DEEP HOLE DRILLING INSERTS,COMMON TURNING INSERTS,CARBIDE INSERTS

This article originally appeared on our sister site, Additive Manufacturing. Explore more AM topics at additivemanufacturing.media.

Could additive manufacturing be used to produce a tungsten carbide cutting tool for use in CNC machining?

In principle, yes, says cutting tool maker Kennametal. Tungsten carbide, the principal material used in high-performance cutting tools for machining, is a material the company is already applying through AM. However, tools for metal cutting are not the current opportunity the company has found for 3D printed carbide. Instead, it delivers 3D printed carbide wear parts for applications in oil and gas, power generation and defense, among others — and material development efforts have focused on these applications as well.

During a recent visit to the company’s Latrobe, Pennsylvania, technology center, I spoke with two members of the AM team: Kennametal Additive Manufacturing General Manager Jay Verellen and Director of Advanced Machining and Additive Solutions Ed Rusnica. The different ways the company is advancing AM illustrate the various channels by which additive is finding opportunities in and around conventional manufacturing.

For Kennametal, they say, efforts in AM can be characterized as “powder, printed parts and [the company’s own] products.” These are three different pursuits, not all of them necessarily related to one another. Taking each on in turn:

•Powder. The company develops tungsten carbide and Stellite powders adapted to 3D printing via binder jetting for its own part production efforts. An example is the company’s newly introduced KAR85-AM-K carbide grade. Targeted for wear parts in uses such as downhole oil and gas applications, this grade emphasizes corrosion resistance — particularly valuable for the downhole applications.

•Parts. For industries that can benefit from new design options in carbide hardware thanks to material such as the new grade, Kennametal also offers part engineering and production services on its array of binder jetting machines (from various providers) in Latrobe. Wear parts are a great application, Carbide Drilling Inserts as they are made in low quantities and subject to redesign according to the specific uses. By contrast, carbide cutting tools do not have this same suitability to 3D printing; they are frequently made in high volumes through molding and grinding, processes that remain unchallenged.

•Products. Within Kennametal’s own cutting tool product line, the opportunity for AM is instead found in the tool bodies. 3D printing allows for precise curving and branching channels for cutting fluid inside of tool bodies that in some cases could not be achieved any other way. The company’s KenTIP FS line of modular drills, for example, includes tools 10 mm in diameter and smaller that employ through-tool coolant passages despite the small cross-sectional area of the tool, thanks to AM’s ability to surface milling cutters economically create the small tool body with these passages inside. Notably, though, these tool bodies are made with a different process — powder bed fusion rather than binder jetting — and they are produced in Kennametal’s facility in Germany, not Latrobe. That is, Kennametal’s own AM production is an effort distinct from the AM opportunities it is realizing for other industries.

Another, very different example of success in 3D printing a tool body involved a very large tool rather than a small one. A boring tool used to produce electric vehicle components was made 15 to 20 pounds lighter than it would otherwise need to be, in addition to accommodating branching internal coolant passages, all thanks to AM. We covered this development on The Cool Parts Show — see our episode on the Kennametal stator bore tool.

Machining very large cast iron parts often requires large amounts of material removal using wide cuts and deep bores, so the speeds seldom exceed 5,000 rpm. The need in this setup is not faster speeds, but a tough spindle that stays rigid while it attacks wide areas of hard metal.

Bechert Brothers Manufacturing of Forestville, Connecticut, is a 35-person, three-shift machining operation founded in 1977 by Jim Bechert, father of James and Bill Bechert who now handle day-to-day operations. Bechert Brothers specializes in machining these high precision cast iron and steel parts. Examples are rotary screw compressor housings of cast iron for HVAC systems that weigh 200 to 1,000 pounds, steel components used in couplings for helicopter rotors and bearing housings for gas turbine engines made from investment castings of 4140 carbon alloy steel.

These are difficult parts to machine accurately and cost effectively. Getting the accuracy needed on complex parts while maintaining productive feeds and speeds takes good planning as well as the right equipment, according to James Bechert, president. Also important are quality and precision, along with the avoidance of costly downtime. Bechert Brothers decided that a way to meet all these goals was to standardize its equipment. All of the company's machines are Matsuuras, and virtually all of its toolholders are from Command Tooling (Ramsey, Minnesota), according to Mr. Bechert. "The standardization makes a big difference in our consistency and repeatability. Our operators intimately know these machines, their software and the toolholder capabilities without having to deal with the vagaries of three or four different machine brands and models. The same is true with the toolholders.

