WHAT IS CALIBRATION?
The process of determining the accuracy parameters of an instrument or system by comparing it with measurement standards. Adjustment may be a part of a calibration, but not necessarily. A calibration assures that a device or system will produce results which meet or exceed some defined criteria with a specified degree of confidence.
WHAT IS PREVENTATIVE MAINTENANCE?
It is a program that is designed to reduce your overhead costs and down time by identifying errors, problems and faults that have not fully developed so as to cause a breakdown. It helps to identify faults in your weighing system before they are fully developed.
Some breakdowns may still occur due to accidents, Short circuits, faulty voltage, abuse or lack of housekeeping. Each Environment is different and there exists many influencing factors that need to be considered and addressed. Minor calibration errors may remain unnoticed for long periods of time and one may not realize minor losses. But when accumulated over long periods one does not realize the extra revenue that could have been earned.
Global Scales and Systems Inc. understands the unique requirements and environments of different industries. Therefore it has developed Standard Testing Procedures (STP’s) that help identify the source of the problem and eliminate critical issues with weighing systems before they turn into costly repairs.
WHAT SHOULD I CONSIDER BEFORE INVESTING IN A SCALE?
Industrial scales are designed for factories, shipping, transportation and manufacturing plants. They are different from the weighing machines that are used at home and in medical laboratories. There are various options to choose from. The precision of the devices varies depending on how you intend to use them. Your business needs to determine the type that you need. Before you select weighing machines, there are various factors that you need to consider.
The first thing that you should do is to check for a product that is reliable. Do a lot of research to determine the best type to use. Check what your competitors are using in the industry that you are involved in. You also need to set a budget for the purchase. The amount of money that is available will also determine the type you will get. There are several brands and it is easy for you to find something that suits your budget.
Another factor to think about is whether the device that you need meets the standards that have been put in place by the authorities. Using devices that meet the standards set is important because it enhances efficiency and customers will be more comfortable about using your services if they know that you are using quality devices for your operations.
As a business owner, you also need to know what your requirements are before you select a weighing machine. Once you have identified what your requirements are, you are in a better position to choose. There are various types of design, construction, accuracy class, various capacities, etc. Each type is designed for a particular purpose therefore you need to understand what your business requires and then choose wisely. Some of the aspects that you should think about include the minimum increment sizes, weight limits, and size of the product.
When choosing these types of products, you also need to consider their precision and accuracy. Before purchasing one, make sure it undergoes several tests to determine if it meets your needs. Look for any defects in the product before purchasing. Manufacturing defects can affect readings and this is not good for a business that relies on weights for efficiency.
The type of environment that you have in your organization also determines the kind of device that you should purchase. Some of the things to consider in terms of environment include temperature, heat, moisture, dust and vibration, among other critical factors. Choose a machine that is capable to perform in your industrial environment.
These types of machines are not low cost therefore you should make the right choice the first time ;if you want to avoid costly repairs down the road. Keep the requirements of your organization in mind when making a choice. The requirements must be well defined in advance. This kind of purchase is a long term investment that is aimed at increasing profitability from the enhanced efficiency offered by the devices.
You also need to have adequate space for the device especially if you are getting one of the large digital scales. There is no need to get something that will not be able to fit in your workplace.
Global Scales and Systems Inc. offers sound advice and helps its customers in making the right choice.
WHAT IS NIST?
NIST stands for National Institute of Standards and Technology, and is a division of the United States Department of Commerce. The NIST makes regulations that manufacturers must follow to ensure industry standards. When purchasing NIST weights or weight sets you are being assured that your weights have been tested to meet their standards. NIST weights are most commonly used for commercial and legal for trade scales.
WHAT IS NVLAP?
NIST also runs the National Voluntary Laboratory Accreditation Program (NVLAP). This program evaluates and accredits laboratories in their respective fields and ensures they meet ISO standards.
WHAT IS ASTM?
ASTM stands for American Society of Testing and Materials. The ASTM is an international organization that establishes and develops methods for testing materials. ASTM weights and weight sets are made to the tolerance, construction, finish, and magnetism set by them. ASTM requires that weights be made of one piece (no fillers or air to compensate for small adjustments). ASTM weights are recommended for calibrating other weights or high resolution balances.
WHAT IS OIML?
OIML stands for Organization International de Metrology or better known as The International Organization of Legal Metrology. OIML is an international organization that sets guidelines for legal metrology. (Metrology involves measurement, measurement devices, and procedures.) OIML guidelines encompass everything from how the weights are manufactured to how they are to be used in calibration procedures.
WHAT IS A TRACEABLE CERTIFICATE?
Many weights and weight sets are available with traceable certificates as an additional option. These certificates are issued by laboratories and manufacturers that are accredited by NIST/NVLAP, ASTM, and/or OIML depending on the type of weight, manufacturer, and class. These certificates are traceable to NIST and contain information such as type of weight, weight class, density, uncertainty, and environmental conditions at the time of calibration.
WHAT IS A CERTIFICATE OF CALIBRATION OR CALIBRATION REPORT?
This report is similar to the traceable certificate however it will have a smaller uncertainty and more precise values. This has to do with the methods involved as well as the number of times the tests are repeated.
