How do I prevent shock loading on my scale?

When you drop a one kilogram object on a scale from a height of one inch or one foot, the impact on the scale is not the same as gently placing the weight on the scale. Shock loading can affect a scale’s functionality and performance and can damage load cells. All scales are subject to minimal shock loading during normal use by an abrupt change in the weight placed on a scale. An example is when weight is dropped onto the scale rather than being placed on it.

Remedies to stop or reduce shock loading:
1.  Stop dropping objects on the scale (which is the most obvious).
2.  Use shock absorbing material on top of the scale to absorb some of the shock.
3.  Install larger capacity load cells.

If the first two remedies can't be done, you'll need to install higher capacity load cells.  To figure out what capacity load cell to use, based on estimated shock force, you need to know the weight of the object being dropped, the vertical distance that it’s dropped, and the empty weight of the scale structure.  There are formulas available on the world wide web, but dropping an object four inches can double the weight on impact.  Another two inches again doubles the weight on impact.  As the height increase so does the weight on impact. 

Overload stops will not help with impact damage.  The damaging impact force is felt long before the load cells bend down and touch those overload stops.  Over load stops are just that.  For the times when you place too much weight on the scale.

Once you've estimated the shock impact load for a scale, determine how that force will be distributed over the load cells. If an object is dropped in the center of four load cells, the shock force will probably affect all four load cells equally. If it’s dropped on one side of the scale, the shock force could be concentrated on two of the load cells. Divide the shock force by the number of load cells to estimate the shock loading per load cell. Compare that shock load with allowable download ratings and if the shock loading is too large for the nominal load cell capacity, you will need to use higher capacity load cells.

If larger load cells cannot physically replace the ones that are damaged, or places your accuracy range requirements in jeopardy you may need to revert to the first two remedies mentioned above. I hope this explanation helps reduce the amount of load cells that get damaged from shock loading.  Product handling is the key to solving this problem.

Installing a overload stop is not a remedy to stop shock loading damage.  The shock load will cause the problem due to acceleration before the load cell can travel the distance to the overload stop.

Example:

Looking at a 180 Lb. Keg that is traveling down a gravity conveyor@ ~ 15^o.

With an estimated platform dead weight of 50 lbs. and a spring rate (K) of the cell (capacity/FS deflection in inches) of 22000, shock/force can conservatively be expected to exceed 2,725 Lbs.

As this keg dead ends into a mechanical stop, the sectional pair of load cells can easily see 75% of th