The biggest obstacle in quality control for aerospace manufacturing has been programming from a computer-aided design (CAD) model versus using automated tools to erase ambiguity to decipher tolerancing, features, and characteristics.
Using product manufacturing information (PMI) in the model is where design intent is derived. However, an overabundance of suppliers still don’t use a CAD model or CAD with PMI to program inspection tools, leaving the door open for mistyping and misinterpretation.
The PMI barrier
One of the greatest reasons more aerospace manufacturers haven’t embraced PMI is the relatively high cost related to updating or purchasing software to automate the process. CAD is an open architecture in a public domain, but it must rely on the original CAD company for export, and different CAD companies make their own CAD creation software.
The lack of PMI adoption contributes to continued embracing of CAD models for measurement equipment programming, despite entities such as the National Institute of Standards and Technology (NIST) working to overcome adoption hurdles. Aerospace suppliers must decide what tools will be used, how data will be transferred into the system, and how needed features and characteristics will be supported.
A secondary issue is a lack of top software leaders for creation of CAD model design in the U.S. Leaders are reluctant to allow their programs to be exported in a common neutral file compatible in other forms of measurement such as EMF or laser systems. Instead, they prefer to sell their CAD software, which is the norm in the aerospace industry.
The software might be harder to learn but it’s what most aerospace engineers understand and are familiar with. Large aerospace companies typically use software from leading providers – the first ones to come out with most features aerospace manufacturing required.
Overcoming challenges, embrace digital
To mitigate quality inconsistencies for aerospace given the multiple providers, measuring equipment developers take the different software offerings into account so they can support all versions.
Certain tolerance characteristics are supported or unsupported in the CAD model but not the PMI information. Certain software can’t read a graphical picture. Data in the PMI file needs to be manually added using other software tools, leading to a significant inconsistency in what’s supported on the PMI part of the equation.
While tolerancing characteristic information in a CAD model isn’t always required, data is needed for inspection. If you were to ask CAD vendors and measuring companies using their software how much inspection data they support, you might find it’s 50% to 60%.
To close the data support gap, the American National Standards Institute (ANSI) committee is considering revamping the geometric dimensioning and tolerancing (GD&T) system to eliminate 80% of current tolerances in favor of profile and position tolerancing for everything. This recommendation is part of a larger debate with serious development implications in terms of scrapping composite tolerancing and replacing it with surface profile.
The biggest problem with how GD&T tolerances are set up is interpretation by different engineers and failure to correctly indicate them on a print, since error checking around GD&T wasn’t included when CAD tools were built.
If you’re a major aerospace company creating a new aircraft, you want electronic data to rely on for each part and give to anybody who’ll be manufacturing components or entire assemblies. If you’re a manufacturer who tells an aerospace company you don’t work with CAD models and need a blueprint, you won’t be hired. Digital is the future.
Where the shift begins
It starts with aerospace companies spending money on CAD systems, developing parts, then measuring equipment to check part accuracy. Why wouldn’t they want to have the same tool for inspection as for everything else? The CAD model with the correct information for inspection can generate an inspection program automatically.
With today’s digital technology, what previously required three hours using a paper print could take a minute or less – open a model, read the information, determine how to measure it with the configured machine, where to take points, what order to make it as fast as possible, identify all the datums needed, then with the single click of a button generate the part program. That’s time and money savings, a significant return on investment (ROI), and a significant reduction in errors.
Modern technology dictates measurement strategy based on a feature size. The diameter could be 0.5", and you can set up a rule for anything 0.5" or smaller ? or dictate whether you want 37 points on everything or the number that suits your needs. The ability to set up rules based on the feature goes a long way toward improving consistency and accuracy. This is important for streamlining the process, given companies look closely at how much time they’re spending on coordinate measuring machine (CMM) part programming versus measuring. Machine tools were programmed at the machine but with the advent of computer-aided manufacturing (CAM) software, this process became a digital plan uploaded to the machine tool. This increased production time, whereas inspection equipment programming can be more efficiently planned, accurate, and consistent using a digital CAD model with PMI. This will reap the same rewards as a machine tool, with less time programming parts on the CMM and more parts being inspected.
Digital technology for aerospace industry
There are ultimately three key takeaways to highlight in measurement automation in the aerospace industry:
- Cost savings: Automation streamlines and accelerates the process, while eliminating human error that can lead to costly scrap and delays.
- Commonality: Automated programs are created the same way so the same set of tools can be used to determine how to measure a part. There’s no operator influence on development of the program.
- Cloud-based repository: Digital tools reduce the data storage footprint and allow easy review and access of measurement data.
In the aerospace industry, accuracy is critical. Parts produced impact safety and people’s lives. While there are significant checks and balances companies perform to catch anomalies ? especially around the creation of prototype parts ? automation can add another layer of assurance and remove the possibility that a mistyped input for diameter or tolerance by a CMM operator could lead to issues down the line.
NEWS AND PRODUCTS
Robot-ready frameless servo motors
Frameless servo motors simplify the design of collaborative, aerospace, defense, and other robots while delivering optimal performance in a lighter, more compact package.
Offering high-performance torque in a compact electromagnetics package, next-generation motors enable robots with lower joint weight, higher load-carrying capacity, improved energy efficiency, lower thermal rise, and faster, smoother movements.
While frameless torque motors typically deliver their best performance at low speeds but suffer at higher speeds, this limitation is removed through advanced windings and materials for consistent power, torque, and efficiency across a wide speed range.
The motors remove the sizing limitation engineers face when using strain wave gearing (harmonic gearing). The motor series are sized for available strain wave systems, eliminating the need for extensive customizations.
The motors are available in seven frame sizes with three stack lengths each – a total of 21 standard motors that can be integrated directly into robotic joints and similar embedded equipment. Typical applications are cobots in the 3kg to 15kg range, powered at 48VDC and below. The motors are designed to perform at high speeds without exceeding the 80°C limit typically needed to safeguard humans working in proximity to cobots and to prevent degradation of grease and electronic components. They’re available with thermal sensor options to meet the requirements of drives and control systems used in the cobot market.
Grip Pallet system
The addition of five Grip Pallets and three new inserts for 52mm and 96mm quick-change receiver systems enables more applications using existing fixturing systems in machining centers. The Grip Pallets are designed to simplify how parts are loaded, reduce scrap, and increase spindle up-time.
Available in 150mm, 225mm, and 300mm square pallets, they offer quick-change and adhesive workholding of complex and hard-to-hold parts for EDM, grinding, inspection, laser, and milling operations, providing increased machining access on five to six surfaces using standardized fixturing systems already in place.
The grippers are inserted into external inserts, designed specifically for the pallets, and the external inserts are available for small, medium, and large grippers. The inserts allow for simple installation of the grippers at the required height for maximum holding power.
The 150mm square pallet is available in aluminum and steel with a 52mm pattern for a quick-change receiver that will hold up to nine grippers. The 225mm square pallet is available in aluminum and steel with a 96mm pattern for a quick-change receiver that will hold up to 21 grippers. The 300mm square pallet is available in aluminum with a 96mm pattern for a quick-change receiver that will hold up to 33 grippers.
Each grip pallet includes two handles with multiple color choices and four spacers with a 25.4mm standoff allowing for the recommended nominal of 1 mm joint thickness between gripper and part. Clamp studs are optional and available for both 52mm and 96mm patterns for 5th axis, Jergens, Lang, and Mate systems.