Deburring
Burrs are removed during deburring . Burrs are sharp edges, fraying or splinters of a mostly metallic workpiece that arise during a machining or manufacturing process . On the one hand, these can impair the (faultless) functioning of the machine element within the end product (poor thread run-through, inaccuracies of fit, etc.), and on the other hand cause considerable risk of injury such as deep cuts.
The term “deburring” is mainly used in the metalworking industry. In the woodworking industry, one speaks of edge breaking, mostly using sandpaper . If a dimensionally defined (width and angle) bevel arises when removing the burr on the edge, this is called this bevel .
Formation of the ridge
During mechanical processing, for example with milled or turned parts, a burr is created on the edges due to material displacement.
When processing sheet metal , burrs occur during punching , especially with a high smooth cut portion of the cut surface and sheet thicknesses from 0.5 mm, less often also with laser cutting , especially if the focusing of the laser beam is incorrect. Thicker sheets are cut with the plasma or oxy-fuel process. This can lead to very strong burr and slag formation.
Deburring Methods
Burrs are removed by brushing , files , Countersink , grinding , milling , vibratory finishing , thermal deburring (z. B. Thermal Energy Machining , TEM), electrochemical deburring , Hochdruckwasserstrahlentgraten , pressure flow (DFL) hydroerosives loops (HE-grinding) or cutting.
There is also the option of dipping the workpiece in caustic or corrosive liquids or heating it to soften the edges.
Small workpieces are often deburred using the so-called vibratory grinding process. With increased demand for a uniform rounding of the entire part contour z. For example, with fine-cut gears and small bores, the process reaches its process limits. Special throughfeed systems that are equipped with grinding u. Brush units are designed to remove the burrs reliably and gently.
For larger sheets there are throughfeed machines in which the sheets pass under a grinding unit that grinds off the raised burr. Since the sheets are often warped after thermal cutting, it is particularly important to work with a flexible grinding tool that compensates for tolerances and warpage. In general, the following applies: the softer the grinding tool (brush), the more grinding result in the edge area (where the burrs occur) and the less on the surface.
Cross bores can be deburred using the HSD (High-Speed Deburring) process.
Backward deburring of bores
Bores have the property that they have a burr on the drill entry side as well as on the exit side. While the removal of the burr on the front is usually possible conventionally, problems arise with the back. The rear edge of the hole is often difficult to access (e.g. cross holes, fork pieces) or the workpiece has to be turned around and clamped again for processing. In 1976 Heinrich Heule developed a tool under patent (DE-PS 26 49 208) which removes the burr on the front and rear edges of a hole in a single operation. This was later followed by a tool with a new functional principle for deburring flat and uneven bore edges.
Deburring plastics
In the injection molding process produced plastic parts often have a ridge. They are mostly cut off with special knives, sometimes sanded off . Since plastic parts are significantly softer when they are still lukewarm than after they have hardened, this is usually possible without any problems. There is also automated deburring with hot air for plastics. The burr material is melted and the surface tension rounds off the remaining material edge .
Deburring trends
Most of the innovations in deburring can be found in the automation of this process. One of these trends is the use of robot-assisted deburring processes. Another trend is the use of special tools that have been specially developed for deburring. A new development in the field of deburring is high pressure water jet deburring. With the help of rotating multiple nozzles or individual lances, water is directed onto component areas with burrs. This leads to a deformation of the burr, which then breaks off from the component. Another deburring process is the laser-based deburring process, which is in constant development. It is characterized by the very fine achievable accuracies. Edge dimensions of up to 500 μm and 0 to 30 μm can be achieved with laser fine deburring.
literature
- Friedrich Schäfer, Fritz Breuninger: Deburring: Theory, Process, Systems. Krausskopf, 1975, ISBN 3-7830-0097-1
- Hans-Michael Beier: Manual Entgrattechnik Carl Hanser Verlag Munich Vienna, 1999, ISBN 3-446-19583-1
Individual evidence
- ↑ HSD deburring from Dr Beier-Entgrattechnik
- ^ Patent Heinrich Heule: Tool for deburring the edges of through holes on both sides
- ↑ COFA functional principle for the automated deburring of flat and uneven hole edges from HEULE Werkzeug AG
- ↑ Automated deburring of plastic parts with hot air , company publication from Leister Process Technologies, Sept. 2007 ( Memento of the original from February 20, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 1.5 MB)
- ↑ Deburring in forming technology: description, trends and implementation. Retrieved November 5, 2018 .
