An alternate toolholding technology has allowed a Brookville, Ohio manufacturer’s shop to redline spindle speed on an HMC purchased to machine short runs of aluminum billet workpieces. Changing toolholders has also greatly increased feed rate and throughput for a variety of components that make up the specialty and pneumatic actuators the company produces.
The shop is part of IMI Norgren’s Actuator Division, located just west of Dayton. This facility manufactures various air cylinder actuators for automotive, packaging and other industries. A little more than a year ago, the company purchased a 30-horsepower Mori Seiki NH4000 HMC to produce many of the specials and low-run jobs primarily from aluminum billet. Rated at 14,000 revolutions per minute, this machine is the shop’s fastest in terms of spindle speed.
Until recently, Jason Ballin, CNC programmer and operator, could never run the machine at such high revolutions per minute. That’s because the traditional setscrew end mill toolholder the shop used was holding the machine back by introducing chatter at speeds faster than 8,000 revolutions per minute. The toolholder design, which uses two set screws directly in contact with a tool’s shank to secure it in the toolholder, didn’t provide the balance and runout necessary to deliver a quality surface finish at high speeds.
Mr. Ballin and the shop’s manufacturing engineer, Norm Howard, tested an alternate toolholder technology that ultimately enabled their fast machine to reach its full potential. That toolholder is the Sino-T from Schunk Inc. (Morrisville, North Carolina). The Sino-T toolholder employs compressive toolholder design similar to that used by hydraulic toolholders at a cost comparable to collet-style toolholders. Rather than fluid, this device uses an elastic material that when pressurized provides an Face Milling Inserts equally distributed clamping force around a tool’s shank for effective vibration resistance at high spindle speeds. Its compact body avoids contact with components on the tombstones commonly used to fixture multiple workpieces in the two-pallet HMC.
One machined component is illustrative of how the shop has benefited from the change in its toolholding method. It is a 6061 aluminum body for a pneumatic gripping device that requires milling, drilling and grooving operations. The machining of two features, in particular, was hampered by the original end mill toolholder. One is a 0.83-inch-wide, 0.82-inch-deep slot in which gripper fingers must freely articulate. The other is a 1.25-inch-diameter, 1.35-inch-deep bore that receives a pneumatic piston.
When high spindle speeds were attempted in producing the slots, excessive Tungsten Carbide Inserts runout and chatter caused match line problems while roughing with three cutting passes using a 0.75-inch indexable insert end mill. By using the same end mill with a Sino-T toolholder, the HMC’s spindle speed could be increased from 8,000 to 14,000 revolutions per minute. In addition, the feed rate increased from 60 inches per minute to 150 inches per minute, which significantly decreased cycle time for these operations. After roughing, the HMC takes two finishing passes using a solid carbide end mill in another Sino-T toolholder. These passes bring the slot to its final depth and width while providing 32-root-mean-square surface finish and no match line problems.
The bore opposite the slot is roughed through circular interpolation using the same 0.75-inch inserted end mill that machined the slot. A finishing pass with a solid carbide tool yields a 16-root-mean-square surface finish. By creating holes via circular interpolation, the shop can machine a number of hole diameters with a single tool that remains in a known pocket in the machine’s 60-tool ATC carousel. It also eliminates the use of an adjustable boring head, which would require adjustment to a new bore diameter, off-line measurement to verify the diameter and touch-off before boring.
The shop uses a custom tool change-out fixture created by IMI Norgren and a C-spanner wrench to change tools out of the Sino-T. The wrench secures a new tool by compressing the toolholder’s clamping sleeve and elastic material around the tool’s shank. A hard stop prevents over-tightening with the wrench and possible toolholder damage. The toolholding mechanism is completely sealed for the through-spindle coolant (the shop’s HMC has a 1,000-pounds-per-square-inch system).
IMI Norgren’s shop machines approximately 200 gripper bodies per month. For the first month after switching to the SINO-T, Mr. Howard says the shop did not have to change a single insert from the 0.75-inch roughing end mill. Using the previous tooling method, he estimates that 10 inserts would have been consumed during that one-month period. The shop went on to machine more than 2,000 gripper bodies with the same set of inserts, he says.
