ADM Instrument Engineering supplies a comprehensive range of load cells
in different shapes and sizes. Some load cells are more suited to certain
applications than others. ADM explains the different types of load cells and
the corresponding applications for each type.
A load cell is a device that measures force; while some can measure
compression forces, others can measure tension forces. Some load cells can measure
both compression and tension forces.
Miniature button load cells
Miniature button load cells measure only compression forces and are
ideal for any application involving limited space. The load cell is usually
cemented into position because it is too small for mounting hardware. Offering measuring
ranges up to a maximum of 500kg, the load cells can be ideally retrofitted for load
measurement in machinery that wasn’t originally designed to take load cells.
Standard button load cells
Bigger than miniature button load cells, standard button load cells are also
designed to measure only compression forces. Featuring weight module hardware, these
load cells are mainly used to weigh tanks and silos. The weight module hardware
ensures the forces are correctly applied and prevent the connection being
opened. This is particularly important with tall silos, where wind forces on
empty silos can cause them to topple.
Bending beams
Featuring a compact beam shape that allows easy fitting, bending beams are
used in many applications and incorporate stainless steel bellows to make them
impervious to water. Bending beams are not suitable for measuring low weights as
they can have slightly reduced accuracy at lower weight ranges.
Tension/compression canister
load cells
Typically found on weighbridges, these load cells are available in a
wide range of physical sizes, with a good choice of measuring ranges. A rocker
column type load cell can be used where alignment of the load will vary. Rocker column load cells have a unique dual radius loading surface with
a large radius in the centre where the load measurement is made and a smaller
radius at the outer extremities, allowing the load cell to rock, and avoiding
serious adverse loads due to the differential expansion of the weighbridge.
Torque transducers
The reaction torque transducer is used to mount a motor to a fixed frame
and measure the torque of the motor body on its mount, while the rotating torque
transducer spins with a shaft, but sends plus and minus torque measurements. Older
rotating designs use slip rings, and may have speed limits on the device. More
modern designs use magnetic sensing and have fewer limitations.
Shear beams
Often used in bulk handling equipment, shear beams find application in
filling machinery, industrial floor scales, tank and silo weighing. They are
suitable for multi-load cell floor scales, but should not be exposed to
corrosive fluids.
Single point load cells
Single point load cells have an internal parallelogram structure that
ensures the internal strain gauge only responds to force in one direction. If
the load cell is levelled, it only responds directly to weight and is not
affected by any side forces, making it perfect for weighing applications where it
is difficult to control side forces. They are very often used with a small
scale base for measuring lower force levels.
S-Beams
Extremely versatile, S-Beams are capable of measuring either compression
or tension forces and are particularly good for weighing heavy objects that are
cumbersome to handle. Instead of lowering a bulky object down onto a scale base
risking overloading and damage from the load being dropped, lifting the load
with a tension S-Beam in line will give immediate and accurate measurement of
weight while minimising handling. S-Beams require a safety chain when used in
crane applications to avoid the risk of an overload failure that could cause a
dropped load.