CALIBRATION OF WEIGHBRIDGE

Maintaining accurate weight data is critical for business of all sizes, whether you are small business which relies on accurate weight to sell products or a large cooperation which keeps all its employees and products to track, weighbridge calibration is essential.

In this blog post we’ll discuss about legal requirement, what is weighbridge calibration, process and requirements of weighbridge calibration.

Legal Requirement:

If you’re using your weighbridge for trade purposes, there is a legal requirement to ensure your weighbridge meets the stated accuracy (within certain tolerances) at all times.  Anyone operating a weighbridge would be strongly advised to have it calibrated every 12 months to ensure compliance.

If a weighbridge is not calibrated at regular interval, it will be inaccurate by a percentage. For example a weighbridge may be low by 50kg when a 1 tone weight is placed on the scales, but when 10 tones are placed on the scales it will not read 9950kg. Instead, it will read 9500kg because the scale is reading 5% too low.

What is weighbridge calibration:

Calibration is the process of ensuring that a measuring instrument’s performance matches the standard of known or traceable accuracy; the measurement error is the difference between the measured value (the reading) and the correct value (the reference weight).

A set of weights ranging from weight equal to maximum capacity of the weighing machine to weight equal to the minimum reading indicated by the weighing machine is placed on the weighing machine one by one and the reading is noted simultaneously. The change in indication of reading is noted simultaneously after placing each weight, from maximum to minimum.

Weights are again placed on the weighing machine, this time from minimum to maximum capacity and change in indication is noted. Indication error is calculated. Following the series of calculations uncertainty of the weighing machine is calculated.

Benefits of weighbridge calibration:

Weighbridge calibration is critical to achieve accurate weighing results. the life of your weighbridge and its weighing accuracy is greatly prolonged when combined with periodic calibration and frequent routine testing. 

Calibration performed by an authorized calibration provider using accurate reference standards ensures that the weight measurements will be accurate thus improving industrial process and therefore increases profitability.

Metrological requirements for reference standards used to calibrate the weighbridges:

The maximum permissible error of the Standard weight used to calibrate the weighing machine must not exceed one third of the maximum permissible error for the corresponding load considered on the weighing balance under verification. This is minimum requirement for calibration of the weighing balance.

The standard weight must be coated with materials suitable for providing protection against the corrosion.

Why chose our reference standards for calibration of weighbridges:

We here in Shanker Wire Products Industries (S.W.P.I.) produce 100 kg to 1000 kg high denominational weights as per OIML R 47, in all OIML accuracy class. Our Laboratory is NABL accredited in accordance with ISO/IEC 17025. We deliver NABL certificates of Calibration covering the basic reporting of conventional mass correction, uncertainty and traceability of standards.

Calibration Measurement Capability (CMC) of our 1000 kg weight is 6.102 g in M1 accuracy which is one of the best in India.

This standard weights are used for testing (and adjusting) of high capacity weighing machines in medium or ordinary accuracy class.

To find out more about our  standard weights Please get in touch

Calibration Weights

Standard Weights Easily fork-lifted to be placed on scales

Calibration Weights and test weights are standardized masses certified by international, national, or industrial laboratories, such as NIST, ANSI, ASTM, or ISO. Each weight has a precise mass that makes it suitable for calibrating scales to ensure subsequent weight measurements are accurate. Documents often accompany calibration and test weights to guarantee they meet the standard body’s specifications for properties such as tolerance, material, surface finishing, design, cavities, and adjustments. Units of measurement are typically based on the kilogram, but other units are designated.

Calibration and test weights calibrate scales, balances, weight cells and other masses or weights. Weights are often accredited for certain applications, with those used in scientific settings held to higher benchmarks than those used for commercial or industrial uses, such as materials testing, material handling equipment load evaluation, pressure generation on deadweight testers, and cable testing.

ISO/IEC 17025: The International Organization for Standardization (ISO) is an independent non-governmental organization comprising a membership of 164 national standards bodies. The International Electrochemical Commission (IEC) is an international standards organization for electrotechnical fields. Together with other liaison organizations, they created the ISO/IEC 17025 standards. This is the international reference to be used by testing and calibration laboratories that want to display their ability to provide reliable results.

