Common features on aerospace parts, holes can provide simple weight reduction, component access, mechanical assembly/movement, or critical location alignment. Feature requirements – such as diameter tolerance, finish, positional tolerance, roundness, and cylindricity – also vary. Often one of the fastest material removal operations, hole making can present challenges due to the materials, machinery, and methods used.
1) Which drill to use; indexable carbide or solid carbide?
It depends on the specifics of the hole and application. For example, holes with very long length-to-drill-diameter ratios require the strength and rigidity provided by solid carbide drills. This is also true when the hole requires a tighter International Tolerance (IT) grade. Replaceable tipped carbide drills such as Iscar’s SumoCham and Logic3cham can provide IT8 hole tolerances while delivering high material removal rates.
If you cut a variety of materials, replaceable tip drills allow users to change drill head diameter and geometry to optimize specific applications by using ISO material group-specific heads such as the SumoCham ICP, ICM, ICN, and ICK drill heads.
2) What is the benefit of having material-specific drill heads?
Changing drill geometry by quickly removing and replacing the self-clamped head tailors the drill to the material – decreasing cycle time, improving tool life, and making the process more stable. This allows more spindle uptime and throughput. For example, a SumoCham ICP head cutting Inconel 718 may suffer from chipping on the cutting edge or the chisel point due to the shearing force of the material. Changing to the ICM provides a reinforced cutting edge to withstand the pressure to shear high nickel/super alloys.
3) What are some challenges for producing holes in different materials, and do indexable products for drilling and reaming address that?
Materials with low melting points, such as aluminum, present reaming challenges as the hole tends to close on the tool, increasing friction and heat that impact tool life and finish. Diamond coatings reduce this and an indexable reaming solution, such as Iscar’s Bayo T-Ream, make it easy to apply a different head with a diamond coating. High nickel content materials, such as Inconel and titanium, also exhibit the phenomenon, so material-specific heads for drilling, such as ICN and ICM for SumoCham drills, will not have large margins that create additional friction and heat.
4) What about solutions for composites?
Layered carbon fiber reinforced plastic (CFRP) and hybrid titanium laminates can fray or delaminate from heat and cutting pressure, and composite materials are very abrasive. Iscar’s SumoCham semi-standard ICF and ICF-Ti drilling heads are diamond coated with unique cutting geometry to direct cutting forces out radially instead of axially. Iscar also offers these geometries in solid carbide with diamond coating, brazed PCD wafers, and brazed solid PCD nibs (tips).
5) Are there solutions for automated drilling units (ADU)?
Power and available force limitations on portable drilling units indicate using high-speed steel (HSS) or cobalt solid tools. Advances in cutting tool geometry and materials that reduce cutting force and horsepower required have made indexable solutions viable. Iscar offers semi-standard items, from both SUMOCHAM indexable drilling and BAYO T-REAM product lines, which feature the required special shank connectors used in popular air-driven ADUs for in-station drilling, allowing for increased performance and decreased cycle times.
Siemens Digital Industries Software Vice President of Aerospace and Defense Industry, Dale Tutt, explains the difference between digitization and digitalization.
To understand digitization vs. digitalization, you need to know the differences between the digital twin and digital thread. To successfully transition to the digital enterprise, you need to have both.
Digital twins
The digital twin, which has been around for decades, is a virtual representation of a product or process in the proper context so teams can analyze, study, and improve the product or process under development.
A digital twin enables companies to better predict product performance and production processes prior to verification and physical production, minimizing risk. Ultimately digital twin users win new business, get to market faster, and manage costs better than their competitors.
A digital twin can do all the right things, but if it’s not connected or integrated to all phases of product lifecycle development, you’re not realizing the twin’s full potential.
You can set up a digital twin for just about anything in engineering or manufacturing. Many examples manage the digital twin and 3D CAD implementations, but you need a digital twin seamlessly connected to other digital twins or to other phases of program development for the continuous exchange of data – the enhanced automation of data – up and down the product development lifecycle.
