Planning for successful machining of titanium starts

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Photo courtesy Okuma America Machining Titanium Typical aerospace turbine blade that is machined on an Okuma machining center shown minus the high volume of coolant required to machine titanium.

1 Photo courtesy Okuma America Machining Titanium Typical aerospace turbine blade that is machined on an Okuma machining center shown minus the high volume of coolant required to machine titanium. Optimize Process for Best Performance It takes a well thought-out process to machine titanium Jim Lorincz Senior Editor Planning for successful machining of titanium starts where machining of any material begins with a capable machine tool, appropriate spindle power, tooling connection, cutting tool geometry, and secure workholding. Machining titanium and heat resistant super alloys (HRSA) is complicated by the very characteristics of the materials that make them highly desirable for aerospace components high strength-to-weight ratio and high heat resistance. They require high-volume coolant delivered under high pressure if possible to remove heat from the cutting zone and tool. They generally exhibit poor machinability characteristics. Titanium is expensive, adding to the risk involved in tooling failure, or the need to scrap workpieces after extensive value-added machining time. In the case of titanium machining, optimizing the process can be considered essential to achieving cost-effective and quality machining results. March 2015 AdvancedManufacturing.org 87

Machining Titanium Photo courtesy Makino An optimized process for machining titanium begins with Sandvik Coromant and Iscar Metals to optimize titanium four elements, according to Scott Walker,

2 Machining Titanium Photo courtesy Makino An optimized process for machining titanium begins with Sandvik Coromant and Iscar Metals to optimize titanium four elements, according to Scott Walker, president, Mitsui cutting toolpaths working from the same base unoptimized Seiki USA Inc. (Franklin Park, NJ). Aerospace components toolpath supplied in a STEP NC file by Boeing. Kosmala and require rigid machine structures. We design and evaluate machines for two types of stiffness, static and dynamic using Tap Trends in Advanced Machining, Manufacturing and Materials Odendahl shared their titanium cutting experiences at the Test excitation tests. Low stiffness can jeopardize surface integrity of workpieces. The tool taper interface must be able to STEP NC is an ISO standard that acts as a universal (TRAM) conference held concurrently with IMTS. accommodate long tools. For example, tool/spindle interfaces CAM translator, similar in some ways to what MTConnect like HSK 100A, KM4X100, CAPTO, and Big Plus are specifically designed to provide stiffness required for the demanding STEP NC is a modern associative language that connects does for data transfer between machines, said Kosmala. high-speed and high-torque cutting conditions encountered the CAD design data with the CAM process data. It can be used as a collaborative tool that includes process information beyond machining axis motion of traditional G-code, as well as GD&T information. STEP NC streamlines the flow of information between companies using different CAM vendors. Previously, the supplier was forced to purchase the customer s CAM package or burn engineering hours recreating the existing CAD drawings. STEP uses a translator to create a bridge between two dissimilar CAD/CAM systems, said Kosmala. In the demonstration, Iscar and Sandvik Coromant each imported an unoptimized Boeing cutting tool file in T4 horizontal machining center featuring Advantige Technology, a 4-m X axis, 100-kW STEP NC, optimized the toolpath in spindle, and 100 N m torque was the first of a series of machines specifically designed their respective CAM programs, saved by the Makino Titanium Process Development group for machining titanium. the optimized file in STEP NC, and re- machining titanium, titanium alloys, and HRSA metals. And, turned it to Boeing ready to be installed in the machine. In the of course, you can never have too much coolant delivered by demonstration at Okuma s booth, the three files could be seen high-volume/high-pressure delivery systems. Finally, achieving running directly on the Okuma machine tool controller using the right balance of machining time and tool life, which is measured in minutes when machining titanium rather than hours has one STEP NC file with the ability to choose portions or all the STEP NC Explorer software from STEP Tools Inc. Boeing machining aluminum, is critical, said Walker. from the three STEP NC files simply by checking boxes on the screen. They could cut the part three different ways, for example choosing roughing from one file, edge cleanup from the STEP NC Standard Allows Optimizing File Swapping According to Jim Kosmala, vice president of technology, Okuma America Corp. (Charlotte, NC), optimizing the when they hit go, the machine starts cutting, said Kosmala. unoptimized file, or pocketing from the third. The point is that cutting process is essential when cutting more expensive In addition to collaborative machining, there are some and difficult-to-machine materials like titanium, Inconel, and very real benefits from being able to communicate using the hard metals. At IMTS 2014, Kosmala and Boeing s David STEP NC standard, said Boeing s Odendahl. For a manufacturer like Boeing with products like airplanes that have a Odendahl, associate technical fellow, demonstrated how the STEP-NC ISO standard enables suppliers in this case very long life cycle, it would eliminate the need to start from 88 AdvancedManufacturing.org March 2015

scratch in recreating toolpaths for parts where programs simply didn t exist anymore or were created on out-of-date CAM programs or machines. We would have an archived STEP NC file to work from.

