Despite the challenges, the removal of burrs from the production process is an absolute must for the high quality, precision parts required in aerospace. In many applications, cross-drilled holes act as conduits for fluids, lubricants and gases. Failing to remove burrs can cause blockage of these critical passages or create turbulence in the flow. Burrs can also lead to part misalignments, affect dimensional tolerances, and limit the overall efficiency of machined components.
“Getting rid of burrs is really important because if there is any loose material that gets dislodged when the product is in use, it can cause major problems,” says Anthony Scott, lead machinist at Orange Vise Company, a manufacturer of machine vices and quick change fixturing components used throughout aerospace.
Although there are many techniques for deburring internal passages at cross-holes, the majority require sending out parts or investing in equipment to complete the work in-house that can cost tens of thousands of dollars.
These options, which include thermal, abrasive flow, electrochemical, and high-pressure water, effectively remove excess material but they also build time into the manufacturing process and add to costs.
The more ideal option, however, for many aerospace operations is to integrate deburring into the automated process with a simple, effective crosshole deburring tool such as the Flex-Hone from Brush Research Manufacturing (BRM). By doing so, operators can speed up the manufacturing process and ensure uniform quality for precision parts.
According to Scott, flexible hones are ideal because it is a cost-effective solution to smooth edges and produce a blended radius for crosshole deburring.
“It is really about accessibility, because there aren’t many tools that can do this,” he says. “Whether it is internal grooves or multiple cross-holes, there is really no way to reach those areas with any other tool we have found.”
For engineers in aerospace manufacturing, the ball-style hone is a highly specialised abrasive tool that is instantly recognisable by its appearance.
Characterised by the small, abrasive globules that are permanently mounted to flexible filaments, the product is a flexible, low cost tool utilised for sophisticated surfacing, deburring and edge-blending.
Available in sizes ranging from very small diameter hones (4mm) to those up to 36 inches or more in diameter (a size appropriate for large engine cylinder bores), these deburring tools can be custom designed to the size, shape and abrasive grit to fit any application’s needs.
“I use the Flex-Hone quite a bit working in aerospace,” explains Ken Spaulding of Zodiac Engineering, a contract manufacturer in California. “We do a lot of parts that involve tubes with multiple crossholes and slots. Getting inside there to reach the burrs, particularly if the walls are thick, is extremely difficult.”
Spaulding particularly appreciates how the flexible hone’s abrasive globules each have independent suspension that is self-centring, self-aligning to the bore, and self-compensating for wear, all of which facilitate close-tolerance finishing work.
“The hone conforms to whatever you are working with, even if it’s irregular,” he says. “For example, if the back side of the part is not flat or not on consistent level plane in Z, the tool is flexible enough to still remove any burrs.”
For best results, the deburring tool is typically rotated into the main bore into which the crossholes break. After a few clockwise strokes, the tool is removed and the spindle reversed to rotate and stroke the flexible hone in a counter-clockwise direction for a few more strokes.
The forward and reverse rotation creates a symmetrical deburring pattern. Coolant should be used to keep metal cuttings and deburred metal in suspension.
According to Orange Vise’s Scott, although the Flex-Hone is often used with automated production equipment it can also be used for secondary deburring options offline as needed.
“The tool can be used in CNC machines and also with a cordless drill,” says Scott. “So, if you manage to deburr 90% of the holes in a machine, but have a few left you can’t access easily, you can use it with a handheld drill and maintain the uniformity in surface finish and process.”
Additional customisation from BRM in a variety of shapes is also possible to meet the requirements of non-traditional applications. This includes spherical-end configurations, stepped or multi-diameter configurations for double diameters and counter-bores, tapered or cone shapes, segmented shapes, or combining Flex-Hone globules with other filament materials.