Drilling Is Only the Beginning

2009-6-26 9:20:58

When Sure-Fab L.L.C. (Two Harbors, MN) wanted to speed up the process for putting a 5.125" (130-mm) counter bore 3.25" (82.5-mm) deep on the end of a large cylinder ram, it called on its drill supplier, Allied Machine & Engineering Corp. (Allied; Dover, OH). Sure-Fab is a contract manufacturer that specializes in manufacturing medium-to-large workpieces for the scrap, demolition, logging, material handling, and commercial towing equipment industries.

"Sure-Fab had heard about our Revolution Drill and our Opening Drill and wanted to see if they would work on this ram application, one of many different sizes they produce," explains Allied's Larry Stenger, field sales engineer. "I went to the facility with tools in hand and found, to my surprise, that there were two existing gundrilled holes 5' [1.5-m] deep on the end of the cylinder. They were currently using a Mitsubishi high-feed mill running at 1000 rpm and 60 ipm [1.5 m/min] to produce a roughed hole for the counter bore. This counter bore took about 38 min on average to produce, including indexing inserts after each part and, sometimes, during the process.

"The Revolution Drill was set to 2.46" [62.5 mm] and run at 930 fpm [283 m/min]. We had to be careful with the chip load because of the lack of centerline material and went with a conservative 0.0025 ipr [0.003 mm/rev], 3.25" [82.5-mm] deep flood application. We double-cut chips the whole way, and overcame a double interruption in an unbalanced cut [with more material on the bottom half of the tool than on the top]."

The Opening Drill was set to 5.01" (127 mm). "Because there was a lot of material being removed, we were double-cutting a lot of chips so we dropped to 350 fpm [106 m/min] with 0.006 ipr [0.15 mm/rev]. This tool was taking a wicked offset, no material at the bottom of the hole, and 0.630" [16 mm] on the top and interrupted the whole distance. The tool was set to 5.01" [127.3 mm] and it cut 5.01". The result was that 30 min was shaved off the application with minimal insert usage," Stenger says.

Success stories like this are typical of today's cutting tool advances in holemaking technology. It isn't a stretch to say that virtually every part has some kind of hole that must be produced in it.

The criteria by which holemaking solutions are judged include cylindricity, straightness, finish, and accuracy. Taken together, they add up to productivity gains through extended tool life, reduced scrap, and process stability.

Major cutting tool manufacturers are attacking holemaking by developing full lines of products with capabilities that range from making holes to finishing them. "Traditionally, users look to Kennametal for drills to make the hole, but we are increasingly focused on finishing holes with precision boring and reaming products. For example, the Romicron fine-boring system is a true one-micron adjusting tool. In addition, Kennametal offers a reaming portfolio that includes solid-carbide reamers, single and multi-bladed reamers, and padded insertable reamers," explains Chet Parzick, product manager.

For critical aerospace applications, Kennametal has introduced the Y-Tech solid-carbide drill for drilling holes in tough engine materials, and the SPF solid-carbide drill for drilling holes in carbon-fiber composites. The Y-Tech drill features two asymmetrically angled cutting edges and three margins for straight, true drilling in Inconel, Waspaloy, and titanium. The SPF drill has a unique point angle and geometry, and a CVD diamond coating to prevent delaminating the composite materials used for aircraft fuselages.

Tapping, which has long been regarded as the slowest process, is benefiting from Kennametal's focus on carbide taps. "Today, with carbide taps, we can tap at drilling speeds and above, or as fast as modern machines can run, whether machining short-chipping or long-chipping materials," says Parzick.

For production of internal and external threads for wind turbine components, Emuge Corp. (West Boylston, MA) provides taps up to 4.5" (114 mm), roll-form taps up to 2" (51 mm), and thread mills up to 4" (102- mm) diam. These tools are designed for all thread sizes—with special focus on large and deep threading.

"We are addressing the requirements for three basic material groups: cast iron; alloy steels; and structural steel. The castings could be the housing for gears, and gears are primarily alloy steel," explains Alan Shepherd, technical director.

"Machining the components is a challenge, because the parts are so large. We have to make taps with extra length, as some of the holes are deeper than we normally tap. Going deep in a hole you have to be able to get lubrication down to where you're cutting, at the same time extracting the chips while tapping," says Alan Shepherd.

