The article below is courtesy of Mr. Boon Lim who has been involved in the weighing industry for many years. It really hammers home the points that we have been trying to discuss with customers for literally decades!
There are differences in quality between certain brands of scales. We’ve discussed this numerous times over the years either here in our learning center or on our Youtube channel or perhaps via phone or email with you. A lot of times it’s a balancing act between value & accuracy. Many customers don’t have the budget or the requirements for the top of the line most expensive scale… but they also don’t need to buy the cheapest scale under the sun either. Let’s take a look at what Boon found when he purchased some of the cheapest scales available online. We hope you enjoy the article below.
Have you noticed a quality shift in the weighing industry? Quality standards have decreased significantly on consumer scales with “assembly only” operations making big waves in the scale community. Large sellers are dominating the online retail space for consumers, and this is not any different for scales. Whether you support the unstoppable rise of these ecommerce giants or not, there is no denying the profound impact associated with their operation.
So, we bought some of the “Best Selling”, highly rated, affordable scales and balances to test the quality.
You can step on a scale at the doctors office or buy fresh produce off a scale at the farmers market. Either way the scale you are looking at includes a load cell inside. But, how exactly does that load cell work? What does a load cell do? How does a load cell send weight data to a digital weight display? Let’s find out.
What is a Load Cell?
For our example, we are going to focus on the most common load cell which is the strain gauge cell. A strain gauge load cell is a type of device used to measure weight or force. It is commonly used in a variety of applications, such as weighing scales, process control automation, and testing and measurement. The load cell works by converting a force, such as the weight of an object, into an electrical signal that can be measured and send weight data to a computer.
There are several types of strain gauge load cells. This type of load cell consists of a small metal beam or rod, often made of aluminum or alloy steel, which is attached to a base. The beam is designed to flex or bend slightly under the weight or force applied to it.
How Do Load Cells Work?
At the heart of the strain gauge load cell is a thin, flexible strip of material called a strain gauge. The strain gauge is attached to the beam in a specific pattern, known as a Wheatstone bridge configuration. When the beam is subjected to a force, it will flex or bend slightly, causing the strain gauge to stretch or compress. This change in the length of the strain gauge results in a change in its electrical resistance. Continue reading →
A truck scale is a rather large purchase for many businesses. In many cases, whether you choose a 70×11 legal for trade truck scale, or portable truck scales, or portable axle scales… Once these items are purchased and installed on a concrete foundation, it’s likely going to cost over $100,000 when it’s all said and done.
So, anytime that you invest that kind of money into a new truck scale, you would like to know as much as possible about the items and the companies who build the items. So, in today’s article we’re not going to answer questions like how much does a set of truck scales costor how long should a truck scale last? We’ve already answered those questions. Instead, we’re going to look at some of the top vehicle weighing scale factories in the U.S.
Who are the Top Truck Scale Manufacturers?
As we’ve established, truck scales are a relatively expensive purchase for most companies. So, you want to make sure that you make a smart buying decision.
We’ll discuss this later in more detail, but it’s also important to rely on your peers and your trusted local scale company too. For example, maybe you think that you have found the right scale, but it turns out that it actually has a load cell issue. Perhaps, it’s becoming difficult to source load cells for that scale or perhaps it’s something else.
More on the local scale company influence later….
So, who are the best truck scale builders? In our opinion, the following scale manufacturers are the top companies in the business. And, this applies to all you fans of used truck scales too. Continue reading →
Using scales at a concrete batching facility is extremely important to guarantee the quality and consistency of the final product. In fact, it can be argued that the use of scales and weighing equipment, is one of the most critical aspects of the entire concrete production process. There are several reasons why this is the case, which we’ll discuss below.
Accurate Ingredient Mix
Using scales and strain gauge load cells helps to ensure that the correct amount of ingredients are used in the concrete mix. Concrete is made up of a mixture of cement, water, sand, and aggregate, and the proportions of these ingredients play a major role in determining the strength and durability of the final product.
If the amounts are not accurately measured, the concrete may be too weak or too brittle, which can result in costly failures or repairs down the line. By using hopper scales and load cells to measure the exact quantities of each ingredient, concrete producers can ensure that the batch is consistent and accurate.