In addition to the 0.75-inch indexable insert and solid carbide end mills, the shop has also used 0.375- and 0.5-inch solid carbide end mills in the new toolholder. Mr. Howard notes that other diameters are possible using reducer collets.
There are three ways to create programs that run on CNC machines: manually write them, use a shopfloor-programmed conversational control or use a CAM system. The last is the most popular method of creating programs because almost every company that has CNC machine tools has Thread Cutting Inserta CAM system.
Just as a CNC control can be customized through parameter settings to work with a wide variety of CNC machine tools, so too can a CAM system be tailored to work with a wide variety of CNC controls. However, given the numerous CNC functions involved, customizing the CAM system to a given CNC machine and control can be challenging.
To complicate matters, most CNCs allow users to handle nearly every programming feature multiple ways based on preference. With cutter radius compensation, for instance, the user can decide whether the generated tool path is for the cutter centerline or the work surface. Choices are often based on legacy because CNCs are “backward compatible.” This means they allow older programming methods to be used for years (or decades) after newer, more convenient features became available.
Given the these complexities, most companies tend to quit customizing CAM system G-code output as soon as they get something that works. They stop short of making the CAM system output G-code programs that are properly structured, or that takes advantage of current, more desirable CNC features. Resulting G-code programs are lengthier, less efficient and more cumbersome than their manually created counterparts.
Here are four suggestions to help you streamline G-code programs created by CAM systems.
Certain CNC features are designed to make life easier for manual programmers. The tradeoff is often more work for setup people and operators. Consider tool nose radius compensation, a turning center feature that deals with imperfections caused by the tiny radius on single-point cutting tools. While it simplifies programming, CNC-based tool nose radius compensation requires the setup person to enter tool nose radius data.
All current CAM systems can output tool paths based on a specified tool nose radius. If you make your CAM system do so, you can save setup time and minimize potential for mistakes. Other CNC features that can have an impact on operator time and effort include other compensation functions like machining center based fixture offsets, tool length compensation and cutter radius compensation, as well as turning center based geometry and wear offsets.
While they may not regularly modify CNC programs, setup people and operators should be able to understand what a G-code program is doing. This can be a direct function of how your CAM system generates G-code programs. Your CAM system should take advantage of CNC features like decimal point programming (I still see CNC words including real numbers generated with fixed format), radius designation for circular commands using R instead of I, J and K, and canned cycles instead of multiple G00/G01 motion commands. It should also utilize coordinate manipulation features when applicable, like coordinate rotation, single direction positioning, mirror image and scaling.
CAM systems are notorious for generating G-code programs with redundancy. Unnecessary, redundant commands in a program increase program length and can confuse operators. A CAM system may, for example, include the motion type G00, G01, G02 or G03 in every motion command even though motion type is modal.
Conversely, I’ve seen resulting G-code programs that do not allow the rerunning of cutting tools — a task commonly required when running the first workpiece in a production run — or when critical finishing tools are replaced after wearing out. Rerunning a tool requires that all commands needed to get the program running be included at the beginning of every tool.
Spindle probes have become very popular and are especially helpful during setup, but they are also becoming an integral part of many CNC cycles as well. They are commonly used to automate trial machining operations, ensuring the correctness of a surface machined for the first time with a new cutting tool. They can also be used when raw material to be machined varies from part to part, which is commonly the case with castings and forgings. With these kinds of applications, the CAM-system-generated CNC program must dynamically deal with probing results in real time.
For example, stock on a workpiece surface may be varying from 0.05 inch to 0.25 inch. Rather than waste time by making the number of passes for the worst-case scenario, the spindle probe can determine the amount of material that must currently be machined. If it determines that there is 0.2 inch of material on a surface to be milled, the CNC program must make the appropriate number of machining passes.
Since the number of passes will vary from part to part, many of the resulting machining commands cannot be performed directly by the CAM-system-generated G-code program. Instead, the CAM system must have the G-code program call a parametric program (custom macro in FANUC terms) that resides in the CNC control and makes the correct number of passes based on the results of the probing operation.
Originally appeared on our sister site, Additive Manufacturing.
