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.

1. Interface Webinar Wednesday
Load Cells 101
with Albert Luna

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

5. Bending Beam
Dual Bending Beam
Column Style

6. S-Beam
Load Button

7. Hub
Strain Gage
Mounting Ring
Interconnecting Wires
Base
Diaphragm Inner Load Ring Outer Load Ring
Connector
Gage Cavity

8. Flexure
 Load bearing component
 Deflects under load
Strain Gages
 Measure strain of flexure
 Form load cell’s electrical circuit
using a Wheatstone bridge
Low Profile Flexure
Flexure deformation
changes gage resistance Strain Gage

9. Construction materials:
 2024 aluminum
 E4340 steel
 17-4 PH SS
Design considerations:
 Beam Thickness
 Beam Height
Beam functions:
 Stress Concentration
 Gage bonding location
Beam Thickness
Beam Height

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

18. Positive Signal Negative Signal

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

21. 280.0
278.0
276.0
274.0
272.0
270.0
268.0
266.0
Output Signal (Uncompensated)
0 45 90 135 180 225 270 315 360
Output (μV/V)
Rotation (Degrees)

22. 222.5
222.0
221.5
221.0
220.5
220.0
219.5
219.0
Output Signal (Compensated)
0 45 90 135 180 225 270 315 360
Output (μV/V)
Rotation (Degrees)

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

25. Performed to verify
load cell meets
performance parameters
 Hysteresis
 Non-linearity
 Static Error Band
Calibration Setup

32. Questions?

33. Thank You!