Drilling, Grinding and Shop Machines flashcards

Feed rate = feed per rev $\times$ RPM: 0.10 mm/rev at 600 rpm gives 60 mm/min. Time $t=\frac{\text{travel}}{\text{feed rate}}$: 30 mm at 60 mm/min takes 0.5 min. Multiply, never add, the two given values.

$v_c=\frac{\pi DN}{1000}$, D in mm, N in rpm, $v_c$ in m/min. A 10 mm drill at 1,000 rpm gives about 31.4 m/min. Larger diameter means faster edge speed at the same RPM.

$N=\frac{1000v_c}{\pi D}$, with $v_c$ in m/min and D in mm. At 30 m/min with a 10 mm tool, N is about 955 rpm, before checking machine and material limits.

Work rest (below, supports the work): at most 1/8 inch from the wheel. Adjustable upper tongue guard: at most 1/4 inch. Never adjust either while the wheel is moving; do not swap the two values.

Ask what rotates and what feature results. Rotating bit feeding along its axis: drill press. Rotating workpiece with a moving tool: lathe. Rotating cutter with work fed on a table: mill. Abrasive wheel: grinder.

A power shear cuts sheet metal along a straight line (for example, to reduce width). A press brake bends sheet to an angle with matched tooling, such as forming an L-shaped flange.

Remove it. A key left in the chuck can be thrown out when the spindle starts. Also secure the work in a vise or clamp, never by hand, and stop the machine before clearing chips or measuring.

$V=\pi r^{2}h$, using the radius, not the diameter. A 10 mm hole through 20 mm stock: $\pi \times 5^2\times 20\approx 1571$ mm³.