• What causes SDS drill breakage?


When a user breaks the tip off an SDS drill bit, the blame is often placed on the quality of the drill itself or the toughness of the material being drilled. However, the condition of the SDS drill chuck is often overlooked.

The Inner Workings of SDS Drills

SDS drills operate in the following way when fitted into the correct SDS chuck:

  1. The SDS drill's two square-sided slots or keyways open to the end of the drill and align with two keys inside the chuck. These keys transfer rotational force and torque from the drill to the drill bit.
  2. The two rounded slots that do not open to the end align with ball bearings inside the chuck. These ball bearings grip the drill bit and stop it from falling out of the chuck during use.

The Role of Chuck Maintenance

Due to the significant forces and hammering action, the keys inside the chuck must remain well-lubricated with grease. Over time, especially if not lubricated, these keys can wear down. This wear compromises the stability of the drill bit within the chuck, allowing for movement that can lead to the ball bearings taking some of the rotational force and torque load.

Consequences of Chuck Wear

The drill bit is not operating in optimal performance conditions when the integrity of the chuck is compromised due to wear. One side effect is increased vibration, which transfers from the chuck right to the drill bit tip. The excessive vibration causes the tip to heat up significantly more than it would under normal operating conditions. Once the tip's temperature surpasses 450° inside the concrete, the temperature is high enough to cause a catastrophic failure between the carbide and the drill body.

Therefore, a poorly maintained or worn SDS chuck can lead to the breakage of SDS drills.

Preventative Measures

It is essential to adhere to preventative maintenance measures to mitigate the risk of SDS drill breakage caused by a worn chuck. By prioritising proper maintenance, users can expect a longer lifespan of their SDS drills and avoid any costly disruptions caused by unexpected breakages.

  1. Regular Lubrication: Always ensure the chuck is internally lubricated with grease. A lack of grease on the SDS drill upon removal from the chuck is an indicator of insufficient lubrication.
  2. Inspect Routinely: Inspect your SDS drills for signs of wear. If you notice sideways wear or deformities on the sides of the open-ended slots, it's recommended to replace the chuck with a new one.
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