Digital threads
The Siemens’ Xcelerator portfolio represents a comprehensive digital twin that brings a series of adaptable digital threads to the aerospace and defense (A&D) industry. Siemens is the only company today to offer a digital twin that’s fully connected to a series of digital threads for increased automation and digitalization. With the digital thread, all processes are connected. Customers gain a deeper understanding and greater visibility into all product development phases up and down the value chain.
Digitization? No, digitalization
As a company goes through its transition into a digital enterprise, it often stops short, not realizing the full benefits of its digital enterprise.
When companies begin, information is placed into a Word or Excel file. Simulation or modeling programs are started, but nothing is linked. When a user moves something from paper to a software-based program, they are digitizing that artifact. This is primarily a document-based system.
Most companies today import and translate data from external sources, but nothing is fully connected. One team may manage engineering data in one system while other teams manage production data, program management, scheduling, and tracking on different systems.
Many companies think they’ve achieved digitalization once the digital twin is in place and functioning at full maturity using 3D CAD models, simulations, etc. However, even with a virtual representation in place, there is no sharing across the product lifecycle or supply chain (hence, no fully operational digital thread).
A fully digitalized enterprise connects virtual representations or twins with a digital thread. Seamless integration of the entire value chain has been achieved. Common tasks are automated and everything’s networked together. Requirements drive entire design, manufacturing, testing, and service systems. Updates are automatically shared up and down the value chain. The digital thread connects all processes to provide integration throughout the entire lifecycle of product development. This is also where a fully mature digital twin and a fully operative digital thread come together.
Siemens provides A&D digital threads that take advantage of our Xcelerator portfolio, and when combined with our deep industry knowledge, provide a key competitive advantage for our customers.
Figure 1: Position jitter showing servo versus floor vibration in µm.
All images courtesy of Aerotech
Eventually, automation hardware becomes obsolete. It’s hard to know exactly when to retrofit or redesign, but some indications cannot be ignored. It’s time to upgrade when:
The system’s tolerances and throughput no longer meet market demand
The tolerances of the previous generation system can only reach thousandths of an inch, and the market is requiring ten-thousandths
The machine’s throughput is being compromised due to higher tolerances or because of a high failure rate
In all cases, servo-drive technology will have a significant impact on the success of the new system. Servo drives provide motion where human interaction is not possible. Drive technology must be carefully selected to ensure the automation process does what’s intended. Selecting the right hardware will increase performance value and improve costs.
The goal for next-generation products is to align the market’s performance requirements and price points. Project managers must thread the needle between engineers’ desires to work with a proven and known technology and marketers’ desires to include the latest advancements. Select components wisely while mitigating the risk of using new and untested technology. All changes should increase performance, capabilities, or ease of use.
At Aerotech, we followed the same approach when designing our next- generation X-series servo drives. We built upon a technology that could run multiple motor types (brush, brushless, stepper) from the same drive with only parameter changes, supporting 20 digital and 4 analog I/O points per drive, and accepting more than one encoder per axis. We improved an already reliable product, increasing bus speed and making it immune to electrical interference. The drive has lower in-position jitter and faster encoder sampling rates.
Communication breakdown
When the network fails or glitches occur in the industrial workplace, downtime and loss of productivity are sure to follow. However, servo-drive communication hardware can reduce potential connectivity issues.
Even though wireless technologies have come a long way throughout the past 20 years, a hard-wired connection is still preferred for industrial motion control, and Ethernet connections are the gold standard. However, these copper cables also provide a path for noise. Electromagnetic interference (EMI) has always caused issues with inter-drive communications over copper connections because low-level electrical signal communication packets can become corrupted.
Grounding practices and additional line filters, capacitors, metal shielding, and inductors are traditional methods of eliminating EMI by minimizing noise spikes. In a motion control environment with large motors, amplifiers, and I/O, there are many noise sources that need to be addressed. These additional components and cabling add material costs and a significant amount of engineering and labor costs since they must be designed into the machine and installed by hand. Some noise sources are only on the factory floor and are not discovered until the machine is being commissioned.
