An In-depth Guide to Scale Service and Calibration

scale service and certification check being done to a truck scale

Industrial weighing scales are central to everyday operations in different sectors worldwide. From counting bolts and nuts in factories to weighing cargo in shipyards, the potential uses of weighing scales vary widely.

Industrial scales often go through repeated loading and unloading. Coupled with everyday wear and fluctuating environmental factors, the efficiency of the weighing scale may decrease over time.

Profitability, reputation, legal compliance, and client satisfaction depend on your weighing scale’s accuracy. Regular scale service and maintenance can help improve your scale’s accuracy and reliability. Here is a complete guide to different industrial scales and how you can benefit from professional scale calibration.

What Are the Different Types of Weighing Scales?

Indian man getting ready to weigh coffee beans on an industrial scale.

Industrial scales determine the weight of an object by measuring the force needed to stop its downward acceleration due to gravity. Digital and mechanical scales are the main categories from which many weighing scales are derived. Mechanical weighing scales often use a spring system with a moving dial to indicate the object’s weight.

Digital scales utilize a unique electrical circuit to determine the weight of an object. Upon placing the object, the voltage flowing in the circuit fluctuates, and a processor converts the fluctuation to a weight reading. Your choice of weighing scale depends on your industry type, bulkiness, working conditions, desired capacity, and scale service needs.

A few of the most notable weighing scales derived from the two main categories include:

Vehicle Scales

Vehicle or truck scales help to weigh heavy vehicles and the loads carried at toll stations. These scales help companies calculate the net and gross weight of courier trucks. The readings are crucial to calculating taxes or duty fees that impact the product’s final selling price. 

Truck scales mainly comprise a deck, foundation, weighbridge, indicator, junction boxes, and load cells. Each part comes in various materials and forms depending on your environment and weighing needs. Vehicle scales are available in either surface-mounted or pit-mounted models on steel and concrete platforms.

Steel Platform Vehicle Scale

The steel deck truck scale uses heavy-duty structured steel in the form of I-beams running the entire model length. Depending on the manufacturer, your I-beam design and structure may vary in shape, size, and number. This truck scale variety has a lower initial investment cost as it is lighter and much easier to relocate when the need arises.

The steel platform modules are easy to lift, allowing quick and regular scale repair and calibration services. With no concrete curing time required, you can expect timely installation and resumption of operations. The scale surface can, however, get slippery during wet conditions.

Concrete Platform Vehicle Scale

Each scale module in concrete platform vehicle scales has an open top for pouring concrete. The concrete takes about 21 to 28 days to cure and bond with the support beam in each module. The concrete provides excellent resistance to corrosion by rock salt used to de-winterizing roads. They require less scale repair than steel platforms and have a longer scale life.

The concrete surface further offers improved traction during wet or snowy days. Their design also allows for better weight distribution over a wide area. They take a longer installation time than the steel scales as the curing process helps them acquire the appropriate Pound Per Square Inch (PSI) strength. However, each panel is heavier than the standard steel platform scale module. They are thus less portable and more technical to subject to calibration services.

Railroad Track Scales

Railroad scales or rail car scales are another common industrial weighing scale. They play a crucial role in different parts of railroad operations, including preventing overloading penalties and monitoring the delivery of goods.

This weighing scale can assess the cargo’s weight when in motion or stationary. You can install the scale directly onto the railroad track temporarily or permanently.

Floor Scales

Floor scales are broad flat scales that are in direct contact with the floor. They can withstand shock overloading and tough conditions like warehouses where forklifts with loads can easily roll over the scale.

Bench Scales

This commercial scale is commonly used on a tabletop or bench.

The scale is compact, enabling easy portability and use in tight spaces. You can find bench scales in packaging or chemical handling setups like factories or pharmaceuticals. The weighing scale can come as a single bench base with a separate weight indicator or an all-inclusive unit with an inbuilt weight display.

Counting Scales

These scales can uniquely and efficiently count many similar objects. The counting weighing scales have extra features that allow them to assess the mean weight of an item and calculate the total count of items present. Counting scales need regular scale service calibration to accurately weigh tiny parts like screws, washers, and bolts.

Checkweigher Scales

A scale with check weighing functionality is common in production lines to ensure the product’s weight falls within the recommended range. The in-motion or static scale helps to ensure client satisfaction by detecting underweight products. You also avoid wasting excess raw material on overweight packages. Regular maintenance through scale services can help maintain the accuracy of your checkweigher scale.

