BIZOMAT MAKEOS · Mechanics
Gravity Chute Check (Sliding Acceleration, Exit Speed, Impact Energy, Least Angle)
Will parts slide down this gravity chute, how fast will they be going at the bottom, and is that slow enough not to damage them?
Check of a sliding gravity chute or slide: the forces along the slope from the part weight and friction (as the inclined plane tool), the acceleration and whether the part slides at all, the least chute angle to slide, the exit speed and time over the chute length from the entry speed (as the uniform acceleration tool), and the impact energy at the bottom, against the largest exit speed you accept.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Chute angle | ° | Slope of the chute from horizontal. |
| Sliding friction coefficient | Friction between the part and the chute surface (lined chutes and rollers are lower). | |
| Chute length | m | Length the part slides. |
| Entry speed | m/s | Speed of the part entering the chute. |
| Part mass | kg | Mass of the part (for the impact energy). |
| Largest exit speed | m/s | Fastest the part may arrive without damage or noise. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Chute angle
- What it is
- The slope of the chute bed from horizontal, along which the part slides under its own weight.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 0° to 89.9°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 30° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A steeper chute raises the driving force, acceleration and exit speed.
- Get it right
- Measure from horizontal with an inclinometer, not from vertical.
What this means: Sliding friction coefficient
- What it is
- The sliding friction coefficient between the part and the chute surface, for the actual materials, lining and condition.
- Units and format
- Enter a plain number with no unit. The form accepts 0 to 3. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.3 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Higher friction lowers the acceleration and exit speed and raises the least angle to slide.
- Get it right
- Measure it by tilting a sample chute until a part starts to slide steadily; surface wear, oil and damp change it.
What this means: Chute length
- What it is
- The distance the part slides along the chute from where it enters to where it leaves.
- Units and format
- Enter a number in m: metres. The form accepts 0.000001 m to 10000 m. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 m as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A longer chute gives more distance to accelerate, so the exit speed rises when the part is speeding up.
- Get it right
- Measure along the slope, not the horizontal run or the vertical drop.
What this means: Entry speed
- What it is
- How fast the part is already moving along the chute when it enters, for example from a conveyor or a previous chute.
- Units and format
- Enter a number in m/s: metres per second. The form accepts 0 m/s to 100 m/s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0 m/s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A faster entry raises the exit speed and can carry a part along a chute that would otherwise stop it.
- Get it right
- Enter 0 if parts are placed or dropped onto the chute from rest.
What this means: Part mass
- What it is
- The mass of one part sliding down the chute, used for the forces along the slope and the impact energy at the bottom.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 1000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 20 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- It does not change the acceleration or exit speed; impact energy rises in proportion to it.
- Get it right
- Weigh the heaviest part that uses the chute.
What this means: Largest exit speed
- What it is
- The fastest a part may arrive at the bottom of the chute without damage to the part, the stop or the next station, or excessive noise.
- Units and format
- Enter a number in m/s: metres per second. The form accepts 0.000001 m/s to 100 m/s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4 m/s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Only moves the pass or fail line; the calculated exit speed does not change.
- Get it right
- Base it on part damage tests or your process requirement; this tool does not give a value.
Method and formulas
- Driving force = W (sin θ − μ cos θ) (as the inclined plane tool); acceleration = force ÷ m.
- Slides only when tan θ > μ; least angle = atan μ.
- Exit speed v = √(u² + 2 a L) and time t = (v − u) ÷ a (as the uniform acceleration tool); impact energy = ½ m v².
- Example: 2.3555 m/s² down the chute; 3.7594 m/s at the bottom after 1.596 s (141.33 J).
Limitations
- Sliding friction constant along the chute; damp, oily or worn surfaces change it.
- Part slides without rolling or tumbling; air drag ignored.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Set the angle of a parts chute
- Check parts are not damaged at the bottom of a slide
- Find why parts stick in a chute
Who it is for
- Automation engineers
- Materials handling engineers
- Machine designers
What you get
- Slope and friction forces
- Acceleration and least angle
- Exit speed, time and impact energy
Interpreting the result
- A few degrees above the friction angle gives a slow, reliable slide; much steeper and the parts arrive too fast.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 165–171, 175–181. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Discharge rate and the hourglass law
In Bulk Solids Flow by the Numbers
What it covers: Why a coarse material's discharge rate depends on outlet size to the power 2.5 and not on the head, the Beverloo correlation and its limits, why fine powders are slower, and chutes below outlets.
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