Broaching with Long Insert Life, High Surface Quality - cnc tool insert

 2024-07-08 11:32:13

“Previously,” Laprade said, “this had been accomplished through external cooling lines that had to be manually adjusted for each setup and (were) time-consuming.”

Long threads pose a further hurdle when machined on a Swiss-style CNC machine. Because Swiss machines use a guide bushing to support material, which moves through the tooling rather than the tooling moving to the workpiece, Laprade said long threaded parts must be pulled back through the guide bushing after being cut, resulting in lost support of the workpiece.

Cylindrical sleeve, typically made from high-grade tool steel, inserted into a jig fixture to guide cutting tools. There are three main types: renewable, used in liners that in turn are installed in the jig; press-fit, installed directly in the jig for short production runs; and liner (or master), installed permanently in a jig to receive renewable bushing.

“Once material support is removed,” he said, “a machinist runs the risk of the part deflecting under the tool pressure with each subsequent pass. Thread whirling eliminates this concern, and it can take stock diameter and machine it to a complete thread in a single shot.”

Roland produced the first desktop CNC milling machine, earning praise from Core77 community members as early as 2005: "Go with the Roland if you want something more of a plug’n’play." "90% of the people I asked recomended a Roland…" and "The Roland and other similar machines are more geared toward commercial environments (nice enclosures, more power, etc.)"The MDX-50 is a benchtop CNC mill with automated milling and unmatched ease-of-use features. An ideal solution for short-runs and prototypes, it reduces operation time and simplifies production so that anyone can produce accurate prototypes in metal, wood, plastic and many more materials.• Machining area: 15.8" (x) x 12" (y) x 5.3" (z)• 3 Axis, optionally 4 Axis

A desktop CNC milling machine can be a practical addition to your prototyping or small-scale fabrication operations. Entry level CNC mills allow you to create parts in a variety of materials, from wood to foam to soft metals. They are precise, consistent and can produce smoothly finished and strong pieces. As a skill CNC milling has a learning curve with software and material/tool combinations (speeds & feeds) that you’ll need to budget time for.There are some sweet-spots that CNC milling fits for a designer: it can be used to post-process 3D prints to produce high-tolerances in prototypes, used in furniture design it enables digital manipulation of wood, for self-manufacturing it can be time and cost efficient. In the production of art or one-offs CNC milling permits a broader range of material and surface expression than 3D printing. Some things to shop for are machining area, number of axes, and material capabilities. Which software the machine uses, and whether it is included in the cost is important as well. CNC milling is a unique process that yields rewards in the right scenarios, let your particular use guide your choice.

Core77 Editor Rain Noe writes: "I'm typically skeptical of tools that claim to do multiple things. (One notable exception is the LogOx, which I've confirmed performs all of its tasks well.) I'd be extra-skeptical of a tool that claimed to be able to handle three separate digital fabrication operations. But 5,050 Kickstarter backers were not skeptical, and thus a couple of years ago the Snapmaker Modular 3-in-1 3D Printer was successfully funded, and the company has thrived. Snapmaker's invention is a desktop machine that can 3D print, and do lasercutting, and do CNC milling. The metal-framed machine has different heads that can be attached, depending on which operation you'd like to perform." • Maximum axes operation: 9" (x) x 7" (y) x 9.84" (z) • 3 Axis

“Thread whirling can be used to produce worm gears and of course standard 60-degree UN threads, as well as metric standard threads,” said Scott Laprade, applications supervisor at Westfield, Massachusetts-based Genevieve Swiss Industries Inc., which does business as GenSwiss.

“These machines offer the most stable cutting condition due to the bar stock being supported by a guide bushing that is in the machine’s spindle/chuck, where the material is fed through the guide bushing, allowing for the cutting tools to be very close to the material being machined,” Loughney said. “The machine must have a c-axis that the thread whirling unit is driven by. The thread whirling ring fits into the unit. The rings consist of multiple indexable carbide inserts with up to three cutting edges depending on the pitch of the thread.”

“To help accommodate that,” he said, “shifted cutter rings that bring the inserts closer to the guide bushing are available for more readily available live tooling attachments on the market.”

The improvement in surface finish from thread whirling is a result of the unique tangential cutter path and increased rigidity. Burrs also are minimized due to reduced chip loads and longer tool life.

