Shops wishing to reduce their costs and increase efficiency often invest heavily in automation equipment and high-speed machinery. But what many shops fail to realize is that the savings they are looking for don’t necessarily have Cutting Inserts to come from hardware used on the shop floor …they can also come from software used in the office. A small amount of time spent at the computer to prepare NC tool paths properly and thoroughly before sending them to the shop can deliver big savings at the machine. One tool developed specifically for this preparation work is NC verification software.

Many shops now rely on verification software to prove-out their programs. The software can ensure the first part is a good part, so no operator has to stand by the machine to watch the first part run. Thus, dry runs and cutting test parts become a thing of the past.

In addition, verification software can offer automatic feed rate optimization features that can deliver several benefits. Cycle time, part quality and tool life can all improve as a result of more refined control over feed rate. A program with Cutting Tool Inserts "optimized" feed rates may also make it easier for the operator to turn attention away from the machine.

NC verification software enables a programmer to check the integrity of tool path files before sending them to the shop floor to begin cutting metal. Not only does this reduce the possibility of an expensive machine crash, it also saves re-work during the prove-out cycle, and it often eliminates the physical prove-out process altogether. This can mean big savings in terms of materials, labor costs and machine hours, as various shops have discovered.

One such shop is Contour Aerospace (Everett, Washington), a manufacturer of components and subassemblies for aerospace applications. Before adding verification software to the production process, the manufacturing team at Contour had to cut a test part, lay it out and perform an inspection. If there were any problems, the shop would have to correct the NC program, cut another test part and re-inspect it before proceeding with production.

"On our large parts, this was very time consuming," says NC programming manager Dan Hornung. The company makes wing spars in the range of 20 to 40 feet long, and the freedom to prove out jobs for parts like these in the computer instead of in real life offers an important advantage.

A maker of big parts of a very different sort is Delaware Machinery & Tool (Muncie, Indiana). Delaware Machinery specializes in designing and building large die-cast molds used to make engine blocks and transmission cases. The company also has a reputation for using the latest manufacturing software technology. The first transmission dies for Ford, GM and Chrysler to be designed and built using CAD were provided by Delaware.

Today the shop’s software toolkit includes verification software. "Checking tool paths at the computer has enabled us to reduce the number of shopfloor prove-outs and reduce redundancy," says CAM manager Dennis Main.

The software also helps streamline the programming process. It offers the capability to check for gouges by embedding the design model inside the virtual stock model. When the cutting tool contacts the design model within a user-specified tolerance range, an error is reported.

CGTech’s Vericut is the software both shops use. Delaware’s Mr. Main says, "After posting our code, we’re able to run the G-code for an electrode job through Vericut and electronically check the cut-under for spark gap. We can intentionally cut the part to 0.020 ‘under,’ then check the as-machined model against the CAD model to make sure that all areas have been cut into the graphite blank . . . and to verify that no areas of the electrode will cause an over-burn." This feature helps Delaware meet tight machining tolerance requirements.

Contour’s Mr. Hornung sees similar advantages. "The constant gouge protection feature really started to pay off around the time we began manufacturing parts for the Boeing 777…because that’s when the customer went to solid design models."

For Delaware, it was when company director of engineering Dan Swartz sent an engineer to a verification software update course that the shop learned about feed rate optimization functionality available as an add-on module for the same software. That engineer returned excited about what he saw as a way to dramatically improve the company’s machining process.

With the optimization function, the software reads NC tool path files and automatically adjusts the existing feed rates to more appropriate values based on cutting conditions and tool capacity. Machining with feed rates tailored to each individual cut increases machine tool efficiency, so parts take less time to cut. In machining graphite electrodes, Delaware’s team calculated that feed rate optimization saves 30 percent in machine run time. "We’ve seen 45 percent in some cases," says Mr. Swartz.

Feed rate optimization works by reading the NC tool path file (G-code or APT format) and dividing motion into a number of smaller segments. Based on the amount of material removed in each segment, the software assigns the best feed rate for the cutting condition encountered. It then outputs a new tool path that is identical except for the feed rate setting. The tool path trajectory is unchanged.

This solution could be said to offer the best of both worlds. On one hand, the optimization is automatic and works before the NC program is ever loaded on the machine. On the other hand, it draws on the expertise of the NC programmer and machinist in the way it responds to specific cutting conditions. Users input ideal feed rates for a number of pre-determined machining conditions. Factors include machine tool capabilities such as horsepower, spindle type, rapid traverse speed, coolant and other characteristics; plus fixture and clamp rigidity; as well as cutting tool characteristics including material, design, length and number of teeth. These factors suggest the chip thickness, volume removal rate, entry feed rate and other parameters used to calculate the optimum feed rate for each segment of the cut.