Quality is important. But, utilizing scales at a concrete batching facility can also help to reduce waste and save the concrete company quite a bit of money. If the proportions of ingredients in the concrete mix are not accurately measured, it can lead to excess or shortages, which can result in wasted materials and additional costs. By using hopper scales with strain gauge load cells to measure the exact quantities of each ingredient, concrete producers can become more efficient.
Load Cells for a Hopper
Scales and weighing equipment is used at batch plants. Strain gauge load cells are installed on hoppers to weigh the elements of the mix. It is very important that any moving parts of the batching system are inspected on a regular basis for any buildup or seizing.
Furthermore, using scales at a concrete batching facility can help to improve efficiency and productivity. Accurate measurement of ingredients using scales allows for the production of consistent batches of concrete, which can be processed more quickly and efficiently. This can help to reduce the time and labor required to produce each batch, resulting in increased productivity and profitability for the concrete producer. Continue reading →
We’re going to try & help you understand all the truck scale terminology that you need to know. Especially if you’re new to truck scales.
So let’s say your business has decided to purchase a truck scale in order to determine accurate and reliable vehicle weight for your application. That’s great! Understanding fundamental truck scale basics and how a truck scale works will help you know which questions to ask your local scale distributor to ensure you purchase the truck scale style that fits your needs with the options and accessories that can enhance your application.
Whether monitoring a vehicle’s weight for safety guidelines or to complete business transactions, you should know what the info determined by a truck scale means to your business.
Gross weight is the total weight of the vehicle and loaded product. Tare weight is the weight of only the vehicle. Net weight is the weight of only the loaded product.
Today, most scales at solid waste facilities or recycling centers are installed with above ground or concrete pit foundations. Depending on state or regional requirements, scales can also be installed in a shallow pit, as opposed to the deep pit required by older mechanical scales. A pit installation requires less space than an above ground scale since longer approaches are generally required for above ground configurations. However, pit-styles require sump pumps and drains, and are generally more vulnerable to corrosion due to potential standing water.
The indicator, also called a controller, or terminal, can display basic weight functions, as well as serve as the command center for a weighing system with truck in & out programs to control the entire truck scale system, including any remote displays and ticket printers.
Load cells are vital to truck scale performance. There are various types of load cells, but they all basically have the same function—to accurately measure weight on the scale. How do load cells work, you may be asking? All load cells take an analog measurement, and then that signal is converted to a digital output either at the load cell, junction box, or in the scale indicator. Load cells are typically constructed of steel and are integrated within the weighbridge, usually at the corners of each module.
A junction box properly manages multiple load cells. By matching the signal of each load cell and summing them into a signal that’s sent to the indicator, junction boxes equalize the system for accurate and reliable weight readouts.
We’re going to wrap up our entry on truck scale basics and terminology. I hope we made all this truck scale jargon a little easier to understand for those of you in the market for a truck scale. If you need some truck scale buying advice or scale recommendations, we are just a phone call or email away.
The Basics of Load Cell Wiring and Trimming Load cell wiring and trimming are critical to a weighing system’s accuracy and should always be performed by trained scale technicians.
However, general load cell wiring knowledge can help you better understand how your weighing system works and how potential errors occur.
Load cell cables typically have four or six wires. Both versions have positive and negative signal and excitation lines, though a six-wire cable also has positive and negative sense lines. Sense lines are linked to the sense connections of the system’s indicator, sometimes through a junction box, allowing the indicator to sense a load cell’s actual voltage. If there is a voltage drop between the indicator and load cell, the sense lines send that information to the indicator, which automatically adjusts voltage. This compensates for the loss of voltage or amplifies the return signal to compensate for loss of power to the load cell.
Load Cell Color Codes
Load cell wires are color coded to help ensure proper connections. Different load cell brands use different color codes, which is why there are load cell wiring guides available for scale technicians to use during installations.
Adjusting / Trimming / Summing Load Cells
Load cell trimming is sometimes called load cell summing because it involves tying or summing multiple load cell output signals together. This happens in a junction box, also known as a summing box, which sends one system signal to the weight indicator. It’s necessary to trim load cells in a multi-cell system when the weight distribution to each load cell isn’t equal. Click the following link for more about how a load cell works.
