ISOinsertnomenclature pdf

When it comes to cutting tool selection, machinists have three basic choices: brazed carbide tool bits, indexable tooling with carbide inserts, and solid tools made of carbide or high-speed steel (HSS). This article will explain why the middle choice—indexable turning, milling, and drilling tools—is often the best choice for productive, cost-effective machining.

The added cobalt content makes these drill bits harder and more resistant to heat buildup than a typical HSS bit, giving them much greater durability. Also, unlike carbide tips or titanium coatings, cobalt drill bits can be resharpened when the tip becomes worn. These bits offer precision to users who drill stainless steel and other hard materials.

Drill bit numbers are related to wire gauge size. The larger the bit number, the smaller the diameter of the resulting hole. For example, a number 80 drill bit creates a hole with a diameter of 0.0135 inches. As the diameter grows larger, the bit number grows smaller. A number 1 drill bit, in comparison, has a diameter of 0.2280 inches.

Stainless steel is an extremely hard material. Low-carbon steel bits, like those used to drill into wood, do not perform when applied to stainless steel. Therefore, a drill bit for use with stainless steel must be harder than the steel itself. One way that manufacturers achieve this hardness is by infusing materials that facilitate penetration and protect against overheating.

Following the guidelines on this revolutions per minute chart, we used each bit to drill four holes into 0.125-inch thick stainless steel, observing the ease of penetration, any bit travel across the steel surface, and the formation of metal chips/dust. We also noted how securely the bit was retained by the drill chuck and, when drilling by hand, how smoothly it transitioned from point penetration to the full diameter of the bit. Finally we used a bench grinder to sharpen the bits and drilled another hole with each one. Each of the sets we picked tested successfully, with the primary differences or improvements being edge retention, tip and shank design, and set configuration.

We liked the compact round carry case that these bits come in. The screw-on top held securely and seemed to be watertight after we accidentally dropped it in a puddle. However, the bit-size indexing was all but impossible to read. Although the large quantity of bits makes the set heavy, this would be a good choice for carrying to project sites where precision drilling is required.

Simply put, if there’s an alloy out there, the chances are excellent that a material-specific carbide grade is available to cut it. However, some shops machine aluminum one day, iron the next, and titanium the day after that, often in low quantities. Does this mean they need to bloat their tool crib with dozens upon dozens of different carbide insert grades and geometries, many of which will only be used occasionally?

We also keyed in on bits with 135-degree points as the recommended angle for efficient drilling into hard metal at the required lower speed and higher pressure. Other variables, such as split or pilot point, flat or 3-flat shank, or various coatings held lower priority. Lastly, we factored in top brand names, which often equate to greater consistency and availability.

That leads us to indexable carbide inserts, the workhorses of the machining industry. As with old-fashioned brazed tools, indexables also utilize small bits of carbide. The difference is how they’re attached. Rather than a permanent braze, indexable tooling relies on a screw or clamp to secure the carbide insert to the tool body. When the edge becomes worn, swapping it out only takes seconds. More importantly, there’s no loss of position or need to “touch off” the tool. Just remove the old insert, stick in a fresh one, and get to work.

ANSIinsertnomenclature

We spent several days researching drill bits for stainless steel and shopping around for the best options available online. Although solid carbide drill bits may be the professional machinist’s choice for drilling stainless steel, they are incredibly expensive. Other options like titanium-coated HSS are inexpensive but lack durability. We narrowed our search to cobalt drill bits because they can drill hard metals repeatedly without dulling right away, and they can be resharpened many times to extend their working life.

The 3-flat shanks of these bits eliminate slippage in the drill chuck. The combination of secure chucking, easy starting, and smooth operation make these bits an excellent choice for use in cordless drills at low speed for hard stainless steel or higher speed for mild steel. The kit includes Milwaukee’s #1, #4, and #9 step bits. The #1 drills from 0.125-inch to 0.5-inch holes in steps of 0.03125 inch. The #4 bit makes holes 0.1875 inch to 0.875 inch in 0.0625-inch steps. The #9 bit drills 0.875-inch to 1.125-inch holes in 0.0625-inch steps.

Carbide is one such material found in drill bits for stainless steel. Titanium and tungsten carbide are nearly as hard as diamond, making them ideal for penetrating steel. These carbide-infused drill bits are one strong option when drilling straight into stainless steel.