Typically, different types of optimization techniques are best suited for different materials or machining processes. During planar roughing of aluminum structural components, for example, material is removed at a constant axial depth, but the radial width of cut varies greatly throughout the cycle. In an operation such as this, maintaining a constant volume removal rate keeps the cutter at its maximum rate of advance into material for the varying cut width. Employing the same information used to verify the tool path, the software is able to determine the amount of material removed in each toolpath segment. The software then assigns the appropriate feed rate based on information supplied by the NC programmer and/or machine tool operator.

A very different operation is semi-finishing or finishing a tool steel mold cavity. Here, the cutting is typically characterized by widely varying chip loads as the tool profiles over the contours of the workpiece. In order to achieve a constant chip load, feed rates are optimized based on the maximum chip thickness for each cut segment. The software takes into account where the material meets the cutter along its profile, and it adjusts the feed rate to keep chip thickness constant. This is especially critical when cutting with a ball end mill, or when contouring a surface with a small step-over. The feed rates continually change over the course of the cut in order to maintain the constant maximum chip thickness. The result is an improvement in both tool life and surface finish.

Engineers at Contour Aerospace were quick to see the benefits of machining with optimized tool path files. Mr. Hornung says, "We see a big savings in areas like pocketing routines." The optimization let the shop abandon a preference for conservative feed rates, he says. In addition, "Optimized feed rates provide a more constant spindle load—usually around 80 to 90 percent—and eliminate our reliance on manual feed rate changes to cut the pockets correctly."

The rear wing spars and ribs for the Gulfstream IV corporate jet are typical of the parts Contour manufactures. The company uses three-spindle, three-axis gantry machines with 30-hp spindles and 2-inch carbide insert cutters to rough the parts. The stock billet for the rear spar measured 480 inches and weighed 2,500 pounds before machining, but with 95 percent of the material removed during machining, the finished part weighed 128 pounds.

"On parts like this, we use the software to maintain a constant volume removal rate—in this case around 85 cubic inches per minute—to keep the spindle load where we want it," says Mr. Hornung. By optimizing the roughing passes on the part, Contour cut about 25 percent from the machining time. "That equates to saving thousands of dollars a year," he says.

Software optimization not only speeds machining, but also helps make the entire manufacturing environment more efficient. Before optimizing tool paths, Delaware’s graphite electrode machining department had not been able to take full advantage of its high speed milling machines, even those equipped with robust look-ahead capability. According to Mr. Main, those machines were "a bit ineffective when machining intricate or involved shapes." They tended to slow down in areas where the axes changed direction and not slow down in areas of heavy material removal, so manual feed rate adjustment at the machine was necessary. This required the shop to assign one operator per machine on each job. If the operator needed to leave the machine even for a short time, he had to "dial down" the feed rate until he returned.

The optimization software changed that. Now, when running optimized programs, operators are able to run two or more machines at a time. "It’s really reduced our costs and increased our manpower productivity," says Mr. Swartz.

It can make for a "smarter" process, too. For example, Contour Aerospace’s machines have a variety of controls. "The great thing about the optimization software is that it takes the particular control into account, so we’re running the most efficient feeds for each individual machine/control combination," says Mr. Hornung.

In addition, most shops have at least one "resident expert" who knows the best feed rates to use for different machines, cutters, cutting conditions and types of material. Storing this information in the software creates a "machining database" available to everyone in the shop. This library of information can help the shop achieve more consistent machining results between different operators, machines and shifts. "We see a lot more consistency and all around better part quality with the optimized feed rates," says Delaware Machinery’s Mr. Main.

In fact, the improvement in part quality is a major benefit to mold maker Delaware, because this shop is accustomed to devoting significant labor hours to polishing. With the optimization software, the shop has been able to eliminate this labor-intensive process. Driving the machine with a more constant chip load results in a smoother machined surface.

The tool often comes away looking better, too. "With the improved feed rates and constant chip load, our cutters are lasting longer and we’re spending less time changing out tooling," says Mr. Main.

Contour Aerospace’s Mr. Hornung agrees. By running optimized feed rates on the machine, he says, the shop is able to more accurately project how long tooling will last. Contour stops production less often to replace worn inserts.

A good example of how Delaware Machinery benefits from optimizing tool paths came from a recent job for a small engine block containing many small cooling fins. "This isn’t the type of job we necessarily specialize in, but we’ve done these before," says Mr. Swartz. "In the past, we really needed to be careful when machining and handling these electrodes because the fins can be broken easily." But this time, due to the more constant chip load and cutting pressure resulting from optimization, the shop had no problems with breakage. "The capability is helping us gain a new type of business," he says.

