Five-Axis Brush Deburring for Crankshafts

Compact machine is more effective than robotized finishing for high-volume, finishing of complex workpieces

Deburring of complex engine components — like crankshafts or camshafts — usually is performed by specialized or customized process technologies, and KADIA Produktion GmbH + Co. has long experience in this. Now, the honing and deburring specialist has developed its first standard brush-deburring machine for these applications.

Loose particles or flaky burrs on the bearing surfaces must be removed before a crankshaft can be finish-machined. Otherwise, these foreign bodies could enter the new engine interior and cause damage there. The most common approach for this stage involves robotized handling, with a gripper handling the workpieces and conducting the deburring sequence with different tools (brushes, discs, etc.) selected from a console.

A complicated, complex motion sequence has to be programmed, because each workpiece edge must be brought exactly into the machining position. For each dimensional variation of a crankshaft, the robot must be taught again — i.e., new coordinates must be entered and stored.

This is demanding of plant managers, programmers, and operators, and incurs frequent downtimes. In addition, the robot may take up to two minutes to machine each crankshaft. However, the typical cycle times in high-volume automotive production are 30 to 60 seconds. As a result, engine manufacturers often operate several deburring cells in parallel in order to manage production volumes.

KADIA developers, who have their own experience in this process, developed a new plant concept. It involves flexibility for short cycle times and requires less support and maintenance. The result is a new standard brush deburring machine, the EC-Brush.

What sounds simple in fact has several novel details. The machine has a total of five programmable axes: one rotary drive each with right/left rotation for the brush and the workpiece. The workpiece is clamped against a point in a three-jaw chuck. The brush rotates at about 500 rpm, the crankshaft at 30 rpm.

Linear axes also provide the brush’s back-and-forth movement and side-to-side oscillation, and a traversing range for the center. The latter detail means that different crankshaft lengths may be clamped, so that any variant for 3- to 6-cylinder engines (for passenger cars or small commercial vehicles) can be machined in any desired succession.

Loading and unloading can be carried out manually, semi-automatically or fully automatically.

The core of the EC-Brush deburring machine is the brush, made from fibers of abrasive nylon. The fibers’ cross-section is oval, i.e., long and short fibers adapt to the eccentric design of the crankshafts. Only one operation is required, as the shaft is completely immersed in the brush. The long fibers reach from the cheeks up to the connecting rod bearings, the short fibers machine the main bearings area.

There are always certain fibers in mesh. The long ones are deflected at short workpiece distances to create an additional impact effect. Particles and flaky burrs, which typically result from drilling or grinding, are reliably removed. The choice of fiber type allows adaptation to the component’s material, too.

Another important contrast to robotic finishing is that the EC-Brush deburring machine allows wet machining. The workpiece is rinsed at the same time in this case.

"The main time for deburring a crankshaft is only about 20 seconds, including loading and unloading," according to Kadia managing director Henning Klein. "Cycle times of about 30 seconds or just above are possible.

"Three cells are required to achieve the same output as a deburring robot, the investment costs for which are about twice as high," he offered, by contrast.

As this is a standard machine designed according to a modular principle, Kadia noted that its delivery time is also significantly shorter than for a special solution. The small space requirement creates a further advantage. The designers have equipped EC-Brush deburring machine with an inclined bed on which the brush moves back and forth. This results in a compact design with a footprint of just 2.6x2.3 m.

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