system, which Kinder noted is “good down to about 1 micron,” but setup and wall effect light reflection issues can impact repeatability. “If we can’t establish repeatability to half of what we’re trying to discriminate, then we’re not going to hang our hat on it.”

“It’s good for local communities because with the extraction units we can create local jobs and it is good for the planet because by mining less tungsten and using less virgin material we use less resources and emit lower amounts of CO2. And it is good for Sandvik because it is a cost save. We can produce the same quality drill bits with a lower material cost. It is just good for everybody,” says Kangleas.

Unlike trepanning, thermal drilling uses a tool without a hollow core and doesn’t produce any chips. When flow drilling, a tungsten-carbide tool bit with a four-lobe geometry contacts the workpiece material using an axial pressure from 180 to 900 thust lbs., depending on tool bit diameter and the material type and thickness, and heats the workpiece to be soft and malleable enough to be formed and perforated, according to Flowdrill (see photo on page 30). “Those four lobes generate the friction, or heat, as the tool spins against the material,” Ray said. He added that the typical spindle speed is from about 900 to 3,000 rpm.

In his latest Laser Points column on MICROmanufacturing.com, the Web site for CTE’s sister publication, Ronald D. Schaeffer, CEO of laser job shop and systems integrator PhotoMachining Inc., Pelham, N.H., stated that the three most common laser holemaking methods are single shot, percussion and trepanning. All can be performed with a fixed-beam system or one in which mirror movement is controlled by a galvanometer. In practice, though, single shot and percussion are done more often with fixed-beam systems while trepanning tends to be performed with a galvo system.

Process that vaporizes conductive materials by controlled application of pulsed electrical current that flows between a workpiece and electrode (tool) in a dielectric fluid. Permits machining shapes to tight accuracies without the internal stresses conventional machining often generates. Useful in diemaking.

The majority of trepanning applications, whether producing drill collars and pipes for the oil field industry, aircraft landing gears or assorted parts at a job shop, are horizontal. Removing a large, heavy core can be a challenge. To pull out such a core, end users often drill and tap a hole in one end and insert an I-bolt, Sollich noted.

John Bradford, micromachining R&D team leader for Makino Inc., emphasized that when EDMing microholes, an end user must purchase its metrology equipment at the same time it purchases the EDM to validate hole quality. “As holes get smaller and tolerances get more stringent, that piece of inspection equipment is critical to support the internal manufacturing process,” he said.

The company’s drill bits range from 1⁄16 " to 2½ " in diameter and can be coated to extend tool life in severe conditions. Typical tool life ranges from 3,000 to 5,000 holes when drilling stainless steel, 8,000 to 10,000 holes in mild steel and 10,000 or more holes in softer alloys, such as aluminum and copper, according to Ray, who estimates that 30 to 35 percent of sales are for specials, such as ones for also creating a chamfer or an oil groove. He noted that the cost per hole is 0.01 to 0.03 cents.

Science of measurement; the principles on which precision machining, quality control and inspection are based. See precision machining, measurement.

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.

Sandvik is implementing a unique cemented carbide recycling program. It will provide huge benefits to customers, local communities and the planet.

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.

An end user can then thread the bushing. “If it’s a threading application, we exclusively use a roll-form tap to keep the process clean and chipless,” Ray said. “There is no debris through either the drilling or tapping cycles.”

An alternative to laser drilling is electron beam drilling, which is able to achieve a depth-to-diameter ratio up to 25:1, according to Kenneth E. Norsworthy, manufacturing engineer for new product development at Owens Corning Ridgeview, Duncan, S.C. Initially developed for internal use, the company provides electron beam drilling as a service.

Tungsten is a key component in cemented carbide and the extracted inserts are being sent to the Sandvik owned Wolfram Bergbau und Hütten AG tungsten plant in Austria. A new process is used to turn the recycled cemented carbide into powder that has the exact same premium quality as that produced from virgin material. It is then used to manufacture new inserts.

On a rotating tool, the portion of the tool body that joins the lands. Web is thicker at the shank end, relative to the point end, providing maximum torsional strength.

He added that producing through-holes is more common than blind-hole trepanning, which requires a core-cropping tool to enter the approximate ¾ "- to 1½ "-wide kerf, actuate a knife-style cutter at the bottom of the hole and cutoff the core during a secondary operation.

