This document summarizes an upcoming webinar on load cells. The webinar will cover load cell basics, components, types, strain gage technology, moment and temperature compensation, and calibration. Key topics include how load cells convert force to electrical signals using strain gages in a Wheatstone bridge configuration, common load cell designs, and factors considered in load cell design like materials and flexure geometry. Compensation techniques are discussed to reduce errors from eccentric loads and temperature variations.
2. Definitions
Load Cell Basics
Strain Gages
Moment Compensation
Temperature Compensation
Calibration
Performance
Application
Q & A
3. Axial Load
Calibration
Capacity
Creep
Deflection
Eccentric Load
Hysteresis
Nonlinearity
Output
Rated Output (RO)
Static Error Band (SEB)
Symmetry Error
Additional definitions and
more are available in our
website library under:
Load Cells >
Load Cell Terminology
4. Device that converts a force into an electrical signal
Designed to measure loads:
Tension
Compression
Both
No moving parts
No wear and tear
between main
components
10. 1. Grid Lines
▪ Strain sensitive pattern
2. End Loops
▪ Provide creep compensation
3. Solder Pads
▪ Solder wires to gage
4. Fiducials
▪ Assist w/ gage alignment
5. Backing
4
3
1
2
5
▪ Insulates and support foil
▪ Bonded to flexure Parts of a strain gage
11. Linear
Measure strain under bending
Mini Beam (MB Cells)
Shear
Measure strain under shear
Low Profile cells
Poisson
Measure strain under normal stress
2100 Series Column cells
Chevron
Measure strain under torsion
5400 Series flange cells
12. Identical gages
Half in tension
Half in compression
Gage resistance varies:
Increases under tension
Decreases under compression
13. Wire under tension strains:
Cross section decreases
Decreased current flow
Increased electrical resistance
Wire under compression strains:
Cross section increases
Increased current flow
Decreased electrical resistance
14. No deflection in gage area
Designed to be weakest section
Gage
Areas
Low Profile Load Cell Section View
15. Deforms under load
Shear stress concentration
Compression Tension
Strain lines in gage area
(Not to scale)
16. Grid lines parallel to strain lines
Gage is under tension
Resistance increases
Shear gage under tension
17. Grid lines perpendicular to strain lines
Gage is under compression
Resistance decreases
Gage under compression
19. Proprietary Interface foil strain gages are thermally
matched to the load cell material.
As a result our load cells do not require modulus
compensation resistors.
This allows for far superior temperature
performance along with higher output (typically
4mV/V) at lower mechanical strain levels.
Higher output means higher resolution and better
signal-to-noise ratio.
20. Reduces force measurement
errors due to eccentric loads
Performed by
Loading cell eccentrically
Rotating load
Recording output signal
Compensating to
minimize errors
Moment Setup
23. Reduces force measurement
errors due to ambient
temperature changes
Performed by
Recording output signal
▪ Cold – Hot (15 – 115F)
Under a No-Load condition
Adding compensating wire to
minimize temperature induced errors
24.
25. Performed to verify
load cell meets
performance parameters
Hysteresis
Non-linearity
Static Error Band
Calibration Setup