What is FMSS Technology?

Thayer Scale’s proprietary Force Measurement Suspension System (FMSS) is an interposed active structure, consisting of one or more articulated members, placed between the load receptor (hopper, platform, weigh suspension, etc.) and a load cell. FMSS functions as a force filter; it discriminates between net load measurement forces and all other undesirable extraneous forces. In standard weighing systems, load cells often interpret vibration as weight variation. FMSS technology makes load cells virtually immune to the detrimental effects of vibration.

We employ FMSS in the following designs:

  • Constant sensitivity platforms (flexure and cable scales)
  • Graded sensitivity weighbridges (conveyor belt scales)
  • Lateral torque transmitting devices (Model D)

FMSS enables:

1) Adjustable mechanical tare balancing of dead loads (typically as high as 200 times net loads) to maximize measurement signal

  • Reduces signal transmission problems
  • Enhances zero temperature stability
  • Reduces susceptibility to moisture migration
  • Lessens dependency on high-quality terminal connections
  • Sums all load forces to one load cell, simplifying troubleshooting and reducing costs

2) Significantly-reduced load receptor deflection

  • Desensitizes belt tension effects (conveyer belts and weigh scales)
  • Desensitizes inlet/outlet flexible connections and weigh loops wiring (loss-in-weight feeders)

3) Reduced zero-shifting as a result of foundation distortion

  • Substantial zero-shifts can occur if a structure’s supporting frame yields under load or settles over time. Loss-in-weight feeders and belt scales mounted to conveyor stringers are particularly sensitive to foundation distortion.

4) Accessibility for load cell inspection or removal

  • Leaves load cell undisturbed during inspections
  • Expedites realignment and removal, reducing downtime

5) Simplified test weight application for calibration

  • Provides remote tracking and reporting of weight storage and application
  • A test weight calibration is always part of the FMSS system. (A resistor calibration is never used on Thayer scales.)

6) Lower signal velocity and acceleration under dynamic conditions

  • Enables accurate conveyer weighing at speeds in excess of 1,000 feet per minute on conveyor belt scales

Load Cell Utilization Factor

The performance of a load cell and its associated instrumentation is determined by the load cell’s rated output. The load cell utilization factor is the percentage of a load cell’s rated output that is available for actually weighing material. If the load cell is supporting dead weight (i.e., hopper, screw feeder) the output left to weigh material is only a fraction of the load cell’s total rated output. The limited availability of conventional load cell capabilities further diminishes a load cell’s performance.

As a result, the load cell utilization factor can often fall to as low as 20 percent, resulting in drift, non-repeatability, and temperature-induced weight shifts that can be as much as five times the value specified by the load cell supplier.

Thayer Scale maximizes the load cell utilization factor on many applications by:

  • Custom-building our LVDT-based load cells with capacity ranges that step up in fine increments
  • Choosing a load cell that will have a range ideally suited to the service it will perform
  • Combining the load cell with our cable suspension system, which mass counterbalances the dead load of the hopper and feeder
  • Sizing the load cell for the maximum measurement of the net load, while still enabling overload protection for the system
  • Using strain gauge load cells with utilization greater than or equal to 65 percent in most, if not all, applications

Thayer’s FMSS technology also increases overload capacity when using strain gauge load cells.

FMSS Configurations

Thayer Scale is well known for proprietary flexure plate and flexure cable force measurement suspension systems, and multiple-idler belt scales that benefit from FMSS. These systems ensure accuracy, repeatability, and maintenance of scale zero; they are available in an array of capacity ranges and configurations to accommodate our customers’ unique requirements and needs.