Bradford has recently noticed a substantial increase in EDM holemaking. “Four years ago, 10 percent of our activities were around fine-hole testing and manufacturing, and today it may be as high as 65 percent.” CTE

A moldmaker monitors a Makino EDGE2 sinker EDM at Plastic Design Corp., which often uses the machine to rough 0.006 "- to 0.007 "-dia. start holes in 400 series stainless steel.

The cemented carbide recycling program is the only program of its kind in the world. It has been made possible through two major developments by Sandvik; extraction units that separate used cemented carbide inserts from the steel body of drill bits at customer sites, and a process for creating premium cemented carbide powder from the recycled material.

Group of alloy steels which, after proper heat treatment, provide the combination of properties required for cutting tool and die applications. The American Iron and Steel Institute divides tool steels into six major categories: water hardening, shock resisting, cold work, hot work, special purpose and high speed.

Process similar to ram electrical-discharge machining except a small-diameter copper or brass wire is used as a traveling electrode. Usually used in conjunction with a CNC and only works when a part is to be cut completely through. A common analogy is wire electrical-discharge machining is like an ultraprecise, electrical, contour-sawing operation.

Any manufacturing process in which metal is processed or machined such that the workpiece is given a new shape. Broadly defined, the term includes processes such as design and layout, heat-treating, material handling and inspection.

“I don’t think a hole popper is suitable for precision holemaking,” concurred Mark Kinder, president of Plastic Design Corp., Scottsdale, Ariz., a moldmaker and part molder. He added, though, that some users have tweaked to their hole poppers to go beyond a machine’s precision limitations.

“We want the inserts back,” says Dean Kangleas, VP Product Line Services at Sandvik Rock Tools Division. “And the program brings many benefits to customer too. First of all we are buying back the inserts from customers, so we are paying for them. And by separating the cemented carbide from the drill bit the steel value also increases. As we do this on site, customers can then sell the scrap steel to local scrap dealers for a premium. It’s a win-win.”

The process takes place in a vacuum chamber, where electron beams are accelerated to about two-thirds the speed of light. The process produces holes from 0.001 " to 0.040 " in diameter, with the typical range being from 0.004 " to 0.040 ", in metal, ceramic and composite materials up to 3⁄8 " thick, Norsworthy noted. The facility controls hole diameter by varying the power density, focus and pulse width, and reports that size accuracy is ±0.001 " and hole placement accuracy is ±0.0005 ".

Although PDC is EDMing micro ejector and core pin holes for molds it uses internally, achieving the required tolerances is necessary to precisely mold parts for customers. For example, Kinder said PDC molds a lot of PEEK (polyether ether ketone) and knows that the material flashes when the clearance between the mold and pin is from 0.0003 " to 0.0004. " However, a pin will start to bind when the clearance is less than 0.0002 ". Therefore, the company must hold all working clearances to less than 0.0003 " but greater than 0.0002 ".

In general, trepanning requires 7 to 10 hp per 1 " of cutter diameter, with difficult-to-machine materials requiring more horsepower and thrust. Trepanning requires 15 to 30 percent less horsepower than solid drilling and is 10 to 15 percent faster, according to Sollich.

The process is also suitable for percussive laser drilling, where the laser is quickly turned on and off to ablate a hole through the workpiece material. “The laser basically pounds its way through the metal,” Woods said. “You’re trying to knock atoms off.”

Although fine-hole EDMs are able to create holes smaller than 0.0005 " in diameter, Bradford noted that tube electrodes are generally not available below 0.003 " in diameter, which has about a 0.001 "-dia. through-hole. “You need a source pressure of 1,500 psi or more to get even a low-viscosity dielectric to flow through the tip of that electrode,” he said.

Workpieces up to 1m in diameter receive from 35,000 to six million holes, which can be angled up to 40°.

Single-shot drilling is the fastest method and produces a hole approximately the diameter of the incoming beam. Taper tends to be more pronounced with single shot because there are no subsequent pulses to “clean” the hole. Percussion drilling involves application of multiple pulses to pierce the material. It’s a slower process, but it produces a rounder hole with less taper than a single-shot hole. Trepanning, when performed on a galvo system, yields holes with the best circularity and smallest taper, according to Schaeffer.