Loughney said getting thread whirling right from the beginning, setting up and understanding how the thread whirling unit works on a machine are critical for first-time users.

Thread whirling is important to manufacturers of implant screws, for which orders can range from 1,500 to 5,000 pieces or more per production run. Bone screws are being designed with more complex thread forms, including deep threads, multiple leads and unique thread pitches. Inserts are designed and manufactured specifically for individual threads.

Bantam Tools offers a complete ecosystem for their desktop CNC mill, with software and education courses. As they say: "a proven prototyping solution that is built with professional reliability and precision to support world changers and skill builders.• Maximum axes operation: 7" (x) x 9" (y) x 3.5" (z) • 3 Axis, optionally 4 Axis

"The Ready to Run Desktop Milling Machine from Carbide 3D" — The Nomad 3 Desktop CNC Mill is the third major revision of the Nomad 883 that launched Carbide 3D. Nomad 3 includes MeshCAM V8 to take your STL files and generate gcode without any additional CAM software.• Maximum axes operation: 8" (x) x 8" (y) x 3" (z)• 3-axis

Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

Shown above is a typical arrangement of cutting inserts in a thread whirling ring, which affixes to the dedicated live tooling attachment used to perform the process. Image courtesy of Genevieve Swiss Industries

As with everything else for a Swiss-style CNC machine, Laprade said thread whirling depends on the guide bushing for support, so ensuring that cutters are as close as possible is paramount, especially for smaller-diameter threads.

A productive method often used for thread forms that need to be produced quickly and at tight tolerances, typical parts for thread whirling are medical bone screws, implants, feed screws, worm gears and other microcomponents.

Loughney said when using a sliding-head machine, users have the support of its guide bushing close to the cutting head, with multiple inserts applying even cutting pressure. Trying to thread long, slender components using a single-point method would be almost impossible and could cause high scrap rates, poor-quality threads and excessive tool wear and breakage.

“Grade GC1105 offers sharper edges for burr-free component surfaces and long and predictable tool life,” he said. “This is especially important when machining titanium and stainless steel bone screws.”

With thread milling, the tool cuts on the way into the material and up to the full tangent point. As the heel of the cutter makes an exit path, the direction of the finish pattern changes and results in a crosshatch pattern.

One of the most recent improvements for thread whirling has been cutter rings that are capable of delivering high-pressure cutting oil directly to threading inserts to better clear chips, as well as cool the cutting edges.

Internally cooled thread whirling rings eliminate the need to have perfectly aimed coolant nozzles for chip evacuation and insert cooling. Cutting oil is delivered to the insert edge through internal channels in the cutter ring. Image courtesy of Genevieve Swiss Industries

Process of both external (e.g., thread milling) and internal (e.g., tapping, thread milling) cutting, turning and rolling of threads into particular material. Standardized specifications are available to determine the desired results of the threading process. Numerous thread-series designations are written for specific applications. Threading often is performed on a lathe. Specifications such as thread height are critical in determining the strength of the threads. The material used is taken into consideration in determining the expected results of any particular application for that threaded piece. In external threading, a calculated depth is required as well as a particular angle to the cut. To perform internal threading, the exact diameter to bore the hole is critical before threading. The threads are distinguished from one another by the amount of tolerance and/or allowance that is specified. See turning.

The company specializes in tooling and accessories for Swiss-style machining and has expertise with thread whirling given its exclusivity to Swiss machines.

Tormach's entry-level CNC for desktop use. It includes their inhouse CAM software and access to an online simulator to test code before sending to the machine. From their site: "The Tormach PCNC 440 is designed for prototyping, production, and education and with its compact footprint it can fit just about anywhere." • Maximum axes operation: 10" (x) x 6.25" (y) x 10" (z) • 3 Axis, optionally 4 Axis

Another company, Sandvik Coromant Co. in Fair Lawn, New Jersey, provides CoroMill 325 thread whirling rings and inserts, which meet the needs of a large number of sliding-head machine types. The rings and inserts can thread long, slender components from rough stock at high speeds without use of a dedicated thread whirling machine, said Patrick Loughney, who handles business development for small part machining and is product specialist for indexable drilling tools.