Fiber-optics use light rather than electricity to transmit signals, making such communications immune to EMI. This increases system reliability by minimizing downtime and motion errors. A fiber-optic bus increases communication reliability and minimizes the tediousness of tracking down noise problems.
With a fiber-optic connection, the distances between drives can lengthen without increasing EMI susceptibility along the cable run. Transmission distances can grow to hundreds of meters or more, compared to less than 10m for drives connected with copper wires, allowing distributed panels throughout the machine or factory floor and eliminating the need to run all motor power and feedback cables back to a centralized location.
Keeping motor cable runs shorter lowers the cost of cable and the need to have elaborate cable trays and runs through the floor or ceiling. Drives can be closer to the moving hardware and farther away from the controlling PC. As control communication reliability increases and wiring cable placement becomes easier, machines benefit from reduced downtime and easier installation. This builds upon the proven technology of distributed I/O and applies it to motors and drives.
Figure 2. X-Series linear servo induced jitter, 10nm pk-pk
Tooltip jitter, blurry Images
Uncontrolled and unwanted motion can cause havoc in any process. A cutting tool bouncing around causing a wavy cut or a camera shaking and creating a blurry image will impact system throughput. A common way to compensate for this type of motion is to lower velocities and acceleration rates.
The level of this unwanted motion is called the noise floor (see Fig. 1, pg. 10), the ambient level of disturbance in a system. When measuring features, it’s imperative to observe this noise floor and understand how it affects measurement and how precise the measurement can be. Analyze the noise floor with and without the servos active to get a picture of natural versus servo-induced vibrations.
Jitter in the motion system, ground floor vibrations, and drive jitter contribute to the noise floor. A servo loop corrects positioning errors, an air isolation system minimizes ground floor vibrations, and a current-loop control minimizes drive-induced jitter. Aerotech’s X-drives correct two of the three vibration sources.
For a lower noise floor, increase the current-loop resolution. This provides smaller current steps and increases the servo loop rate, allowing earlier detection and compensation of vibration. Our newest drive hardware has implemented both features, reducing the noise floor by 2x to 4x compared to older drive technology. This in-position stability is critical while taking measurements or triggering an operation while the part is in situ.
Since the new servo hardware has 2x to 4x less noise, it may be possible to get away from more expensive linear amplifier-based drive hardware and use economical pulse width modulated (PWM) hardware. For applications that formerly required less efficient, costlier, and bulkier linear amplifiers, PWM amplifiers can minimize cabinet space and lower the cost of the finished machine. PWM drives generate less heat than linear drives and can operate at higher power ratings.
Figure 3. ADC noise reduction.
Analog noise, data rate bottlenecks
Most positioning systems require feedback to accurately sense system position. The control system uses this information to generate an error signal. The control loop’s determination is based on this signal so that it can compensate for this error. Incremental encoders are typically digital or analog. Digitizing a signal removes fidelity and takes a true sinusoid and turns it into a staircase. Optical encoders are still analog, but this signal gets digitized either in the encoder electronics or at the drive end. Drives that take analog feedback signals eventually digitize these signals internally. The higher the interpolation value on these analog signals, the closer the representation is to a pure sinusoid.
Analog encoder signals have their own noise floors. Filtering techniques minimize this noise. The higher the sampling of the analog encoder, the more the drive electronics can oversample and filter this signal to remove this noise. Figure 3 (pg. 14) shows the results of this increased sampling rate. Since this noise directly relates to position jitter, we can see an improvement of 100x compared to older drives.
Another benefit of higher sampling rates is increased speed. A drive can only read so many counts per second – the higher the sampling rate, the more counts per second. Encoder manufacturers come up with finer pitch scales every year that are affected by a drive’s maximum input rate. Moving from a 40µm pitch scale to a 4µm pitch scale results in 10x lower potential max. positioning speed if the drives are not also upgraded to read these scales faster. The X-Series drives have 4x the encoder input rate compared to their predecessors.
Since higher performance is always the goal of a new design, using analog encoders with the X-drives creates an environment with a robust controls package to minimize audible noise and maximize velocity stability.
