Senior CAM and application engineers from Sandvik Coromant discussed the latest tool technology and CAM programming technology for aerospace manufacturing.
As the industry continues to transition to newer technologies, I see more near-net-shape inventory components with more complex shapes. They are machined on advanced multi-axis CNC machines to reduce settings and maximize efficiency. Materials continue to become more exotic, and with the adoption of powder metal materials and additive manufacturing, it has spawned some exciting new processes.
Sandvik Coromant is proud to lead the development of tool solutions and their applications. We actively cooperate with industry partners, such as CAM software developers and machine tool OEMs. We work with our partners to develop tool path technology to effectively utilize the tools of a given application. Our R&D and training support team will continue to help our employees and customers train on these latest developments.
In terms of tools, we have developed new blade materials and technologies to process difficult-to-machine materials such as titanium and nickel alloys. This includes PCD CD10 material for titanium finishing, or CBN 7014 material for nickel alloys, which can greatly increase cutting speed. We also released a revolutionary new insert geometry and CoroPlus® toolpath method through the PrimeTurning™ solution. These blades and toolpaths allow high-feed turning of aero engine parts, and because of their double-edged geometry, they can be used as traditional C-shaped blades to clean feature corners. We have also developed solid carbide milling cutters, such as the 1745 grade for titanium alloys and the 1725 grade for nickel alloys. The materials and geometries of these tools are specifically designed for dynamic milling toolpaths, enabling rapid metal removal, especially in aero frame groove features. In addition, our ceramic, 600 and 390 series indexable milling cutters can perform 5-axis turning and milling composite machining of complex aero-engine shells and other conical materials. All these examples enable our customers to produce parts more efficiently.
Many customers do not realize that we not only develop blades and tool holders for our aerospace customers, but also develop tool path technology, cutting data calculators, and even CAM programming service solutions. We are also actively involved in digital processing solutions, such as machine monitoring, as well as on-site application support and training. These solutions and services contribute to the success of our customers and complement our cutting tool products. So yes, we are more than just a plug-in provider.
For more information or examples of tool/CAM technology, please check our website. There you will find more examples, such as OptiThreading™-a thread turning toolpath solution for optimizing performance based on cutting forces. Invomilling – Our tool/CAM solution for milling gears and splines. Or as mentioned earlier, our Prime Turning solution is being integrated into CAM software, such as Siemens NX CAM and MasterCAM with fixed machining cycles.
More information: https://www.sandvik.coromant.com/en-us/products/coroplus-toolpath/pages/default.aspx
Emuge-Franken's ZGF-S-Cut thread milling cutter has several obvious advantages.
The left-hand cutting geometry used in traditional milling cutting paths, the combination of holes and threads entering from the outside to the inside or from top to bottom, creates a very stable cutting action for this intermittent thread cutting process. In addition, the combination of left-handed helix and left-handed spindle rotation moves clockwise into the part to produce a down-milling cutting effect, thereby extending tool life.
The first cutting tooth on this type of tool is an incomplete thread profile with a pitch, which is used for roughing, removing most of the material before completing the subsequent cutting teeth of the thread. This design, combined with the clockwise movement of the tool into the part (conventional milling movement), can perfectly extend tool life when cutting very difficult and worn-edge materials found in the aerospace industry.
When thread milling processing challenging super alloy materials (such as 718 Inconel, Haynes 25, Ti-6Al-4V, 455 stainless steel or high temperature alloy steel), the carbide cutting edge will significantly extend tool life and increase productivity. For example, the single-face carbide Emuge-Franken ZGF-S-Cut thread milling cutter reduces cycle time by minimizing the need for tool compensation for edge wear. By distributing the material load of the cutting edge among the 3 carbide cutting teeth, the cutting edge wears more slowly. This reduces the need for operators to participate in stopping the machine to add more tool wear compensation values. When the need to adjust the thread size decreases, the machine uptime will be greatly increased, thereby reducing the cycle time of each part.
By modifying the programming instructions, select thread milling cutters that can cut through holes or blind holes and produce STI threads and different tolerances. Emuge-Franken ZGF-S-Cut thread milling cutter provides internal cooling supply from 1/4" and above, and guarantees the processing of threads within 1 pitch from the bottom of the hole.
Emuge-Franken ZGF-S-Cut thread milling cutter has TiAlN-T46 proprietary PVD coating, which is designed to harden and protect the cutting edge from the heat generated when cutting high-temperature steel alloys and nickel-based alloys with rotating tools Demanding jet engine components. The ZGF-S-Cut tool contains three principles for successful thread milling process: 1. Efficient chip removal and control; 2. Follow Emuge programming instructions, high feed rate safety; 3. Stability due to its geometry and design . From #2-56 to 1/2-20 of 2XD and #4-40 to 1/2-20 of 3XD and M3 to M16, Emuge-Franken ZGF-S-Cut thread milling cutters maintain h6 metric tolerance cylindrical shanks, should Use with very sturdy knife handles.