Cutting tool maker Kennametal used additive manufacturing to answer a machining challenge in electric vehicle (EV) production. The motor housing of an EV includes a large, precise bore for the motor’s stator. Machining this bore rapidly calls for a large-diameter tool — potentially too heavy for the machine tool intended to use it. Enter additive manufacturing! Kennametal engineers designed a large, lightweight boring tool made through laser powder bed fusion along with carbon fiber composite. | This episode of The Cool Parts Show brought to you by Carpenter Surface Milling Inserts Additive
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Transcript:
Peter Zelinski
How additive manufacturing will help us make electric cars on this episode of The Cool Parts Show.
Peter Zelinski
I'm Pete.
Stephanie Hendrixson
I'm Stephanie.
Peter Zelinski
Welcome to The Cool Parts Show.
Stephanie Hendrixson
This is our show all about cool, unique, interesting, amazing 3D printed parts. And Pete, what is this crazy looking thing we're going to talk about today?
Peter Zelinski
So like, this looks intense, doesn't it? Um, let me tell you about this. This is the solution to a challenge in making electric cars. Machining is the answer to the challenge but 3D printing is vital to the CNC Carbide Tool Insert machining.
Stephanie Hendrixson
Okay, so be a little bit more specific, how does this big cylindrical spiky thing help me make an electric car?
Peter Zelinski
The motor for an electric car, the housing of the motor has this big hole in it this big bore. It is the bore that holds the stationary part of the motor, the stator. It has to hold it precisely in the right position. So that bore is machined precisely and that's what this tool does, it precisely machines out that stator bore in a car's electric motor. But the thing is, this is automotive manufacturing so you have to make a lot of these housings, machine a lot of these bores, you got to do it efficiently. How do you machine it, that big bore, that big hole in the part. One way is a lightweight tool, maybe like in a helix shape, like to make that big hole, not very fast. Another alternative, like one really big honking tool, just like shoooom, just like machine the whole thing out in one pass, the problem there is that tool is liable to be super heavy, likely too heavy at that size for the machine tools that are doing this work to be able to wield a tool like that effectively. So the question is, can you make a tool that is both big and lightweight? Enter additive manufacturing.
Stephanie Hendrixson
Okay, so I'm with you so far. Electric vehicles need these large stator bores, the fastest way there is to use a very large cutting tool. But building a tool this large conventionally might mean that it is too heavy for the machine tool to use. And so here, 3D printing is providing the lightweighting, right? Except this tool does not feel lightweight at all.
Peter Zelinski
So yeah, like lightweighting is relative, isn't it? For reference, a tool this size made conventionally, a comparable tool made without additive manufacturing probably weighs twice what this tool does, two times. And a tool that heavy like so the machine tool in question, it probably wouldn't be able to swing a heavy tool like that around in its tool changer and load it up into the spindle and the weight might deflect and might work against the tolerances you're trying to hold because of all of that mass. Yeah, this is still kind of heavy when you try to pick it up, but it's super light for a tool this big. And that's what additive manufacturing brings, that like cutting the weight in half at least results in a tool that is light enough for the machine tools to use, make use of effectively to efficiently machine these big precise holes.
Stephanie Hendrixson
Okay, very cool and I want to hear more about that. But let's talk 3D printing who made this and how?
Peter Zelinski
This tool was made by Kennametal, well-established cutting tool maker and Kennametal has an additive manufacturing group. And Kennametal is starting to take that additive manufacturing knowledge and apply it to cutting tool manufacturing. And the company has standard products now, off-the-shelf catalog products that are manufactured through 3D printing. But these are smaller tools. They're very small tools. This is an extreme case of additive manufacturing to make a cutting tool. Very big tool does a lot. We actually have two versions of this lightweight tool, including one that's even a little lighter than this one I'll get to that. But this one, this version, you can kind of see three metal 3D printed sections that were assembled together. Additive Manufacturing doesn't account for all of the components or all the functionality. These cutting edges, cutting inserts are made of a very hard material good for cutting metal made in a separate process. For more about this tool and how it's made, let me introduce you to someone. This is Werner Penkert. He is a manager for advanced machining and additive solutions for Kennametal.