Infusing drill bits with cobalt is another way that manufacturers achieve ultrahard drill bits. High-speed steel, also known as HSS, is the most common drill bit for metal drilling. Cobalt drill bits are an extension of HSS bits. They are made with a special steel alloy that includes 5 percent to 8 percent cobalt.

If converting fractions of an inch to the metric system seems like no fun, this 19-piece drill bit set can help. Not only are these Stroton bits metrically sized in increments of 0.5 millimeters, from 1 millimeter to 10 millimeters, they also feature a unique three-stepped pilot-point design that penetrates stainless steel without traveling across the flat surface. The bits are constructed of tough M42 cobalt alloy steel for improved durability.

In testing, the Bosch M42 drill bits made drilling a pleasure thanks to their unique combination of design features. The M42 alloy itself allowed the bits to hold their sharp edge longer than others we tested, which meant more holes with less work stoppage to resharpen. The split-point design was easy to sharpen when needed and only required two or three additional passes on the grinder compared to M35 bits from other sets. The 3-flat shank was fast and easy to chuck securely, and we never had to worry about the bit slipping or becoming stuck in the work surface.

Long story short, carbide insert selection is much easier than it once was, even though the number of cutting tool options has grown exponentially since the days of brazed carbide and HSS tool bits. Download a catalog, log in to NOVO, or give your local cutting tool representative a call. You’ll be making chips in no time.

For affordable drilling options, we chose these bits made of a proven material with a simple and functional design. The Comoware cobalt twist bit set includes 15 bits made of M35 cobalt alloy steel that dependably penetrate stainless steel. The bits feature an easy-to-sharpen split point and a straight shaft. They range in size from 0.0625 inch to 0.375 inch, including two each of the popular 0.0625-inch, 0.09375-inch, and 0.125-inch sizes, for a total of 12 different bit sizes. The kit comes in a lightweight plastic carry case with easy-to-read printed bit-size indexing.

ISOinsert chart

This set of M42 cobalt drill bits from Drill America includes 29 pieces from 0.0625 inch to 0.5 inch in 0.015625-inch increments. The bits are finished with gold oxide, which acts as a built-in lubricant to minimize heat, making this one of the best choices for a long working life when drilling tough metals. Each bit is made of high-grade M42 cobalt alloy steel and features a split point and straight shaft.

Milwaukee Cobalt Red Helix drill bits make it easy to drill into hard stainless steel. This set includes 15 bits made of M35 cobalt alloy steel. They feature pilot points for fast, precise surface penetration without a center punch or pilot hole and 3-flat shanks to eliminate the hassle of bits spinning in the chuck. Bit sizes range from 0.0625 inch to 0.375 inch.

While the Stroton M42 cobalt bits feature round shanks, which can allow slippage in the chuck, we did not experience any slippage during tests, possibly thanks to the unusual low-profile stepped split-point design. Unlike the more pronounced pilot points on other bits we tested, the low-profile Stroton tips featured a three-step tip that seemed to penetrate faster and smoother than other designs, with or without a center punch starting point.

Folks who want to be ready for tough steel drilling projects that might come up should consider these cobalt bits from Bosch. The kit includes 14 bits ranging in size from 0.0625 inch to 0.5 inch. They are made of M42 cobalt alloy steel, which is one of the best bit materials for drilling hard metals like stainless steel, cast iron, or titanium. The bits feature easy-to-sharpen split points and 3-flat shanks for easy, secure chucking into the drill. They also feature thicker threading than other twist bits, which helps them remove material more efficiently in less time.

The DeWalt 14-piece Industrial Cobalt Alloy drill bit set is built for working on hard stainless steel, with features to prevent bit breakage, shank slippage, and travel on the work surface. The set includes 14 bits made of durable M35 cobalt alloy steel. It includes the most popular bit sizes from 0.0625 inch to 0.375 inch. Pilot points make it easy to start drilling precisely where the hole needs to be, while the 3-flat shank design prevents slipping in the drill chuck.

Indexable cutting tools are especially important on CNC machinery, where the need to keep spindles turning at all times is critical. Here, machinists rely on indexable drills—often with coolant running through them—to make holes quickly, followed by indexable boring bars to finish machine them. Indexable face mills true up large flat surfaces; indexable end mills rough out pockets and cut slots; indexable profiling tools trace complex part shapes. There’s very little that can’t be machined with indexable cutting tools.

