1) The CKB modular system allows for unlimited combinations other than the number of components that users can stack up for an assembly.
In any assembly the number of components should be limited to four or five, not including boring head insert holders. Since there are usually two-to-three length options for a given taper- and connection-size combination, most applications only require two-to-three different components (shank, extension/reduction, boring head). When users need more gage length, independent of boring depth, the best option is to use the largest CKB connection on the shank end and reduction adapters to minimize the assembly length-to-diameter (L:D) ratio. When bore depth requirements exceed what standard taper adapters allow, extensions can be used, but a maximum of two is recommended.
For 0.787" to 1.614" (20mm to 41mm) bore diameters, CKB1 to CKB3 cylindrical shank carbide bars can be an alternative. The bars’ higher stiffness permits boring L:D ratios up to 10:1, and combined with a hydraulic chuck toolholder, provide vibration damping. Overlapping this range slightly (1.260" to 8.000") are Smart Damper boring heads, which feature an internal assembly for absorbing chatter. The final option is the CKN modular assembly, a special version of CKB that is cross-compatible but uses three connection screws instead of one and features an aluminum extension to reduce tool weight.
2) How have digital boring heads changed process reliability and/or capability in aerospace?
They take the guesswork out of size adjustment. Instead of measuring the input rotation of the adjustment dial, these heads place displacement scales along the tool carrier to measure linear travel and can display diameter corrections of 1µm. In addition, clamping displacement can be seen with these heads.
Storing incremental diameter adjustment values in the boring head allows companies to track insert life and tell operators to change insert corners when the adjustment values reach a predetermined value. Otherwise, the operator may re-zero the display to make the compensation value on the head equal to the next adjustment.
Connected to the BIG KAISER app via Bluetooth, the incremental value from the EWE fine boring head can be fed into the preset parameters to give the true output diameter of the tool. With tolerance information added for the bore, the connected device indicates where in the target range the actual tool setting lies. The head stores up to 200 cycles of this information (target diameter, tolerance, incremental adjustment) for each adjustment along with a date/time stamp, providing process traceability for ISO and other certifications.
3) What types of aerospace precision hole finishing options do precision fine boring heads enable?
Many aerospace components are made from high strength aluminum or magnesium, making it easy to manage tight-tolerance bores, even with tooling developed decades ago. In many applications, however, bores use a hardened steel bushing pressed into the hole, requiring final bore size to be done with jig grinding. The process is slow and requires a highly skilled dedicated operator. CNC machines equipped with our CK fine boring tools using new cubic boron nitride (CBN) grades have successfully replaced jig grinding. Even jig grinding holes smaller than 0.25" have been replaced with standard fine boring heads.
4) How have aerospace manufacturers used BK for turning centers when boring cross holes with live tools?
Landing gear components have many applications typically done on a lathe. However, linkages with precision cross holes require fine boring to complete the job. When lathes with a 4th axis and driven tools became popular, Kaiser had to adapt our fine boring heads to process the parts completely. One constraint was to keep the tool projection as short as possible due to the short travel of the Y-axis. With most driven tools using ER collets, we developed a series of fine boring heads that takes the place of the standard ER clamping nut, making the tool ultra short and very rigid. Boring cross holes on a lathe became very easy with off-the-shelf tools.
5) What does BIG KAISER recommend for boring precision holes on aerospace parts using angle heads?
A large contractor needed to replace a manual process for boring the lug holes that attach wing assemblies in commercial fuselage components. The only practical solution was boring with angle heads.
While the process seems like it should be simple, there was a basic problem – if the angle head is not truly 90°, the boring tool will not produce a perfect round hole. Think of a machine column that is not square to the table. As the spindle rotates and travels across the table, it will generate an elliptical shape. The same result will happen if the angle head is, say 89°; it will never track a perfectly round hole. The accuracy of the finished hole is only possible if the angle head tolerance is closely controlled.
For more information: https://www.bigkaiser.com
1) Additive manufacturing (AM) is increasingly used for aerospace parts.
Aerospace engines are currently the main application for (AM) parts. However, we are starting to see more interest from the airframers as well. Some formerly cast parts are now candidates for AM. Titanium, Inconel, stainless-steel, and other heat resistant super alloys (HRSAs) long used in aerospace are now able to be used in AM. And parts designed for AM that combine features of several, separate parts onto a single piece are becoming more common.
2) Additively manufactured metal parts are challenging to machine.
AM’s ability to produce more complex shapes – and use of hard materials – make them challenging to machine with traditional tools. The complicated shapes AM can create makes it difficult to apply inserted tools because of space constraints or the need for complicated tool paths not encountered in machining solid billets. Solid tools can reach intricate features more easily than inserted tools.
3) Metal AM is driving higher demand for solid carbide end mills.
Because metal AM can produce near-net shape parts, there is less need for heavy roughing to achieve the desired finished part. Solid carbide end mills fit perfectly with additively manufactured parts because of their longer lengths of cut, up to 5x the diameter. Solid carbide tools designed for high-feed side milling, such as Sandvik Coromant’s CoroMill Plura line, are offered in grades and geometries to match AM materials and shapes.
4) Proper tool path can increase tool life, improve productivity.
Tool path has a large impact on overall productivity and cost per part. Many CAM software providers now offer tool paths optimized for AM. Better tool paths maintain consistent cutting forces, offer improved metal removal rate (MRR), produce better part finish, and provide longer tool life. With less material to remove from near-net shape parts, less radial contact with deeper passes from a well-designed tool path makes machining more productive and saves time. Plus, lighter roughing allows use of smaller spindle, smaller horsepower machining centers, which reduces energy use.
5) Solid carbide end mills offer advantages in machining additively manufactured parts.
The long length-of-cut capabilities of solid carbide end mills require fewer axial passes to achieve a finished part compared to a similar diameter inserted tool. Although the initial cost can be higher than inserted tools, solid carbide end mills can be more effective, with higher MRR using more efficient tool paths, and the tooling can be reconditioned, reducing overall tool cost.
May 2020 winner:
George Macri, Quality Engineer, The Boeing Co., New Orleans, Louisiana
How long have you been in the aerospace business? I joined the U.S. Air Force in 1972, so it’s been 48 years.
How did you become interested in aircraft? At age 13, I was fascinated with the space program and in 1986 had the opportunity and honor to work with the Space Shuttle Program for 24 years. Now I am with the Space Launch Systems working on Artemis.
What is your favorite aircraft and why? The North American F-100 Super Sabre because it was the first aircraft I worked on.
VP Environment & Technology
Syracuse, New York
Southwest Inspection & Testing Inc.
To enter the contest, visit www.AerospaceManufacturingAndDesign.com/form/NameThatPlane and fill out the provided entry form. Only completed forms will qualify. A full set of rules is provided.
The entry deadline for this issue’s contest is August 2, 2020. Winners will be announced in the October 2020 issue.
Have fun, and good luck!
Look what George won!
Enter today to win your own high-quality desktop aircraft replica!
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