More information: https://www.emuge-franken-group.com/de/en/
A general material guide for certifying replacement parts for 3D printing opens up the MRO market for small and large manufacturers.
A shortage of aerospace spare parts inventory, high costs, and regular production delays for purchasing cast parts, coupled with the pandemic’s impact on normal aircraft/supplier production, transportation, and labor, put the industry in trouble. Not only are new aircraft orders and standard inventory support having problems, but aging, useful and still profitable aircraft are left idle due to lack of parts.
This is the complex and constantly changing environment currently faced by aerospace original equipment manufacturers (OEM), lessors, and maintenance, repair and overhaul (MRO) companies. Advanced Additive Manufacturing (AM) is about to democratize aerospace MRO throughout the supply chain, thereby reducing the cost of parts delivered in a shorter time.
The MRO multi-source business environment includes aircraft original equipment manufacturers and specialized large and small suppliers. Most companies want bigger roles and higher profits, which are currently required for parts replacement. The challenge is how to best solve the high cost, low output and strict delivery schedule.
It is problematic to replace worn tools used for castings of blades, stators, casings, and other engine parts. Tools can cost tens of thousands to hundreds of thousands of dollars; this is a tedious and rigorous process involving thousands of part types, used for high storage costs, 20 to 50 year product cycles, or as few as 1 to 10 runs at a time Components of components.
Casting is a capital-intensive technology that cannot flexibly design changes with long lead times, thereby forcing high inventory to stabilize the supply chain. Commercial additive manufacturing (AM) has its own problems: calibrating machines for mass production, achieving measurable quality, good yield, acceptable unit cost, and reasonable turnaround through post-processing. But large MRO manufacturers that use commodity AM have the resources to obtain certification to manufacture specific, limited, flight-friendly parts, sometimes costing millions of dollars.
In order to catch up with the demand for aviation parts and avoid the shortage of commodity AM, advanced AM systems are required. Various forces and events are working together to democratize AM for OEMs and MROs, regardless of size, and to make on-demand production of parts fast, cost-effective, and almost as predictable as CNC machining.
The largest commercial aircraft manufacturing companies have developed internal materials that enable them to produce flight-certified AM components. For these early adopters who have invested heavily in AM characterization and testing, FAA 14 CFR 21.1 allows airframe and engine type certificate holders to serve the market.
For others in the MRO field, there are few or no FAA-recognized specifications or licenses. The MRO market has encountered serious certification challenges that hinder the widespread use of AM.
Access to a powerful standardized data set, MMPDS Volume 2 Additive Materials, will enable MRO to accept AM without the need for extreme, time- and cost-intensive separate work. Metal Material Characterization Development and Standardization (MMPDS) is the industry source of design licenses recognized by FAA, DOD and NASA. It references specifications for materials that can be used for parts and repairs, usually AMS (Aerospace Material Standard).
The most pressing MRO requirement is to produce copies of stator blades, bearing housings and other key components to keep existing aircraft flying. Although AM is known for its extraordinary part integration and blank paper design capabilities, it also applies to the economics of direct (precise) part replacement. Although the incremental increase in casting capacity may cost tens of millions of dollars, the cost of using AM to produce parts may be between 1 million and 2 million dollars per machine. In addition, compared with the casting process, additive manufacturing has flexibility in terms of the number that can be produced and the countless geometric shapes that can be printed from each machine. AM can also produce the same parts with better drawn material quality and higher density than castings.
A series of AM machines can handle the entire production volume of the same part stream and then switch to near-on-demand inventory fulfillment suitable for MRO. Or they can design conceptual prototypes from design to manufacturing for future products. This low-cost, flexible AM alternative can be matched with the manufacturer's existing cast and processed product portfolio to improve supply chain dynamics. Faster, better, more flexible and lower cost.
Both casting and traditional additive manufacturing have limitations. The recent additive manufacturing materials guidelines encourage change and may accelerate investment in newer MRO additive manufacturing solutions. Advanced AM has provided automation, quality and process monitoring, non-contact coating machine blades, controllable atmosphere and software to open the market.
Analyzing the composition of the atmosphere is critical to meeting aerospace quality standards. When a manufacturer prints a metal part in an imperfect build room environment at high temperatures, it may incorporate unwanted atoms or molecules in the atmosphere into the material as the material solidifies. Too much oxygen in the room can cause oxidation and porosity. Hydrogen reacts with the finished metal and embrittles it. A small amount of moisture will ionize under the laser, which may affect the quality of the part. The best AM developers have borrowed from the atmosphere control strategy of the microchip industry to ensure quality and design freedom.