Conclusion
The design phase offers the opportunity to look for partners who are willing to get the most out of your new machine. Picking the wrong servo drives could limit the overall performance of the machine. Improved communication reliability, positioning accuracy, and encoder sampling built into a proven drive technology that is reliable, robust, and performance-enhancing is the safe choice when designing your next system.
About the author: Matt Davis is senior applications engineer - Control Systems Group, Aerotech Inc. He can be reached at mcdavis@aerotech.com or 412.963.7459.
Modular, high-strength framing systems
Features - framing systems
Controlled Dynamics Crosslink system uses reusable rivets for rigid support structures made from lightweight aluminum.
Amelia the tank sits on an aluminum framing system made by Controlled Dynamics.
All photos courtesy of Controlled Dynamics
In a manufacturing shop in Grafton, Wisconsin, a 50-ton army tank named Amelia is parked on an aluminum-framed platform. Amelia drives on and off its platform several times each year, but the aluminum frame never budges.
Similar aluminum framing systems are all around the factory, holding everything from granite surface plates on the floor to a 100+ lb Smog Hog mist collector hanging from the ceiling. A single aluminum overhead shelf supports a heavy air compressor that “vibrates like crazy,” according to Frank Oetlinger, the energetic owner and president of Controlled Dynamics. He adds proudly, “That air compressor runs all the time. It’s been up there for three years and that shelf never moves.”
Oetlinger designed and patented the aluminum framing systems that he uses throughout Controlled Dynamics and in his other company, Blanking Systems Inc., located next door.
“The hardest thing to design is something simple that works,” Oetlinger says with a smile. He’s spent more than 45 years in the manufacturing industry and holds 150 patents, so he knows a thing or two about designing things that work. And Oetlinger enthusiastically predicts that his Crosslink aluminum framing system, “will ultimately change every aluminum structure on Earth.”
Controlled Dynamics owner and President Frank Oetlinger points to a 600 lb. transformer that sits on an aluminum shelving system. The shelf remains stable despite constant vibration from the heavy electrical system.
Common fixtures
Aluminum framing systems in manufacturing enclose machining cells and support conveyors and other automated material handling systems. They’re used to build workstations, carts, storage racks, and walls. It would be difficult to find an aerospace or automotive manufacturing facility anywhere that doesn’t use some type of aluminum framing system. But most of those are unstable, Oetlinger says, especially when used in environments subject to movement.
“If there’s any vibration they just fall apart,” he says.
That universal problem inspired the Crosslink system that maximizes extruded profile strength by creating mechanically locked, precision-aligned joints and components that can withstand heavy industrial vibrations. Oetlinger’s system becomes stronger and more rigid under dynamic conditions.
“The problem you have with other systems is that they’re all pivot-based. You’re dealing with 100% friction,” Oetlinger says. “Our system is a mechanical lock. We’re not pivot-based.”
Crosslink does not need gussets or cross brace supports, and can withstand direct, cantilevered, and torsional forces while maintaining alignment and stability.
Pointing to its supporting legs, Oetlinger says, “If you put a plate on top of these four columns and put a load on it, it would hold 1.4 million lb. And it’s all aluminum.”
More importantly, results are consistent and predictable. Engineers can run finite element analyses (FEA) on the structures and get predictable results.
Early adopters include Boeing, Northrop Grumman, 3M Corp., and Disney. Other customers include Caterpillar, Snap-On Tools, Eaton, and Rockwell Automation. Oetlinger is confident that the list will continue to grow, if he can get people to understand how the system works. The key is in understanding how his connectors mate the aluminum extruded parts.
Controlled Dynamics President Frank Oetlinger estimates that four Crosslink columns could safely hold 1.4 million lb.
Removable, reusable buck rivet
“When you’re sitting on an airplane in the window seat and you look out at the wing and you see all those little round things, hundreds, thousands of them, those are buck rivets,” Oetlinger explains. “Those dimples you see all over the side of a semi-trailer truck that you pass on the expressway, those are buck rivets, too.”
Buck rivets never loosen because, unlike pop rivets, they completely fill the holes into which they’re inserted. There are no gaps between the rivet and the surrounding material, so they don’t shift under dynamic conditions. They’re the preferred fastener for moving assemblies in trucks, aircraft, and trailers.
