Millwright Level 1 Practice Exam

The efficiency of electric hand drills is primarily limited by what factor?

1. Size of the drill bits

2. Amount of feed pressure and RPM

3. Battery lifespan

4. Material being drilled

The correct answer is: Amount of feed pressure and RPM

The efficiency of electric hand drills is primarily influenced by the amount of feed pressure and RPM (revolutions per minute). When drilling, the feed pressure is critical because it affects the contact force between the drill bit and the material being penetrated. Too little pressure can lead to ineffective drilling, where the bit may spin without making significant progress, resulting in energy waste and prolonged drilling times. Conversely, excessive feed pressure can overload the bit and the motor, potentially causing overheating and damage. RPM also plays a vital role in drilling efficiency. Different materials require specific RPM settings to optimize cutting performance. For instance, harder materials often need lower speeds to prevent burning the bit, while softer materials may be drilled more efficiently at higher speeds. The combination of appropriate feed pressure and RPM allows for efficient material removal and minimizes the risk of damaging the drill or the workpiece. In summary, the interplay of feed pressure and RPM directly impacts the operating efficiency of electric hand drills, making it the primary limiting factor.