GenSwiss has partnered with Utilis AG of Müllheim, Switzerland, since 2006, and the companies have worked to further the technology used in this machining process. Laprade said Utilis and GenSwiss introduced to the Swiss-turn industry thread whirling systems that use up to 12 thread cutting inserts. The addition of tooling with more cutters enabled users of whirling attachments to increase productivity over the conventional three- and six-insert systems that were available at the time.

“Many thread whirling units have a 50-1 gearbox reduction,” he said. “Take this into consideration that the programmed rpm will not be the actual output in most cases.”

Although similar to thread milling, thread whirling has inserts mounted on the inside of a cutting ring, or cutter holder, rather than on the outside of a milling tool. The thread whirling ring rotates around a cylindrical component to cut a thread in one pass. Image courtesy of Sandvik Coromant

Core77 Editor Rain Noe writes: "What do you get when a machinist marries a mechanical engineer? If you're Matt (the machinist) and Michelle (the mechanical engineer) Hertel, you get what may be the world's first desktop-sized 5-axis CNC mill... The Montana-based couple spent four years developing the device, picking up some help along the way: Another machinist named Gary and a software guru named Duane (sorry, no last names available). Here is the result of their collaboration, dubbed the Pocket NC" • Maximum axes operation: 4.55 " (x) 5.0 " (y) 3.55 " (z) • 5-axis

Standard inserts for thread whirling HA and HB thread forms are available as stocked items from Sandvik Coromant. These threads have the specific dimensions and tolerances needed for bone screws and other medical implants. However, the majority of thread forms on bone screws are special forms that would be offered as engineered solutions.

Swiss-style CNC machines use thread whirling to generate complex, complete thread forms that normally would be difficult to produce efficiently in high volumes. Thread whirling is a milling process used primarily for thread forms that require large amounts of removed material, such as medical buttress threads designed to thread into bone.

Evo-One CNC can be easily used by anyone: a hobbyist, a maker, a fab lab or a company. Thanks to its ease of use and to its polymethyl methacrylate covering you can use it inside any room, in your garage or in your office with no filth or dust coming out of the machine during the process and with a considerable reduction of noise.• Maximum axes operation: 14.4” (x) X 8.7” (y) X 4.4 (z)• 3 Axis

Another recent advance is quick-change capability. Sandvik Coromant provides that with its whirling rings, along with high-quality carbide and coatings, such as Grade GC1105, which Loughney said is a popular choice for medical machining.

Compared with thread milling a zero-degree thread wall, which commonly is found on the trailing side of a bone screw thread, the finish pattern of thread whirling is better thanks to the tangential radial entry and exit of the cutter, which leaves a uniform pattern.

Thread whirling offers several advantages over single-point threading. First, users can machine high-quality threads on long, slender components without the risk of bending or vibrating. Single-pass threading from stock diameter reduces cycle time, increases productivity and helps produce accurate threads by tilting the whirling ring toward the helix angle. Also, good chip control enables continuous machining, and finishing treatment is not required. Finally, deep thread forms, such as Acme, can be achieved easily with thread whirling.

2-D or 3-D path generated by program code or a CAM system and followed by tool when machining a part.

Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

Number related to the applied load (usually, 500 kgf and 3,000 kgf) and to the surface area of the permanent impression made by a 10mm ball indenter. The Brinell hardness number is a calculated value of the applied load (kgf) divided by the surface area of the indentation (mm2). Therefore, the unit of measure of a Brinell hardness number is kgf/mm2, but it is always omitted.

Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.

Yesenia Duran is a Chicago-based freelance journalist who covers cutting tools and technology. She can be reached at sennyx@gmail.com.

He said whirling can produce long threaded parts accurately and efficiently with exceptional surface finishes, whereas traditional single-point threading methods require multiple passes with a threading tool. An additional advantage is that aggressive, deep thread forms can be achieved in a single pass with a high level of precision.

With thread whirling, the cutter enters and exits in a radial arc, which is similar to the thread radius direction. As the heel of the insert exits the thread form, the resulting finish leaves a crosshatch pattern. But this pattern would not be seen on any thread wall with a positive wall angle. That is because the cutter contacts the workpiece only at the full tangency of the cutting path.

Broaching with Long Insert Life, High Surface Quality - cnc tool insert

You Might Also Be Interested In