Emuge has also developed tap extenders for standard taps. "Because a lot of these components are made on newer, modern machine tools, you have the advantage of synchronous tapping or rigid tapping. Basically, the CNC does all the control of feed and speed," Shepherd concludes.

Seco Tools Inc. (Troy, MI) has introduced the DP2000 drilling insert grade with the Duratomic coating for machining steel and cast iron, applications where high cutting speeds can be used. The Duratomic process allows the aluminum oxide (Al₂O₃) coating, which is arranged at the atomic level, to be adjusted to fit specific applications and workpieces.

"DP2000 is optimized for steel and cast iron applications where high feed per revolution is required to improve productivity," explains Thomas Sandrud, product manager. "The DP2000 grade imparts reduced heat transference and wear resistance to achieve low thermal conductivity, resulting in longer and predictable tool life and chemical stability with the workpiece," says Sandrud.

To gain all the benefits from this new grade, Sandrud explains that "it's important to have a strong drill body that can provide the support and strength needed for the higher cutting speeds without incurring vibration. Our low-friction coated Perfomax drill body offers excellent bending torsion rigidity, as well as chip evacuation." The DP2000 grade can also run with Seco's SD542/SD572 indexable drills or Capto drills.

Some developments have very specific applications in mind. Such is the case with the new QF series of indexable drills from Ingersoll Cutting Tools (Rockford, IL) for producing flat-bottom holes. Flat-bottom holes are required for applications including deep counterbores for standard socket head capscrews, counterbores, die-spring pocket holes, and gas die-cylinder mounting pockets.

"A different design is needed to drill an accurate hole with a good finish within tolerance and, at the same time, produce a flat bottom," explains Bob Jennings, product manager. "We have incorporated the twisted-flute manufacturing technology from our Quad series indexable drills into the QF drills. It allows producing deeper flutes and larger coolant holes without compromising the strength and stability of the drill body. The result is better chip evacuation, increased coolant volume, and better hole size tolerance and finish," Jennings says.

The QF series can drill flat-bottom holes to 3xD depth and uses standard square inserts with four indexes, and the same insert in all pockets. Standard sizes from 0.625" to 2.000" (15.9–50.8 mm) are available.

For mass production finishing applications, Ingersoll Cutting Tools has introduced its Qwik-Ream high-speed for reaming applications of 9.5–32-mm diam holes with H7 tolerance range. "The Qwik-Ream system uses a three-piece design with a replaceable carbide multiflute head attached to a steel or solid-carbide shank by means of a bayonet screw and a special key," explains Mike Butler, product manager.

There's no need to remove the tool because it is a frontal indexing system, and one shank can be used for a range of hole diam and various types of cutting edges. The Qwik-Ream can be used for blind and through holes, as well as for holes with cross holes or keyways.

Iscar Metals Inc. (Arlington, TX) has introduced the SumoCham drill, the third generation of its replaceable tip series, which was initiated with the ChamDrill followed by the ChamDrillJet. "We're always upgrading our product lines," explains Tom Edler, national holemaking product manager. "As soon as a product line comes out, another team is assigned to begin the process of developing a product that will outdo the existing product line."

Improvements to the SumoCham drill family include improved head and pocket designs that allow more insert indexes and improve tool body life, while achieving better penetration rates.

"The tool is designed so that there are four different styles of cutting edges for each of ISO class of metals," says Edler. "SumoCham drills are available in sizes from 0.315 to 1.02" [8–26 mm] in 0.004" [0.10-mm] increments. With one tool body able to hold a range of sizes, inventory is reduced."

"Once you get above 1.25" [38 mm] you can go to indexable two-insert types of drills like The DR drill and DR Twist drills. For deeper-hole drilling, 7xD and larger, the DRDH drill uses standard equipment and coolant systems. With the DRDH drill coolant and chips are evacuated more up the flute on the outside, without machine modifications," Edler explains.

Sumitomo Electric Carbide Inc. (Mt. Prospect, IL) has expanded its SMD replaceable carbide tip product line with the addition of an 8xD drill to the 3xD and 5xD lineup. The SMD features a nickel-plated body for longer tool life, and a rigid serration coupling system for affixing the replaceable carbide tips to the drill face for improved drill accuracy and repeatability.

