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Cutting Tools For All Occasions

Jim Lorincz
By Jim Lorincz Contributing Editor, SME Media

Whenever a discussion turns to standard tools (catalog) vs. specials (custom-designed tools), some interesting distinctions arise. For end users, the distinctions are straightforward. OEMs, job shops, and manufacturers up and down the supply chain—whether in automotive, aerospace or general engineering—want to know what, how soon and how much.

XSYTIN-360 solid-ceramic end mills use Greenleaf’s tough XSYTIN-1 substrate, which allows the application of chip loads similar to solid-carbide end mills with the higher machining speeds common to ceramic machining. (Provided by Greenleaf)

This seems simple enough until you consider all the permutations in applications, materials and every aspect of machine tool technology. The mix of cutting tools available depends to a great degree on where they are needed. Shops that face daily changes in workpieces and materials value versatility of cutters; high-volume manufacturers benefit from cycle reduction, time savings and long tool life.

Here’s how leading cutting tool manufacturers describe the pros and cons of standard vs. custom cutting tools. Tools range from their highly engineered, application-specific, material-specific solutions created using their custom design engineering services, to the versatile solutions found off the shelf in catalogs of standard tools.

General-Purpose vs. Special Tools

Thomas Raun, chief technical officer, Iscar USA, Arlington, Texas, associates general-purpose cutting tools, or commodity tools, with short-run or small-batch production that shops encounter daily. They require versatility in machining diverse materials and workpieces; steel today, aluminum and others tomorrow. “Special tools, on the other hand, are more application specific,” he said. “Tool choices are narrowed down to be used in a specific operation or on a specific material or specific part. Those applications are typically found in high-production environments such as automotive and aerospace where the largest number of special tools are used.”

According to Raun, just about any cutting tool application or machining operation can come down to “do I choose a tool that is versatile? Or do I need to drill down and get more application-specific? Or do I need more productivity or is there something about a special tool or design that will be more productive?

“When we bring our customers to seminars, we discuss the approach of making good decisions by keeping the concept of versatility vs application-specific in mind,” Raun continued. “Choosing general-purpose rather than special application-specific cutting tools really boils down to having the kind of machining environment or operations where you can measure the value of the tool—the overall cost, not just the price. If you can’t, you will tend to lean to general-purpose or commodity cutting tool selections, and if can you’re going to get more application specific to drive down your overall cost per unit or overall cost of producing your parts,” Raun explained.

An interchangeable head type system like Iscar’s Multi-Master system provides extreme versatility and can be optimized for specific applications and materials. (Provided by Iscar)

A simple example of an application-specific solution in a high-volume production environment would be combining several operations to machine features where a socket head cap screw would be used, drilling, counterboring, and chamfering the diameters to break corners in a single tool. For versatility, an interchangeable-head type system, such as Iscar’s Multi-Master system, provides extreme versatility and can be optimized for specific applications and materials.

Raun believes that 3D printing of indexable cutting tool bodies is the next big technology and Iscar is already using it to print indexable bodies for milling, drilling, and turning tools. Iscar is introducing a robust 3D printed quick-change system for Swiss-style machining that Raun says will drive down costs. “With 3D printing, we can do some creative things like adding coolant ports and getting coolant to the cutting edge in designs where subtractive processes would be virtually unable to effectively do so. We’ll also be able to maximize coolant volume and/or pressure because we’ll be able to optimize the design attributes of the coolant ports, in particular the internal portions which could only be changed/optimized by using a 3D printing process. Abilities such as this may make specials more attractive and more cost effective when compared to standard options.”

Special Designs for Many Reasons

Walter USA LLC, Waukesha, Wis., offers standard tools for a wide range of applications within its four machining product groups of milling, holemaking, turning and grooving and threading tools. “End users like to rely on standard product tools because of price and their ready availability, said Luke Pollock, product manager. “A lot, if not most, components can be manufactured using a variety of standard tools, particularly if the engineer of the component is aware of which standard tools are available and can incorporate them into the design.”

