Metal Additive Manufacturing technology developer Optomec, Inc., Albuquerque, New Mexico, USA, has published a white paper which presents the business case for automated laser cladding in aviation component repair. The paper compares manual and automated processes for aviation Maintenance Repair and Overhaul (MRO) and analyses how companies can make the best investments.
Referring to a study by Grandview Research, Optomec notes that the global aircraft MRO market was valued at USD $75.71 billion in 2018 and is expected to grow at a CAGR of 4.7% from 2019–2025. Whether carried out by OEMs or outsourced to aerospace Engineering Service Providers (ESPs), a significant amount of money is spent every year on MRO activities to ensure safety and airworthiness compliance.
“The grounding of the 737 Boeing Max and growing pressure on capacity means that older aircraft and aircraft parts are in service longer in the short to mid-term. Industry analysts, therefore, are calling for a steep increase in engine MRO demand over the next ten years, putting additional pressure on service providers for higher quality and improved throughput and underscoring the importance of MRO,” Optomec states.
“With so much at stake, it is surprising to see that so many OEMS and ESPs are still primarily relying on highly-skilled manual labour for welding engine components when automated laser cladding has shown to provide higher yields and increased quality. To understand why this is, we set out to take a closer look at what it takes for companies to adopt automated laser cladding for MRO today.”
Optomec’s LENS systems use Directed Energy Deposition (DED) Additive Manufacturing technology and are said to be able to additively manufacture full parts at a fraction of the time and cost of systems based on Powder Bed Fusion, as well as adding material to existing parts for repair and coating applications to extend the use life of components. In November 2019, the company reported that it had integrated the Huffman AutoCLAD vision system with its LENS machines. AutoCLAD is a vision and software system that generates a custom toolpath for each part prior to processing.
Proprietary to Huffman, the AutoCLAD system is used extensively in production by major manufacturers and servicers of aircraft engines and industrial gas turbines to restore worn or damaged components. Adding this capability to the LENS brand of solutions was expected to enable customers to use automated DED for the repair of reactive metals like titanium in a controlled, argon atmosphere.
To ensure that its report was fair and impartial data, Optomec commissioned Terry VanderWert PE, a forty-year veteran in the laser process industry, to conduct an independent study and objective investigation into current MRO practices and challenges within the aviation industry. According to the company, its goal was to learn how service centres can take advantage of laser cladding and what impact it would have on its business.
While there is already a strong business case for repair, much of it is still done manually. The cost of repairing high-value gas turbine engine (GTE) components is around 70% lower than that of purchasing new ones. However, the high difference in cost between new and repaired components has fostered tolerance for inefficient, labour-intensive manual repair processes, explains Optomec. Among those manual processes used, tungsten inert gas (TIG) welding, also known as gas tungsten arc welding (GTAW), is the most widely used for repair.
While TIG welding is the most widely used manual process for the repair of GTE components today, automated laser cladding is becoming an increasingly popular alternative. In laser cladding, a metal powder, or sometimes wire, feedstock is delivered into the focal point of a high-power laser beam. The resulting molten metal pool is moved under computer control as the feedstock additively rebuilds an existing component or additively manufactures a new part, layer by layer.
For GTE components, material is added to replace sections worn or damaged during operation of the engine. Compared to manual welding-based processes, automated laser cladding offers important benefits for GTE component repair, including less overbuild due to the focused laser beam, less impact of the repair process on the part, and improved performance of hardfacing alloy deposits.
An informal survey of users of automated laser cladding machines, undertaken as part of the study, indicated that ‘Repair cost’ and ‘Financial return’ are the top factors in their selection of GTE repair equipment and processes. Automated laser cladding has the potential to significantly reduce repair costs and, Optomec states, the investment in this technology can also provide an attractive financial return. VanderWert’s research shows how automated laser cladding can deliver an ROI of 184%, with a payback of 1.7 years. This was demonstrated through analysis of the business case for replacing manual TIG welding with automated laser cladding for repair of the Z-form of a low-pressure turbine (LPT) blade.
Automated laser cladding represents a significant investment. In addition to laying out the business case, the paper highlights the top five factors having the greatest impact on the financial return of automated laser cladding.
This paper hopes to assist MRO facilities in creating a business case analysis to ensure investment in the right technology and equipment. In addition to the financial return and the key lessons learned, Optomec states, the benefits of automated repair processes include other less tangible measures such as: reduced turnaround time on repairs, reduced scrap, superior metallurgy and the potential for longer life of the repaired parts, faster order fulfilment, and greater machine utilisation.