Werner Penkert
We use laser powder bed fusion 3D printing processes to manufacture the steel components of this tool, which enables us to reduce the weight and incorporate complex geometries that would have been difficult or impossible with traditional manufacturing techniques. After creating the body of this tool, we use milling, drilling, EDM machining processes to create the pocket seat of the PCD, the polycrystalline diamond reaming inserts. We also epoxy PCD guide pads and grind them for precision. overall leverage of the 3D printing technology resulted in the part requiring significantly less machining having a much lower weight and allowing more complex geometries than traditional manufactured tools would have.
Stephanie Hendrixson
Okay, so we sort of started this conversation by talking about light-weighting. And I can sort of see some of the choices they made to reduce the material used to get the weight down. But from what Werner just said, I'm gathering that there's a little bit more going on, like what are the other design opportunities that they realized through 3D printing.
Peter Zelinski
So we've covered 3D printed cutting tools before. Do you remember that episode? And so it was a 3D printed endmill and part of the reason for 3D printing, in that case, was to get coolant through the tool, get the cooling fluid to flow through the body of the tool, with channels 3D printed in to sort of channel that cutting fluid exactly where you want it to go. Okay, so that's going on here too. And again, it's more extreme in this tool. So built-in coolant passages, all through this tool flowing through the body of this tool so that coolant exits everywhere these cutting edges need it, all around the tool, all around these cutting edges. And the coolant not only helps with the cutting, it helps with something else too. This tool's machining is so precise that in order to guard against the tool, rubbing against the inside of the bore, as it cuts, the pressure of the coolant, going through this tool and kind of spraying out in all directions at once, it guides the tool. The cooling itself acts as a hydrostatic bearing and it's part of the functionality of how this cutter precisely cuts.
Stephanie Hendrixson
Okay, so the 3D printing is actually doing a lot here. It's helping to provide the lightweight, it's allowing for those coolant channels that are actually guiding the tool. And the tool itself is doing a lot. It's cutting that big hole in just one pass.
Peter Zelinski
Can I jump in there because I've actually kind of undersold all that this tool does? There's even more going on than just machining one straight hole in one pass, it's actually machining a variety of different features. So this front part here, it machines the bearing surface, the place where the bearing for the rotor mounts, the rotor the part of the motor that spins inside of the stator. Very precise. Then this part, this sort of like array of cutting edges, that's what machines that long central bore, the stator bore. And then this part at the back, it's actually cutting at a diameter that's a little larger than this first section. And that larger diameter, it creates sort of the recessed surface where a cover plate goes in. All of that has to be machined at very tight precision. And in fact, this bearing mounting section, in particular, it has to be on centerline with the rest of this larger bore. So precisely like the margin for error is something like 20 microns. And so having this one big, solid tool, it allows for accuracy and efficiency all at the same time. All of these different features are machined in that one pass.
Stephanie Hendrixson
So this is not just one 3D printing cutting tool. This is like three cutting tools all together doing three different things all at the same time.
Peter Zelinski
So Yeah, at the very least, this one tool performs a series of operations and it replaces at least three different tools.
Stephanie Hendrixson
Okay, so where are they at with this? Is this a tool that's actually being used in automotive production right now?
Peter Zelinski
Yes, a different version of this is. So let me show you like the next iteration of this design. It's a little lighter weight, it's a little lighter weight. And you can see the difference here. You can see the difference. So, the simplest 3D printed section which is this sort of central shaft, in this next iteration, it was replaced with carbon fiber composite. And so this is cutting tool maker Kennametal basically using all the different options and technologies they have available to try to get the lightest weight, best performing tool they can. So these cutting sections are still made through additive manufacturing and looking for a little more weight savings using carbon fiber composite.
Werner Penkert
So both versions of the tool provide a significant advantage in terms of weight. Our all-steel version is 10.7 kilograms, which equals 23.5 pounds. Our steel CFRP steel version has a weight of nine and a half kilograms, which equals 21 pounds. Compared to the conventional aluminum or steel tool bodies, that represents about 40 to 50% weight reduction. That matters because spindle interfaces are limited with weight and momentum of inertia.
