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Deburring small, intricate parts is almost an art form, requiring fine motor skills, an understanding of critical part features and attention to detail. In some industries, like aerospace, deburring has been considered a trade and there have been people who have spent their entire careers at the burr bench.

Burrs left on parts can also injure workers. Most of the recordable injuries at our shop are lacerations to hands. Many of these injuries come from parts that were not properly deburred. Therefore, removing burrs before moving parts to the next operation is critical to maintaining a safe working environment. It is given considerable attention at our shop.

A&L Machine, a shop that serves primarily the energy sector and its often on-demand needs, is always on the lookout for ways to expedite critical processes. For Allen Dvoracek, A&L Machine president, this occasionally means travelling to suppliers for a firsthand look at how their products work.

Single- or multiple-point precision tool used to bring an existing hole within dimensional tolerance. The head attaches to a standard toolholder and a mechanism permits fine adjustments to be made to the head within a diameter range.

I experienced a situation with one of my employers where a newly hired employee was assigned to deburr an extremely expensive part. The “new guy” was not a machinist and had little experience around machine tools or machining. It was decided he should deburr until he completed his training as a machine operator.

When I worked for a manufacturer of power steering gears, an automated assembly machine was a continual source of part failures. The machine screwed ball joints into the steering unit and then verified that the parts had been assembled correctly. If a part went in farther than expected, the machine alerted us about a bad part.

Deburring is an option that is critical to quality. When its importance is minimized, serious quality and safety issues case arise. Removal of burrs should be considered during process design and should also be part of an organization’s training regimen. Learning to properly remove burrs should be considered as important as learning to use micrometers and calipers.

Machining grooves and shallow channels. Example: grooving ball-bearing raceways. Typically performed by tools that are capable of light cuts at high feed rates. Imparts high-quality finish.

Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.

After many rejections and many dollars spent investigating, we found that burrs left from machining were getting trapped between the parts, causing erroneous measurements. We eliminated the burrs, and the problem went away.

It is easy for machinists, programmers and engineers to get lost in the possibilities and forget about simple, but necessary, processes like deburring. Very few parts, if any, don’t need to be deburred. Nearly every machining process leaves some sort of burr that must be removed.

Machine designed to use a serrated-tooth blade to cut metal or other material. Comes in a wide variety of styles but takes one of four basic forms: hacksaw (a simple, rugged machine that uses a reciprocating motion to part metal or other material); cold or circular saw (powers a circular blade that cuts structural materials); bandsaw (runs an endless band; the two basic types are cutoff and contour band machines, which cut intricate contours and shapes); and abrasive cutoff saw (similar in appearance to the cold saw, but uses an abrasive disc that rotates at high speeds rather than a blade with serrated teeth).

In other situations, special-purpose deburring tools can be purchased. These tools are made with retractable blades that deburr both sides of a through-hole. Many machine solutions exist to support deburring in the machine tool.

Depending on the lay, a burr may not be detectable visually or by feel, making it easy to overlook. This is often the case with close-tolerance holes. When a burr is left on the edge of a hole, plugs and thread gages may not fit properly, resulting in rejected parts.

Runs endmills and arbor-mounted milling cutters. Features include a head with a spindle that drives the cutters; a column, knee and table that provide motion in the three Cartesian axes; and a base that supports the components and houses the cutting-fluid pump and reservoir. The work is mounted on the table and fed into the rotating cutter or endmill to accomplish the milling steps; vertical milling machines also feed endmills into the work by means of a spindle-mounted quill. Models range from small manual machines to big bed-type and duplex mills. All take one of three basic forms: vertical, horizontal or convertible horizontal/vertical. Vertical machines may be knee-type (the table is mounted on a knee that can be elevated) or bed-type (the table is securely supported and only moves horizontally). In general, horizontal machines are bigger and more powerful, while vertical machines are lighter but more versatile and easier to set up and operate.

Stringy portions of material formed on workpiece edges during machining. Often sharp. Can be removed with hand files, abrasive wheels or belts, wire wheels, abrasive-fiber brushes, waterjet equipment or other methods.

Deburring is almost always considered a secondary operation performed after machining, by hand and off the machine. A better option is to develop machining processes that eliminate the need to deburr off the machine.

I worked in an aerospace shop that made hydraulic components. The components had small orifices that could easily become blocked by burrs if they were to break free. Blockage of the orifices could result in a failure of an aircraft’s hydraulic systems—a potentially life-threatening event.

As Vacio had forecasted to Dvoracek, when subsequent batches of the part arrived for finishing, the print didn’t call for face grooving. It wasn’t a problem. The outside grooving insert was simply re-positioned to face the OD boss and reset to the boss diameter for rotationally symmetric rouging (RSS). Two inserts performing the same cut doubled the feed rate, reducing production costs in additional ways.

When he returned home, Dvoracek reached out to BIG KAISER, the exclusive dealer of KAISER tooling, and explained what he saw on his trip. When Gerard Vacio, BIG KAISER’s regional sales and support engineer, visited A&L, Dvoracek showed him how they were using the combination of a small-diameter, long-projection end mill and a grooving tool for the job. The end mill machined an OD boss and the inside wall of a face groove at the bottom of the boss. The grooving tool then cut the remaining face groove geometry. Dvoracek explained to Vacio that in addition to the time involved with resetting depth offsets to blend the end mill and grooving tool, the end mill was prone to breakage.