PDC uses a Makino Edge2 sinker EDM with a fine-hole option and typically applies a rotating copper-tungsten, hollow-pipe electrode and low-viscosity dielectric oil. “It won’t suspend the swarf as well as some of the more viscous fluids, but it allows us to do finer burns,” he said.

About the Author: Alan Richter is editor of Cutting Tool Engineering, having joined the publication in 2000. Contact him at (847) 714-0175 or alanr@jwr.com.

Woods pointed out that laser drilling and holemaking offers the advantage of lower cost compared to mechanical holemaking. Typically, this is about a 10 to 50 percent cost reduction, depending on the type and thickness of workpiece material. While the initial hardware cost of a laser is higher, the savings come from lower maintenance and the elimination of the need for post-processing. Lasers also reduce maintenance downtime and don’t produce any warping or punching effects. The latter occurs because lasers are a noncontact and focused thermal source, as opposed to conventional drilling, which exerts pressure on the workpiece and can negatively impact material shape.

Step that prepares a slug, blank or other workpiece for machining or other processing by separating it from the original stock. Performed on lathes, chucking machines, automatic screw machines and other turning machines. Also performed on milling machines, machining centers with slitting saws and sawing machines with cold (circular) saws, hacksaws, bandsaws or abrasive cutoff saws. See saw, sawing machine; turning.

Bradford added that the EDM process can achieve accurate, virtually burr-free results with aspect ratios up to 100:1 whereas mechanical drilling is often only effective to a 15:1 aspect ratio. “EDMing, along with the possibility of laser machining, is a superior solution to that of mechanical drilling,” he said.

Alan holds a bachelor’s degree in journalism from Southern Illinois University Carbondale. Including his 20 years at CTE, Alan has more than 30 years of trade journalism experience.

System in which information is extracted from visual sensors to allow machines to react to changes in the manufacturing process.

In addition, the coolant must be filtered so the coolant system isn’t pumping chips and fines back to the cutting edge for recutting. “When we design coolant systems, they’re filtered to 10 microns,” Sollich said, adding that the coolant tank needs to be large enough so oil or coolant has time to dwell and cool off. If coolant is constantly recirculating, it can become extremely hot and shorten tool life and cause unacceptable part growth. “You might possibly incorporate refrigeration, or chiller, units to cool the oil,” he added.

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To achieve maximum tool life, Ray recommends applying a paste lubricant for manual operations and a liquid lubricant for automated ones every two to four holes to prevent bits from gathering metal particles from the workpiece material and provide some lubricity. He also suggests wiping a bit in use with an emery cloth to dislodge any debris on a daily basis. Flowdrill doesn’t regrind bits because of the inevitable tiny cracks that form in the transition zone between the conical and cylindrical sections, where torque is the greatest.

Space provided behind a tool’s land or relief to prevent rubbing and subsequent premature deterioration of the tool. See land; relief.

In addition, lasers yield higher processing speeds, especially when drilling hard and brittle materials. “You blink your eye and it’s done,” Woods noted, adding that lasers are typically two to five times faster, depending on material type and thickness.

An option for achieving greater aspects is to sinker EDM a blind-hole, flip and relocate the part and EDM a second connecting hole to create a single, deep through-hole, explained Bradford, noting that higher aspect ratios require flushing through an electrode.

Dimension that defines the exterior diameter of a cylindrical or round part. See ID, inner diameter.

Cylindrical tool that cuts internal threads and has flutes to remove chips and carry tapping fluid to the point of cut. Normally used on a drill press or tapping machine but also may be operated manually. See tapping.

A wire machine also doesn’t have an aspect ratio restriction and because managing electrode wear is not an issue, hole size consistency is only limited by the wire EDM’s mechanical and electrical capabilities. “A wire EDM is by far the best choice if you’re doing holes that require consistency from one to the next,” Bradford said. “And if you require a sharp edge transition, a wire EDM is by far the best choice.”

Process of both external (e.g., thread milling) and internal (e.g., tapping, thread milling) cutting, turning and rolling of threads into particular material. Standardized specifications are available to determine the desired results of the threading process. Numerous thread-series designations are written for specific applications. Threading often is performed on a lathe. Specifications such as thread height are critical in determining the strength of the threads. The material used is taken into consideration in determining the expected results of any particular application for that threaded piece. In external threading, a calculated depth is required as well as a particular angle to the cut. To perform internal threading, the exact diameter to bore the hole is critical before threading. The threads are distinguished from one another by the amount of tolerance and/or allowance that is specified. See turning.