For example, in vessel loading processes, the presence of agitators or the type of material, such as powder, can affect how material and weight are distributed to each load cell. Additionally, it’s nearly impossible to make every load cell exactly alike. Tolerances in the manufacturing process allow for some variation in individual load cell specifications, which, if trimming isn’t applied, doesn’t allow for the accuracy necessary for most applications.
Signal trimming is the most common and popular type of load cell trimming because it is the easiest to use. Signal trimming is compatible with nearly all indicators and is relatively unaffected by temperature changes or excessive system vibrations. It involves adding a relatively high parallel resistance between the signal of each load cell, which creates a leakage path that diverts some of the available load cell signal away from the indicator. More load cell signal will be available to the indicator as parallel resistance increases.
Be sure to visit Central Carolina Scale.com often for all your weighing related needs.
It may be tempting to save a few dollars by purchasing an inexpensive floor scale imported from overseas. After all, the capacity and size may appear to be the same as the more expensive brand and the pictures of the products look virtually identical! So, what is it that really separates the Expensive Floor Scale and makes it better than the Less Expensive Floor Scale?
Imported Floor Scales Worth the Hassle?
This is something we’ve discussed before actually. We’ve seen just about every possible brand of platform scale over the years. Some of the scales shipped over from China are decent. Some aren’t as good. Some of the weight indicators are not very user friendly or reliable.
When it comes to floor scales, we generally rank them in different levels of floor scale quality. For example, top of the line would be the B-Tek Clydesdale or Rice Lake Roughdeck. Second level might be the Pennsylvania 6600 or Digi Summit 3000. Third level might be a Brecknell floor scale. Lowest level would be brands & models that we won’t mention…
Do I Need Legal for Trade?
First thing that you want to determine is NTEP legal for trade status. You will need to determine if your floor scale needs to be legal for trade. Some cheap floor scales you find on the internet are not legal for trade. It’s almost always a good idea to buy a legal for trade floor scale. In our opinion, it’s a good idea to purchase a platform scale that is capable of earning a Certificate of Conformance (CoC#).
Quality Scale Components Make a Difference
Next, compare the electronic components that make up the scale There are typically four load cells in each floor scale, one in each corner. Some lower-quality floor scales use load cells that you cannot replace just one of the cells. When checking for causes of scale weight error, if one goes bad, all four need to be replaced! Some manufacturers also use cheap load cells that are sourced overseas and have little if any documentation. It is important to use quality components to ensure longevity and accurate weighing. Some of the load cell brands we recommend include Revere Transducers and Rice Lake Weighing Systems among others.
Next, is the Junction Box with Summing Board. Does the scale you are considering have a junction box with summing board inside? The purpose of the junction box is so you can adjust the output of the loadcells so the scale weighs the same regardless of where the load is placed on the scale platform. If a loadcell needs to be replaced the junction box allows you to easily remove the bad cell and replace it with the new one and wire it back into the scale without having to unwire and re-solder all the cells back together. Some cheap platform scales just tie the wires together and eliminate the junction box in their design. We do not recommend this and it makes replacing a load cell and/or troubleshooting difficult.
Heavy Duty Steel Platforms Can Last for Many Years
Maybe equally as important as the scale components is the build of the scale itself — The steel weighbridge. Pay attention to the shipping weight of the scale. The heavier the scale typically means the better build quality.
Thicker deck plate and substructure is an important key to giving the load cells the structure they need to perform properly. If the floor scale is flexing and bending, the scale will not last and it will cause inconsistent weights. Thin, short welds are also a sign of mass-produced low-quality scales. These welds could break over time and cause inconsistent weights and/or significant down-time.
Weight Displays are an Important Part of the Scale System
The last item, and possibly most important to consider, is the indicator that comes with the floor scale. Is an indicator included in the price? If it is, there are a few questions to ask. Is the indicator calibrated to the scale base? Does the indicator include a user manual that is easy to read and understand? Do you need a certificate of calibration with certified weights for your ISO program? Do you need a full numeric keypad to enter a tare weight? Do you want to tie your scale into a computer or printer?
These are all common issues people come across when purchasing a cheap floor scale online. And, many times this leads them to spending significantly more money with their local service company to get their scale up to the actual functionality they need.