The proper height of the powder bed is essential to ensure that AM can manufacture previously cast aerospace components. During the construction process, the correct powder bed height must be maintained without ridges, waves or changes. The powder bed is the raw material in the welding process, and consistent raw materials are critical to quality. In the product AM, solid metal protrusions in the powder bed are the most common problem because the blades are used as windshield wipers. The next-generation AM system provides a non-contact recoater arm and integrated metering, so it can continuously and quantitatively measure and monitor the topological structure of the powder bed for inconsistencies. This is another example of AM's process control beyond the traditional manufacturing process.
The options for solving the intertwined manufacturing and economic challenges faced by aerospace OEMs and MRO parts replacement services are expanding. Frustration with the slow progress of AM is no longer justified. Aerospace contract manufacturers with advanced AM are ready to produce replacement parts with the same or better quality as the original casting, as needed, in small batches and at lower cost.
About the author: Will Hasting is Velo3D's head of aerospace and power turbine solutions. You can contact him at will.hasting@velo3D.com.
Murata Machinery USA’s Western Regional Sales Manager Troy Kattenhorn and Mechanical Engineering Director Andrew Lilly explained their MW35 machines.
As the aerospace market gradually returns to full production, processing and machining shops must now be prepared for short, medium, or high-volume production of multi-size fasteners and accessories. They need machines integrated with current production to provide greater flexibility for rapid tool and workholding changes.
Andrew Lilly (AL): If you visit some aerospace machine shops, you will see machines that are more than 50 years old all over the floor. Our solution can replace multiple machines with smaller packages.
Troy Kattenhorn (TK): Usually, only a few operators can run these old machines. Our equipment adopts the latest CNC control, allowing new operators or higher-level operators to run these machines.
AL: Some machines can only do one job. This is not a lot of flexibility, so you need a lot of people to do a lot of different jobs. Our MW35 machine provides this flexibility.
TK: Fully enclosed, safe, clean, low oil mist, fully electric. There are no hydraulic or mechanical cams, belts or pulleys. Customers can make offset changes during the cycle. It reduces the setup time from 4 to 8 hours to 20 to 30 minutes. Some customers like to use three-jaw chucks, while other customers like chuck chucks, we can use any one.
AL: Our new feeding system can adapt to various part sizes, and provides customers with one machine that can process multiple series of parts on one machine. We can do this with very short cycle times and very few conversions.
TK: Our turnkey project makes us a one-stop solution. We are responsible for a complete package, seamless integration, with little risk. Through active automated monitoring, machines and robots can monitor each other's actions so that they always know exactly where everyone is.
TK: All our machines have great potential in the aerospace industry.
AL: MW35 enhances the pick-and-place loader, which can automatically feed materials, allowing the operator to quickly load a batch of original fastener materials to keep the machine running continuously. Usually, adding automation will make your footprint larger because it is located next to or in front of the existing machine, but our loader fits the footprint of the MW35.
TK: Because we do all our own automation internally, we do not rely on third-party supply chain issues. We have multiple MW35 machines in stock, ready to be integrated and shipped.
AL: The simplicity of the machine allows multiple operators to learn quickly. With intuitive controls, it is designed for a single operator to control multiple machines.
More information: https://www.muratec-usa.com/machinery/turning/twin-spindle-machines/mw35/
The innovative AC-DC conversion topology provides higher efficiency, active PFC for demanding aerospace applications.
The efficiency of the power conversion subsystem is important to overall system performance. For every watt of power consumed, the aircraft’s range decreases or its energy storage increases. The selected topology and its efficiency performance will affect the size, weight, reliability, and cost of the power converter. All these factors have important and serious effects:
In addition to the benefits of high efficiency, other electrical performance factors are also important. When converting from AC platform power, this method must provide active power factor correction (PFC) to minimize current harmonic distortion and adjust DC output characteristics. When combined with smaller, lighter packaging at a competitive initial cost, a compelling proposal is at hand. By adopting a new single-switch method to achieve power factor correction AC to DC regulated power supply conversion, these goals can be achieved through qualified packages suitable for aerospace and military applications.
The traditional path from three-phase 115VAC to a regulated DC power supply requires a multi-step topology. There are two main legacy methods:
The first type-RTRU-is widely used for airframes that require slight adjustment of output. It uses an unregulated TRU topology, followed by a boost converter. The latter maintains the output voltage under high load demand, where the output of the TRU will drop.
It should be noted that TRU and RTRU do not use power factor correction circuit, and will show a high level of current harmonic distortion when the load is less than 50%. Although not complicated, the converter relies on a large and heavy transformer and many diodes to provide the desired function.