Calibration Weights for precision value

Calibration Weights

Re: Hanger and slotted Weights for Torsional stiffness set up Bigger size cycloids

From: Moses David Francis Samuel <fmosesdavid@eppinger-gears.com> on Fri, 02 Sep 2022 17:26:56 Add to address bookTo: You | See Details

Hello Mr. Singhania ,

Good day , Just today I have received the Orders slotted weights and hangers .

I was not in a comfortable position till I open the packages, even with your confident communication due to my worst experience with other suppliers.

On opening the package I was extremely satisfied , as the packaging , the marking , painting finish and the quality was 100% beyond expectation .

Really appreciate the workmanship and you kept you word in maintaining Quality at its best .

Much impressed and looking forward for more business with you. I would love to recommend you to fellow industry people.

Regards / Mit freundlichen Grüßen

Moses David F

Asst.Manager Gearbox Assembly

Eppinger Tooling Asia Pvt Ltd

SF No 345/2A-2B ,Kondampatty Village ,

KinathuKadavu,Pollachi Taluk,

Coimbatore 641202

Tel :         +91 4259-201148

Mobile : +91 73977 85848

Mail:        fmosesdavid@eppinger-gears.com

 Web:       www.eppinger.de

Calibration Weights for Scales & Balances

SWPI‘s world-leading expertise in metrology extends to Calibration Weights or Test weights, weight sets. Our weight portfolio covers weights according to OIML from fifty micrograms to one ton in all accuracy classes. Our test weights are used all over the world, not only for testing balances but also as primary standards in mass laboratories.

Calibrating Scale: Premium-quality weights to satisfy stringent testing requirements

Calibrating scale testing requirements have become more complex, requiring that the scales survive years of use in rough industrial environments. Ensuring scale calibration is key to extremely accurate and efficient production using a fully calibrated scale. Test weights for scales are important tools for weighing scale calibration.

If a scale is not calibrated, it can significantly cost a company financially, and even worse, it can damage its reputation. SWPI’s calibration Weights are perfectly designed to support testing and calibration of industrial scales. With a strong engineering focus on safe and productive testing, cast-iron weights up to 1 ton is perfect for this application, satisfying even the most stringent testing requirements. These test weights are available in different shapes and accuracy classes to ensure proper scale calibration and scale recalibration.

FAQ’s on Test Weights

1. What are calibration weights for balances?

Weights are predominantly needed for performance tests and routine testing of balances and scales. In metrological terminology, a distinction is made between reference weights or “mass standards” (to calibrate other weights) and certified weights. National regulations and international recommendations define the error limits of certified weights. Weights are classified into tolerance limits which are defined either by OIML or ASTM. The conventional weight value (and not the mass) is used as the nominal value of the weight. For a high level of accuracy, certified weights are calibrated and traceable back to primary standards, which are usually national standards maintained by a National Metrology Institute (NMI).

2. What are OIML and ASTM calibration weight classes?

Weight classes are separated according to the error limits that are classified either according to OIML (International Organization of Legal Metrology) or ASTM (American Society for Testing and Materials) declarations as follows.

The OIML weight

  • Class E1 weights are intended to ensure traceability between national mass standards and weights of class E2 and lower (i.e. F1 and F2). Class E1 weights or weight sets shall be accompanied by a calibration certificate.
  • Class E2 weights are intended for use in the initial verification of class F1 weights and for use with weighing instruments of accuracy class I. Class E2 weights or weight sets shall always be accompanied by a calibration certificate. They may be used as class E1 weights if they comply with the requirements for surface roughness and magnetic susceptibility and magnetization for class E1 weights (and their calibration certificate gives the appropriate data).
  • Class F1 weights are intended for use in the initial verification of class F2 weights and for use with weighing instruments of accuracy class I and class II.
  • Class F2 weights are intended for use in the initial verification of class M1 and possibly class M2 weights. They are also intended for use in important commercial transactions (e.g. precious metals and stones) on weighing instruments of accuracy class II.
  • Class M1 weights are intended for use in the initial verification of class M2 weights and for use with weighing instruments of accuracy class III.
  • Class M2 weights are intended for use in the initial verification of class M3 weights and for use in general commercial transactions and with weighing instruments of accuracy class III.
  • Class M3 weights are intended for use with weighing instruments of accuracy class IIII.
  • Classes M3 and M2-3 are lower accuracy weights of 50 kg to 5 000 kg and are intended for use with weighing instruments of accuracy class III.*

*The error in a weight used for the verification of a weighing instrument shall not exceed one third of the maximum permissible error (MPE) for an instrument. These values are listed in section 3.7.1 of OIML International Recommendation 76 Non-automatic Weighing Instruments (1992).

