Fabricators seeking smaller diameters can look to Iscar’s SumoCham line, now available down to 4 mm in up to 5×D applications, said Craig Ewing, national product specialist for Iscar Metals.

“The biggest thing we’ve done is introduced new grades optimized for steel, stainless steel and cast iron,” he continued. “Our Zertivo technology uses a PVD process, and we are able to achieve better bonding between the substrate and coating to where we have significant improvements in edge line security—resulting in longer, predictable tool life.” Grades include –PM 4334 for low alloyed and carbon steels, –MM2334 for stainless and –KM3334 for cast iron. While there is no grade specifically for heat-resistant materials, Loughney added, “we can cross over our geometries into those areas” for multiple industries.

Calcium carbide is used to determine the moisture content of soil. When soil and calcium carbide are mixed in a closed pressure cylinder, the water content in soil reacts with calcium carbide to release acetylene whose pressure can be measured to determine the moisture content.[23][24]

As a result, the DIAEDGE STAW demonstrates “excellent chip disposability and achieves high-efficiency machining,” Griggs noted. “STAW replaceable carbide tips/inserts are designed for extreme sharpness, precision, positioning and rigidity in our unique clamping system. The wavy edge design delivers a sharp peripheral edge to enhance cutting performance, complemented by a strong center point geometry for initial cutting at entry. A high helix offers a low-resistance drill pocket design that improves chip breaking for superior chip disposal.” The STAW’s clamping system has more material behind the tip for added strength and durability.

Carbide lamps are still used for mining in some less wealthy countries, for example in the silver mines near Potosí, Bolivia. Carbide lamps are also still used by some cavers exploring caves and other underground areas,[17] although they are increasingly being replaced in this use by LED lights.

But what about performance? Ultimately, using replaceable-tip drilling tools generally does not mean sacrificing much penetration rate or tool life—to a point—experts assert.

SumoCham is available from 4-32.9 mm diameter in 0.1 mm increments, Ewing explained. Heads are offered in 10 geometries for various material groups and applications, and bodies are offered in 1.5×D, 3×D, 5×D, 8×D and 12×D through most of the diameter range. Each body accepts a range of head diameters: from 4-14.9 mm, bodies come in 0.5 mm increments, and from 15-32.9 mm, bodies come in 1-mm increments.

Carmex recently introduced new coatings for its Slim MT line. “This nano coating can handle temperatures 30 percent higher than TiAlN and is 25 percent harder than other coatings typically used for indexable cutters,” said White. “These coatings outperform others in high-temperature alloys like inconel and titanium.”

Calcium carbide is produced industrially in an electric arc furnace from a mixture of lime and coke at approximately 2,200 °C (3,990 °F).[5] This is an endothermic reaction requiring 110 kilocalories (460 kJ) per mole[6] and high temperatures to drive off the carbon monoxide. This method has not changed since its invention in 1892:

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Jim White, national sales manager for Carmex Precision Tools LLC, Richfield, Wis., concurred. “The reason most customers go with indexable is versatility—using one holder for multiple pitches—or cost,” he said, adding that “indexable thread mills are more cost effective in large-thread diameter applications or low-volume jobs where cycle time is not a consideration.”

“Various grade options allow better flexibility and optimization vs. solid carbide tools” and feature proprietary Sumo Tec PVD post-coating technology that provides “improved toughness, improved flaking, and chipping resistance, which in turn provides very reliable and repeatable results.” Those grades are:

“For example, if I would expect to get a thousand inches of tool life with a solid, then I would expect the same from a modular tool—but of course exceptions apply,” said Bill Pulvermacher, director of marketing for YG-1 Tool Co., Vernon Hills, Illinois. “I would expect the overall penetration rate of the solid to be just a little bit higher.” Furthermore, some users say replaceable-tip drills over 0.5" (12.7 mm) tend to perform better in lathe applications “because they are much more tolerant of the misalignment that lathes tend to have.”

The option of smaller diameter, high-feed end mills is “a popular option for harder tool and die steels, especially in the aerospace and mold industries,” Wilshire continued. “Customers tend to run the replaceable-tip drills and indexable end mills faster than their solid-carbide counterparts to shorten cycle times because the replacement costs are less and the time to index is shorter.”

Calcium carbide is sometimes used as source of acetylene, which like ethylene gas, is a ripening agent.[19] However, this is illegal in some countries as, in the production of acetylene from calcium carbide, contamination often leads to trace production of phosphine and arsine.[20][21] These impurities can be removed by passing the acetylene gas through acidified copper sulfate solution, but, in developing countries, this precaution is often neglected.