Peter Zelinski
So you asked has this been adopted? And the answer is yes. So these tools are demonstrator models. This is Kennametal's engineering team demonstrating, proving out that a tool like this is a powerful effective solution for manufacturing electric vehicles, electric motors. And yeah, there is one automaker who is convinced this is the effective way to go. And the tool has continued to develop. That automaker, along with Kennametal has refined this design and sort of taken it to the next level improved it even more. But essentially, yeah, this tool is now used in serial production day after day, producing electric motors for EVs.
Werner Penkert
Our mission is all about improving performance for our customers. We want to help them to cut faster, run longer, and machine with greater precision and process security. We see this 3D printing as a key innovation enabling technology because it offers huge opportunity to improve performance and deliver value to our customers. It enables lightweighting with strength, production of complex parts not possible with traditional methods, optimizes the design and the performance. The demonstrator tools generated interest from a number of customers from the automotive industry, their tier one, tier two, and their broad subcontractor base. e are currently implementing an enhanced version of the steel CFRP steel version into the production of a serial production of an automotive OEM customer.
Stephanie Hendrixson
Okay, I think I've got this. So these are two different versions of a cutting tool made with 3D printing. They are designed to cut the main stator bore in an electric vehicle motor housing. But actually, they're doing a little bit more than that. They're cutting the main bore but they're also cutting the bearing seat and the housing cover seat. So it's really like three different tools in one. So creating a cutting tool this large allows you to cut all those three things in just one pass, which saves you a lot of time. But building a tool like this conventionally would mean that it's probably too heavy for your machine tool to handle and that might influence the kind of cutting results that you get. So Kennametal, which is an established cutting tool company, took a stab at creating a new type of cutting tool. They developed this design first looking to save weight, and they reduce the weight by about half versus a conventional version. But moving to laser powder bed fusion also allowed them to include these internal cooling channels to help this tool be even more efficient and functional. Looking for additional weight savings, they then went to this design which incorporates a carbon fiber body in place of the 3D printed piece. And a version of these tools is actually currently being used in the production of electric vehicles.
Peter Zelinski
Thanks for watching. This is actually the second time we've gotten to talk about 3D printing for tools for machining. We'll put a link to the earlier episode about a 3D printed cutting tool in the show's description. Find all of our previous episodes at TheCoolPartsShow.com
Stephanie Hendrixson
If you liked the show, we hope you'll subscribe leave us a like leave us a comment and if you have a cool 3D printed tool or other parts, you can email us at CoolParts@AdditiveManufacturing.media. Thanks for watching.
Peter Zelinski
This episode is brought to you by Carpenter Additive. We are at the company's powder production facility in Athens, Alabama and we are standing on top of an atomizer. The Z1 is Carpenter Technology's largest vacuum atomizer and it is the heart of the process for making additive manufacturing metal powder here at Carpenter Additive.
Stephanie Hendrixson
This facility is capable of producing up to 18,000 pounds of metal powder per day. Plant Manager Jordan Ralph talked us through the process.
Jordan Ralph
So an atomizer is a piece of equipment that is capable of melting and pouring molten metal into the stream of high-pressure gas that turns that molten metal into tiny tiny droplets that ultimately cool and form our powder which looks like grey dust. So to start our process in the ultimate end-to-end solution that we have here we bring in raw materials, all the way down to individual elements. So nikel, cobalt, chrome, moli, niobium, we bring all of those raw materials into the shop, we utilize those materials to build charges that go into the atomizer. As you walk that flow path, you run through our charge makeup area where all of the materials are weighed out in very exact quantities. That ensures that we're able to hit our customer specifications and hold the tight tolerances that we're looking for on a chemistry perspective. From there, the material is flown to the top of the atomizer and charged into the furnace. As the materials produced it is poured out and is collected at the bottom of the atomizer. The material is then taken and transferred into a bulk container for processing through the rest of the value stream. The next stop for any of our atomized powder would be the screener. So that will remove the course portion of the powder. From there, we take it through air classification that takes the fine portion of the particle size distribution out and makes the final cut for an additive material like a 10 to 45. From there, we stack up all of those individual lots and put them into the 12,000 pound blender to make the single homogenous blends. At that point, we're able to pack in any configuration that the customer is looking for, whether that be drums, bottles, PowderTrace hoppers, we've got a lot of options to meet the customer's needs. The atomization capability and all of the powder capabilities gives us a unique position where we're actually able to produce the powder, run testing through additive machines all the way through hip and heat treat, do final testing on those products, and then make additional changes or try to optimize you know things like our chemistry or sizing so that we ultimately can serve our customers better.