Contour Aerospace is also seeing improved part quality from the more targeted feed rates. "Because the feed rates are pre-determined by the optimization software, they run the same way each time, regardless of who is at the machine," says Mr. Hornung. "This supports our quality-based variability reduction and lean manufacturing efforts."

And the move to computer-optimized feed rates as an alternative to overriding feed rate manually has generally been accepted by programmers, operators and management alike, he says. "At first, some of them thought we were nuts. They’re used to seeing the feed rate needle stay somewhat constant when we start cutting a part, usually around 80 ipm. With the optimized programs, the needle is jumping up and down from the very beginning." It was only after seeing the results that most were convinced, he says.

About the author: Jeff Werner is marketing communications manager for CGTech of Irvine, California.

The Carbide Inserts Website: https://www.estoolcarbide.com/cutting-inserts/vnmg-insert/

Ganesh Machinery’s twin-spindle, eight-axis SL-20Y2 Swiss-type lathe is designed for “Done-in-One” machining to complete the work without follow-up operations that require fixtures and tie up multiple machines and operators. According to the company, it is capable of performing as much as ¾" of work efficiently in one operation with all the axial and radial milling features accurately timed and deburred.

The multitasking, 20-mm lathe can be operated with or Carbide Turning Inserts without a guide bushing for job flexibility. The 10,000-rpm main spindle is powered by a 5-hp spindle motor; the subspindle turns at 8,000-rpm. A toolholder accommodates 30 tools, of which eight are driven using ER-16 collet spindles. The main spindle can bring 17 tools to work the part, and the subspindle can use 13 tools in the basic machine configuration. Many tooling options are available to address the specific requirements of each workpiece. A high-performance C axis on both the main and subspindle provides accurately timed axial and radial milling feature placement.

A parts catcher and parts conveyor facilitate the removal of valuable parts from the machine without Carbide Drilling Inserts any damage. A cutoff confirmation sweep-arm switch is provided to ensure that the part is separated from the barstock successfully. Cutting oil flow confirmation monitoring ensures that the cutting oil is properly lubricating the cutting tools.

In addition to the SL -20Y2 20-mm lathe, Ganesh also offers 32- and 42-mm models.

The Carbide Inserts Website: https://www.cuttinginsert.com/product/ccmt-insert/

Almost any milling tool can be used in a slow, conventional milling application. But when it comes to high speed or “high performance” applications involving fast cutting and more numerous passes, the differences between tools become more important. Specific tool shapes have specific applications.

What follows are some tips for using different tool shapes effectively. The four basic types covered here are extensively used in 3D milling and profile milling, but within that broad range of work there are more narrow applications where a given tool type may perform more effectively. At least one of these tools deserves to be used in applications where it isn’t often considered.

The important thing to know about square-end tools is that the heat generated in the cut tends to go into the square corner. In high speed milling, the cutting speed may have to be decreased in order to reduce the heat so this corner doesn’t wear too quickly. In hardened metal, it is best to use this tool only if the corner is not used to cut at all. An example is finish milling of a straight sidewall surface where the part has an open bottom. In non-heat-treated materials, typical uses include roughing or finishing of straight walls.

A square-end tool that adds a corner radius permits higher cutting speeds because the heat is dispersed across a larger area of the tool. Like the cornered square-end tools, typical uses for these tools include roughing or finishing of straight walls in non-heat-treated materials. Other uses for these tools include finishing of straight sidewall surfaces in hardened materials—with or without an open bottom—as well as corner picking of floors in cases where the machined corner requires a small radii.

Another application for these tools is trochoidal machining. This is a milling process in which the Indexable Inserts tool path continually re-crosses itself as the tool feeds through a pattern of constant-radius arcs. (See illustration, below left) Square-end tools with sharp corners can only be used for trochoidal machining in cases in which the cut has no bottom. But tools with corner radii can be used for trochoidal machining at various depths of cut.

Toroid cutters have a distinctive shape, shown in the photograph above, left. Do not confuse a toroid cutter with a multiple-insert button cutter. Button cutters do have important uses, but because they have multiple inserts, they don’t have the accuracy to perform the way a toroid can. The toroid tools are used to rough pockets, cavities and cores at mid-range cutting speeds and fairly heavy chip loads. An even better use of toroid tools is the finishing of flat surfaces, including WCMT Insert parting lines.