Overhead Rail Scales

This weighing scale comprises an overhead conveyor system where the object hangs on during the weighing process.

Overhead rail scales are common in foundries for weighing molten metal-laden carts and meat processing factories. They have a robust build that allows for long-te use with minimal disruption.

Pallet Truck Scale

Product palletization involves stacking large volumes of similar products into a pallet before shipping. The products are arranged according to weight to promote product integrity and stability.

Pallet truck scales allow you to weigh and move palletized items in one swoop. Utilizing this scale eliminates the extra step of weighing your products on a floor scale and improves operational efficiency.

Crane Scales

Crane scales are crucial to the transport and manufacturing sector for weighing cargo. You need to know the exact weight of the goods you’re transporting by ship, train, or plane, as it may alter the freight’s weight distribution.

Failure to accurately monitor your cargo’s weight may endanger the crew and the rest of your shipment.

What Is Scale Calibration?

The scale calibration process takes place under regulated conditions to establish a relationship with a standardized set of calibration weights. It involves testing your weighing scale to determine its level of accuracy. Even the highest grade of industrial scales doesn’t remain accurate over an extended duration. Inaccuracy in your scales can arise from exposure to electrical shock and environmental factors like moisture, metal chips, soil particles, and oils.

Inaccurate readings can result in quality inconsistencies, ditched batches, and batch recalls. When weight readings don’t match up, you need to restore the scale’s accuracy to the required calibration tolerance. 

What Are the Main Types of Scale Calibration?

Factory, external and internal scale settings make up the main types of scale calibration.

Factory Scale Calibration

Weighing scales come with a default factory calibration at the time of purchase. After production, the industrial scale is calibrated at the factory before sale or initial use. Before you can assume the weighing scale is ready for use, remember the production factory and your factory have different prevailing conditions. You need expert on-site scale calibration to confirm your unit’s accuracy.

External Scale Calibration

Many industries hire a calibration service technician to calibrate their units regularly. You can achieve proper scale calibration with the help of a professional scale service provider like American Scale.

The scale service provider will use a certified calibration weight to assess the accuracy of your industrial scale. If the readings for the certified weights match calibration tolerance standards, your scales don’t need repair. When the readings don’t match, your weighing scales need correction to achieve appropriate accuracy.

Scale service repairs often occur at the use site to mimic the mechanical vibrations and airflow disruptions that can contribute to weighing errors. The scale service technician usually turns on the weighing scale a few minutes before testing. 

This step allows the devices’ internal mechanics to warm up before taking any readings. The standard calibration weights are usually handled with gloves or forceps to prevent residue or oil from the technician’s hand from sticking and changing its mass.

Internal Scale Calibration

You can have your internal expert perform an in-house scale repair at set intervals throughout the day to ensure accuracy. There are weighing scale units with an internal calibration feature that helps users perform self-calibration. It has a built-in system of motor-driven calibration weights that allow the user to make alterations whenever needed. Still, it doesn’t fully calibrate your weighing scale, which calls for periodic external scale services.

How Does Scale Calibration Differ From Scale Adjustment?

Scale calibration and scale adjustment are sometimes used interchangeably but have different meanings. Both help improve your weighing scale’s accuracy but differ in the procedure used to achieve it. Weighing scale calibration helps you to understand how your unit behaves, while scale adjustment alters the behavior of your scale.

Adjusting your scale will involve modification to meet prescribed value readings. Some weighing scales don’t require any adjustment as long as test readings fall within the industrial scale’s tolerance.

What Is Scale Calibration Tolerance?

The calibration tolerance refers to the allowable deviation from a specified value. The tolerances are available as absolute values or as a percentage of the reference point. In an ideal setting, all readings should exactly match your nominal or standard reading. 

The calibration tolerance provides a range within which your scale can measure without affecting your business negatively. Manufacturers often specify their scale’s tolerance in the accompanying tolerance guide.

How to calculate calibration tolerance formula with icon of a scale weighing weights

Which Tests Happen During Scale Calibration?

The tests done during scale service calibration may vary according to the industry, application, and regulation. The calibration method also depends on the manufacturer’s specifications, as some units allow for custom calibrations.