In our experience, customers usually experience a better overall scale buying experience by contacting an experienced scale sales person first. Price and budget can certainly be an important component. But, scale construction, quality components and more can also be considered as well. By working together with a scale company, you get the type of industrial floor scale that you actually need. You also get any custom features that you may require.
As always, Central Carolina Scale would like you to make the most informed decision possible to help your business. We are here to help you with any questions you may have to help guide your decision.
Our local scale calibration and repair customers throughout the central sections of North Carolina are very important to us. We typically stock 90%+ of the standard replacement scale parts that they may need.
However, if you have certain types of scales that aren’t as common or if you have a large number of scales or load cells at your facility… then it can be a smart strategy to keep some spare parts on hand to minimize any downtime. Call us today (919) 776-7737 to determine what replacement scale parts and hardware you need.
If your business relies heavily on your scale(s), then it’s imperative to stock some spare parts to minimize unplanned downtime. Downtime can be a real problem. Especially for certain businesses and at certain times.
Our suggestion is to contact our scale repair & service department and discuss your scales and down time and identify any spare parts that are really important or any spare parts that are difficult to obtain.
Unfortunately, customers often don’t think about downtime and potential failures until it’s too late. This year, we’ve seen some scales that were down for weeks while they wait for replacement parts to arrive from the manufacturer. This is why we encourage you to contact us to determine what items you need to stock.
Supply Chain Issues & Longer Lead Times!
You’ve likely experienced this in your business and we certainly have as well. Between rising prices and labor shortages and continued medical issues, it’s greatly affected the manufacturing and logistics industries. We have seen parts that used to be a 2 day lead time, turn into a 2 month lead time. This is why it’s important to contact us today and discuss what item(s) you need to stock so you can experience the least amount of down time as possible.
These are real concerns that in the past we haven’t had to think much about. However, with certain lead times at record levels… it just makes good sense to plan.
How much money could you potentially lose if your scale is shut down for a couple weeks? What about a couple of months? When you think about it in those terms, if can sometimes lessen the burden of spending a few thousand dollars to keep some spare scale parts on your shelf.
Which Spare Replacement Scale Parts should I Keep on my Shelf to Minimize Unplanned Downtime?
The truth is that spare parts can be expensive to keep on your shelf. We see this every year when we analyze our inventory and determine what items sold and what items collected dust.
And, as mentioned earlier, we stock A LOT of replacement scale parts like load cells, weight indicators, main boards, etc… But, the truth is that we can’t possibly stock every single spare part that every single customer of ours might need. That’s why it’s important to discuss this with our service department and determine what item(s) we feel you should stock.
This will cost you some money but we would argue it’s still not as expensive as a few weeks of unplanned downtime with a broken down truck scale. It goes without saying, but this suggestion regarding spare parts also needs to factor in how important a particular scale is to your business.
For example, if you are a metal recycler, one broken floor scale might be easier to manage since you likely have several other floor scales you could use. However, if you have a broken down truck scale and that’s the only truck scale you own, that item would be much harder to do with out. In our opinion, if you want to reduce potential down time… you might want to stock the following items:
Replacement Weight Indicator
Digital Weight Indicators are items that often break or get damaged on job sites. Sometimes the damage is through lightning, while other times it’s from being knocked off a desk and dropped to the floor or perhaps being run over or hit. Other times “nobody knows what happened“….. In any of these scenarios, the weight indicator is a very important component to a scale system. Without a functioning scale controller, your employees can’t see the actual weight on the scale platform.
To take it one step further… some companies use very sophisticated weight controllers that are programmed for various tasks like truck in/out or truck storage, batching, etc… Those scale indicators need to function and if they fail, there needs to be a replacement available ASAP. For applications like this, it can be a good idea to stock a spare indicator with the custom software installed.
Replacement Scale Boards
Boards are one of the most essential components to a scale. These boards connect all of the components required to power the scale. It’s smart to have the main board, display board, analog output board, summing board(s), remote display main board, etc…. This will vary depending on the customer and which scale(s) you have.