Machining with a ceramic cutter in an energy industry application. (Provided by Walter USA)

Special tools can be designed for multiple reasons, according to Pollock. “The part may have a special need that can’t be performed by a standard tool, such as a long reach, an extremely tight tolerance, or even a particular size. Probably the most common reason for a special tool is to combine several operations into one tool. This can often significantly reduce cycle time by eliminating multiple passes, tool change time, and having to perform several operations.

“High-volume production is typically where we look to incorporate special design tools,” Pollock continued. “If a special form can be built into the tool rather than requiring multiple tools with multiple passes to create a special shape, production time can be greatly reduced and part quality can improve. In these cases, even a slight reduction in cycle time can have a huge impact on the production rate and cost. The savings in cycle time far outweighs any additional cost of a special tool and if the cycle time improvement is high enough, it can even reduce the number of machine tools required.”

The main benefit of special-design tools is most often time savings at the spindle. “When calculating the cost benefit vs. the price of a special tool, the time savings multiplied by the burden rate of the machine and operator typically far outweighs any additional tool cost,” he said. “Other benefits can also be simplification for the operator. Implementing a special tool shifts the complexity of manufacturing from the operator or programmer to the tool manufacturer. The tool comes already equipped to account for the challenges of the operation. Trying to hold a specific size, a specific form, or a specific tolerance should fall on the design of the tool, not the operator.”

Generally speaking, special tools are designed for a specific customer or specific component. “That’s what makes them ‘special.’ If you think about it from a tool manufacturer’s position, what makes the tool special is that it is custom-designed and custom-produced for a specific customer,” said Pollock. “However, there are common designs for common components. If there is a proven technique for a specific component, tool manufacturers can take advantage of the tool design knowledge. That creates a situation where, for a known component or a known feature, the correct design and correct approach is predetermined. That design is then applied with the specific requirements—such as size, lengths and angles—for the application.”

Holemaking is probably one of the most common applications for special tools. It is easy to incorporate multiple diameters, chamfers and even back boring into a single tool. Milling special shapes and forms is also a common application. Mass-produced parts such as in automotive, aerospace, or even general engineering are all applications for special tools.

Improvements in cutting tool materials have enabled great advances that significantly improve their productivity, according to Pollock. “Advancements in coating technology for both round tools and indexable inserts allow higher running speeds and higher chip loads, producing maximum material removal rates. Advancements in carbide substrates also allow for increased tool performance. In some applications, we can even use advanced materials such as PCD or ceramics to maximize productivity.”

Suitability Depends on ROI

A coolant-fed carbide feed mill. (Provided by GWS Tool Group)

Improvements in cutting tool technology for both general-purpose and special-purpose tools include new substrates and PVD coating technologies as well as refinements in geometry—especially as they pertain to blending different relief and cutting edge geometries into tools with varying diameters and helices, according to Drew Strauchen, executive vice president, GWS Tool Group, Tavares, Fla. According to Strauchen, general-purpose tools are typically suitable for low-volume/short-batch jobs where the application of a high-performance tool produces a lower ROI due to the short-run nature of the application. Another reason would be simply for the immediate availability of the general-purpose tool versus the lead time required for a custom tool.

There are many reasons shops require custom tools, said Strauchen. A special form on the part may require a special form tool to mirror that of the part. Cycle time and tooling costs can be reduced by combining two or more tools into one tool and productivity and tool life can be improved by developing a tool that is optimized for the specific application.

“While the nature of custom cutting tools is just that, namely, custom, they can often be designed to be all-terrain in nature where possible. Dovetail cutters, chamfer mills, keyseat cutters and back chamfer tools are several examples of custom tools that can typically, but not always, be general purpose in nature,” he observed.

Custom Tools Have Different Origins

YG-1, Vernon Hills, Ill., a global producer of indexable insert, round tools, drills and end mills, offers many general-purpose standard tools and special-purpose standard tools. Both general-purpose and high-performance standard tools are made for the catalog and are immediately available off the shelf from distributors or YG-1 and sold by the hundreds and thousands at list price.