And, of course, you can never have too much coolant delivered by high-volume/high-pressure delivery systems. (189 L/min) through-spindle coolant and another 25 gpm (94.

Tap the Toughest Materials With 3 NEW Emuge Technologies: Z-TAPS At the Okuma booth, the titanium cutting demonstration was done on an entry-level GENOS M560-V VMC, which switched from machining

To see Okuma/Boeing IMTS presentation go to https://www.youtube.com/ watch?

3 scratch in recreating toolpaths for parts where programs simply didn t exist anymore or were created on out-of-date CAM programs or machines. We would have an archived STEP NC file to work from. Also it wouldn t be necessary to send experts around the globe every time a new product was planned. We would just have to send a STEP NC file with the optimized toolpath programming. And, of course, you can never have too much coolant delivered by high-volume/high-pressure delivery systems. (189 L/min) through-spindle coolant and another 25 gpm (94.6 L/min) on nozzle so we can supply inserted coolant-through roughing tools and solid carbide finish and semifinish tools with a lot of coolant at very high pressure, said List. Tap the Toughest Materials With 3 NEW Emuge Technologies: Z-TAPS At the Okuma booth, the titanium cutting demonstration was done on an entry-level GENOS M560-V VMC, which switched from machining titanium to machining a picture on an aluminum die mold with ease. When asked which Okuma machine tools cut titanium, Kosmala said: All of them. To see Okuma/Boeing IMTS presentation go to watch?v=ue8qs66r_jc Titanium Machines Meet Material Challenges Over the last five years, the Titanium Process Development group at Makino Inc. (Mason, OH), has focused on designing machines specifically to address titanium machining challenges including high hardness, plasticity, harmonic issues and thermal conductivity, according to Brian List, titanium process development engineer. The T4 horizontal machining center with Advantige Technology with a 4-m X axis, 100-kW spindle, and 100 N m torque was the first of a series that now includes the T2 with 2 meter square work envelope, and the T1 with 1.5 m in X. To handle the heat generated in machining titanium, the T4 has a 50 gpm A Full Line of High Performance Cutting Tools SST Ni Ti Introducing 3 NEW Ranges of Emuge Taps with advanced geometries and coatings, each designed to tackle today s most challenging materials. Z-Taps with GLT-1 coating for Stainless, VHC Technology for Nickel alloys and HRG Technology for Titanium. Dramatically increase your productivity, process security and tool life today! Learn more at March 2015 AdvancedManufacturing.org 89

Machining Titanium PRODUCTIVITY DRIVE We learned very quickly that we weren t going to process titanium like we had in the past. We were going to have to identify different tooling methods.

We studied how individual cutting parameters, even the elementary ones like surface footage, radial and axial engagement and chip load, influence each other.

Makino devised Design of Experiments to determine the optimal parameters, which provided some interesting and somewhat unexpected results.

However, what we found was that high radial engagement can extend tool life in heavier roughing as long as you stay within the stable area of the machine.

Get a competitive edge and drive down your costs by partnering with Weiler to solve your deburring challenges.

4 Machining Titanium PRODUCTIVITY DRIVE We learned very quickly that we weren t going to process titanium like we had in the past. We were going to have to identify different tooling methods. So we spent a lot of time developing tools with various partners to get coolant into the cutting zone without creating a bottleneck at the tool, said List. We studied how individual cutting parameters, even the elementary ones like surface footage, radial and axial engagement and chip load, influence each other. The goal was to determine how to optimize the process not just for long tool life but for the lowest cost per part, said List. Makino devised Design of Experiments to determine the optimal parameters, which provided some interesting and somewhat unexpected results. It s fairly well known that as you get larger radial engagement, the insert is going to be in the cut longer and get hotter, reducing tool life. However, what we found was that high radial engagement can extend tool life in heavier roughing as long as you stay within the stable area of the machine. When you are semifinishing or finishing the lower radial engagement is better, said List. Photo courtesy M.A. Ford DEBURRING AUTOMATION Don t settle for the status quo. Get a competitive edge and drive down your costs by partnering with Weiler to solve your deburring challenges. Implementing the latest process automation will increase part-to-part consistency, reduce health and safety issues, and enable your business to be more efficient and ultimately more profitable. The recipe for successful machining of titanium and high metal removal rates with long tool life starts with tool geometry. Don't Compromise. Optimize / weilercorp.com APPS / weilercorp.com/app-help Similarly, for axial engagement you must stay within the stable area of what the machine can handle. For example, if you move from 1" [25 mm] axial to 2" [51 mm], you ve actually doubled the forces on the tool. But as long as you have a stiff machine platform, the axial engagement has virtually no influence on tool life. With the Makino Ti machines, we often find that using about 30% radial engagement and just cutting as deep as the flutes on the tool, we can achieve huge productivity gains and still run 90 minutes tool life or more in cutting titanium, said List. 90 AdvancedManufacturing.org March 2015