Ball cutters are, in my opinion, the most versatile tools for high speed machining. They can be used to rough any cavity, core or 3D shape. They can also be used for finishing of all materials in all hardness ranges. Because the round shape allows the heat of cutting to be absorbed into the tool across a wide area, this tool permits higher cutting speeds than other tools. It also permits a higher depth of cut, because the ball shape causes a larger percentage of the tool pressure to go up toward the spindle where rigidity is high, as opposed to sideways, where the rigidity is less. The same effect decreases tool vibration, which further helps to control heat. Given the combination of speed and depth of cut that results from these advantages, a ball cutter can achieve a high metal removal rate compared to the other tool types described. (See example below.)

For slotting, pocketing and machining ribs, a cylindrical end mill is often used because the shape of this tool seems to correspond to the shape of each of these features. However, a ball cutter can perform well in these applications, too. For example, I would machine a deep slot, whether open-ended or closed, by using a ballnose tool along with shallow ramp and Z-level milling techniques typical of high speed machining. The slot could be produced much faster this way than through milling with a cylindrical end mill. Also, the side walls would probably have better straightness and perpendicularity with the rest of the part, instead of being tapered as they often are when a long end mill deflects. Ribs can be machined in a similar way.

One application I have observed involved milling 3/4-inch-wide slots in P20 steel that were 5 inches long and 2 inches deep. A cross hole in the middle of the part created an interrupted cut. Originally, six slots were finish milled in 30 minutes, not including the roughing time. But with high speed machining techniques using a ball cutter, six slots were roughed and finished in a combined operation that lasted only 10 minutes.

About the author: Ron Field is a vice president for cutting tool maker Millstar of Bloomfield, Connecticut.

The Carbide Inserts Website: https://www.cuttinginsert.com/product/ecmn-parting-and-grooving/

Big Daishowa has introduced the C3 program, an expansion of the Big Capto toolholder line, designed to increase efficiency and precision for small Cemented Carbide Inserts lathes.

The C3 series of Mega New Baby chucks has a clamping range of .010-.630" with a maximum rpm of 30,000. According to the company, these make excellent choices for drills, reamers, taps and finishing end mills. Ultra-slim and strong, they provide reliable gripping for even the smallest workpieces.

The Big Capto C3 square holders for turning applications come in left and right orientation. The turning application holders — C3-180-BH16R-2058 and C3-180-BH16L-2058 — are mono-block holders. Their insert clamps are tough and reliable, adding to the high rigidity of mono-block holders. The resulting higher rigidity minimizes vibrations and movement during cutting, improving accuracy and efficiency.

The new square tool holders are available in 90-degree and 180-degree types. The 90-degree type Carbide Inserts offers a variety of orientations, including perpendicular to the workpiece. Its compact design also enables for work in spaces that are tighter or have limited clearance. The 180-degree type, meanwhile, enables the tool to machine harder-to-reach areas of the workpiece.

Due to the limited space for smaller lathes and mill-turn machines with C3 clamping systems, integral C3 turning adapters are compact and rigid with both left- or right-hand units for most common turning geometries. C3 boring bar holders also are available to clamp 6-, 8-, 10- or 12-mm boring bars. All turning toolholders feature through-spindle coolant. Big Daishowa offers the Kombi Grip (model KG32R) tool assembly device to work on C3 tools outside the machine, and cleaning of internal C3 clamping units is quick and efficient using Big Capto spindle cleaner SC-C3.

The Carbide Inserts Website: https://www.estoolcarbide.com/product/vbmt-steel-inserts-cnc-lathe-turning-p-1205/

Iscar’s GEHSR/L-SL tool family for Swiss-type and screw machines are an improved version of its current GEHSR/L screw-clamped tools. According to the company, the new system enables securely clamping inserts with a key from either free side of the tool. After the clamping torx screw is activated from one side of the tool, a sealing plastic screw blocks the opposite side to prevent chip entry. If indexing is required from the opposite side, the screw can be switched to the other side. Inserts can be indexed without removing the tool from the toolholder, and the tools’ shorter head design is said to offer higher rigidity and improved machining stability, enabling higher cutting conditions and improved surface finishes.

The grooving and turning Surface Milling Inserts tools are available in 10-, 12- and 16-mm shank sizes with GEPI and GEMI inserts in different geometries and widths ranging from 2.2 to 3.2 mm. Iscar also offers the GHSR\L-JHP-SL variant with WNMG Insert high-pressure coolant capability, featuring three independent coolant inlet ports.

The Carbide Inserts Website: https://www.estoolcarbide.com/pro_cat/milling-inserts/index.html