![Metal burr](https://upload.wikimedia.org/wikipedia/commons/8/8b/Metal_burr.jpg)
A burr is a raised edge or small piece of material that remains attached to a workpiece after a modification process.
It is usually an unwanted piece of material and is removed with a deburring tool in a process called 'deburring'. Burrs are most commonly created by
machining
Machining is a process in which a material (often metal) is cut to a desired final shape and size by a controlled material-removal process. The processes that have this common theme are collectively called subtractive manufacturing, which utilizes ...
operations, such as
grinding
Grind is the cross-sectional shape of a blade.
Grind, grinds, or grinding may also refer to:
Grinding action
* Grinding (abrasive cutting), a method of crafting
* Grinding (dance), suggestive club dancing
* Grinding (video gaming), repetitive and ...
,
drilling
Drilling is a cutting process where a drill bit is spun to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multi-point. The bit is pressed against the work-piece and rotated at ra ...
,
milling
Milling may refer to:
* Milling (minting), forming narrow ridges around the edge of a coin
* Milling (grinding), breaking solid materials into smaller pieces by grinding, crushing, or cutting in a mill
* Milling (machining), a process of using rota ...
,
engraving
Engraving is the practice of incising a design onto a hard, usually flat surface by cutting grooves into it with a Burin (engraving), burin. The result may be a decorated object in itself, as when silver, gold, steel, or Glass engraving, glass ...
or
turning
Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates.
Usually the term "turning" is reserved for the generation of ...
. It may be present in the form of a fine wire on the edge of a freshly sharpened tool or as a raised portion of a surface; this type of burr is commonly formed when a
hammer
A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as w ...
strikes a surface. Deburring accounts for a significant portion of manufacturing costs.
In the
printmaking
Printmaking is the process of creating artworks by printing, normally on paper, but also on fabric, wood, metal, and other surfaces. "Traditional printmaking" normally covers only the process of creating prints using a hand processed techniq ...
technique of
drypoint
Drypoint is a printmaking technique of the intaglio (printmaking), intaglio family, in which an image is incised into a plate (or "matrix") with a hard-pointed "needle" of sharp metal or diamond point. In principle, the method is practically ident ...
, burr, which gives a rich fuzzy quality to the engraved line, is highly desirable—the great problem with the drypoint medium is that the burr rapidly diminishes after as few as ten impressions are printed.
Types
There are three types of burrs that can be formed from machining operations: ''Poisson burr'', ''rollover burr'', and ''breakout burr''. The rollover burr is the most common.
Burrs may be classified by the physical manner of formation. Plastic deformation of material includes lateral flow (Poisson burr), bending (rollover burr), and tearing of material from the workpiece (tear burr). Solidification or redeposition of material results in a recast bead. Incomplete cutoff of material causes a cutoff projection.
[Tool and Manufacturing Engineers Handbook (TMEH), Volume 3, Materials, Finishing and Coating. Society of Manufacturing Engineers, 1985.]
Burrs can be minimized or prevented by considering materials, function, shape, and processing in the design and manufacturing engineering phases of product development.
Burrs in drilled holes cause fastener and material problems. Burrs cause more stress to be concentrated at the edges of holes, decreasing resistance to fracture and shortening fatigue life. They interfere with the seating of fasteners, causing damage to fastener or the assembly itself. Cracks caused by stress and strain can result in material failure. Burrs in holes also increase the risk of corrosion, which may be due to variations in the thickness of coatings on a rougher surface. Sharp corners tend to concentrate electrical charge, increasing the risk of static discharge. Burrs in moving parts increase unwanted friction and heat. Rough surfaces also result in problems with lubrication, as wear is increased at the interfaces of parts. This makes it necessary to replace them more frequently. Electrical charge buildup can cause corrosion.
Deburring
![Deburring tool](https://upload.wikimedia.org/wikipedia/commons/0/03/Deburring_tool.jpg)
There are many deburring processes, but the most common are
mass-finishing Mass finishing is a group of manufacturing processes that allow large quantities of parts to be simultaneously finished. The goal of this type of finishing is to burnish, deburr, clean, radius, de-flash, descale, remove rust, polish, brighten, surfa ...
,
spindle finishing,
media blasting
Sandblasting, sometimes known as abrasive blasting, is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove sur ...
,
sanding
upright=1.35, Sheets of sandpaper with different grit sizes (40 (coarse), 80, 150, 240, 600 (fine)).
Sandpaper and glasspaper are names used for a type of coated abrasive that consists of sheets of paper or cloth with abrasive material glued to ...
,
grinding
Grind is the cross-sectional shape of a blade.
Grind, grinds, or grinding may also refer to:
Grinding action
* Grinding (abrasive cutting), a method of crafting
* Grinding (dance), suggestive club dancing
* Grinding (video gaming), repetitive and ...
,
wire brushing
A wire brush is a tool consisting of a brush whose bristles are made of wire, most often steel wire. The steel used is generally a medium- to high-carbon variety and very hard and springy. Other wire brushes feature bristles made from brass o ...
,
abrasive flow machining Abrasive flow machining (AFM), also known as abrasive flow deburring or extrude honing, is an interior surface finishing process characterized by flowing an abrasive-laden fluid through a workpiece. This fluid is typically very viscous, having th ...
, electrochemical deburring,
electropolishing
Electropolishing, also known as electrochemical polishing, anodic polishing, or electrolytic polishing (especially in the metallography field), is an electrochemical process that removes material from a metallic workpiece, reducing the surface roug ...
