XL Machine was a Top Shops winning company in 2017. Plus, General Manager Chris Orlowski was part of a panel discussion with representatives from the other winning shops that year at our inaugural Top Shops Conference in Indianapolis.

In checking back with him a few months ago, I learned about a neat robotic cell the Three Rivers, Michigan, shop had recently added to machine three- and four-blade cast propellers (a family of 20 part numbers) for outboard boat engines. I mentioned that holding such contoured parts for five-axis machining had to be tricky. In fact, that was the most challenging part of the project, he said.

That, my friends, is a story hook, so I scheduled a visit to learn more.

Founded in 1976, XL Machine (now part of the Burke Porter Group) began as a prototype machining company. It still does prototype work today, but pairs that with production machining capability. The shop serves various customers in markets such as automotive, heavy industry, entertainment and marine.

At first, the customer with the propeller job turned each part’s hub in house. XL Machine would then mill either side of the contoured blades on two stand-alone three-axis VMCs and a stand-alone HMC that blended the verticals’ cuts near Tungsten Steel Inserts the hub. When its customer asked it to turn the hubs as well, creating a multi-machine, automated process seemed like a logical next step.

The photo below shows the castings as they are now received by the shop. The material is “nibral,” an alloy consisting of nickel, bronze and aluminum. It is useful for marine applications because it is durable and resists corrosion in seawater. Machining-wise, it’s said to be like stainless steel in that it’s a bit gummy.

The U-shaped cell designed to finish these parts features four Okuma machines: two side-by-side 2SP-V760EX vertical lathes for op. 10 and op. 20 hub-turning work, and two MU 6300V five-axis machines for op. 30 and op. 40 blade-milling work. These machines are served by a large FANUC M-900ib robot.

The cell includes two multi-level tungsten carbide inserts racks with drawers into which the cell operator places raw castings and removes completed parts. To start the process, the robot opens a drawer to grip a raw casting by its hub. A camera mounted above the rack views the part number on tabs on the end of each blade to verify the robot is picking the correct part. (These tabs are also used for locating and clamping the parts in the five-axis machines’ fixtures.) Another camera on the robot’s arm then detects the part’s orientation so the robot properly positions the gripper without contacting the blades.

Next, the part is delivered to the op. 10 vertical lathe for internal and external machining of the hub half facing upward. The other half of the hub is secured by a custom power chuck from Co-Op Tool, a division of Hammill Mfg. The machine also uses a custom plunge tool from Cline Tool, which combines four operations into one cutter body. This is helpful because many tools for the turning and boring operations are so large that adjacent ATC pockets must remain empty to accommodate them. The custom cutter saves three ATC pockets. The machine also makes use of flood coolant and through-tool air delivery to help remove chips from the insides of the freshly machined hubs.

Once op. 10 work is completed, the robot grips the part, the power chuck disengages and the robot takes the part to a flip station. The station then lowers, and the robot, now with the gripper, facing down, grips the other side of the hub. It then takes the part to the second lathe for op. 20 hub work, which is similar to the op. 10 work. (See video below.)

Five-axis blade milling is next. The op. 30 machine mills one side of each blade, and the op. 40 machine mills the other side. This is where the trick fixturing created specifically for this application shines.

In addition to the custom lathe workholding devices, Co-Op Tool supplied the two unique hydraulic workholding fixtures for the op. 30 and op. 40 blade milling work. Dave Bermudez, the company’s senior design engineer, created the fixtures. When pallets of fixtured parts shuttle in and out of machine workzones, the pallet with locating elements that seat into the machine is typically separate from the fixture. However, given the size of the propellers, and being that Z-axis space is limited in such five-axis machines, the pallets had to be integrated into the fixtures themselves. Mr. Bermudez says this reduced the height of each fixture by approximately 4 inches. But he notes it also meant that hydraulic circuits that normally would be routed internally in the fixtures had to be plumbed externally.

These fixtures feature a center collet chuck designed by Co-Op Tool onto which a propeller locates and is secured after the robot places it in the fixture. (Prior to clamping, the robot rotates the part slightly so the tabs contact stops to ensure proper positioning in the fixture.) Hydraulically actuated swing clamps from Vektek then move into position to pinch the tabs at the end of each blade. Next, spring-loaded workholding supports under each blade lock into position once they contact the underside of the part to prevent vibration during machining.

Because each casting varies as to how much flash or extra material it might have, the single finishing pass is preceded by a roughing pass that removes extra material. This pass might do a good bit of air cutting, but it reduces the chance of tool breakage on the finishing pass.

Touch probing is performed for both the op. 30 and op. 40 blade-milling operations. Once a fixture with part is loaded into a machine, a spindle-mounted touch probe locates the center and top of the hub to ensure it is properly positioned and seated in the fixture. It then touches off on the tabs to ensure the propellers are oriented correctly in the fixture. These probing routines add 10 minutes to the overall cycle time (bringing the total to 40 minutes), but the shop justifies this because they ensure proper positioning in the fixture. In addition, all cutting tools are probed to check for insert breakage before being delivered back to the ATC carousel. If it is determined that a tool did break, a redundant tool is called up and that operation is repeated.

