Deburring metal

Machine deburring uses milling or brushing tools to remove burrs from workpieces and round off edges. This method is ideal for series production, large components and the precise deburring of metal parts. The machines enable high precision, speed and repeatability in the deburring process, which makes them particularly essential for fast-cycle processes in the automotive industry.

The strength of mechanical processes lies in their ability to process large quantities of parts efficiently. Process automation ensures consistent quality of the deburred parts. This method is adaptable to different materials and enables precise control over the deburring process. If exact edge radii are to be set on CNC parts, there is often no way around machine deburring. However, there are also innovative and flexible alternatives for this, see plasma deburring.

However, mechanical deburring requires an investment in specialized machines, which incurs initial costs. In addition, tool wear requires regular maintenance. Accessibility for these tools is also restricted, particularly on complex geometries, meaning that deburring is not possible.

Thermal deburring is a process based on thermal-chemical deburring. A mixture of fuel gas and oxygen is ignited in a closed reaction chamber. The resulting heat energy dissipates within less than a second, burning or vaporizing the burrs protruding from the edges of the component. This method is particularly effective on hard materials and can remove burrs caused by machining processes such as milling or grinding.

Applications for thermal deburring often include parts where high accuracy and precision are required. It is well suited to industrial applications where burrs need to be removed from hard-to-reach areas or complex geometries inside the component. The strengths of this process lie in its ability to efficiently and precisely remove burrs from metal components. Thanks to the targeted combustion, even internal bores with a large aspect ratio are no problem. In addition, thermal deburring has one of the lowest unit costs for machining, especially in series production.

The disadvantages of thermal deburring result from the effect of the combustion gas - oxidation, discoloration and other undesirable effects are to be expected. These must be corrected in a post-process, particularly in the case of ferrous materials. It may also not be suitable for sensitive materials, as these could be damaged by the heat treatment. It is not possible to round off edges using thermal deburring, which limits its use in medical technology in particular. In addition, the maximum component size is limited by the size of the combustion chamber.

Chemical deburring is a process that uses chemical solutions to remove burrs, which dissolve the material to be processed. The chemicals used are tailored to the machining task. This attacks the component at all points, even those that are difficult to reach, but preferably at protruding burrs. These are dissolved more quickly, but not exclusively. Depending on the exposure time in the bath, this results in a more or less pronounced processing of the surface by reducing roughness. The process is particularly suitable for complex geometries and areas that are difficult to access, as the solution is able to reach all burrs with ease. Industrially, it is mostly used for unalloyed steels as bulk material, as a particularly efficient deburring effect is possible here.

One of the strengths of chemical deburring lies in its ability to deburr evenly and gently. Particularly in the case of fine burrs, this ensures reliable removal with short cycle times. However, it is important to exercise extreme caution when handling the chemical solutions, as these are generally highly hazardous to the environment and health.

Deburring by vibratory finishing uses abrasives and water to remove burrs from metal components. This process is particularly suitable for less complex parts without areas that are difficult to access. It enables uniform processing and generally contributes to improving the surface quality at the same time.

The strengths of mass finishing lie in its adaptability to different shapes and materials as well as the ability to deburr various geometries simultaneously. As the system technology is established and inexpensive, processes can often be set up with low investment and operating costs.

The maximum component size for mass finishing is limited by the system. However, it is more time-consuming than some other methods and can lead to surface changes if handled incorrectly.

Electrochemical deburring is a precise process based on electrochemical reactions to remove burrs from metal components. The component, the counter electrode and an electrolyte form an electrochemical cell in which protruding surface features such as roughness peaks and burrs are specifically removed under a DC voltage. Basically, it is the opposite of electroplating. The removed metal accumulates in the electrolyte and must be removed from it. Electrochemical deburring is often used to remove burrs from hard-to-reach areas or complex geometries.

The strengths of this process lie in its precision and independence from the hardness of the material. This means that even hardened metal components that would pose a mechanical challenge can be processed without any problems. The fast deburring effect enables one of the fastest cycle times of all deburring processes.

The main disadvantage is the geometry-specific tool cathode. This requires a corresponding initial investment for each new component shape. In addition, electrochemical deburring requires specialized equipment and expertise as well as precise knowledge of material compatibility, as not all metals are suitable for the process. Furthermore, the technology is only suitable for metal parts with fine and very consistent burrs, as larger ones can protrude beyond the working gap to the cathode and lead to a short circuit.

Ultrasonic deburring does not work through the ultrasonic waves themselves, but utilizes the inertia of water. In this process, the component is placed in a process water basin, accompanied by a sonotrode - an ultrasonic transducer - guided close to the burr. This oscillates back and forth so quickly that the surrounding medium cannot keep up and implodes in so-called cavitation bubbles. This causes a highly accelerated jet of water to be ejected, which tears off burrs in a process-safe manner.

Ultrasonic deburring works selectively and can gently remove burrs from metal components. The method is well suited to smaller parts and enables precise deburring. The process medium used is not considered critical in terms of occupational safety - it is usually water with calcium carbonate as an additive.

Ultrasonic deburring reaches its limits in larger components or with massive burr formations, especially pronounced burr roots. In addition, not all materials can be processed.

In abrasive blasting technologies, abrasive particles are used to remove burrs from metal components. These are accelerated using compressed air or rotation and hit the component with correspondingly high kinetic energy.

This method proves to be effective and can be controlled in a targeted manner due to the localized effect in the impact area, although not exactly in a defined area due to the ricochets. Manual guidance is also possible for particle blasting.

The method may be less suitable for softer materials. Precise control is important to avoid damage to the component. In addition, this technology often requires close monitoring of the process, e.g. the wear of the blasting medium, which significantly influences the result.

Cryogenic deburring involves treating parts at extremely low temperatures to safely remove burrs. Using liquid nitrogen, the burrs are cooled to temperatures below -100°C, which makes them solid and brittle. The metal component is then bombarded with granulate, usually plastic, which knocks off the burrs.

Cryogenic deburring is gentle and distortion-free, with no negative impact on the surface.

This process is effective, but equipment costs can be high and handling extremely low temperatures is a challenge. It is well suited to a variety of metals, but also has limitations. For example, cryogenic deburring of steels is not possible.