Where machinists and toolmakers once had to grind special shapes into their brazed or solid carbide tools, they now have the option of buying off-the-shelf indexable inserts in a huge variety of geometries and styles. Need to cut a 1/16” wide groove in a shaft? How about an Acme thread, or a 45-degree chamfer around a part periphery? These and other insert shapes are readily available, no grinding necessary.

This 29-piece professional-grade drill bit set from Irwin Tools covers an abundance of applications. The bit circumference spans 0.0625 inches to 0.5 inches by increments of 0.0156 inches. The bits themselves are heat- and abrasion-resistant, thanks to their industrial-grade high-speed steel cobalt-alloy construction. To aid penetration, these bits feature 135-degree split-tip points. Besides making these bits suitable for ultrahard materials like steel, the quality construction materials ensure longevity.

For as long as there’s been tungsten carbide (which is roughly nine decades), machinists have been brazing small hunks of it to steel shanks and then grinding a sharp edge on the result. These brazed carbide tool bits and boring bars are easy to make, customizable to the application, and inexpensive. Unfortunately, their effectiveness depends on the machinist’s brazing and grinding skills. And since the tool must be removed from the mill or lathe for sharpening, they also lead to significant and costly machine downtime.

Titanium nitride (TiN) protects high-speed drill bits. Distinctive for their golden color, TiN-coated drill bits are ideal for high-speed drills. The coating provides the ancillary benefit of being ultradurable, making them an excellent value for consumers who intend high-frequency use.

In addition to ultrahard materials and protective coatings, drill bit users who seek longevity should ensure the bit can be sharpened. While drill bits infused with carbide or cobalt keep their edge longer than a standard bit, investing in a set for life often means resharpening the dull drill bits over time.

Available in several grades, each with at least 10.5 percent chromium, stainless steel is popular because of its low maintenance, high sheen, and resistance to stains and rust. DIYers and trade professionals often need to drill stainless steel to complete a variety of electrical, plumbing, and automotive projects. Whether you’re expanding the size of a junction box punch-out or boring out a broken bolt, having the right drill bit matters. Drill bits built to work on softer material, like wood, won’t do the trick against stainless steel. Luckily, manufacturers design special drill bits capable of puncturing even the hardest grade of stainless steel.

High-speed metal drilling creates excessive friction and heat. The extra stress placed on standard drill bits tends to wear them out quickly. Individuals who intend to drill stainless steel frequently should be sure to buy bits designed with longevity in mind.

Last but not least is the whole topic of insert nomenclature. It’s a deep subject, one filled with exceptions and cutting tool-specific rules. Regardless, most manufacturers follow the ANSI or ISO tool identification system (and sometimes both). We won’t get into the details here except to say that it uses an alphanumeric code to specifies an insert’s shape (round, square, triangular, etc.), clearance angle (neutral to positive), tolerance (some inserts are pressed to size, while others are ground), the size of the locating hole (if any) and clamping method, its size and thickness, corner radii, and various other defining features (see the chart above for an example).

Not all drill bits achieve results in the same way. To identify the best drill bits for stainless steel, learning about characteristics like material, coating, frequency of use, and drill bit number are critical. Read on to learn the factors to consider as you search for the best drill bits for your projects that involve stainless steel.

In our tests, we appreciated the Milwaukee step bits’ ability to drill precise holes without a center punch using a handheld drill. They tapped into the stainless steel quickly and worked smoothly. We also noted how easily they worked to enlarge existing holes—a task that’s nearly impossible to do well with regular twist drill bits. Sharpening the bits was surprisingly easy but required a completely different technique than twist bits. We used a diamond sharpening stone to flatten the smaller flute edge, and it only took about 5 minutes.

With the above considerations in mind, we selected the following drill bits as our top picks for drilling stainless steel. Read on to find out the details on each set, how they performed in our drilling tests, and why we included them among the best drill bits for stainless steel.

CarbideinsertidentificationchartPDF

The 3-flat shank prevented bit slippage in the chuck and eliminated most snags in the drill work when excessive pressure was applied. The heavy-duty plastic carry case was easy to use and light enough to tote in a tool bag. Overall, it’s a nice all-purpose choice for everyday use with stainless steel and most other metals.