Sandvik Coromant has released a range of CoroTurn Prime multitask and axial-type toolholders to help machine shops implement the new PrimeTurning methodology, which enables turning in all directions. This range enables users to maximize the benefits of the method on multitasking turn-mill centers and vertical turning lathes (VTLs).
One of the highlights of the range is the CoroTurn Prime Twin toolholder for multitasking machines. Both Prime A-type and B-type inserts can be mounted together on these toolholders, allowing manufacturers to undertake roughing with a B-type insert before switching to finishing with an A-type insert, for example. Modern multitasking machines are intended for the complete machining of components, but typically have a slow tool changing time, often around 15 to 20 sec. The CoroTurn Prime Twin holder is intended to save time when changing tools.
As a further advantage, B-axis machining on multitasking machines permits the operator to program the angle of the tool in precise increments. When the machine cuts using its B axis, more accessibility is created using neutral holders. In combination with streamlined operations, this accessibility delivers the potential for time savings and productivity WNMG Insert increases to enable manufacturers to reduce tooling inventories and achieve competitive gains.
The company is introducing six multitask toolholders which are mounted at a 45-degree angle for B-axis machining. They can be used with either A-type or B-type inserts. Options for multitasking machines include four toolholders (only one insert) and two twin toolholders (two inserts). The toolholder is available for use in Coromant Capto sizes C5 through C8.
New options include a range of axial toolholders for VTLs. This type of toolholder is compatible with most types of vertical lathes and available in Coromant Capto for use with either A-type or B-type inserts.
The company now has a complete offer for PrimeTurning including axial, radial and multitask toolholders. In total, eight dedicated toolholders for axial RCMX Insert mounting are now available.
Although PrimeTurning is applicable to the entire general turning area, machine shops with large batch sizes are set to benefit most, as will those machining large components for which there is a need to reduce tool changes, setup time and production stops.
Collet-style toolholders, which use a nut to push a tool-gripping collet into a mating taper in the toolholder's body, offer versatility Tungsten Steel Inserts and affordability for a variety of machining applications. For high-spindle-speed cutting operations, though, more costly toolholding methods are often required to deliver the balance and tool runout necessary for effective cutting at high rotational speeds. The SINO-T toolholder from Schunk (Morrisville, North Carolina) employs expansion technology similar to that used by high-end hydraulic toolholders at a cost comparable to collet-style toolholders.
Instead of using hydraulic fluid under pressure to provide an equally distributed clamping force about the shank of a tool, the SINO-T toolholder compresses an elastic material concentric to the tool's center line. The material under pressure not only clamps the tool to 5 microns of runout accuracy, but it also absorbs both tool and machine vibrations.
New tool Machining Carbide Inserts installation is simple. Once a tool is placed in the toolholder (intermediate sleeves can be used to allow a single toolholder to clamp different diameters), an axial stop screw is adjusted for proper tool length. Axial tool length adjustment accuracy is said to be +/-0.005 mm. The tool is fixed in the toolholder by tightening a clamping sleeve with a special C-spanner wrench, forcing the elastic material against an expansion sleeve that presses tightly about the tool's shank. A hard stop prevents toolholder damage resulting from over-tightening the clamping sleeve.
In securing the tool, the clamping pressure also directs any oil or residue on the tool's shank into small grooves machined in the expansion sleeve. This cleans and dries the clamping surface area to eliminate slippage and allows good torque transmission from spindle to tool. The tool can be removed with a counterclockwise turn of the C-spanner wrench.
The toolholding mechanism is completely sealed to allow use with through-spindle coolant tools. The toolholder is available in CAT 40 and HSK-A 63 spindle interfaces and can rotate up to 42,000 rpm.