WHAT IS A TRACEABLE MASS VALUE REPORT?
This report is traceable to NIST and reports the actual weight values, tolerances, and uncertainties. However the ratios reported are not guaranteed and is not considered an accredited document.
WHAT IS A CERTIFICATE OF ACCURACY?
A certificate of accuracy is not accredited or traceable. This report is required to be completed to NIST standards and will have an NIST report number. This report will contain the weight or weight sets serial number, description, nominal value, class and tolerance.
DO I NEED A CERTIFICATE FOR MY WEIGHT(S) OR WEIGHT SET(S)?
This depends upon your needs and requirements. You need to check with your governing agency, quality control department, or product literature. Usually if dealing with ISO-9000 requirements you will need some form of an NIST traceable certificate.
HOW OFTEN DO I NEED TO HAVE MY WEIGHT(S)/WEIGHT SET(S) CALIBRATED?
There is no set industry standard, but it is recommended that it is done annually.
WHAT CLASS WEIGHT/WEIGHT SET DO I NEED?
Class 0, Class 1, E1, E2- These weights are the most sensitive and accurate. These require clean environments and special handling. These classes would be used to calibrate Class I/II balances, balances accurate as 0.001mg, and as a laboratory standard. These classes are considered to be of extra-fine accuracy. Class 2- This class is considered to have a fine accuracy and designed for Class II balances. This class would be recommended for balances that are as accurate as 1mg. Class 3- Recommended for analytical balances as accurate as .01g. Class 4- Recommended for semi-analytical balances accurate to 0.1g. These are ideal for balances in school laboratories and industrial settings. Class5, Class 6, and Class 7, Class F- These classes would be ideal for industrial and harsh environments. These are most often used for scales used in the home and production settings.
HOW MANY TYPES OF LOAD CELLS ARE AVAILABLE AND WHAT ARE THEIR APPLICATIONS?
Load cells come in many different shapes, sizes and capacities and are now the industry standard for all types of weighing. It can be a bit of a mine field trying to find the correct load cell for your application. Some of the most common found today and their uses are listed below:
Single points are probably the most versatile type on the market today. Because of their price and reliability, they can be found in most types of retail scales, counting scales, medical scales, parcel scales, postal scales and low capacity bench scales. This type of load cell can also be used in platform scales and industrial weighing systems to provide accurate readings regardless of the position of the load on the platform, reducing manufacturing costs.
Canister type have been around for a long time and tend to be the industry standard for most high capacity, compression applications. Canister type load cells are used for single and multi-weighing applications. This type of cell has a button on the top and bottom side and can be used in compression only. Canister type load cells are used in tank scales, vessel weighing applications, axle weighing scales, truck weighing, vehicle scales and weighbridges. Canister type load cells offer accurate weighing in harsh environments.
Double Ended Shear Beam
For medium to high capacity applications, the double ended shear beam offers a number of advantages over other designs. This type has the ability to rock on its mountings to accommodate any misalignment in mounting surfaces whilst still being retained, this also permits limited movement to allow for thermal expansion and contraction as well as lift off protection. This type of cell is also available as a weighing module kit.
Single Ended Shear Beam
Single ended shear beam are commonly found in all types of floor, platform and shipping scales today and provides an ideal solution for most medium capacity weighing applications. Single ended shear cells have the ability to withstand full capacity side load without any problems which makes them particularly suitable for weighing systems with mixers, blenders and agitators. These types are extremely durable but can become costly and cumbersome to mount above 10,000kg. This type of cell is also available in weighing module form.
The tension link is suitable for applications such as wiingnch, hanging scales, crane weighing scales and lifting systems. This type of load cell offers superior accuracy at high capacity weighing. This type of cell has openings at either end to allow for easy connection to shackles, wire rope, D links or other rigging. Tension link load cells provide a rugged design for resistance to side loading.
Torsion ring are a relatively new concept in design and provide an excellent low profile solution for a wide range of weighing applications. Unlike standard compression load cells, which can readily suffer from off-axis loading problems, torsion rings are loaded through a centrally located annular ring. By using a central floating pin to transmit load to this ring, optimum load introduction is assured and off-axis loads up to three or four degrees can be tolerated without loss in performance. Proprietary mounting modules, which offer excellent versatility, are now available for both process weighing applications and platform scales.
Weighing module generally consists of a load cell with mounting kit. Many types of now come supplied as modules but generally single or double ended shear beam and canister type are the industry standard. Load cell weighing modules are used in tank scales, silo weighing, vessel weighing applications, axle weighing scales, truck weighing, vehicle scales and weighbridges.
All of the above have one major flaw; they are connected to devices via cable. One of the main problems with any weighbridge or floor scale is the chance of damaged cables. Using the latest technology, wireless, load cells are now being made available and could one day be the industry standard. All of the above load cells are now available in wireless format, although this technology comes at greatly increased price.
S type gets their name from their shape, being the letter ‘S’. S type load cells can provide a digital output when used in either tension or compression and provide superior side load rejection. This type of cell has two female threaded fixing points, top and bottom were eye bolts or thread rod ends can be attached. This type is used in crane scales, hanging scales, hoist scales and most tension applications.