ASTM Weight

  • ASTM Class 0: Used as primary reference standards for calibrating other reference standards and weights.
  • ASTM Class 1: Can be used as a reference standard in calibrating other weights and is appropriate for calibrating high-precision analytical balances with a readability as low as 0.1 mg to 0.01 mg.
  • ASTM Class 2: Appropriate for calibrating high-precision top loading balances with a readability as low as 0.01 g to 0.001 g.
  • ASTM Class 3: Appropriate for calibrating balances with moderate precision with a readability as low as 0.1 g to 0.01 g.
  • ASTM Class 4: For calibration of semi-analytical balances and for student use.
  • NIST Class F: Primarily used to test commercial weighing devices by state and local weights-and-measures officials, device installers and service technicians.

3. Why should I use certified calibration weights?

ASTM class 0 and ultra-class as well as OIML class “E0” and E1 should be used for the highest level of precision i.e. mass standards (calibrating other weights), micro-balance testing and calibration, and critical weighing applications.
ASTM classes 1 & 2 and OIML classes E2 & F1 should be used for precision applications i.e. analytical balance testing and calibration.
ASTM classes 3 & 4 and OIML classes F1 & F2 are best suited to top-loading balance calibrations and testing and moderate precision applications (laboratory non-critical).

Note: If a balance or scale is calibrated, the weight set used and the class must be documented.

4. Why / how often do I need to recalibrate my test weights?

Accurately calibrated test weights are the basis of accurate weighing results. The accuracy of test weights becomes less reliable over time. This is the result of normal wear and tear caused by regular use, dirt and dust. Periodic recalibration of test weights at an accredited mass-calibration laboratory is essential to ensure ongoing traceability. At our accredited mass-calibration laboratories, we clean, calibrate, and adjust each weight and then document the results in a calibration certificate. Our calibration services cover the basic reporting of conventional mass correction, uncertainty and traceability information in accordance with ISO/IEC 17025 requirements.

The frequency with which to recalibrate your test weights depends on the criticality of the weighing process. Selecting the correct test weight and weight class and also provides recommendations on how often to recalibrate your test weights. All of this information is determined based on your specific processes and risks. 

5. What are buoyancy artifacts?

Air density is usually calculated from relevant air parameters such as air temperature, pressure, humidity and CO2 concentration. An alternative method of determining air density may be applied by utilizing two specially designed buoyancy artifacts. Both artifacts are compared in vacuum and in air. By comparing the two artifacts of identical nominal weight, the large volume difference reflects the air buoyancy and therefore results in a highly accurate determination of air density. The buoyancy artifacts are mainly used for the M_one vacuum mass comparator.

6. Why is a silicon sphere used for specialized volume measurement?

Spheres are used because the volume can be determined according to the definition of volume by a length measurement. Silicon (Si) spheres have the same homogenous atomic structure as a perfect diamond without voids or dislocations, so the density is more accurate than other materials. This is why a silicon sphere with a homogenous atomic structure serves as a reference for specialized volume measurement.

7. What are heavy-capacity weights used for?

Mass comparators go up to a capacity of six tons. Industrial scales go up to several hundred tons. Heavy-capacity weights—typically those in the range of 100 kg, 200 kg, 500 kg, 1 t and 2 t are used for sensitivity, eccentricity, linearity and repeatability testing of these higher-capacity devices. Weights are less than 2 t due to the maximum lifting capability of machines, typically forklifts and cranes. However, these weights can be combined to reach the desired weight. Check out our range of heavy-capacity weights, Click here

Heavy-capacity weights must be transported in heavy-duty trucks and it is important to ensure trucks do not exceed their rated load limit due to safety and government regulations. Heavy-capacity weights are generally constructed of cast iron not stainless steel due to the cost.

8. What are calibrated test weights used for? Are they used to calibrate weight scale systems? Do you offer test weights for scales?

