load cell type for weighing system

G

Thread Starter

gingldg

I am trying to design a weighing system with a maximum capacity of 5 kg. I plan to do this using a single load cell (due to budget constraints) of 10kg capacity in the middle of a rectangular / circular platform. I am not sure though which type is appropriate for this. Initially, I opted for the ring type (round / pancake type) but it seems most of the available load cells of this type are for heavy-duty applications. I have read that the single-point / shear beam load cell is recommended for low-capacity systems. Am not sure though if this is ok to use as one since these are high-deflection types and may cause imbalance when the load is applied on the platform. I would appreciate any comments / suggestions. Thanks in advance.
 
A

Alex (Sam Hing)

I recommend you to use a single point loadcell, as they are designed to work with single cell applications. These cells are much cost effective in low capacity applications and good for eccentric loading.

Shear beam and column type loadcells usually require multiple cells installation (at least 3 points). They are sensitive to eccentric loading which would induce a large weighing error if u use only one cell. Loading assemblies are usually required which increase the overall cost. Also they are usually used for higher weighing capacity.

Single point loadcell are usually made of aluminimum, though special version of stainless steel is available in some model. One thing you have to be careful when choosing a single point loadcell is its maximum allowed platform/load receptor size, u should be able to find that information in its specifications. If you plan to load outside this area, expect increased error than the one stated in its specification. Also, be careful with the output rating of the cell (in mV/V) and make sure you have enough mV signal voltage per display resolution to ensure stability of the reading. You may also consider the disadvantages of this type of cell like high installation profile (in high capacity applications, e.g. above 300 kg), and, low life expectency in wet or corrosive enivornment.

Please excuse my English if I have made any written mistake.

Hope this will help.
Alex
Sam Hing Scales Fty. Ltd.
 
Also, be careful with the output rating of the cell (in mV/V) and make sure you have enough mV signal voltage per display resolution to ensure stability of the reading. You may also consider the disadvantages of this type of cell like high installation profile (in high capacity applications, e.g. above 300 kg), and, low life expectency in wet or corrosive enivornment.

Why not to use a digital load cell in this case?

Please check before the article 'Digital Load Cells. A Comparative Review of Performance and Application', Mesurement + Control, Journal of the Institute of Measurement and Control, pp. 13-16, Vol. 36/1, February 2003 at
http://www.sensorsportal.com/HTML/SENSORS/Load_Cells.htm
 
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