Layoffs, Social Distancing May Drive Machine
Shops to Automate Finishing Operations
Secondary finishing operations are able to be automated by mounting abrasive tools into the CNC machine toolholder without taking
the part offline.
By Jeff Elliot, Brush Research Manufacturing
Whether driven by the reduction of in-shop ersonnel due to layoffs or to maintain so- cial distancing guidelines into the future, many machine shops will likely be re-evalu-ating ways to eliminate labor-intensive manual operations ifthey can be automated instead.
At the top of this list are secondary finishing operationsthat are conducted offline to remove excess material on partsfabrication. Today, much of this work is still performed byhand using oscillating tools, grinders, files, abrasive handpads, and wire brushes.
Fortunately, secondary operations such as honing andpolishing can be accomplished using a variety of abrasivetools mounted in the CNC machine toolholder and carouselwithout taking the part offline. The better news is that inaddition to reducing in-shop labor requirements, completing surface finishing simultaneously in the same operationas machining also speeds production of high-volume parts.
“When the economy begins to recover in the coming
months, machine shops are going to be driven to continue
to find a way to increase efficiency and one way is through
automating offline processes,” says Tim Urano, Quality Man-
ager at Wolfram Manufacturing, a company that machines
metal parts with complex geometries on 4 and 5-axis ma-
chines. “So, any time we can incorporate secondary opera-
tions right into the machining process, we save time, money,
and also reduce our in-house labor requirements.”
According to Urano, Wolfram Manufacturing produces
a variety of complex parts with through-holes and so has
automated the cross-hole deburring process. Removal of
burrs and sharp edges in cross-drilled holes and other dif-
ficult-to-access areas such as undercuts, grooves, slots, or
internal holes is critical. Failing to remove burrs can cause
blockages or create turbulence in the flow of fluids, lubricants,
and gases through critical passages.
To do this, the machine shop incorporates Flex-Hones in
a variety of sizes in its tool carousels. The Flex-Hone, from
Los Angeles-based Brush Research Manufacturing (BRM), is
characterized by the small, abrasive globules that are perma-
nently mounted to flexible filaments, the product is a flexible,
low-cost tool used for sophisticated surfacing, deburring, and
edge-blending. The hones are available in a variety of abrasive
types, sizes, and grit selections.
Urano says the hones have been installed for eight yearsand are used daily, usually several times an hour, on some ofthe shop’s highest volume parts.
“On a given part, we might deploy two to three different
size hones, depending on the number of cross port intersec-
tions and different hole sizes,” explains Urano. “It is very easy
to put a Flex-Hone in a toolholder, give it a simple toolpath
cycle, and let it run.”
“Automating cross-hole deburring eliminates a lot of of-
fline work,” adds Urano. “The parts we make are complex
and have a lot of intersecting holes, so relying on a person
to repeat that process every single time to the quality level
required will always introduce some potential inconsistency
there. However, if you just let the CNC machine do its work,
it will achieve more consistent results.”
The same tool can also be used to create a high surface fin-
ish on the internal bores of a valve assembly actuator that the
shop manufactures. As part of a multi-step process, Wolfram
Manufacturing uses a coarse grit Flex-Hone to smooth out
any irregularities left during drilling and finishes the bore
with a fine-grit hone.
In addition to honing, there are a variety of other finishingoperations that can be automated using abrasive nylon brushes in a disc, wheel, cup, and end brush designs.
When an application calls for surface finishing, cleaning,polishing, deburring, edge blending, or removal of paint,rust, or other contamination, these types of tools are theideal solutions. In some cases, these multi-purpose toolscan even eliminate machining operations traditionally performed by chamfer tools and face mills.
For JR Precision & Welding, a machine shop in Houston, Texas, the issue of removing large burrs from machinedholes in an extremely hard 4140 steel alloy part used as amuzzle brake for firearms was proving a challenge. To remove these burrs, the company decided to automate theprocess using a 3” diameter abrasive nylon wheel brush withsilicon carbide filaments from Brush Research.
Muzzle brakes are devices connected to the barrel of a rifle orpistol to help control recoil and the rising of the barrel that normally occurs after firing. The parts use slots, vents, holes, andbaffles to redirect a portion of propellant gases to counter recoil and unwanted muzzle rise. Where and how these holes areplaced has a tremendous effect on recoil and muzzle movement.
When machining these holes, however, large burrs wereforming at the oval-shaped gas ports. The cylinder wasmade of 4140 steel, which is a 1% chromium-molybdenumsteel alloy that is generally hardened and tempered to a tensile strength of 850 to 1,000 Mpa.
According to says James Mawazeb, Director of operationsand lead engineer at JR Precision & Welding, the abrasivenylon fit well into the shop’s 5-axis machine magazine holder and existing toolholders.
“In addition to removing the large burrs, the wheelbrush also provided a soft edge break to the ports so theywere not razor-sharp without affecting the surface finish,”says Mawazeb.
Even miniaturized brushes as small as 0.014” in abrasivenylon, carbon steel, stainless steel, and diamond abrasivefilaments can be used with adaptors on CNC equipment.These tools are ideal for deburring internal and externalthreads. Internal threads often have micro burrs at hole entrances and exits, on thread crests, and on most slot edges.External threads on bolts, screws and spindles have similarissues, particularly at the start of the thread.
Regardless of the type of finishing operation or abrasivetool used, automating secondary processes is one-way machine shops can reduce unnecessary in-shop labor to replace lost personnel and to maintain social distancing intothe future.
JEFF ELLIOTT is a Torrance, Calif.-based technical writer. Hehas researched and written about industrial technologies andissues for the past 15 years.
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Brush Research Manufacturing
Brush Research Manufacturing