These drills are being used heavily in structural steel applications like beams and bracketing in areas such as bridge towers, Pisorn said. Planetary gears with flanges might feature 20 to 50 shallow holes; bearing rings for wind energy can feature 50-100 holes. Tube sheets for heat exchangers is another sound application. And, a filtration system plate for the paper industry might feature thousands of shallow holes.

“Some smaller sizes come in smaller shank diameters and shorter OAL (overall length) without a flange for Swiss lathe and live tool applications,” he added. “There are also drill bodies with integrated chamfering inserts.”

On the larger side, Iscar’s LogIQ-3-Cham is a three-flute, interchangeable-head drill in 14-23.9 mm diameters, in 0.1-mm increments and bodies in 1.5×D, 3×D and 5×D. “Eventually, the line will include all head sizes from 12-25.9 mm. The three-flute design will provide extended tool life and/or increased feed rates,” mostly for ISO-P and ISO-K materials, Ewing said.

Also for hard-to-machine materials, Sandvik Coromant’s recently introduced CoroMill 316 exchangeable milling heads are optimized for titanium and nickel-based metals. For titanium, grade 1745 with its 1.5×D cutting edge “is a little bit longer of a replaceable-tip end mill compared to our standard 316s,” explained Scott Lewis, aerospace industry specialist for Sandvik Coromant. To be released in the near future is grade 1710 for nickel alloy, which will also have 1.5XD capabilities. Both grades feature unique substrates and geometries and are currently available in the company’s solid-carbide end mills. These replaceable-tip end mills “can run, cutting data wise, quite close to what a solid is, with a solid being perhaps more rigid because it is shorter—a stouter setup,” Lewis said. “We also have very short, stout adapters for our 316s.”

In terms of drilling, the number and type of holes to be made is generally the key determinant for opting to use replaceable-tip tools, according to Allied’s Pisorn. The more holes (from 1,000 to 50,000 or more) and the shallower (up to 13×D) the better.

Toolholding is vital to precision holemaking with replaceable-tip drills, he continued. “You have to remember that you have collective tolerances—of the body itself and then a tip on top of it.”

This reaction was the basis of the industrial manufacture of acetylene, and is the major industrial use of calcium carbide.

The high temperature required for this reaction is not practically achievable by traditional combustion, so the reaction is performed in an electric arc furnace with graphite electrodes. The carbide product produced generally contains around 80% calcium carbide by weight. The carbide is crushed to produce small lumps that can range from a few mm up to 50 mm. The impurities are concentrated in the finer fractions. The CaC2 content of the product is assayed by measuring the amount of acetylene produced on hydrolysis. As an example, the British and German standards for the content of the coarser fractions are 295 L/kg and 300 L/kg respectively (at 101 kPa pressure and 20 °C (68 °F) temperature). Impurities present in the carbide include calcium phosphide, which produces phosphine when hydrolysed.[7]

Applications of calcium carbide include manufacture of acetylene gas, generation of acetylene in carbide lamps, manufacture of chemicals for fertilizer, and steelmaking.

Another inventory factor to consider: Shops that routinely send solid-carbide tools for regrinding must keep an adequate supply of solid tools in reserve to maintain production, said Patrick Loughney, a product manager at Sandvik Coromant, Fair Lawn, N.J.

Calcium carbide, together with calcium phosphide, is used in floating, self-igniting naval signal flares, such as those produced by the Holmes' Marine Life Protection Association.

The pure material is colorless, while pieces of technical-grade calcium carbide are grey or brown and consist of about 80–85% of CaC2 (the rest is CaO (calcium oxide), Ca3P2 (calcium phosphide), CaS (calcium sulfide), Ca3N2 (calcium nitride), SiC (silicon carbide), C (carbon), etc.). In the presence of trace moisture, technical-grade calcium carbide emits an unpleasant odor reminiscent of garlic.[4]

The current crop of replaceable-tip milling and drilling tools features a host of new substrates, geometries, PVD coatings and coolant solutions geared for a range of applications across numerous industries and materials. As always, the decision to use a particular tool is application specific.

Calcium carbide is used in toy cannons such as the Big-Bang Cannon, as well as in bamboo cannons. In the Netherlands calcium carbide is used around new-year to shoot with milk churns.[22]

In China, acetylene derived from calcium carbide remains a raw material for the chemical industry, in particular for the production of polyvinyl chloride. Locally produced acetylene is more economical than using imported oil.[14] Production of calcium carbide in China has been increasing. In 2005 output was 8.94 million tons, with the capacity to produce 17 million tons.[15]

Replaceable-tip tools can also provide users with a significant reduction in setup times, Loughney added, for instance on transfer lines for automotive manufacturing. And, with the ever-pressing shortage of experienced manufacturing labor, quick and easy tool switchouts instead of more intensive setups help ease that burden.