Burrs can cause issues in downstream machining processes by preventing proper location of the part in a fixture or result in erroneous measurements when a burr interferes with a metrology device.

“This tooling has proven much more durable and efficient than the original end mill setup,” Dvoracek added. “We’ve run more than 10,000 parts and have never had to change an insert. And we’ve only changed the offset once, and that was only because we originally set it on the high side of the limit and decided to put it on the low side.”

Sometimes, burrs can be eliminated by programming a machine’s CNC to add a deburring operation while the part is on the machine. Examples include programming a chamfering tool to take a pass along the edge of a hole, milling a chamfer on a sharp edge and programming a radius on the edge of a part.

Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

While on the tour, Dvoracek saw a demonstration of SW Twin Cutter heads, but the KAISER representative made a point to show that this body could facilitate much more than just common boring jobs. He demonstrated face grooving, balanced- and stepped-boring, and even compatibility with insert holders for back boring and chamfering. That got Dvoracek thinking about a challenging feature that A&L is often called on to produce that requires two different types of tools, and makes for long, complex cycles.

Just in time (JIT) manufacturing, by nature, increases setups and shrinks batch sizes. This puts shops in a bind, because more setups and smaller batches are typically less profitable; but saying "no" to work can be even more painful. The burden to search out creative ways to reduce cycle and setup time in order to realize a profit falls to the shops that commonly perform JIT work and on the shops that can’t afford to turn it down when the opportunity arises.

In the not-so-distant past, young tool and die apprentices were trained to deburr parts for journeyman tool and die makers. It was a practical activity that taught patience and hand skills.

Enlarging a hole that already has been drilled or cored. Generally, it is an operation of truing the previously drilled hole with a single-point, lathe-type tool. Boring is essentially internal turning, in that usually a single-point cutting tool forms the internal shape. Some tools are available with two cutting edges to balance cutting forces.

So confident it was a match, Vacio offered a no-risk trial of the boring head and Dvoracek agreed. He took the print specifications to the BIG KAISER engineering team and was able to quickly turnaround a ready-to-run solution. The head was configured with two insert holders. The inside grooving tool would machine the boss. Once the face of the part was reached, the outside grooving tool finished the outside of the groove.

A host of methods exist for deburring parts, such as this motorized brush from the Deburring Applications Laboratory at Matrix Design LLC. Image courtesy of Alan Richter.

One such trip took Dvoracek to Europe to visit a machine tool builder. But, it was a side trip to Switzerland that proved most fruitful. Dvoracek swung through Rǖmlang, Switzerland, and KAISER Precision Tooling’s headquarters in search of insight into how Swiss toolmakers are addressing high-cost JIT production.

Philosophy based on identifying, then removing, impediments to productivity. Applies to machining processes, inventory control, rejects, changeover time and other elements affecting production.

Deburring is an important skill; it should be given attention because removal of burrs is critical to safety and quality.

Vacio agreed with Dvoracek’s initial instinct, that the SW Twin Cutter could improve the process. He also explained that the head’s versatility, whether running as a dedicated tool or only as needed for one of its varying capabilities, fit right in with the JIT work typical at A&L.

Matt Tegelman is the Kaiser product manager for BIG Kaiser Precision Tooling Inc., Hoffman Estates, Ill. For more information about the company’s boring tools and other products, call (888) TOOL-PRO or visit www.bigkaiser.com.

Science of measurement; the principles on which precision machining, quality control and inspection are based. See precision machining, measurement.

Deburring is often performed by hand with simple tools, giving some the impression that it is a task that does not add value. This attitude and the desire to cut costs have created an environment that minimizes the importance of developing and cultivating effective deburring processes, as well as training on the proper techniques.

It seems that many engineers, operations leaders and machinists no longer value the skills needed to properly remove burrs. Only after a part fails do they begin to emphasize deburring.

Enlarging a hole that already has been drilled or cored. Generally, it is an operation of truing the previously drilled hole with a single-point, lathe-type tool. Boring is essentially internal turning, in that usually a single-point cutting tool forms the internal shape. Some tools are available with two cutting edges to balance cutting forces.

Lots of attention is given to improving machining processes. New productivity-boosting developments for drills, mills, boring tools and turning tools abound. Advanced milling and turning techniques are always under development, and software companies regularly announce new features that promise to slash cycle times. Machine tool builders and CNC manufacturers are creating ever-faster machines and controls capable of keeping pace with advanced machining techniques.

“The results were immediate and undeniable, settling in at application metrics of 590sf and .002ipr,” Dvoracek said. “We’re getting better parts off the machine sooner, allowing us to get to the next job ahead of schedule. Reducing the cycle time by 22 seconds per part will save approximately 40 machine hours a year on this job alone. That’s 40 extra hours of machine utilization that we didn’t [previously] have because of a fairly simple tooling solution.”

He was given a die grinder, a box full of burr bits and 5 minutes of instruction and then was set free to remove burrs from a $250,000 component. In his zeal to do an excellent job, he removed far more material than was required and altered the geometry of the part. We were able to salvage the part, but it severely interrupted the schedule, almost delaying shipment to the customer.

Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.