When it comes to weighing equipment, accuracy, reliability, and cost all hinge on one factor most buyers overlook: the underlying technology used in the scale.
Whether you’re managing a warehouse, formulating chemicals, or tracking production yield, the type of scale you choose can impact your bottom line. Yet most decision-makers still rely on outdated or oversimplified comparisons — digital vs. mechanical, lab vs. industrial — without understanding the real trade-offs behind each weighing method.
In this guide, we’ll break down the three main types of scale technology:
- Strain Gauge – the workhorse of industrial weighing
- Force Motor – a high-precision but high-cost option
- SAW (Surface Acoustic Wave) – Arlyn’s ultra-precision solution built for today’s industrial needs
We’ll explain how each works, when to use them, and how to pick the right scale for your environment and accuracy requirements.
Strain Gauge Load Cell Scales
Strain gauge technology is the most widely used method for industrial and commercial weighing. These scales strike a balance between affordability, mechanical simplicity, and acceptable accuracy — making them the go-to choice in warehouses, shipping departments, and basic production environments.
How It Works
A strain gauge scale measures weight by detecting the deformation (strain) of a spring element called a load cell. Here’s how it functions:
- Strain gauges—thin resistive elements—are bonded to the load cell.
- When weight is applied, the load cell bends slightly, causing the gauges to stretch or compress.
- This change alters their electrical resistance, which is measured through a Wheatstone bridge circuit.
- That resistance is converted into a voltage, then digitized via an Analog-to-Digital Converter (ADC) and shown as a weight reading.
This process allows for quick and reasonably accurate measurements across a wide range of capacities.
Strengths
- Affordable and widely available
- Simple design with few moving parts
- Good enough for many industrial and commercial applications
- Easy to maintain and replace
Limitations
Despite their popularity, strain gauge scales come with several inherent accuracy constraints:
- Resolution drops as capacity increases: A high-capacity strain gauge scale (e.g., 1,000 lb) may only measure in 0.5–1 lb increments.
- Temperature sensitivity: Fluctuations can distort readings due to changes in electrical resistance.
- Non-ideal load cell behavior: Real-world springs don’t return to the exact same position every time, introducing small but important errors.
- Imperfect adhesion: Even microscopic inconsistencies in the glue that bonds the strain gauge to the load cell can impact accuracy.
ADC conversion noise: The transition from analog to digital adds signal loss and rounding errors.
Best For
- Warehousing and logistics
- Shipping and receiving
- Basic production or batching
- Applications where ±1% accuracy is acceptable
Force Motor (Electromagnetic) Scales
Force motor, or electromagnetic force restoration (EMFR), scales were developed to meet the needs of labs and applications demanding extremely high precision at low capacities. While they offer impressive accuracy, these scales come with notable trade-offs in cost, complexity, and capacity limits.
How It Works
Force motor scales measure weight using electromagnetic force instead of physical deformation. The system works like this:
- A lever and fulcrum support the weighing platform.
- A force coil on the other end sits inside a magnetic field.
- When weight is added, the system uses an electrical current to rebalance the platform.
- The amount of current required is directly proportional to the object’s weight.
- A microprocessor converts this current into a digital weight reading.
This method avoids mechanical strain, allowing for highly accurate, repeatable readings.
Strengths
- Extremely high precision (up to 1:500,000 readability)
- Ideal for lab-grade weighing under 25 lbs
- Excellent linearity and repeatability
- Often used in scientific environments
Limitations
- High cost due to complex electromagnetic design
- Frequent recalibration required (sometimes daily)
- Capacity limits: Most models max out at 25–30 lbs
- Environmental sensitivity: Temperature fluctuations, dust, and vibration can impact accuracy
- Not rugged — prone to damage if used in industrial or high-vibration environments
Best For
- Research and development labs
- Pharmaceutical dosing
- Chemical formulation in clean environments
- High-precision QC under low load requirements
Ultra Precision SAW Scales
Developed by Arlyn Scales, SAW (Surface Acoustic Wave) technology represents a leap forward in weighing innovation. It delivers lab-level precision at industrial-level capacities — without the high cost or fragility of force motor systems.
How It Works
Instead of measuring force or strain, SAW scales measure time.
- A transmitter and receiver are embedded in a spring element.
- When weight is applied, the spring deforms slightly.
- This changes the distance the wave travels, and thus the transmission time.
- The system calculates the time change to determine weight with extreme precision.
- The result is a direct digital output, eliminating the need for analog signal conversion.
This method removes nearly all sources of error found in strain gauge and force motor designs.
Strengths
- Higher accuracy than strain gauge and often force motor (1:100,000–1:200,000)
- No strain-based error, bonding imperfections, or ADC drift
- Digital-native output ensures stable, noise-free readings
- Handles capacities from 5 lb to 1,000+ lb with ultra-fine resolution
- Requires minimal calibration and low maintenance
- Rugged enough for industrial environments
Best For
- Industrial environments needing lab-grade precision
- Ink and dye formulation
- Precious metal weighing
- Parts counting
- Applications where precision + durability matter
Technology Recap: Which One Should You Choose?
Choosing the right scale technology depends on your accuracy requirements, capacity range, environment, and budget. Here’s a quick decision guide to help you choose:
Use This If You Need:
Strain Gauge
- You want a cost-effective, general-purpose scale for shipping, warehousing, or batching with ±1% tolerance.
- You don’t require ultra-fine resolution and need something simple and rugged.
Force Motor (Electromagnetic)
- You need ultra-high accuracy (up to 1:500,000) and are weighing items under 25 lb in a clean, controlled environment.
- Ideal for labs, pharmaceuticals, or formulation — but expect high costs and frequent recalibration.
SAW (Surface Acoustic Wave)
- You need high precision at higher capacities, like 100–1,000+ lbs.
- You work in a production or industrial setting but can’t compromise on accuracy.
- You want long-term reliability, minimal maintenance, and better ROI.
Still unsure? Contact our team and we’ll help you choose the best fit based on your specific application.
Digital vs. Mechanical Scales: What’s the Difference?
Before diving into advanced scale technologies, it’s worth clearing up a common misconception: digital vs. mechanical isn’t the same as precision vs. basic.
Mechanical Scales
- Operate using springs, levers, and dials
Do not require power
Simpler to use but offer lower resolution - Common in household and low-stakes industrial settings
Example: Spring scales at produce stands or luggage scales
Digital Scales
- Use electronic sensors (like strain gauge, force motor, or SAW)
- Offer higher accuracy, digital displays, and often connectivity features
- Can be used for industrial, commercial, or scientific purposes
- Require power, usually via battery or wall outlet
Important: All three scale types covered in this article (Strain Gauge, Force Motor, SAW) are forms of digital scale technology. The difference lies in how they measure weight — not whether the output is digital.
Frequently Asked Questions
What is the difference between strain gauge and force motor scales?
Are SAW scales better than strain gauge or force motor scales?
Why do strain gauge scales lose accuracy at higher capacities?
How often should I calibrate my digital scale?
Why are force motor scales so expensive?
Ready to Upgrade Your Weighing Technology?
At Arlyn Scales, we believe you shouldn’t have to choose between accuracy, capacity, and cost. Our ultra-precision SAW scales deliver lab-grade performance in industrial settings — without the high maintenance of force motor designs or the limitations of strain gauge systems.
- Better accuracy
- Higher capacity options
- Lower total cost of ownership
- Built and supported in the USA
Contact us today to get a recommendation based on your use case, or explore our full line of Ultra Precision Scales to find the right model for your application.