Machining operation in which a tap, with teeth on its periphery, cuts internal threads in a predrilled hole having a smaller diameter than the tap diameter. Threads are formed by a combined rotary and axial-relative motion between tap and workpiece. See tap.

Making new inserts from recycled material significantly reduces the need to mine resources. This means that energy use is reduced by 70 percent and 64 percent less CO2 is emitted. It also means that Sandvik doesn’t have to worry about tungsten supply, a scarce and finite material.

When the workpiece material is electrically conductive, EDM holemaking is an option, whether sinking an electrode to produce a fine hole as small as 10µm or smaller or using a wire. Although a slower process than conventional drilling, EDMing offers a high level of predictability and repeatability when producing a high volume of small holes, according to John Bradford, micromachining R&D team leader for Makino Inc., who’s located at the Mason, Ohio-based machine tool builder’s technical headquarters in Auburn Hills, Mich. And EDMing may achieve a faster per hole cycle time when the time to correct an unstable drilling process is considered.

Similar to holemaking itself, many methods exist for deep-hole drilling, such as trepanning, which uses a hollow rotary or nonrotary tool to cut a hole in a workpiece.

According to Sollich, trepanning can achieve a ±0.002 " tolerance on hole diameter and impart surface finishes from 83 to 125 rms, depending on the machine setup and material specifications.

Measure of the relative efficiency with which a cutting fluid or lubricant reduces friction between surfaces.

The process is suitable for malleable materials, including mild and stainless steels, aluminum, copper and some brass alloys, whereas high-porosity metals, such as cast iron, as well as some tool steels, Inconel and other hard and difficult-to-machine metals are not appropriate. In addition to being malleable, the workpiece thickness must be relatively thin, from ½ " to 0.020 ". “If it’s thinner then that, the material will deform too much,” Ray said, adding that the process produces a bushing about three times the thickness of the workpiece.

Owens Corning Ridgeview offers electron beam drilling, which is able to produce small holes in ceramics.

Machine designed to rotate end-cutting tools. Can also be used for reaming, tapping, countersinking, counterboring, spotfacing and boring.

Hole or cavity cut in a solid shape that does not connect with other holes or exit through the workpiece.

The program is currently being rolled out across all Sandvik Mining and Rock Solutions customer sites around the world. Sandvik produces tens of millions of inserts every year. It has a target to buy back 90 percent of this volume from its customers. By reusing the recycled material in new tools, the company will achieve 90 percent circularity with cemented carbide.

Producing precise microscale EDMed holes is challenging enough for manufacturers, but they must also be able to measure the holes with repeatability. That’s the challenge Plastic Design Corp. faces when EDMing holes smaller than 0.005 " and trying to achieve a 0.00005 " tolerance on diameter. “I say ‘trying’ because of our ability to measure that,” said Mark Kinder, company president. “We can distinguish less than a tenth, but we don’t know what our true distinction is.”

“The idea behind flow drilling is to get as much material in the bushing as possible,” Ray said. Producing the maximum bushing length can enable a manufacturer to switch from, say, a 3⁄8 "-thick workpiece to a 1⁄8 "-thick one and still have a 3⁄8 " of thread integrity.

More precise metrology equipment is available, but PDC determined that the vision system provided the best value in terms of cost vs. precision.

For one roughing experiment with low-viscosity oil and a 0.010 "-dia. pipe electrode, PDC achieved a 100:1 depth-to-diameter ratio, a 0.001 " bellmouth and a breakout location within ±0.001 " of the start position. However, Kinder noted that PDC tries to avoid aspect ratios higher than 50:1.

The bits are available in two styles: one for creating a collar around the hole and one that incorporates a cutter to spot face the workpiece surface.

Norsworthy indicated that electron beam drilling is suitable for a host of industries, including pulp and paper, aerospace and food and beverage, to produce parts such as those for extrusion, filtration and air flow. According to the company, the process is well suited for high open-area screens and open areas can be up to 45 percent.