Special-purpose tools can be made from print or be a modification of a standard tool, according to Yair Bruhis, aerospace, power gen and medical–global industry project manager for YG-1. “The advantage of special tools vs. standard tools is they can improve a process or solve a unique manufacturing challenge, producing tool savings and increasing tool life. The disadvantages of specials are that they take time to quote and manufacture, aren’t available from a catalog and cost more than standard tools.”

A Y-Coating on a V7 PlusA end mill helps provide longer tool life in heavy cutting conditions, according to YG-1. The tool also features improved chip evacuation by shortening chip length when using chip splitters in long-length cut conditions. (Provided by YG-1)

According to Bill Pulvermacher, YG-1’s technical director of marketing, special-purpose tools can be broken down into two categories: special purpose as a “per print/design” and special purpose as a standard catalog product. General-purpose tools are also broken into two categories: general-purpose high-performance; and general purpose as a value item.

Special-purpose “per print” offers the most significant advantages in performance and part quality. It also requires engineering time and additional costs that must be measured by the customer. Special-purpose tools as a catalog item are the “best of both worlds,” said Pulvermacher. “When the end user can find a special-purpose tool off the shelf, they will experience excellent performance and part quality without the need for engineering time and additional costs,” he said.

Available off the shelf, general-purpose, high-performance tools play the most significant role in cutting tools today, according to Pulvermacher. “They are strong performers in their applications and provide a unique value. And, of course, general-purpose tools as value item tools are utilized in almost every shop today.”

General-purpose, standard, non-specialized tools are readily available in both general-purpose and general-purpose/high-performance versions so there are a lot of standard options in corner radiuses and lengths of cut, drill diameters, length of reach, according to Pulvermacher. “Often, the biggest challenge for the end user is knowing what tools are available,” he said. “Where standard tools aren’t available, custom special-purpose tools can be designed for a single-purpose, application-specific or material-specific application, for example, or to perform multiple operations at one time. We make taps that are designed just for cast iron or tools with coatings and geometries for Inconel 718, for example.”

Pulvermacher explained that customers in a general engineering or job shop, where projects and material requirements change on an almost daily basis, benefit from the ready availability of general-purpose standard tools. Die mold companies, for example, will use special-purpose standard cutting tools where they might need long reach or hard milling capability, but avoid special tools produced by design or from print.

“The aerospace industry is a good example of where they can afford to look for special-purpose tools, whether specials or application-specific or material-specific tools. As the cost of the part goes up, they’ll be looking at specialized cutting tools. It’s only when general purpose doesn’t fit or doesn’t do the job satisfactorily that they’ll go to special-purpose or specialized cutting tools. All of our standard products that today are special-purpose were at one time bona fide specials that customers helped us design.” Today, YG-1 has a catalog of standard special-purpose tools for cutting carbon-fiber-reinforced polymers (CFRP) that were developed in that manner. Through research at its Center of Excellence in Charlotte, N.C., YG-1 performs testing to determine which special-purpose cutting tools can become standard products.

Tough Solid-Ceramic End Mill

The definitions of standard and custom tooling are pretty clear at Greenleaf Corp. “Anything that is in our catalog is a standard product and doesn’t require any modification,” said Martin Dillaman, manager application engineering for Saegertown, Pa.-based Greenleaf. “Anything that is special-purpose custom tooling is designed by our team of engineers. Our special products combine special insert designs with special geometry cutters, or a combination of standard inserts with a special cutter body that are designed for specific customer parts.

“For applications where the customer is trying to reduce the number of setups or reduce the number of required tool changes, we would combine multiple operations into one cutter,” he continued. “This helps minimize the amount of time the part is being machined. By having everything done in one operation, customers can control datums and multiple features at the same time. Overall workpiece quality can be improved by eliminating the use of multiple tools.”