The final operation is milling away the tabs on each blade. This is done with the hydraulic swing clamps still pinching the tabs. The central collet chuck on its own provides sufficient holding force for these relatively light machining operations as each tab is cut off.

XL Machine’s propeller customer performs some subsequent polishing to the machined blades prior to assembly on its outboard engines. That said, Mr. Orlowski says the customer appreciates the quality finish of the machined blades because it minimizes polishing, especially in the corners where blade profiles transition to the hub. This required a bit of five-axis toolpath ingenuity. Specifically, a ball end mill is moved up and down the corners vertically rather than back and forth across the transition, which would leave behind multiple steps that would have to be removed. This little bit of toolpath ingenuity here takes care of the polishing. 

The Carbide Inserts Website: https://www.aliexpress.com/item/1005006037900426.html

I have an application where I am milling a deep pocket in 6061 with a tight corner radius — 3/16 inch — into an angled surface. The maximum depth of the pocket is 1 inch deep (5× deep). The pocket is inside of another pocket, so toolholder clearance is also a problem. What’s more, the cut is very prone to chatter. How can I successfully mill this pocket?

Pockets like this are tricky because of so many competing factors, but identifying the overlying issues and constraints is a good first fast feed milling inserts step to developing a solution. Ideally, you could use a larger tool, but you’re constrained by the pocket radius. Shortening the tool stick could help, but the primary pocket makes this impossible. The angled surface also leads to some interesting limitations as far as tool selection.

Even after you’ve selected the tool, the cut is prone to chatter, so you must determine the magnitude and direction of the cutting forces, as well as the system’s stiffness. Getting the cutting forces up into the spindle can be a huge benefit in this application, just like high feed milling in hard metals. Any cutting forces normal to the tool are the enemy. While you can’t eliminate all normal forces — given the pocket geometry, you must finish-mill the cut — you can reduce them. Anything you can do gravity turning inserts to add rigidity near the cut will also improve stiffness. Because this is a pocket within a pocket, you’ll also face significant clearance limitations.

With these difficulties in mind, it’s time to dive into the different components, and solve each as best as possible given the constraints.

The first thing you are up against is the tool diameter. Unfortunately, barring any design changes, the 3/16-inch tool at 5× deep is here to stay. Since you can’t change it, work with it. You want to reduce the amount of work you’re asking of this tool as much as possible.

One reduction strategy would be to use separate tools for finishing and roughing. A two-tool strategy will reduce the load on the tiny finisher and provide better tool life. It could even shorten the cycle time compared to a single-tool process — roughing’s increased productivity can counterbalance any time added for tool change and positioning.

Next, address the pocket. Since your challenging pocket is within another pocket, you can’t change much with the tool holder to increase stiffness. Yet you still need as much support as you can get, as close as possible to the cutting point. In this instance, a necked-down end mill (an end mill with a larger shank than cutting diameter) is wise. This will give you more stiffness where the tool holder can’t fit without rubbing against other critical features of the part.

The angled surface is the most unique aspect of this cutting problem. Drilling out difficult pockets is typically a good solution. Drilling provides high removal rates, and the forces go where the machine and tool setup are strongest. In fact, it’s a common strategy in large titanium or hard metal parts. However, the angled surface changes that formula a bit. Fortunately, indexable drills or solid carbide flat-bottom drills are up to the task. These drills also have the benefit of being able to drill overlapping holes! Given how small this pocket is, perhaps a carbide flat-bottom drill is ideal here. It can fit tightly into that 3/16-inch radius and leave minimal material in the area at highest risk for chatter.

Bringing together these solutions, start by switching to a two-tool process. The first tool should be a 4- or 4.5-mm flat bottom drill (just smaller than the finish radius) for roughing the entire pocket, leaving only small scallops and a little floor material left for finishing. The second, necked-down finishing tool will greatly improve the overall stiffness, and when combined with the minimal finishing stock, should enable a more productive finishing operation.

The Carbide Inserts Website: https://www.aliexpress.com/item/1005005874893569.html

The CoroMill 419 from Sandvik Coromant is a five-edge, high-feed milling concept designed for for roughing to semi-finishing operations. The cutter is suitable for applications requiring high-feed face and profile milling, and for machining components that require long overhangs. It is said to improve productivity in applications requiring light cutting action and long tool life, particularly in difficult-to-machine materials such as stainless steel, hardened steel and titanium.

Inserts feature five cutting edges. Through-coolant on all cutters enables wet machining, with the option of compressed air cooling for improved chip evacuation in Carbide Turning Inserts deep-cavity milling and helical slot milling cutters interpolation. The cutter is available with a variety of insert grades and geometries in diameters ranging from 32 to 100 mm (1.25" to 4").