Calibration Weights are used in scale calibration. This is a process that ensures scale accuracy. Test weights for scales or precision weights are used to calibrate weight scale systems of various levels of accuracy depending on the use and requirements. Certified test weights or precision weights should be used in these processes to calibrate weight scale systems. It is important to ensure the test weights are calibrated test weights and that they are accurate to provide accurate calibration results. Check out our range of scale calibration weights, click here.

9. What is the weighing scale tolerance limit of any scale? Can all scales offer precision weights?

This is the required accuracy of the scale, and specifically the tolerance of inaccuracy allowed before it is out of tolerance and in need of a weigh scale calibration by certified calibration weights. A calibrated scale will operate at a higher level of accuracy and maintain tolerance better. For this reason, weight scale calibration with certified weights for keeping the weighing scale tolerance limit is key for accurate, calibrated scales and weigh scale calibration. Learn more about keeping your weighing scale tolerance limit in your weighing processes.

10. What are scale weights? Are they calibration weights for scales? Must they be certified weights?

Scale weights are weights for scale calibration. These weights for scale calibration may be certified weights. Generally, weights for scale calibration are certified. When calibrating scale procedures are performed, it is necessary to have calibration weights for scales. Weighing scale calibration with scale weights or test weights should be performed on a regular basis depending on use. Learn more about scale calibration weights and weigh scale calibration.

SWPI‘s world leading expertise in metrology extends to certified test weights, weight sets as well as calibration weights for scales. The weight portfolio covers scale weights according to OIML or ASTM from fifty micrograms to one ton in all accuracy classes. Our test weights are used all over the world, not only for testing balances but also as primary standards in mass laboratories. We invite you to learn more about our certified test weights and consider using them in your weighing scale calibration and weigh-scale calibration processes.

11. What are the differences between OIML classes?

The exact difference is explained in the OIML guideline, but at a basic level, E1 has the narrowest and M1 the highest tolerance limit, i.e. E1 is the most accurate.

12. Plus Tolerance

Weights are calibrated according to OIML maximum permissible errors (+/- in mg). If the result of the calibration is in the plus range, it means that the weight is heavier than the specified nominal value, but still within the tolerance. Since most weights lose weight over time due to wear, it is more likely that this weight will take longer to fall out of tolerance (maximum permissible error). Through our production processes, most of our weights are calibrated in the plus range.

13. How often do you need to re-calibrate your weights?

Depending on how often the weights are in use, weights should be re-calibrated every 1-2 years.

Calibration Weights

Dear Sir/Madam,

I am proud to be linked with you.


We, produce exclusively Cast Iron Weights since 1961. OIML appreciated our Weights in 1973. OIML recognized us as one of the supplier of Cast Iron Weights in their Guides (G 12 – Suppliers of verification equipment) published in Mars, 1987.


Manufacturing Cast Iron Weights as per OIML Recommendation is our specialty. We also manufacture as per design of buyer. Our range is 50g to 1000kg and 4-oz to 3000lb in all accuracy class.

We maintain quality of our products strictly as per International Standards with guaranteed accuracy. Our major production is being consumed by buyers from Germany, Canada, France, Australia, Netherlands, Belgium, U.K., Qatar, Dubai, South Africa, Ireland, Cyprus, Tanzania etc. etc.

Our Calibration Laboratory is accredited in accordance with ISO/IEC 17025:2017.

For our full activity you may see our url https://www.weights-swpi.com

Long term relation is our objective.

Kind regards,


Surendra Singhania

Shanker Wire Products Industries

DEOGHAR – 814112  (Jharkhand) INDIA

Mob: +91 9386142223

E.mail swpi@rediffmail.com

Calibrated Weights

Calibrated Weights are used almost exclusively for adjusting and testing – (calibration of electronic balances). We therefore call them Test weights as this is their purpose of use. Adjusting a balance means that you are intervening in the weighing system, to make sure that the display is set to show the correct nominal value. And Calibration, on the other hand you are testing whether the display is correct and documenting any deviation. Regular servicing is essential for ensuring that a balance or a weighting device performs with specification. Thus adjusting and calibration both requires test weights, which are also used with weighing instruments of all classes. These test weights are also need to be protected and finely coated thus to properly adjust and calibrate our weighing machines, weighing instruments and other weighing systems.

