Bridged threads - Bridged threads exist when the valley between the threads breaks, through into an underlying hole. These can only be addressed Burlytically from underneath. Introduce electrolyte from behind the thread with a cathodic, insulated metal tube to dissolve the thread.
Cutoff burr - This is usually a heavy and caused by a cutoff saw. It is particularly ragged and physically dangerous. Cutoff burrs are easily removed Burlytically with ordinary procedures.
Drill cap - As a drill tip breaks through a metals surface, the combination of speed, tool dullness and feed may cause a cone shaped disk of metal (the same diameter as the drilled hole) to breakout and hang from the hole’s edge with a single thread of metal.
Drill caps can be removed by the Burlytic® Process. Unfortunately, because of their shape, they take more time to remove than other burrs. This raises the possibility of over-processing nearby features. Drill caps are usually easier to remove manually if they are readily accessible. The residual burr is then easily removed Burlytically.
Entry/exit burr - Burr caused by drill bit entry or exit.
Feather burr - A feather burr is essentially fine filaments of metal on edges. They are usually caused by final surface grinding which heats the metal locally and spins these filaments out tangent to the grinding wheel. Feathers should not be confused with burrs kicked up by ordinary grinding.
Feather burrs are very easily removed with the Burlytic® Process.
Flag burr - A thin “flag” of metal attached to the parent feature continuously along one edge is called a flag burr. The burr resembles a flag or pennant. It is most prevalent at the end of milled slots. If the cutter breaks into an internal cavity, this kind of burr can be tenacious and difficult to remove.
Flag burrs require a little more time than hanging burrs to remove.
Flash, casting - Casting flash is not technically a burr. Flash is a thin “fin” or sliver of metal caused by a slight gap between mold components. The casting metal runs into these gaps and sometimes completely closes a hole in the part.
Thin flash on zinc castings is the easiest to remove. Thicker flash may be “identified” by the Process as a feature and not get worked strongly. Holes closed by flash may need to be broken through manually before Burlytic® deburring.
Hanging burr - A burr that is in immediate danger of separating from its parent feature as a result of only a slight jolt or vibration. This is the kind of burr that creates catastrophic failures in precision fitting parts and hydraulic systems.
Hanging burrs break off from the parent part with a gentle mechanical movement or an air or hydraulic blast.
Hanging burrs are easily removed Burlytically.
Hangnail burr - A burr created by volcano mouth that is subsequently swept back into the hole by a facing operation outside the hole. The burr ends up as a crescent of metal attached inside the mouth of the hole along its edge. It looks like a hangnail.
This kind of burr is best removed by re-drilling or punching a drill rod through the hole and bending the burr out where it can be more easily addressed. Countersinking could also handle this burr. This kind of burr is a candidate for production step re-sequencing in order to drill the hole after the facing step.
Hangnail burrs are difficult to remove Burlytically if only an external cathode is used. Even is masking is provided around the hole, severe metal removal will be the only way to remove the burr. Arranging for an electrode to dip below the hole mouth, however, will dissolve this burr quiet easily.
Klingons(Cling-ons) - Any burr which seems easy to remove but is still attached after a deburring attempt. It is usually in a hard to reach position. Sometimes refers to any hanging burr left over after inadequate manual deburring.
Loose burr - A sliver or chip of loose metal. It may have started life as a hanging burr and then broke away from its parent feature to become loose or it may have been just a loose manufacturing chip that lodged in an internal feature and subsequently fell out. It can usually be shaken our or flushed away.
Loose burrs tend to be flushed out and away from the part by the Burlytic® process. They get trapped in the system filter for later removal.
Pipe cutter burrs - These are sharp edges which are only found on the inside of a pipe which has been cut with circular cutting blades. The blades forcibly displace the pipe walls toward the inside of the pipe just before breaking through. This creates a knife-like edge on the I.D.
Pipe cutter burrs are easily removed without special auxiliary cathodes by simply dunking the end into the tank. The field will reach into the end of the pipe and remove the sharp internally swelled metal.
Plowed metal - A relative of the rolled burr, plowed metal looks just like the picture in your mind of how furrows look in a plowed field. Instead of the dirt falling back to earth, imagine the dirt suspended in the air after being plowed up.
The same comments about rolled burrs apply to plowed metal.
Punch or shearing burr - This burr consists of metal that has been seriously displaced as a result of shearing action. The metal is forcibly displaced in order to cut it and some of the metal gets smeared as the shearing cutters pass by one another.
Punch or shearing burrs are easily addressed with the Burlytic® Process with ordinary techniques.
Recast - Recast is a think layer of slag or re-solidified metal that poorly adheres to the surface after EDM machining or laser cutting. Recast is not a burr in the technical sense but can cause similar problems. Removing recast improves fatigue strength.
Recast can usually be removed using the Burlytic® Process.
Rolled burr - This is by far the toughest kind of burr to remove. It is essentially caused by an adverse combination of tool feed, speed and or sharpness. It looks much like the curl formed if you scraped a 90-degree-oriented knife along the top of a stick of butter. This roll then will tuck under itself to create a cylinder of metal. It really isn’t a burr in the normal sense of proper machining. It is more like an extraordinarily created part feature.
Rolled burrs will be “seen” by the Burlytic® Process as a rounded feature which will remain virtually untouched by the process, even if special masking and auxiliary cathodes are provided. If you encounter a burr of this nature, work with the machinist to improve the process. Sharper tools, faster speed and/or slower feed will help.
Swelled metal - Sometimes called “raised metal”. While swelled metal might not be an official burr, it can be a problem in close fitting parts. It is caused by forcibly displacing metal to the sides as s cutter enters the surface. Drills plunged into soft metals will cause swelled metal around the hole entrance.
Swelled metal can be removed or reduced with many of the same techniques that are used to remove burrs.
Volcano mouth - Drill entry or exit point which is characterized by a sharp, raised metal rim looking much like the rim of a volcano. Dull drill bits cause volcano mouths.
Wild threads - When machining around threads, sometimes a thread is left with little or no support at its root. Without support, the thread can bend away from the part. This is termed a wild thread. Sometimes the part can be threaded after the adjacent machine work which would eliminate the problem.
External wild threads can be processed Burlytically as long as they have not been bent away from the part body. Bending will cause a little nub which requires a substantially longer processing time.
Internal wild threads will need the intact threads protected with an insulative shield.
Wire edge - When a knife edge is ground from either side, a wire edge burr is produced along the cutting surface. Under a strong microscope the burr will take on the appearance of a microscopic length of wire running along the cutting edge (on soft metals).
In the production of razors and fine knives, the edges are stropped with a continuous leather belt which removes this burr. If the burr is not removed, it will bend and break off during us. The broken burr will usually take a tiny section of the cutting edge along with it, causing a jagged area. If the burr is larger, it will fold over while pulling the cutting edge out of alignment, or, if you are lucky, it will simply present a curled edge which acts as if the edge were dulled at that spot.
Wire edges are easily removed with the Burlytic® Process. The part must be run at low voltage and for only a few seconds with large (8-10” cathode spacing).