"When our operators set up for one of these jobs, which involve hogging out large cavities and producing dozens of bores and tapped holes, they have the confidence of knowing, for example, that they can successfully get a ½-inch diameter cut in cast iron at 1,000 rpm without tool chatter. Because machines and toolholders have similar features, little things like setting coolant lines at the same height are easy because all the toolholders are the same length, being they are from the same manufacturer," says Mr. Bechert.

"For the same reason, the toolholders tighten up consistently so the operator doesn't have to guess what's right to get good concentric gripping force on the cutting tool—something that can cause a machine shutdown in the middle of a part run if it's not right."

To machine the compressor housings, Bechert Brothers has four MAM 900H Matsuura horizontal machining systems. These are full four-axis systems with scale feedback and dual 24.8-inch deep hole drilling inserts square pallets; 36.2-inch by 28.3-inch by 29.9-inch X, Y, Z travels and 32-second pallet change. The machines have 590 ipm rapid traverse and 15 to 4,500 rpm oil cooled spindles.

Using an array of 40- and 50-taper Command milling, drilling and tapping toolholders plus Command's Urma modular boring tools, two and three operations are done to the housings on each pallet side prior to indexing to the next side. Originally equipped with 50-tool carousels, Mr. Bechert says his company quickly converted to the 100-tool carousel that holds a greater variety of tools because the compressor housings required many different tools to manufacture them in a single part setup.

Because the parts are large and oval-shaped (36 inches by 30 inches by 20 inches), maintaining size with correct tolerance is difficult. This is especially tungsten carbide inserts true for the boring operations where the Urma modular boring tools using coated carbide inserts are employed to achieve the needed ±0.0002 diameter on the wall bores. With depths of 12 to 20 inches required, Bechert utilizes the full boring system range (0.036 inch to 31 inches). This combination allows perpendicular and true position penetration of overlapping bores, which, according to Mr. Bechert, can wreak havoc on ordinary boring tools. With consistent rigidity from one toolholder to the next, he reports getting ±0.0005 true position, bore to bore, and 0.0005-inch perpendicularity to the part face.

Bores are roughed out, then semi-finished and finished. Speeds for the roughing pass are at 600 rpm with 3,500 rpm for the finishing pass. Most of the bores require a 63 micro finish with a smaller number requiring a finer 32 micro finish.

Part runs vary from 15 to 200 a month for the larger compressor housings. Generally, runs are not large, so setup time is an important consideration. Bechert Brothers maximizes runtime on all of its machines by presetting jobs off-line and operating three shifts. "Our goal is to keep those machines in the cut 24 hours a day," says Mr. Bechert. "Downtime is costly so we can't afford to have a hodgepodge of different toolholders that tighten inconsistently and cause a rigidity and chatter problem in the middle of a part run."

Quality isn't compromised with the output of the three-shift operation because the company operates a QC department. Utilizing a Zeiss 850 Carat, known for its size and precision measuring features of large aerospace parts, this department tracks every part and critical part feature to ensure repeatable quality throughout its three shifts.

Platinum Tooling has appointed Frank Twomey as the company’s regional sales manager. In his new role, Twomey will oversee all activities in eighteen states located in the Northeast, Mid-Atlantic and Southeast regions of the U.S.

Twomey brings experience in the aerospace, medical, machine tool, cutting tool, metal and composite industries. His technical expertise includes programming CNC machines using Mastercam and Alphacam CAD/CAM software, and he is said to be well versed in PLC programming. During his career, Frank studied and trained in lean manufacturing, value stream mapping, ISO processes/audits, gravity turning inserts OSHA compliance, cost reduction, facility/line set-up and operator training.

Twomey’s first job after graduating from Piedmont Technical Institute in 1991 was as a machinist at Ross Industries. He then took on the role of applications/service/quality engineer at Walter Grinders and SCM Group as an applications and service Engineer. Between working as an applications and service engineer, he became the CNC shoulder milling cutters manager of Euro-Composites Corporation and later plant manager at MTEQ. In 2015, Twomey took on the role of district sales manager for OSG USA. Continuing his education in 2020, Twomey obtained numerous sales certifications.