The International valid OIML Directive R111-2004 classifies test weights hierarchically into accuracy classes with E1 is the most accurate and M3 is the least accurate weight class. As the appropriate test weight is only classified as checking equipment if it has relevant proof of accuracy. The whole test weight range in OIML accuracy classes are E1,E2,F1,F2,M1,M2,M3. With E1 being the most accurate and M3 being the least accurate one.

Cast Iron Slotted Calibration Weights & Hangers – M1 Accuracy

The  hanger weight is a weight in itself, that also has its weight Calibrated so that the hanger can be used as part of the overall weight under test,  and will hold a number of Cast Iron slotted weights depending on its usable shaft lengths. The slotted weights are discs with slots in them and are designed to sit on the hanger. Several Cast Iron Slotted Weights may be used together to build up from a minimum weight to a maximum test load.

These weights are used to test force gauges, crane scales or other suspended weighing scales. Cast Iron Slotted Weights are primarily used to calibrate large capacity scales.

Shanker Wire Cast Iron Slotted Weights are manufactured from a high quality iron. The surface are free of cracks, pits and sharp edges. All surfaces are smooth and free of scratches, dents and pores. Weights are protected by a durable coat of paint to protect the casting from rusting.

The M1 Cast Iron slotted hanger weights (Newton Cast Iron Slotted Weights, Kilogram Cast Iron Slotted Weights)  are the most common hanger weights we sell and are suitable for testing and calibration in the 5 N / 500 g up to 200 N / 20 kg.

Cast Iron Slotted Weight Hangers:

Cast Iron Slotted Weights are typically used with a hanger that also has its weight calibrated so the hanger can be used as part of the overall weight under test. Weight hangers are available in a variety of lengths and weight capacities. Hangers are calibrated to a mass value, and also have a capacity of how much weight can be loaded onto them.

Calibration Weight Certification:

You will normally need a calibration certificate to satisfy, if the tests that you do are on equipment that can effect the quality of your product and you are audited by an outside organization. Our Calibration Laboratory is NABL accredited in accordance with the standard ISO/IEC 17025 : 2017, So you can be satisfied with the quality and accuracy of the Cast Iron Newton Slotted Weights and Hangers.

Construction and General Shape:

Cast Iron Slotted Weights have adjusting cavities. Each weight has its nominal value cast into the topside of the weight. Weights are protected by a durable coat of paint to protect the casting from rusting.

Click here to enquire about Cast Iron slotted Weights and Hanger:

https://www.slotterweight.com

Newton Weights

A newton is defined as 1 kg⋅m/s2 (it is a derived unit which is defined in terms of the SI base units). One newton is therefore the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in the direction of the applied force. The units “metre per second squared” can be understood as a change in velocity per time, i.e. an increase of velocity by 1 metre per second every second.

In 1946, Conférence Générale des Poids et Mesures (CGPM) Resolution 2 standardized the unit of force in the MKS system of units to be the amount needed to accelerate 1 kilogram of mass at the rate of 1 metre per second squared. In 1948, the 9th CGPM Resolution 7 adopted the name newton for this force. The MKS system then became the blueprint for today’s SI system of units. The newton thus became the standard unit of force in the International System of Units.

The newton is named after Isaac Newton. As with every SI unit named for a person, its symbol starts with an upper case letter (N), but when written in full it follows the rules for capitalisation of a common noun; i.e., “newton” becomes capitalised at the beginning of a sentence and in titles, but is otherwise in lower case.

In more formal terms, Newton’s second law of motion states that the force exerted on an object is directly proportional to the acceleration hence acquired by that object, namely: F = m a , {displaystyle F=ma,}

Where m represents mass of the object undergoing an acceleration a. As a result the Newton may defined in terms of kilograms as 1 N = 1 kg ⋅ m s 2

{displaystyle 1 {text{N}}=1 {frac {{text{kg}}cdot {text{m}}}{{text{s}}^{2}}}.}

Examples

At average gravity on Earth (conventionally, g = 9.80665 m/s2), a kilogram mass exerts a force of about 9.8 newtons. An average-sized apple exerts about one newton of force, which we measure as the apple’s weight. 1 N = 0.10197 kg × 9.80665 m/s2    (0.10197 kg = 101.97 g).

The weight of an average adult exerts a force of about 608 N. 608 N = 62 kg × 9.80665 m/s2 (where 62 kg is the world average adult mass).

To enquire about Newton Slotted Weights follow the link:

https://www.weights-swpi.com/contact/