High-Feed, Pressed Rake Face Geometries, Coatings Are Key Helping manufacturers achieve their goals when machining titanium requires careful attention to cutting tool geometries, coatings, and

5 High-Feed, Pressed Rake Face Geometries, Coatings Are Key Helping manufacturers achieve their goals when machining titanium requires careful attention to cutting tool geometries, coatings, and experience with the latest high-feed cutters, according to Tom Noble, National Aerospace Product Manager, Ingersoll Cutting Tools (Rockford, IL). The most common grades of titanium being used in aerospace today are Ti-6Al4V for structural and engine components, and Ti-5553 for landing gear components, said Noble. Recent advances in pressing and sintering technologies allow us to create some very complex forms which are pressed into the rake face of the insert rather than being ground in, as was typically done in the past. It is critically important to combine the proper rake face geometry with the most efficient insert edge prep, whether symmetrical or asymmetrical (i.e. conventional vs. waterfall), along with the latest technology in coatings. Each is a different piece of the puzzle in optimizing titanium machining, said Noble. Ingersoll recently installed a new coating furnace on its Rockford, IL campus. The new coating furnace uses the cooler PVD process to apply a hard aluminum oxide coating which provides a better thermal blanket, said Noble. Having a high heat resistant coating is a critical factor when machining titanium. We offer a complete line of indexable style high-feed cutters, with the largest range of diameters and DOC capability on the market. As long as you have a stable manufacturing environment, our high-feed tooling families are capable of removing impressive amounts of material utilizing light depth-of-cut and high feed per tooth to produce much higher cubic inches removed, Noble said. Ingersoll s new High-QuadF high-feed mills are available in both a 13-mm IC and 19-mm IC quad-style insert which provides four cutting edges, and a choice of eight different advanced technology cutting edge geometries. Premium March 2015 AdvancedManufacturing.org 91

Machining Titanium insert grades coupled with optimal edge preparations ensure long tool life even under the most demanding applications across the widest range of materials.

6 Machining Titanium insert grades coupled with optimal edge preparations ensure long tool life even under the most demanding applications across the widest range of materials. The maximum depthof-cut ranges from 0.088" (2.24 mm) for the 13-mm IC insert to 0.145" (3.68 mm) for the 19-mm IC insert. The positive axial insert orientation creates the high-shear, free-cutting performance of this new high-feed cutter line. Chip thinning is leveraged to a factor of 5 when calculating feed rates. High-volume coolant can actually be more important than high pressure, especially when dealing with titanium, said Noble. I use the term line-of-sight when I m dealing with coolant discussions. If coolant flow is obstructed by features on the workpiece, or chips are spraying out and deflecting coolant, you ll have poor line-of-sight and the coolant isn t doing the job. Without good coolant flow, machining high-temperature alloy materials like titanium can produce a tremendous amount of heat, causing rapid expansion and contraction of both the carbide insert and coating, resulting in thermal cracking. Engineered Cutting Tools for Machining Titanium OSG USA Inc. (Glendale Heights, IL) has developed cutting tools specifically to meet the challenges of machining titanium. One major challenge is the material s low thermal conductivity. The heat generated when machining is concentrated at the cutting zone and does not leave with the chips, resulting in increased wear of the cutting tool, said Jeff Stephens, sales engineering manager. In addition, the cutting speed is lower, which reduces productivity, but the heat produced is still so high that it rapidly speeds the wear of the tool, said Takuma Aoyama, advanced indexable manager. Cutting tools from OSG address the primary challenge of the material s low thermal conductivity in milling, drilling, and tapping applications. OSG s new Exocarb WDO-SUS has many features that minimize the issues when drilling titanium. It combines a new cutting edge geometry with a special margin and back taper to reduce heat generation between the drill and the hole. We also introduced a brand new coolant hole system, where volume of coolant is increased over 30% than conventional drills, said Stephens. In tapping, titanium has the tendency to shrink. When tapping, there is a huge amount of cutting tool contact with the material due to the thread shape, so a tap with specially ground OD and PD relief coupled with a rigid cutting edge is critical, said Stephens. OSG s Exotap VC-10 features a special relief to counter hole shrinkage and geometry for chipping and breakage resistance. TiCN coating provides resistance to heat and wear. The Exopro-Ti tap with TiCN coating features special left-hand flute design to resist chipping. We also have had great success with form tapping of titanium for small diameters and fine threads, said Aoyama. In milling, titanium has the tendency to create built-up edge. It is common to see chipping on the cutting edge. This is due to the material sticking to the edge then ripping off, taking carbide with it. The Exopro UVX-Ti series has proprietary geometry to reduce the built-up edge. The UVX-Ti series has variable helix index-style end mills which have a uniform rigidity of the cutting edges to reduce vibration and chattering and yet is able to do from side milling to slot milling even with five flutes, said Aoyama. Machining Titanium Made Easier with Tricked Up Geometries Titanium is a fairly hard material that is resistant to corrosion, nonmagnetic and has the highest strength-to-weight ratio of any metal, yet is 45% lighter. It is two times lighter and 60% denser than aluminum. Due to its strength and alloy 92 AdvancedManufacturing.org March 2015