, thermal energy method,
machining
Machining is a process in which a material (often metal) is cut to a desired final shape and size by a controlled material-removal process. The processes that have this common theme are collectively called subtractive manufacturing, which utilizes ...
, water jet deburring, and manual deburring.
Manual deburring
''Manual deburring'' is the most common deburring process because it is the most flexible process. It also only requires low cost tools and allows for instant inspection.
[.]
Manual deburring is either done with tools like scrapers, files, sandpaper, stones and reamers or with handheld power tools that use abrasive points, sandpaper, or cutters similar to those used to deburr during machining.
Electrochemical deburring
''Electrochemical deburring'' is the use of
electrochemical machining
Electrochemical machining (ECM) is a method of removing metal by an electrochemical process. It is normally used for mass production and is used for working extremely hard materials or materials that are difficult to machine using conventional met ...
to deburr precision work pieces and edges that are hard-to-reach, such as intersecting holes. The process uses a salt or
glycol
A diol is a chemical compound containing two hydroxyl groups ( groups). An Aliphatic compound, aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.
The most common ...
solution and electricity to dissolve the burr. The electric current is applied with a specialized tool to reach the burr location. Burrs are removed in 5 to 10 seconds, while the rest of the work piece is unaffected.
Thermal energy method
''Thermal energy method'' (TEM), also known as ''thermal deburring'', is a deburring process used to remove hard-to-reach burrs or burrs from multiple surfaces at the same time. The process uses an explosive gas mixture to provide thermal energy to burn off the burrs. It is the fastest burr removal process, requiring only 20 milliseconds to remove a burr.
The process starts by loading the workpiece into an
explosion-proof chamber, which is then sealed and clamped with approximately . The chamber is then evacuated of air and filled with an oxygen and fuel mix; this mixture is pressurized to . An electrical igniter then ignites the mixture, which burns for approximately 20 milliseconds, causing all of the sharp corners and burrs to burn away. The peak temperature reaches .
Cryogenic deburring
''Cryogenic deburring'' is a
cryogenic
In physics, cryogenics is the production and behaviour of materials at very low temperatures.
The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “cr ...
process used to remove burrs and
flash
Flash, flashes, or FLASH may refer to:
Arts, entertainment, and media
Fictional aliases
* Flash (DC Comics character), several DC Comics superheroes with super speed:
** Flash (Barry Allen)
** Flash (Jay Garrick)
** Wally West, the first Kid ...
from
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
and
die cast
Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened tool steel dies which have been machined into shape and work similarly ...
workpieces. The process works by tumbling and/or abrasively blasting the workpieces at cryogenic temperature levels. The low temperatures (approximately ) are achieved using
liquid nitrogen
Liquid nitrogen—LN2—is nitrogen in a liquid state at low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, low viscosity liquid that is wide ...
, liquid
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
, or
dry ice
Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily a ...
. This low temperature brings the material below its
embrittlement temperature, which causes the flash or burrs to be easily removed via tumbling or media blasting. This process has been around since the 1960s to deflash plastic and rubber. Common materials that are typically cryogenically deburred with blast media include PEEK, nylon, Teflon, Delrin, polypropylene, polycarbonate, acetal, PTFE, PET, HDPE, PVC, ABS and many others.
Mechanical deburring
![Mechanical Deburring Tool](https://upload.wikimedia.org/wikipedia/commons/e/e2/Mechanical_Deburring_Tool.jpg)
''Mechanical deburring'' is a deburring process that either mechanically grinds a burr off of metal or rolls the edge of the dangerous slit or sheared metal burrs into itself. Rolled mechanical deburring was first developed in the 1960s by Walter W. Gauer from Gauer Metal Product, Inc. as a means to speed up the process of hand deburring strips of metal that were used in bakery racks.
Water Jet Deburring
One of the main benefits of ''waterjet deburring'' is a high level of precision and repeatability - and for this reason,
CNC control is used. This eco-friendly process uses high-pressure water to remove loose burrs and chips even in deep holes – all while leaving the parts cleaner and free of debris. Pressurized water is precisely focused via CNC control to remove burrs and chips in and around parts. Depending on the cleanliness specifications, this can be performed submerged or in an open-air environment. Open-air washing/deburring targets specific areas of the part where the water jet is focused. Submerged will clean the entire part, internally and externally.
See also
*
Swarf
Swarf, also known as chips or by other process-specific names (such as turnings, filings, or shavings), are pieces of metal, wood, or plastic that are the debris or waste resulting from machining, woodworking, or similar subtractive (material-r ...
*
Fillet
Fillet may refer to:
*Annulet (architecture), part of a column capital, also called a fillet
*Fillet (aircraft), a fairing smoothing the airflow at a joint between two components
*Fillet (clothing), a headband
*Fillet (cut), a piece of meat
*Fille ...
and
chamfer
A chamfer or is a transitional edge between two faces of an object. Sometimes defined as a form of bevel, it is often created at a 45° angle between two adjoining right-angled faces.
Chamfers are frequently used in machining, carpentry, fu ...
, edge features designed to reduce burrs.
References
Bibliography
*
*{{Citation , last = Warfield , first = Bob , title = Definitive Guide to Deburring for CNC , publisher = CNCCookbook , year = 2018 , url = https://www.cnccookbook.com/deburring-for-cnc/ , postscript =.
Metalworking terminology
Printmaking
Cryogenics
Plastics industry