The Carbide Inserts Website: https://www.aliexpress.com/item/1005005925324127.html

Currently, there is a lot of talk about Industry 4.0, the Industrial Internet of Things (IIoT), data-driven manufacturing and digitalization. All of these terms include the underlying concept that information in a digital format can streamline, unify and enhance manufacturing operations when that data is shared across a computer network. How are machine shops and manufacturing plants implementing this concept? One example that is taking shape is MachiningCloud’s software application for searching and downloading cutting tool data.

MachiningCloud can be described as an independent provider of product data from suppliers of cutting tools and related products. The company hosts gravity turning inserts this data in the cloud, that is, on remote computer databases accessible by Internet-enabled computer networks. After creating an account, a subscriber can log on via a connected desktop or tablet to access the database and use the software functions. The hosted data is stored in standardized formats that enable it to be downloaded through the MachiningCloud app for import into CAM programming systems, CNC program verification/simulation systems, tool management and other shop software applications.

Primarily, the standards dictating the formats for digital representation of this cutting tool data are ISO 13399 (Cutting Tool Data Representation and Exchange) and GTC (Generic Tool Catalog). GTC, which is a complement to the ISO standard, provides a vendor-neutral classification of cutting tools and specifies data file Carbide Turning Inserts structures. GTC tells vendors how to “package” their digital catalog information in a uniform way so that end-users and third-party application developers can access and present information from the vendors’ catalogs more predictably. MachiningCloud also follows MTConnect, the industry standard developed to facilitate the exchange of process information from CNC machine tools. Moreover, the company offers a service by which data from cutting tool manufacturers that is not yet compliant with ISO 13399 or GTC can be published and made available to MachiningCloud app users, who can access the data and convert it to the format required by their own applications.

An important aspect of the company’s cloud-based database is that the cutting tool product data available from the manufacturer includes 2D drawings and 3D geometric models of individual tooling items as well as cutting tool assemblies. This is in addition to the cutting speeds and feeds recommended by the manufacturer. Another important aspect of MachiningCloud is that it offers subscribers various software utilities for creating tooling lists, managing and routing jobs, checking tool pricing and availability, submitting purchase orders, and so on. These utilities enable the user to leverage digital cutting tool data to help streamline work flow throughout a shopfloor operation.

However, many subscribers initially will be attracted by the ability to access one industry-wide database of cutting tool products. For NC programmers, for example, this is a time-saving alternative to searching paper or online catalogs of cutting tool products from individual cutting tool vendors. Tooling items can be downloaded to create a tooling library and to populate the data fields required by CAM software to generate CNC tool paths. Because tooling vendors can upload frequent updates to the MachiningCloud database, programmers have greater assurance that the data is the latest and most complete.

Another benefit is the ability to download 3D geometric models and cutting parameters into CAD/CAM software for CNC machine simulation, verification and optimization. These software functions provide more accurate and reliable results when based on accurate and complete models of cutting tools and complete assemblies. Obtaining these 3D models from vendors or constructing them in-house can otherwise cause delays and inaccuracies that might diminish the value of using the simulation or verification capabilities of CNC programming systems.

Perhaps the most notable takeaway from this look at MachiningCloud as an example of Industry 4.0 and equivalent concepts is that the networked flow of coherent, pertinent data leads to better decisions about machining processes. In this case, by accessing cutting tool manufacturers’ product knowledge and information in a standardized, digital format, CNC programmers can ultimately provide toolpath files that improve machining results on the shop floor.
 

The Carbide Inserts Website: https://www.estoolcarbide.com/product/cnmm190624-cnmm646-turning-inserts-high-quality-carbide-cutting-tool-for-machine-tools/

Equipped with all the standard features of Missler Software’s TopSolid, TopSolid’Progress is?a fully integrated CAD module developed specifically for progressive tool design. The application manages all cutting, folding and deforming stages of sheet metal, as well as non-standard matrices and the creation of die sets, punches and drafts.

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Some of the major cemented carbide inserts additions to the?new?version of?the?software are improvements to?BlankWizard, a module that allows die designers to define required blanks and design strips in a completely associative process. The module now features material characteristic and analytical result analysis. It also can generate wireframe unfolding, touching up curves to obtain simpler geometries in initial strip stages. Other improvements to strip creation include a calculation function of the median surface of sheet metal,?an option to automatically prolong bends on connected neighbor faces and manual calculation tools for geometery of intermediary deformation stages.

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For defining standard die bases, a new assistant can import model die bases equipped with guiding elements, fixations and more. For component management, the software features improved treatment of gravity turning inserts equipped components, extension of process mechanisms associated with components, improved functions for the definition of components and restructuring of ergonomy and libraries.

The Carbide Inserts Website: https://www.aliexpress.com/item/1005005878015710.html