Edge rounding tools

Edge rounding procedures & tools.

In general, edge rounding comes after deburring. During edge rounding, excess burrs (secondary pieces of burr) are removed and the sheet metal edges are rounded. Depending on the application, it can be important to remove the sharpness of the edge. Larger radii in the range of 0.5 mm are necessary to prepare the sheet metal for reliable coating (painting, galvanizing). Occasionally, radii of up to 2.0 mm are required by DIN EN 1090.

In addition to the actual radius, criteria like uniform rounding and the rounding of inner contours play a role when choosing the appropriate rounding procedure or tool. Likewise, the optics (or roughness) of the surface after processing needs to be considered since the tools also process the surface simultaneously. Therefore, a whole range of edge rounding processes that are used in deburring or edge rounding machines.

Edge rounding procedures at a glance:

Disc brushes
Edge rounding blocks
Roller brushes (rotor)

Edge rounding with disc brushes.

Disc brushes are units that are often used in edge rounding operations. Operation and set up are easy to understand. Thus, machines with disc brushes could also be implemented relatively cheap. These are often single-sided machines, which are advanced on a conveyor belt under one or more of the top-acting disc brushes. The tools rotate and strike the parts at the edge. The discs with abrasive filaments are usually mounted stationary if the machine is narrow. Although, they can also cover larger surfaces (and thus larger passage widths) by oscillation or by additional movements.

Disc brushes deliver relatively uniform results. However, they have limits in terms of life, impact on inner contours and removal performance. Nevertheless, for many applications this popular process is a good solution for edge rounding. ARKU uses disc brushes in the EdgeBreaker® 1000 for small parts processing. Unique: The EdgeRacer® uses these tools also in machines that process double-sided, such as in the production of computer cases.

The disc tools come in a variety of designs. Single-row or multi-row arrangements of the abrasives on the disc define the hardness grade of the brush. Keep in mind, the choice of different abrasives or particle sizes impact surface or removal performance.

Rounding with blocks.

Like the deburring blocks for deburring, also edge rounding blocks have the advantage that they can process the sheet metal from the top and bottom in a single pass. Typically, this is almost always the most economical edge rounding process because it is fast. The parts are held by pressure rollers and guided through the machine. Circulating belts guide the tools (edge rounding blocks) double-sided across the materials. Also slightly warped sheets and parts are reliably rounded, all while the part is securely fixed. However, double-sided processing requires a minimum parts length. The edge rounding blocks strike the parts perpendicular to the passage direction. Edges that are hit head-on are rounded slightly more than edges that are running parallel to the tool movement.

The edge rounding blocks are available in different designs. Abrasives, grits and design can vary depending on the job. Edge rounding blocks feature a quick-change system to quickly replace the blocks.

For many applications, this type of edge rounding is the most economical alternative because the tools process double-sided.

Edge rounding with rotary brushes.

Rotary brushes are tools that achieve the best possible rounding. Rotary brushes are equipped with abrasive lamellas. By the rotation of the brushes, the abrasive filaments are pulled across the sheet metal edges and thus achieve their powerful impact on the part edges. While the parts on a conveyor belt are moved under the rotor, the rotary brushes impact the part from above. An additional carousel is particularly effective - the so-called rotor - that holds several rotary brushes, which uniformly process the part from all directions. That is why of all rounding processes, rotary brushes achieve the best and also the most consistent edge rounding results. Up to a 2.0 mm radius can be achieved with a rotary brush.

Rotary brushes are available in different designs. In particular, the lamellar shape, the type of abrasives and the grit size influence the impact on the part. Coarse particles have excellent removal performance, but also leave a rough surface. Fine particles remove less, but can also handle small parts.