TRU usually converts 120 VAC power from an on-board engine or auxiliary power unit (APU) generator or ground power unit (GPU) into 28 VDC to power electrical components. In the TRU, the transformer component isolates the AC input from the output, and generates a DC output through a rectifier diode, and then performs LC filtering to remove most of the AC ripple in the DC. The second step is the boost converter, which can reduce the voltage dip under the load, because the transformer/diode part is not regulated.
Three-phase TRU issues are not just about efficiency and ripple. Since two of the three phases conduct current through the bridge at all times, current discontinuities can cause undesirable harmonic distortion and reduce power factor. Due to the post-rectifier filter capacitor used to smooth the rectified voltage ripple, the input power will see a reactive load, which results in a phase shift of the current relative to the voltage, reducing the power factor from the required unit value. Two 6-diode rectifier circuits are used to reduce harmonic distortion to a usable level of 12%.
The second type-APFC-SMPS-uses switch mode power supply (SMPS) technology to achieve power conversion, thereby generating more changes in primary and output isolation (if required), boost or buck and regulation (Figure 1) High-efficiency active PFC) enters the second stage. In the traditional design, the PFC function and output regulation function are completed in two independent switches or stepping circuits.
The first step is to rectify the AC voltage and apply active power factor correction (APFC), resulting in total harmonic distortion (THD) kept at a low level, usually less than 5%, and individual harmonics less than 3%. The side effect of APFC circuits is that they also act as boost converters. The boosted voltage is fed to an isolated or non-isolated switching regulator to provide a regulated output of the line and load with a lower required DC voltage. The result is a higher-performance power conversion process, although the size, weight, and complexity of the two independent switching circuits will be lost.
Consider a regulated AC-to-DC path with two stages, each with an impressive 95% efficiency near load or full load. Therefore, the overall efficiency is slightly higher than 90%. When you have multiple series switching converters, it is difficult to achieve the required efficiency in the range of more than 92%, including the loss of electromagnetic interference (EMI) filters. The 1kW converter has a power consumption difference of 24W from 90% to 92% at full load, a 22% reduction.
When converting AC input power to an isolated, fully regulated DC output and adding passive or active PFC, each step increases complexity, component count, volume, and weight, while reducing efficiency. With the demand for power subsystems, power conversion needs to be improved.
Marotta Controls has developed a single-step AC-DC conversion based on a circuit solution that provides output voltage regulation, electrical isolation, and APFC at the same time (Figure 2).
The 1-STEP topology uses a switch-mode power converter, where each of the three phases powers a full-wave rectifier and a flyback converter that operate in parallel in closed-loop voltage mode (Figure 3).
The three converters use a single shared control loop to regulate the output voltage, which sends a single pulse width modulation (PWM) signal that controls the current flowing through all three converters. The converter outputs are connected in parallel, and the load is evenly shared due to common control. The power flow is evenly distributed between the input phases, and each phase always supplies current.
The 1-STEP design switches the rectifier current at a frequency of 50kHz, and the line frequency of the TRU is doubled, which fundamentally eliminates low-frequency current distortion. The ratio of current to voltage makes the converter appear to have resistance to the input power, and the higher switching speed also eliminates the need for ripple smoothing filter capacitors that follow traditional rectifiers. These two factors cause the power factor correction to be between 0.95 and 1, depending on the specific 1-STEP model and load, the current harmonic distortion performance is <2%.
Marotta Controls using the 1-STEP architecture provides many AC to DC power conversion models. The overall efficiency of each model is better than 91%, ranging from as low as 30% uniform load to 100% rated load (Figure 4). The power factor is between 0.95 and 1, depending on the model and load.
Of course, a good AC-DC converter does not only depend on its high efficiency and close to uniform power factor. All 1-STEP units have overload capability; over current, over voltage, over temperature protection; low inrush current and rigid response to dynamic loads. The overload capacity of the 28VDC device is specially designed for traditionally configured applications. They all comply with relevant standards for advanced military and commercial platforms, covering environmental testing (temperature, vibration and shock, humidity, salt spray), EMI/EMC characteristics, and power quality and utilization.
About the author: Michael Germinario is the senior technical director of Marotta Controls. You can call him at 973.334.7800.
All 1-STEP models use MIL-STD-704 or DO-160 three-phase 115VAC input, which can support wild frequency input from 50Hz to 800Hz. Among the many 1-STEP units, there are the following models:
The benefits of the 1-STEP method exceed the capabilities of a single unit. Larger systems can be created by paralleling converters, whether for higher loads or to provide N+X redundancy. Up to four modules can be connected in parallel without additional hardware, and 5 to 15 modules can be connected by independent controllers.