The Mini-Mill series of tools—including Nanmill, Nan3feed, Heli4mill, Heli3mill and Micro3feed—complement Iscar’s solid-carbide tools with diameters starting at 0.312-0.75" (7.92-19.05 mm) with multi-edged inserts for 90o milling and fast-feed milling, he explained.

Another drill that’s been on the market a while is the CoroDrill 870 series by Sandvik Coromant. But since its introduction in 2012, numerous refinements have been made. “We found that the body material was wearing, so we made it more wear-resistant, making the drill more rigid,” explained Loughney.

Meanwhile, Kyocera Precision Tools Inc., Hendersonville, N.C. is noting increased demand for smaller, modular indexable end mills, said Technical Center Manager Brian Wilshire.

Slated for release midyear is YG-1’s I-One drill. “We’re performing extensive testing with it in the energy industry, with very good success,” Pulvermacher noted. It will exist alongside the company’s well-established I-Dream drill, which currently has several geometries: Dream Drill General for general purpose (carbon steel, iron); one for stainless (Inox); Dream Drill Alu (aluminum), High Feed (carbon steel, iron); and High Hard (up to 70 HRC).

To more than double the depths of cut previously available in its Multi-Master line of end mills, Iscar Metals Inc., Arlington, Texas, added replaceable-tip mills capable of reaching depths up to 1.5×D, said Tom Raun, chief technical officer.

PVD coatings are most common for smaller diameter tools, he added, “because they help maintain sharper edges than thicker CVD coatings. Kyocera’s R&D efforts in PVD coating technology have resulted in our Megacoat coatings. With high oxidation temperatures and high hardness, they are ideal for running at higher speeds, resulting in reduced cycle times.”

In the United States, Europe, and Japan, consumption of calcium carbide is generally declining.[16] Production levels in the US during the 1990s were 236,000 tons per year.[13]

At Mitsubishi Materials U.S.A. Corp., Schaumburg, Illinois, the company’s DIAEDGE STAW indexable drills “are unique in that they have cutting edge geometry that is the same as the edge geometry on our DIAEDGE WSTAR solid-carbide drill,” said Barry Griggs, assistant business development manager of cutting tools. “The wave designed cutting edge and center point gash is aimed at improving machined hole accuracy.”

When weighing the choice of replaceable-tip mills and drills or solid-carbide tools, consider this succinct statement from one industry expert: carbide equals cost.

Calcium carbide is sold commercially as a mole repellent.[25] When it comes into contact with water, the gas produced drives moles away.[26]

XT Pro carbide inserts have a combination of substrate coating and geometry engineered to survive the wear of high-penetration drilling, which “inherently produces significant heat,” Pisorn noted. “Combating that heat well is critical to extending tool life and increasing drilling rates. We have worked closely with our coating team and partners to develop several new material-specific, proprietary, multilayer coatings designed to withstand increased heat thresholds.”

For large-diameter applications, true helical flutes are the key to the success of the SRH series of replaceable mills by Carmex, said White. Helical flutes cut freer than straight-flute tools, he explained, although “solid thread mills are still the most efficient choice for anything under 1" (25.4 mm) thread diameter because you get more flutes in the cut and the geometry allows for higher cutting speeds and faster feed rates.” The SRH has been most successful in the oil and gas market, threading buttress and Acme threads in large diameters, he added.

This reaction was an important part of the Industrial Revolution in chemistry, and was made possible in the United States as a result of massive amounts of inexpensive hydroelectric power produced at Niagara Falls before the turn of the 20th century.[8] The electric arc furnace method was discovered in 1892 by T. L. Willson, and independently in the same year by H. Moissan.[9][10][11] In Jajce, Bosnia and Herzegovina, the Austrian industrialist Josef Kranz and his "Bosnische-Elektrizitäts AG" company, whose successor later became "Elektro-Bosna", opened the largest chemical factory for the production of calcium carbide at the time in Europe in 1899. A hydroelectric power station on the Pliva river with an installed capacity of 8 MW was constructed to supply electricity for the factory, the first power station of its kind in Southeast Europe, and became operational on 24 March 1899.[12]

Today acetylene is mainly manufactured by the partial combustion of methane or appears as a side product in the ethylene stream from cracking of hydrocarbons. Approximately 400,000 tonnes are produced this way annually (see acetylene preparation).

For deeper, large-diameter applications, the Iscar ModuDrill is a combination of replaceable head and indexable insert drills in larger diameters for depths beyond 12×D. The ChamIQ 700 family is offered in a diameter range of 33-40 mm in 0.5 mm increments and “some common fractional-inch increments,” he said. “The HFP carbide blades, which look more like a spade drill, fit into a range of steel adapter heads (MD-DFN), which also mount onto a long steel drill body (MD-BODY). A combination of two drill bodies and seven adapter heads cover the entire diameter range.”