Oetlinger designed a reusable buck rivet for Crosslink that also leaves no room for movement in insertion holes.
“When you tighten it, it just becomes one piece,” Oetlinger says. “It’s stronger than a weld.”
The key difference is installation – traditional buck rivets are typically installed with an air gun and can only be used once while the reusable buck rivet installs with an Allen wrench and can be removed and reused.
Modular designs
Oetlinger’s employees at Blanking Systems Inc. use Crosslink for storage. Assembler Therese Dallgas says she loves the shelving system she uses to store her tools above her workbench.
“I can use it to assemble anything. If I want to change the layout of my shelf, I can loosen those connectors and change it,” Dallgas says. “I don’t have to get a guy to do it for me. I can put it together and it would hold a tank.”
Oetlinger adds, “Everything we do is simple and uncomplicated. When you take our parts and you put a bracket on and tighten it, it’s perfectly aligned. It locks and the bolt never comes out. It’s foolproof. Anybody can build anything.”
Amelia and the kids
The Leopard A5 main battle tank, Amelia, is named after Oetlinger’s eldest granddaughter and is frequently used to raise money for St. Jude Children’s Research Hospital. The idea came to Oetlinger when his youngest daughter, Liz, was diagnosed with cancer. Oetlinger holds an annual fundraiser, when he lets children with cancer climb on the tank and get behind the wheel. He intends to start his own foundation someday and plans to put the children’s names on the tank in the near future. Children in remission will get a star next to their names, he explains. Children who don’t win their battles with cancer “will have an angel next to theirs,” he says sadly. “3M is going to donate some tape that will stick on there forever.”
Staying up-to-date on new technologies and innovations is critical for a metalworking operation to retain its competitive advantage.
All photos courtesy PRAB Inc.
In metalworking operations, eight common problems sap profitability. The following steps show how to identify those issues and counteract them to maximize growth.
Tooling
Numerous metals are used in manufacturing. Based on their composition, these materials each machine differently. With superalloys, for example, end mills and inserts can burn up if not run properly.
Solution: Select the proper cutting tool for each material. Choosing the most appropriate cutting tool for the material being machined can save metalworking shops up to 15% on overall costs and improve machining productivity by 20%.
Cutting fluids
When not managed properly, cutting fluids are costly expenses. Metalworking fluids make up as much as 10% of the cost of a finished part, and large volumes of waste coolant are expensive to handle and haul away. Outdated, inefficient fluid recycling systems are also problematic.
Most applications use a water-miscible fluid, but oil-based coolants are the best option in precision machining applications. However, oil-based coolant residue can get inside machines and stain parts that need to be cleaned.
Solution: Recycling cutting fluids in-house is easy and can save metalworking operations thousands of dollars per year on new cutting fluid purchases. In-house fluid recycling systems provide machines with a consistent source of clean fluid in the proper concentration. Turnkey in-house fluid recycling systems:
Increase tool life up to 25%
Reduce haul-away costs up to 90%
Lower new coolant purchases up to 75%
If choosing oil-based coolant, consider switching to a synthetic coolant if the application isn’t in precision machining. Synthetic coolants have excellent cooling properties that provide long life in the sump, reducing maintenance and waste. Also, synthetic coolants don’t contain mineral oil so parts come off the machine cleaner, and as a result, don’t require washing and blow-off.
Using metal scrap processing equipment to reduce large piles of turnings to small chips typically yields higher prices from scrap dealers.
Setup, fixturing
Setup time and fixturing are often a major source of lost productivity in metalworking. It’s not uncommon for half of setup time to be wasted.
Solution: Milling and turning applications can use precise quick-change fixturing with high repeatability and accuracy by making some changes to setup and fixturing procedures. First, pursue quick-change tooling that allows operators to switch out tooling via a quick-release screw, significantly lowering setup time.
For fixturing, a workholding vise enables quick change-outs and minimizes downtime. Also, having multiple fixtures nearby and ready to use saves time, making part switches quick and easy when the machine cycle is complete.
