The modern force gauge we are discussing here is the portable strain gauge based instrument with a digital display of the measured force. These instruments allow the user to select the unit of measure for force, with the Newton being the most popular. While these devices are not of the laboratory precision, modern strain gauge technology is quite accurate enough for production testing and quality control work. In point of fact, they are accurate enough for most product development work.
Most force gauges are offered in a form that allows them to be used with external strain gauges, or with their own built in strain gauge.  The external strain gauge feature allows for great flexibility in both the range of force the unit can measure, as well as, the type of force it can measure. The external strain gauge can be configured to measure torque, which is the result of a force applied at a distance in a rotary fashion and is measured in units like foot-pounds. This is an important measurement of output in some rotary devices.

These devices can measure weight which is the force produced by the earth’s gravitational field operating on a mass.  An adapter of some sort is required to allow the force to act in a vertical direction to maximize the force vector.  All of the rules of metrology apply and must be observed in order to produce accurate results.  The acceleration of gravity varies with locations in a significant way, even for strain gauge type measurements.  Altitude has a large effect.  It is required to calibrate the force gauge using a high precision weight to compensate for the local value of gravitational acceleration.
There are a myriad of applications where force gauges are the tool of choice for quality testing and production control, as well as, in design and development. A good example is in materials testing.  The range of applications in this one area go from Concrete testing, paper and pulp shear testing, prosthetic testing (including product life), tension testing of cables, hardness testing, and loads of medical testing applications. Hardness testing is a good illustration of an area where special adapters are required.  In many hardness tests a pointed (shaped) adapter is pushed into the test material until a specified force is reached. The degree of linear penetration of the tip is a measure of the materials hardness.  A plot of penetration versus applied force can reveal a great deal about the material being tested.  The adapter provides the force and measures the penetration, the force gauge measures the force.

Think of the many applications where force is used to activate something and that force must be within defined limits.  Things like computer keyboards, telephones, touch screens, handles, microwave oven door releases, toaster slides, Velcro closures, and many, many other everyday items all need production control testing and QC testing. The force gauge plays a bigger role in your life than you think.