washer load cell

The sensor works like a precision spacer. It’s a ring of high-strength steel with strain gauges attached inside. When you tighten the bolt, the washer gets squeezed, deforming just a few micrometers. The strain gauges detect that tiny compression and convert it into an electrical signal. Kingmach designs the washer so that the deformation stays within the elastic range of the steel, meaning the sensor returns to zero when loosened. The output is linear with force, so you can easily convert millivolts to kilonewtons using the calibration sheet we provide.

Most projects need an accuracy between 0.5% and 1% of full scale, which is typical for this type of sensor. Kingmach’s standard production achieves 0.5% FS linearity and hysteresis, but we can improve that with a special calibration run if your application demands it. Every unit ships with a calibration certificate traceable to national standards, so you have the data for your acceptance tests or compliance documentation.

Yes. We seal the sensor against moisture and dust, usually to IP67, which handles temporary submersion and heavy rain. For permanent underwater use, we offer models with welded covers and subsea connectors, tested to deeper depths. The standard cable is also shielded for industrial environments. Just let us know the corrosion risks, and we’ll select the right material—typically 17-4 PH stainless, but duplex stainless is available for marine settings.

Start with your bolt’s nominal diameter and the available space. The washer load cell needs a flat, rigid surface to seat against. The inner hole must clear the bolt threads, and the outer diameter must fit within the nut’s bearing area or under the bolt head. Kingmach offers a range from 1/2” to 3” bolt sizes and can machine custom dimensions if you’re using metric or extra-large fasteners. We recommend a thickness that keeps the sensor’s strain level within its optimal range for the target load, which we can help calculate.

The base sensor gives a millivolt-per-volt signal, so you’ll need an amplifier or data logger that handles strain gauge inputs. We also build versions with an integrated mini-amplifier, providing a conditioned output like 4-20 mA, 0-5 V, or 0-10 V. That makes wiring easier on construction sites or when connecting to PLCs. For wireless monitoring, we can recommend compatible transmitters from our partners.