attractive properties, machining this metal can prove challenging. It requires precautions, as the material will soften and gall if sharp tools and proper cooling methods aren t used.

There is a recipe for successful machining of titanium and it all starts with the tool geometry, which is where we ve put much of our machining experience, said Dirk Dietsch, regional business

Our newest generation of high-performance end mills, 277 series four flute, 278 series five flute, and 180 series [seven flute] are produced on the latest CNC machine tools with the latest

Even with tricked-up geometries, great attention is given to the cutting edge and flank to ensure the cutting edge is of the best quality.

7 attractive properties, machining this metal can prove challenging. It requires precautions, as the material will soften and gall if sharp tools and proper cooling methods aren t used. One cutting tool manufacturer, M.A. Ford Mfg. Co. Inc. (Davenport, IA) has devoted many years to understanding this super material. There is a recipe for successful machining of titanium and it all starts with the tool geometry, which is where we ve put much of our machining experience, said Dirk Dietsch, regional business manager Great Lakes region. Our newest generation of high-performance end mills, 277 series four flute, 278 series five flute, and 180 series [seven flute] are produced on the latest CNC machine tools with the latest microprocessor technology that can grind all the tricky geometry of varying helix angles and differential teeth pitch. Even with tricked-up geometries, great attention is given to the cutting edge and flank to ensure the cutting edge is of the best quality. Very sharp edges typically work best for titanium and the quality of our grinds are like jewelry, said Dietsch. While using constant radial step-over toolpath and M.A. Ford s high-performance end mills, customers have been very successful with cutting titanium at high metal removal rates and long tool life, said Dietsch. One customer is machining weight pockets in a large titanium turbine vane with a 6-mm diameter cutter. M.A. Ford s four-flute necked 277 series tool is used in a trochoidal toolpath at 3237 rpm, 20 ipm [508 mm/min], 0.04" [1-mm] radial stepover and 0.25" [6.35-mm] axial depth. The tool cuts 254 linear inches per part and lasts for 13 parts, 165 minutes of tool life. High metal removal rates with long tool life are also possible with M.A. Ford s 180 series seven-flute end mills in titanium, according to Dietsch. The ½" (12.7-mm) diameter 180 geometry is typically run at 2005 rpm, 72 ipm (1.8 m/min), 0.05" (1.27-mm) radial step over and up to 1" (25.4-mm) axial depth, with tool life of 60 minutes time in cut. Cutting oil is the preferred coolant due to its lubrication properties and help with cut workpiece material sticking to the tool s cutting edge. Water-based coolant can also be used and typically cools the tool better allowing for even higher RPMs, Dietsch said. Similar results can be seen in machining of TiAl-based alloys at another customer, which is profile milling aerofoils for commercial jet engines. In this application a special M.A. Ford six-flute end mill with a 0.125" (3-mm) corner radius and Altima PNH coating a new power-nitride coating that offers heat and abrasion resistance runs at 1390 rpm, 65 ipm (1.6 m/min), with 0.025" (0.64-mm) radial stepover and 0.300" (7.6-mm) axial depth-of-cut. It delivers 150-minute tool life, according to Dietsch. Super precision, high-performance endmill Ø 20.0 mm With 4 flutes 27.0 mm flute length, cycle time 16 min. Variable helix and unequal index Ground with the new GrindSmart 528XW. The smart choice.?ingersoll Cutting Tools / ingersoll-imc.com Iscar Metals Inc / iscarmetals.com M.A. Ford Inc / maford.com Makino Inc / makino.com Mitsui Seiki USA Inc / mitsuiseiki.com Okuma Corp / okuma.com/americas OSG USA Inc / osgtool.com Sandvik Coromant / sandvik.coromant.com/us STEP Tools Inc / steptools.com solutions@rollomaticusa.com March 2015 AdvancedManufacturing.org 93

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