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Titanium carbonitride (TiCN) is likely the most durable metal coating available. TiCN bits are blue-gray. Their coating makes them incredibly resistant to wear and capable of enduring high-speed and high-frequency use.

Those with lingering inquiries about drill bits for stainless steel may find the info they need in the answers to these frequently asked questions. It should help folks use and maintain the best drill bits for particular projects.

This numbering system chart from the Kennametal Innovations catalogprovides a guide to the company’s extensive assortment of turning inserts. Other manufacturers offer similar guidelines.

Complex naming systems aside, however, choosing the right insert for your machining application isn’t as difficult as it might appear. That’s because cutting tool manufacturers have developed online tool advisors that walk machinists and programmers through the tool selection process. For example, Kennametal’s NOVO prompts users to answer questions about the metal removal process (milling, turning, or holemaking), the machine tool that will be used, workpiece material and removal amount, and expected depths of cut. It then generates a machining strategy along with insert and toolholder suggestions, ordering information, product availability, feed and speed recommendations, and more.

ISO carbideInsert chart

Over the course of 2 days, we spent about 12 hours shop testing the drill bits we selected. After unpacking and noting the physical characteristics of each bit set and the cases they came in, we started drilling. From each set, we tested four different bits, first in a drill press for precision and accuracy, then in a cordless drill to gauge comfort and smooth operation.

But how do you know what carbide inserts and cutter bodies to buy? And why are there so many different grades of carbide inserts out there? Good questions; we’ll start with the second one first. Unlike a few decades ago, when machinists had just a few grades to choose from, there are now dozens of inserts grades, coatings, and chip-breakers available.

Web applications like Kennametal’s NOVO system not only guide users through the cutting tool selection process, but also help with job management and provide numerous video tutorials.

The Drill America bits offered a similar drilling experience as our Best Overall pick because of their similar design features, but this set boasts improved durability thanks to a higher cobalt content. Both sets offered the same drill-bit size assortment, round shank, and 135-degree split-point construction. The Drill America bits remained noticeably sharper after an equal number of test holes, but they required three or four more passes on the grinder to sharpen.

We appreciated the affordability of this kit’s overall packaging and design, which allowed the tool quality to remain high while minimizing branding and engineering costs. The bits functioned comparably to similarly designed bits from bigger brand names, with good drilling capability and an easy-to-sharpen point. We also liked that the kit includes duplicates of several smaller sizes, as they are the ones that dull easiest and are more susceptible to breaking under excessive pressure. The case does feel a bit flimsy and the size selection is somewhat limited, so this won’t be a great fit for those who require high precision. But for occasional drilling, it’s a really good deal.

Many of these are tailor-made for specific materials or material groups. For instance, a shop making aerospace components can greatly increase efficiency by purchasing carbide inserts designed for tough, heat-resistant superalloys (HRSA) such as Inconel and Hastelloy. The same is true for medical shops, which tend to cut corrosion-resistant, biocompatible materials like 316 stainless steel, cobalt chrome alloy, and titanium. Automakers can dial in their processes by using inserts optimized for cast iron and low carbon steel, while oil and gas producers benefit from tooling that excels in duplex steel.

Many manufacturers complement construction materials like drill bits with metal coatings. These coatings promote penetration and protection of the drill bit. Black oxide coatings reduce friction and heat—a significant consideration when drilling metals. Black oxide also protects against corrosion and water, keeping the drill bits functional for a longer period.

We’re committed to testing and reviewing products so you can make an informed decision. Advertising does not influence our product reviews and it never will. We always focus our coverage on standout products and never hesitate to mention their flaws and quirks. By using our affiliate links, you’re supporting our work and helping us continue to provide expert analysis. Find out more about our product evaluation process.

The Mill 16™ series is a perfect fit for most cast iron face milling requirements with high feed rates to boost productivity and reduce cycle time.

TurninginsertIdentificationchart

In our stainless steel drilling tests, these Milwaukee bits surprised us with noticeably faster, more precise penetration into the steel. The elevated pilot point, which is visibly shorter and narrower than others tested, seemed to offer the best balance of accurate placement and rapid material removal. We also noted that the center point did not get in the way of sharpening like some of the other pilot-point bits. Plus, Milwaukee’s hard plastic carry case was our favorite of the entire test group. It held the bits more securely, offered easy-to-read size indexing, and was easy to open and close securely. If the bit size assortment were more comprehensive, this set could have been our Best Overall pick.

