As materials science and manufacturing technology continue to advance by leaps and bounds, so too does product design. As a result, across various industries such as aerospace and automotive, more complex parts are being developed for enhanced performance. In aerospace, for example, passenger jets are being constructed with contoured and seamless parts using advanced metals and metal alloys chosen for their unique properties.
According to Boeing, advanced aluminum alloys are used in the wing and fuselage skins of airplanes such as the Boeing 777 for their strength, ability to form complex shapes, and relatively low weight. The contoured shape of the 777 wing allows for less drag, while raked tips offer increased aerodynamic efficiency. With similar performance goals, the automotive industry is using lighter and stronger metals that allow them to manufacture safer vehicles that also provide a high level of fuel economy. Automotive manufacturers are using an increasing amount of aluminum and aluminum alloys in contoured external body panels for durability and lighter weight. The new 2014 BMW i8, for example, features a lightweight aluminum frame contoured for reduced drag coefficient and increased speed.
In addition to performance benefits including increased lightweight and durability, these parts are having a cascade effect across common industrial practices, including maintenance, repair, and overhaul (MRO). Take surface finishing, for example, a process that uses abrasives to change or improve the surface of a manufactured product to achieve a desired property. Surface conditioning discs are often used to perform tasks such as removing marks, burrs, and other imperfections that can occur during initial machining. Surface conditioning discs are also used to enhance performance, such as increased adhesion, solderability, and durability, as well as corrosion and chemical resistance.
However, contoured parts make it more difficult to reach all surfaces, and require additional products, tools, and process steps to complete a particular job. This complexity can lead to overall reduction of productivity and may require additional labor, overhead, and consumables costs. The good news is that surface finishing technology has caught up with advanced material and design, offering next-generation abrasives products that enable MRO shops to reach all contoured surfaces.
Game-changer
Like trying to fit a square peg into a round hole, contoured surfaces introduce what are referred to as “dead zones,” or areas that conventional surface conditioning materials simply cannot reach due to their inherent design limitations (See: Figure 1). In order to finish a job properly, an operator then needs to insert another process step using additional surface conditioning products. This results in longer cycle-time, as well as increased labor and material costs. In these instances, next-generation, non-woven abrasives with three-dimensional (3-D) unified materials become a game-changer; allowing operators to reach all surfaces using one product and process.
How does it work? Materials science expertise and innovation in abrasive product design have combined to yield enhanced surface conditioning discs featuring a non-woven substrate impregnated with an aluminum oxide (A/O) aggregate grain, non-smear resin technology and the 3-D construction vital to getting into hard-to-reach places (See Figure 2). “Three-dimensional” means that all three faces or sides of a surface conditioning disc can be used during grinding to achieve results. An operator utilizing 3-D unified material can put all three faces of the product to work, accomplishing the task faster using only one product throughout.
In addition to 3-D grinding, these advanced non-woven abrasive products provide various additional performance benefits. With unique non-smear resin technology, MRO jobs can be accomplished without leaving behind any residue that requires a separate product and process step to clean. An open web structure also resists loading on relatively soft materials, such as aluminum – an important benefit when you consider the increased use of aluminum and aluminum alloys in aerospace and automotive product design.
These breakthroughs provide upward of four times the performance in cut rate and surface coverage. Comparisons to conventional surface conditioning materials show a longer product lifecycle, consistent cut rate, and superior finish from beginning to end (See: Chart 1). This allows MRO shops to reduce or eliminate steps in a surface improvement process for increased throughput without requiring additional resources.
Reduced labor costs
So how much can MRO shops actually save using next-generation abrasives? To provide a baseline for comparison, assume that an average MRO operation spends approximately $10K a year on surface conditioning materials (aka “consumables”), and that labor and overhead is set at a $50 hourly rate.
Using a right angle grinder on a piece of 1018 carbon steel 2” x 2” with heavy scale and corrosion, the operator uses as many conventional and next-generation non-woven quick change discs to prep the piece of metal. It takes the operator an average of 15 seconds to change out spent discs for new ones, using as many discs as needed to complete the task.
Field tests show that the next-generation material performs the work much faster with fewer disc changes, requiring significantly less labor and overhead. Extremely durable, the overall abrasive costs are also lower, as the operator does not need to change discs as often, performing more work with fewer consumables, reducing total costs by more than 50 percent, or approximately $20,000 in annual cost savings (See: Chart 2).
Recent advances in aerospace and automotive materials and design have resulted in seamless contoured parts providing much sought-after performance enhancements such as increased speed and better fuel economy. However, these contoured parts have proven difficult during MRO applications using conventional surface conditioning products finish. The irregular shapes of many complex parts create “dead zones” that conventional surface conditioning products simply cannot reach, requiring additional time, labor, and material costs in order to complete.
Next-generation non-woven surface conditioning discs with 3-D construction can conform to irregular shapes, performing in hard-to-reach places. Using three faces instead of only one, operators can finish a contoured piece in less time; requiring far fewer resources. In addition, these innovative surface conditioning products feature non-smear resin technology, eliminating yet another process step – removing any residue left behind. Long-lasting, high-performance non-woven abrasives can reduce overall time, labor, and material requirements, increasing the productivity of any MRO operation, as well as their bottom line.
Paul Krupa is senior product manager, Technical Non-Woven Abrasives at Saint-Gobain Abrasives, a leading global manufacturer and supplier of performance engineered abrasives. Krupa is an abrasives industry expert with extensive product experience in non-woven materials, conventional light- and heavy-weight papers, abrasive grains and resins, and sanding sponges. Norton is a brand of Saint-Gobain. For more information visit www.nortonabrasives.com and www.saint-gobain-northamerica.com.
Figure 1: Conventional surface conditioning discs cannot conform to irregular surfaces, leaving “dead zones” unfinished and requiring additional process steps to complete.
Figure 2: With 3-D construction, all three faces of the next-generation surface conditioning discs can be used to reach “dead zones” in one step.
Chart 1: Next generation abrasives technology generates consistent cut rates and RA Values from beginning to the end of useful life lasting up to 4X longer than conventional aluminum oxide SCM products.
Chart 2: Next-generation abrasives maximize efficiency and cost savings with faster performance, reduced labor, overhead, and cycle time, reducing total costs by more than $20K annually.