Three drill-tip styles are available to improve performance in various materials. The SMD line is available in metric and inch diam ranging from 0.4688 to 1.2008" (12–30.5 mm).

For large-diam hole drilling, Sumitomo has introduced the new WDX indexable drill series for not only accurately drilling holes, but also performing operations such as turning and boring. The drill features a nickelplated steel body, which accepts the same insert geometry for both the outer and inner cutting edges, reducing inventory costs and allowing the use of all four of the insert's cutting edges. WDX inserts are available with three newly developed drilling chipbreakers to reduce thrust.

OSG Tap and Die Inc. (Glendale Heights, IL) has introduced a Helios drill for deephole drilling without pecking and without coolant-through capability. The new drill features HSS-cobalt substrate, rather than carbide, and can drill to 10xD, expanding the line, which already includes 15xD and 20xD versions.

Helios drills produce deep holes without the use of an internal coolant supply, and the flute design improves chip evacuation, making it feasible to drill up to 20xD without pecking. Thinning decreases thrust by nearly 50%, and by utilizing WXL coating Helios can handle a range of materials and reportedly provide three times greater wear resistance than tools with conventional coatings.

The CoroDrill 805 drill from Sandvik Coromant (Fairlawn, NJ) makes it possible to drill deep holes in steel (ISO P) and cast iron (ISO K) materials without moving the workpiece to a dedicated, deep-hole drilling machine. Conventional machines such as HMCs, CNC lathes, and multitasking machines with higher volume internal coolant supply (15–25 gpm) can be used to complete all deep-hole drilling operations in one setup. A minimum of 8% coolant mixture ratio is needed to help lubricate the wear pads.

"There are two important considerations. The hole must be started with a pilot hole, and the machine must deliver coolant in sufficient volume," explains Mike Campbell, deep hole drilling specialist. "Higher coolant volume is particularly important in machining softer, gummy materials like 1018 steel to ensure chip evacuation. A common speed and feed is 300 sfm [91 m/min] at 0.010 ipr [0.25 mm/rev]. This is a much more aggressive machining rate than that achieved by other types of deep-hole drills like spade drills and HSS-piloted drills with indexable inserts," Campbell points out.

The CoroDrill 805 drills holes from 25 to 65-mm diameter with 7–13xD hole-to-depth ratio. The drill features two support pads the on front of the tool. Starting a hole requires a pilot hole that is a minimum of 12-mm deep for a 25-mm diameter hole and a minimum of 20-mm deep for a 65-mm diameter hole. Pilot holes can be made by helical interpolation with a solid-carbide end mill to a tolerance of H8 if the hole size is close (IT10). If not, Sandvik Coromant's indexable shorthole CoroDrill 880 can be used to drill the pilot hole.

BIG Kaiser Precision Tooling Inc. (Elk Grove Village, IL) has expanded its solid-carbide Phoenix drill line from 6xD to include 3xD and 12xD sizes. "The Phoenix drill's high-performance flute and point geometry assure low cutting forces and provide optimum chip control," explains Mike Bojanowski, application engineer. "Internal coolant makes the Phoenix ideal for cutting hard materials like Inconel, stainless, titanium, and cast iron used in aerospace applications, among others."

The Phoenix drills are available in sizes from 1 to 12.7 mm in diam, in 0.1-mm increments with coolant-through for drills 2.5-mm diam and larger. The two new drills use the Helica AlCrN coating, and the 6xD size uses the Futura TiAlN coating. "Drill bodies feature ultra-fine grain composition for increased wear resistance and toughness, optimizing tool life and hole quality," Bojanowski says.

Holemaking? Ask These Questions First

• What material is being machined? In what volume of parts, number of holes, batch sizes?
• How large are the holes? Diameter, depth?
• What kind of hole? Through hole, blind hole, flat bottom?
• How user friendly is the tool with regard to setup time, regrinding, replacement?
• What tolerances are required for accuracy, geometry, and finish?
• What kinds of machines (spindle and taper size) are being used? Machining centers, CNC lathes, specialized and/or dedicated drilling machines like gundrills?
• What level of productivity is targeted? Feed and speed requirements?
• What is the cost per hole of the various alternative processes?