Shaper kinematics — average ram speed over full cycle A shaping machine has a stroke length of 250 mm and makes 30 double strokes per minute. Considering both forward and return strokes, what is the overall average speed of ram motion in m/min along the stroke line?

Introduction / Context:
In shaping machines, the ram travels the stroke distance during the cutting stroke and the same distance back during the return stroke. Production calculations often need the average linear speed over the full cycle (both strokes) for estimating time and power. This is different from cutting speed (usually based on forward stroke only).

Given Data / Assumptions:

• Stroke length L = 250 mm per single stroke.
• Cycles = 30 double strokes per minute (each cycle includes one forward and one return stroke).
• Overall average speed refers to total travel per minute divided by time (1 minute).

Concept / Approach:
Total distance traveled in one double stroke equals forward distance plus return distance, i.e., 2 * L. The number of double strokes per minute times this distance gives total travel per minute. Convert to meters as needed to express m/min.

Step-by-Step Solution:
Compute distance per double stroke: s = 2 * L = 2 * 250 mm = 500 mm = 0.5 m.Compute total distance per minute: S = 0.5 m * 30 = 15 m.Overall average speed over the full cycle = 15 m/min.

Verification / Alternative check:
Dimensional check: stroke (m) * cycles per min yields m/min; numbers are consistent. Even if the return stroke is quicker, the overall average over distance still uses total travel divided by total time, which here is directly given by cycles per minute.

Why Other Options Are Wrong:
3.75, 5, and 7.5 m/min would correspond to incorrectly using only half, one-third, or half the number of strokes or stroke length. 10 m/min does not match any logical fraction of the correct calculation.

Common Pitfalls:
Confusing average cutting speed (forward stroke only) with overall average speed. Here, the question explicitly asks for total motion in both directions.

Final Answer:
15 m/min