Most weighing scales can measure loads within a specific range of weight called the instrument range. The calibration range is defined from zero to a maximum weight to help ensure accurate scale repair. The most common range calibration tests include:

  • Span Calibration: One of the simplest calibration methods involves using a custom weight to determine the maximum capacity of your weighing scale.
  • Linearity Calibration: A variation of the span calibration where your scale service provider uses a standard weight to determine the scale’s midpoint as an additional reference point.
  • Minimum Weight Calibration: In this calibration test, your scale service provider aims to determine the smallest load needed to deliver acceptable readings. The test is common in pharmaceutical labs where smaller loads have a higher relative error.
  • Weighing Test: In this test, your scale service provider will take readings at multiple points within the given calibration range.
  • Eccentric Test: This calibration test measures your standard weight at several predetermined points on the weighing receptor. The test helps to determine if you get similar readings regardless of load placement.
  • Repeatability Test: A custom weight is placed multiple times on a fixed point on the weighing receptor during calibration to check for accuracy.

What Is a Legal-for-Trade Calibration and Why Do You Need One?

Commercial weighing scales require legal-for-trade calibration to meet established standard measures. The specified tolerances and technical requirements are in the annual Handbook 44 publication by the National Institute of Standards and Technology (NIST). Any enterprise that uses weighing scales to calculate the price of their commodity needs a legal-for-trade calibration.

Commercial scale owners need periodic scale service repairs to avoid any operation downtimes. Special state inspectors regularly evaluate weights and measures to identify scales with inappropriate calibrations. Any scale out of the acceptable tolerance range is marked and taken out of service.

When and How Often Do You Need Scale Services?

The proper time to calibrate your industrial scale will vary depending on various factors. Some scales are calibrated annually, monthly, and even daily. The manufacturer’s indications are a key factor to consider as they’ve tried and tested their product long enough to identify its limitations. 

Weighing scales under constant use are more subject to wear and tear. These scales end up needing regular spot checks to ensure proper quality control. The prevailing environmental conditions are another key factor. 

Areas with dust and fluid particles are more likely to develop clogs in their internal mechanics and demand regular scale services. Frequent mechanical vibrations may cause static electricity to build up and disrupt your scale’s electrical circuitry.

What Are the Benefits of Scale Calibration?

Digital display showing the reading from an industrial scale being calibrated.

The key benefits derived from scheduled scale services include:

Improved Accuracy

Regular scale calibration minimizes deviation from approved weighing standards. Industries involving mixing processes like recipe-based enterprises depend on weighing equipment to achieve quality products. They can benefit tremendously from maintaining a high level of accuracy through regular scale services.

Avoiding Legal Action

Potential legal problems can arise from inaccurately weighed products. Clients can lodge complaints when they suspect measurement inaccuracies, which may lead to hefty lawyer fees, financial penalties, and a damaged reputation. Scale inconsistencies also have serious legal implications in the shipping industry, where strict regulations on proper weight compliance exist.

Cutting Costs

Proper scale calibration in industrial weighing can help you avoid potential wastage and product recall. You also avoid extra transit and shipping charges from incorrectly weighed packages and containers.

Maintaining Uniformity and Compatibility

Product quantity and quality variations can arise with poor scale maintenance when your business utilizes more than one industrial scale. With the help of a professional scale service provider, you can prevent inaccurate data and ensure product uniformity.

Ensuring Product Safety

Your products must meet specific standards to ensure the client’s safety. Food products, for instance, need a delicate balance of ingredients. Adding excess ingredients to a mixture due to poor scale calibration may break food safety regulations.

In healthcare, a patient’s weight can point to underlying severe health concerns in the medical industry. It also provides a basis for administering treatment and monitoring recovery. Proper scale calibration can allow health service providers to identify subtle warning signs through weight changes seen in diseases like cancer.

Laboratory weighing scales with inaccurate measurements can result in medical products with imprecise chemical compositions. Medical professionals may end up administering ineffective treatment regimens. Professional scale services can help prevent these unfortunate possibilities.

Enabling ISO Certification

Having scheduled scale calibrations can help companies maintain authenticity and meet ISO certification. Laboratories seeking to hold ISO 17025 certification need credible scale service and calibration.

Choose American Scale’s Calibration Services

American scale test truck performing a test scale calibration on a truck scale in winter.

Industrial weighing scales need regular professional scale calibration to remain within the approved tolerances. A dependable weighing scale helps you avoid legal risks, minimize extra costs, and promote client satisfaction. American Scale can guarantee accuracy in all your weighing demands by providing top-notch scale repair and calibrations.

We use NIST-approved weight calibrations to evaluate different types of weighing scales accurately. Our calibration services come with certification upon completion of scale maintenance. Contact us today to leverage our scale service expertise.