YG-1 touts its 7×D drill as the only one of its type on the market, Pulvermacher noted. “People really like it because 8×D gives up so much rigidity.”

Carbide lamps were also used extensively as headlamps in early automobiles, motorcycles and bicycles, but have been replaced entirely by electric lamps.[18]

“These screw-in heads are available from 8 mm up to 32 mm in diameter and can be mounted on extensions of various lengths,” he explained. “The smaller diameters have replaced solid-carbide tools in many instances. The advantages of both the replaceable-tip drills and modular, indexable end mills are similar: lower replacement costs, because instead of the entire tool being composed of carbide, only the portion actually doing the cutting contains carbide; less variability in position after indexing; the ability to easily change grades or geometries when cutting different workpiece materials; and less downtime when replacing worn tools.” However, he added, solid-carbide tools still provide better rigidity, deep-hole drilling and greater depth of cut capabilities when milling.

When drilling difficult-to-machine materials like stainless steel or titanium, steel bodies for replaceables might torque too much, Pulvermacher cautioned. For that reason, fabricators have tended to split their use of solid and replaceable tools for those materials about 50-50, depending on the diameter. For that to change, he said, replaceable-tip tools would have to outperform solid in the 0.5-0.75" (12.7-19.05 mm) range. Replaceable-tip drills might get the nod in larger diameters, where solid drills could cost up to $750; however, replaceables struggle under 7/16" (11.11 mm) because they are somewhat expensive relative to solids—and the small tools, screws and inserts tend to get lost.

Replaceable-tip cutting tool suppliers offer numerous examples of how those tools surpassed solid-carbide versions. For instance:

However, any time an operator makes changes in the machine, something can always go wrong. For instance, they must take care not to drop wrenches and screws into the machine while replacing tools.

The modular part of the system “is that there are indexable insert heads that also mount onto the two drill bodies,” said Ewing. They are offered in eight metric sizes (33-40 mm) and two inch sizes (1.375" and 1.5") and use standard SOMX inserts from the DR Twist line. “They also use guide pads from the BTA Deep Drill line. The drilling depth of this system is in the 16.5-17" [419-432 mm] range.”

Inserts are available in sizes from 10-18.1 mm, and the VP15TF and DP5010 PVD coated grades feature tough carbide substrates and proprietary crystal coating technology. For machining a wide range of materials, from alloy steels to various types of stainless steel and cast iron, the VP15TF grade ranges from 100-400 sfm, Griggs added. “The drill body is made resistant to corrosion and abrasion by using a superior high-heat resistance alloy and a special surface treatment suitable to counter new hard-to-machine work materials.”

The reaction of calcium carbide with water, producing acetylene and calcium hydroxide,[5] was discovered by Friedrich Wöhler in 1862.

Calcium carbide, also known as calcium acetylide, is a chemical compound with the chemical formula of CaC2. Its main use industrially is in the production of acetylene and calcium cyanamide.[3]

Calcium carbide is used in carbide lamps. Water dripping on carbide produces acetylene gas, which burns and produces light. While these lamps gave steadier and brighter light than candles, they were dangerous in coal mines, where flammable methane gas made them a serious hazard. The presence of flammable gases in coal mines led to miner safety lamps such as the Davy lamp, in which a wire gauze reduces the risk of methane ignition. Carbide lamps were still used extensively in slate, copper, and tin mines where methane is not a serious hazard. Most miners' lamps have now been replaced by electric lamps.

Allied’s new GEN3SYS XT Pro drills feature dual gundrills with four outlets for increased coolant flow and material-specific inserts with coatings developed in-house. “A unique connection design offers superior torsional loads while still allowing the convenience of insert swaps while the tool remains in the spindle,” Pisorn said.

The initial release of the I-One will feature a single grade for the energy industry, with general-purpose grades and geometries to follow. I-One’s multilayer coating is geared to high or low speeds and is designed to tolerate heat and abrasion and prevent sticking. It is fully coolant-through.

“Clearly, a small replaceable insert or tool head made of carbide costs less than an entire solid drill of the same diameter,” noted Andrew Pisorn, solid carbide product manager at Allied Machine & Engineering Corp., Dover, Ohio. And, by extension, using a range of replaceable-tip tools with a smaller number of steel body holders greatly improves operational and cost efficiencies by cutting down on one’s inventory of unique solid-carbide tools. “If your shop can minimize the amount of carbide in your tool cribs and drawers, you’re minimizing inventory costs.”

Pure calcium carbide is a colourless solid. The common crystalline form at room temperature is a distorted rock-salt structure with the C22− units lying parallel.[13] There are three different polymorphs which appear at room temperature: the tetragonal structure and two different monoclinic structures.[1]