Technology, innovation
Technology is constantly changing. Metalworking operations that don’t stay abreast of the latest innovations may lose their competitive advantage.
Solution: New developments pop up every day in machines and tooling that are better solutions for productivity. Using integrated tools to expand functionality is a way to drive efficiency. For example, using a tool for a 5-axis machine that drills, countersinks, and chamfers (instead of three separate tools) reduces the number of individual tools needed.
Metal removal rate
Two aspects of metalworking processes – lackluster metal removal rate (MRR) and manual processes – can significantly drive down production.
Solution: Changing metalworking processes to a higher MRR can positively impact an operation’s revenue. By using the correct toolpaths, depth of cuts, speed, carbide grades, and geometries, MRR can improve productivity.
Improving production in deburring can be done by changing from a manual process to a deburring wheel.
Programming
An improperly programmed machine can create unneeded operational steps, contributing to overtime and weaker production rates. Further, outdated control systems and programming cause many shop inefficiencies, such as low productivity and high maintenance costs.
Solution: Updating or replacing outdated control systems and/or hiring a reputable and knowledgeable automation company with industry specific experience for programming can significantly increase a shop’s efficiency. Updating machine programming or adding automation to current operations:
Reduces time to market
Improves quality
Enhances workplace safety
Increases output
Reduces labor
By remotely monitoring equipment, real-time data can be used to proactively adjust maintenance programs and production schedules. KMC Global Controls & Automation, based in Kalamazoo, Michigan, works with manufacturers to program their machines to reduce labor costs. Features such as maintenance reminders, interactive fault screen controls, user-friendly human-machine interface (HMI) screens, and cloud-based machine monitoring that identifies machine energy wasters that can be shut off when they are not being used, help operators get the most out of their metalworking equipment.
Energy waste
Operations running when they aren’t needed are a primary source of energy waste. Pumps, blowers, conveyor motors, blending, and vessel agitation are a few examples of equipment and processes that are left to run for long periods of time even when product or materials are not being produced. And large power consumers are not the only culprits – wasted energy from small motors will add up through time. For example, a 2hp motor will draw about 1,500W/hour. Running that motor for one day will use 36,000W (3.6kW) of energy.
Solution: Increase energy efficiency and lower costs in four ways:
Replace large motors with lower horsepower motors that match power to the application’s need
Employ speed- and load-altering devices to efficiently manage material delivery from one process to another
Operate motors when needed. Test motors during the initial start by running them briefly, then, pause the motors until product arrives
Use cloud-based machine monitoring systems that can identify machine energy wasters that could be shut off during periods of inactivity
Metal scrap management
Manually handling and/or failing to process metal scrap in-house before it is sent to the scrap dealer is a considerable source of inefficiency and lost revenue. Ineffectively processed metal scrap takes up valuable space and takes operators away from production. It also accrues high haul-away costs and yields reduced prices from scrap dealers.
Solution: Metal scrap processing equipment reduces large piles of turnings to small chips and separates the chips from fluid. Because the pile of metal scrap is reduced to small chips, a larger payload can be sent to the scrap dealer, who will typically offer a higher price per pound for dry chips.
Processing equipment that creates efficiencies or increases the value of metal scrap includes:
Scrap metal conveyance systems: Automate moving of scrap from the point of generation to processing equipment and then to recycling containers; conveyors significantly reduce operator interaction with scrap material and decrease forklift traffic, improving safety
Crushers, shredders: This equipment turns large piles of turnings into shovel-size pieces
Wringers/centrifuges: Separate chips from cutting fluids to create dry chips and collect spent fluid
Briquetters: Compress wet chips into dry compact pucks that are easy to re-melt, transport, and store
Conclusion
Metalworking operations can maximize profits by focusing on these eight problem areas. Prioritize the problems based on the ones that will produce the greatest cost savings and then systematically address the problems, one at a time.
About the author: Teresa Phillips is a senior marketing specialist at PRAB Inc. Kalamazoo, Michigan, and can be reached at 877.705.4931 or tphillips@prab.com.