We certainly appreciated that the Irwin cobalt drill bit set had the best selection of bit sizes, in tight increments of 0.015625 inch from one size to the next. It would make a great choice for anyone who requires a high degree of precision in terms of hole sizes. However, in testing we saw that the straight shanks required a little extra care when chucking to ensure a secure fit without slipping. The straight shanks also made the bit a smidge more likely to get stuck if we applied too much pressure.

We found the 135-degree split tip to be very easy to sharpen. Also, the steel carry case proved durable and well organized with easy-to-read size indexing, although it weighed more than the heavy-duty plastic cases used by competitors. It’s probably best to keep this set in the shop and use a smaller set for traveling work.

Insertnose radiuschart

Though drill bits for stainless steel pull heavier duty, they are also made of more durable materials. Regularly maintained and properly stored, these kinds of drill bits may last a lifetime.

These tips got into the material quickly and smoothly transitioned out to the full diameter of the bit. The edges held up remarkably well compared to M35 bits, but the tip design called for greater care when it finally came time to sharpen. We had to work slowly using extra caution to maintain the multitier tip profile.Though the thin plastic case is nothing to brag about, the size indexing was easy to read.

Because of its hardness, stainless steel is an unforgiving construction medium. Usually, there is only one chance to achieve the perfect drill hole. Another crucial consideration when purchasing drill bits for stainless steel is the drill bit number or size.

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That statement extends to HSS rotary tool bits such as end mills, drills, and reamers, all of which are used daily throughout the manufacturing industry. That’s a shame. Yes, these tools are less expensive than their solid carbide alternatives, but as mentioned, they’re also far less wear-resistant, predictable, and productive. These factors explain why leading cutting tool manufacturers emphasize the importance of carbide tooling to their customers and why many have stopped offering HSS cutting tools altogether.

ISO turninginsertnomenclature

Kennametal's KCS10B turning grade provides easy wear identification. It's ideal for medium machining and finishing operations of nickel-based (S3), cobalt-based (S2), and iron-based (S1) high-temperature alloys.  The extremely hard, wear-resistant carbide substrate allows for longer tool life, while the ultra-fine-grain carbide substrate and smoother coating reduces friction.

We really liked the effectiveness of the pilot-point design. Instead of using a punch to mark the starting point and reduce bit travel, the pilot point allowed us to start drilling directly into the flat surface. However, due to its multitiered structure, we noted that the pilot point complicates the process of sharpening the bit. We worked through it slowly and with extra caution, we achieved satisfactory results.

HSS tool bits present a similar story. They’ve been around even longer than brazed carbide. They’re much less expensive than carbide and there’s no need for brazing—just sharpen the tip however you want and get cutting. Sadly, you won’t be cutting very long or very quickly because HSS boasts a cutting speed of just one-fourth that of tungsten carbide, and even less compared to some of the newer, coated grades. HSS might be fine for hobbyists with loads of time on their hands, but carbide is the first choice for professional machine shops.

In some project settings, a single step drill bit can replace an entire set of twist bits. Step bits offer the advantage of fast, clean precision drilling into thin stainless steel or sheet metal without the need to change between different bit sizes. Each one of the three cobalt step drill bits in Milwaukee’s set is engineered to drill up to 1,000 holes into 14-gauge steel. They feature a rapid strike tip for fast starts without a center punch, elongated dual flutes to minimize heat, and finer step increments for smoother operation. Hole sizes are laser engraved inside the flutes for easy reference.

A rubber-reinforced carrying case protects the drill bits from accidental drops and makes organization and transportation a snap. These drill bits work well on stainless steel and last a long time.

With loads of available bits for hard metal applications, finding the right drill bits for stainless steel can be challenging. We spent more than 40 hours researching the best materials and designs used to make these bits, selecting our top picks, and then testing our picks in the workshop. Read on to find out what makes a durable and effective drill bit for stainless steel, our selection criteria, and how our selections performed in testing.

Probably not. Just as there’s no shortage of indexable carbide tooling optimized for certain materials, there’s also no shortage of excellent general-purpose cutting tools. These represent a middle ground between performance and the tool crib bloat just mentioned. That said, the decision to go the material-specific route is a delicate balancing act—if a job’s going to be in the machine for more than a few days or is sure to come around again in a month or two, it almost always makes sense to buy carbide inserts designed for that material.