In early 2021, Greenleaf launched the XSYTIN-360 solid-ceramic end mill line, its first solid end mill offering. The XSYTIN-360 uses Greenleaf’s XSYTIN-1 substrate, which has strength of material that allows applying chip loads similar to solid-carbide end mills with the higher machining speeds common to ceramic machining.

“These new [solid] ceramic end mills provide customers with significant increases in productivity over current solid-carbide or ceramic products and have opened up new markets in high-temperature aerospace materials, including Inconel, Renes as well as cast and ductile irons and other abrasive materials,” Dillaman said. “We have started out with a limited number of tools in the portfolio and have found success with running at certain feed and speed combinations. Running these tools is more expensive than running with a carbide end mill, but you are able to save more time. Customizing the end mill—for example changing the corner radius or changing flute length—gives the customer the opportunity to specialize, reducing cycle time, improving tool life compared with carbide, and providing a finished product faster.”

Greenleaf has seen success in aerospace, automotive and heavy truck machining applications, which provides the company with other areas to focus on where only Greenleaf indexable tools would have been used in the past. “Success with the XSYTIN-360 has been in high-temperature alloys and cast and ductile irons abrasive materials where ceramic can outperform carbide,” said Dillaman. “We have the ability to grind any geometry that may be required and we are able to match what the customer needs if their requirements fall outside our standard product offering with set lengths and set corner radiuses.”

XSYTIN 360 specials can be ground with shorter flute lengths and reground and remanufactured to the same end mill diameter specification. Shortening flute lengths can result in more regrinds, especially where a deep DOC isn’t required.

“The new solid-ceramic end mills open up opportunities, especially where indexable milling tools faced limits in how small they could be,” said Dillaman. “For our standard line, we could go from 8 to 20 mm. With XSYTIN 360 we can grind smaller diameters to create custom special tools.”

Solutions for Specific Materials, Applications

When it comes to matching standard and custom product solutions to end users’ needs, there’s a common theme running through Kennametal’s product groupings of holemaking, solid end milling and indexable milling. That’s according to a discussion with three Kennametal senior global product managers: Frank Martin for holemaking; Bernd Fiedler for solid end milling (SEM) and Gil Getz for indexable milling. These experts say solutions can be highly specialized for a particular material or high-volume machining application, or as versatile as being capable of machining the majority of materials and applications that job shops and general engineering shops are likely to encounter.

Versatile solid-carbide drills such as Kennametal’s GOdrill offer high performance, ensuring maximum metal removal rates, according to the company. (Provided by Kennametal)

By definition, no matter the depth or diameter or tolerance of a hole, drills can be selected and changed according to the material being machined, said the group. Material-specific tools or application-specific tools are designed to deliver the highest metal removal rate and lowest cost per part required for serial and mass production, applications that are typical in the automotive and aerospace industries. More versatile tools capable of machining different kinds of materials offer the customer the advantage of fewer tool changes, less setup time, and less downtime on the machine. In addition, shops have to carry less tool inventory.

Tools for material-specific applications have different tool requirements. For example, steel, cast iron or high-temperature alloys require different edge preparations, coatings and geometries. For manufacturers looking for maximum ROI, material-specific tools offer a good opportunity for customization, according to the group of Kennametal experts.

A good example is preparing a hole for tapping in a high-volume production application. Thread diameters are predefined, but hole depth and the chamfer may vary. Chamfering would typically require a second tool, including tool changes. A lower performing, general-purpose chamfer tool is usually used for such an operation. However, it might be more efficient to modify a material-specific drill by combining both tools into a step drill for a one-shot operation using the same high-end geometry and the same coating.

There is a growing trend toward using versatile solid end mills for job shops as well as for large manufacturers in the general engineering, aerospace, energy and transportation segments. Versatile tools combine roughing and finishing with the highest metal removal rates and produce excellent tool life. Most of them can perform well in a broad range of materials, including steel, stainless, cast materials, and high-temperature alloys, making it easier to handle stock management and tool inventory. Aluminum, composites, and hardened steels (>56 HRC) require material-specific design, substrates and coatings.

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