Replacement / Spare Load Cells
We have to include load cells on this list since they are so prevalent in most weighing systems. However, in a lot of cases, we do have stock for most standard strain gauge load cells. This is a great example where we recommend contacting us and discussing what we have in stock and what we recommend that you stock. For example, of the past several years there have been multiple new digital truck scales available which take a digital load cell, cables, and digital weight indicator. Similar challenges exist with hydraulic truck scale replacement parts as well.
if you have a scale or multiple scales that are very important to your business process, then you need to contact us and discuss recommended spare parts and what we stock versus what we suggest that you stock.
A little forward thinking can minimize the unplanned downtime and it could mean the difference between a few hours of downtime or multiple weeks without a scale.
And these spare parts discussions (they can be phone calls or emails) probably need to happen every year since things change. Items become obsolete, new products get purchased, etc…
Responsible for channeling both power and communication between the load cells and the indicator, load cell cables are an integral part of building a custom scale. Though not just any cable will work. See, load cell cables are selected based on the distance between the two parts, as well as certain environmental conditions like temperature, contact with abrasive or flammable materials, or even rodents.
Before you can know the right type your custom scale project needs, it is best to have an understanding of the different types of load cell cables available.
4-Wire Load Cell Cable
Perhaps the most common cable, the 4-wire load cell cable is used primarily for short distances. As its name suggests, this type consists of four wires:
Power (excitation) +
Signal (output) +
Once connected, the cable should run from the scale to the indicator display. These wires are calibrated and designed to handle the surrounding temperatures. Many custom scale projects use the 4-wire load cell cable since it is more affordable and suitable for most scales. However, should you need additional length or if your scale is in an unpredictable environment, you may need to reconsider the type of load cell cable you are using.
6-Wire Load Cell Cable
Designed for longer distances and more difficult settings, the 6-wire load cell cable offers a lot more options. Again, as the name suggests, these load cell cables have six wires. They contain the four found above, as well as positive and negative sense wires. The long distances that 6-wire load cell cables cover can subject them to changes in resistance, temperature, and dips in voltage. The addition of these two sense wires helps to keep things flowing steadily.
Because they are not thermally compensated as the 4-wire load cell cables are, the 6-wires can be cut and used alongside other cables with no issue – making them perfect for larger commercial custom scale projects.
Types of Load Cell Cable Shielding
While 6-wire load cell cables offer a lot of benefits when designing a project, it is important to note the surrounding environment and opt for shielding that will protect the cable from any outside environmental factors. Below are the most common types of load cell cable shielding.
Hostile Environment Cable
Hostile environment cable is best used in environments that are, well, hostile. Depending on where the scale is being used, the cables may come in contact with harsh or abrasive substances, such as fuel, ether, or even salt. Over time, these substances can damage the cables.
Hostile environment cables are created with a polyurethane jacket that acts as a barrier against these damaging substances, keeping the cable safe and the scale running smoothly.
Rodent Protection Cable
Rodents and their incessant chewing may seriously interfere with a scale’s functionality. If in an environment where there are rats, mice, or other pests, the load cell cable may become enticing – leaving you with hefty costs to replace some or all of the cable.
Rodent protection cable is a type of cable that protects against this pesky situation. The outside layer of the cable is a braided shield making it difficult to chew. And, as an added defense, it is coated with a chemical that will discourage them from wanting to ever take a second bite.
Intrinsically Safe Cable
Flammable gases or liquids or generally hazardous materials can be damaging to load cell cables, requiring added security in the form of a jacket. For intrinsically safe cables, industry-standard blue double jackets are used to protect the cables from exposure to these dangerous materials.
In environments where the temperatures fluctuate or reach extreme highs, load cell cables need an outer covering that will protect the wires regardless of how hot it gets. A high-temperature cable is designed with a fluorinated ethylene propylene (FEP) jacket that insulates the wires and can withstand the heat without getting damaged.
Should I buy a truck scale with weigh bar sensors? The Avery Weigh-Tronix Weigh Bar® was designed to overcome the shortcomings of the traditional strain gauge load cell and to provide the end user with a rugged, highly reliable and linear load sensing device at reasonable cost.
More than twenty years of extensive use in industrial, farm and transportation applications has demonstrated that the Weigh Bar has met these requirements. The unique, robust design of the Weigh Bar is the primary reason for this success.
The Weigh Bar has proven itself over the past 20 years to be one of the world’s most robust weight transducers manufactured today with over 500,000 installations world-wide.
The IP67 Weigh Bar design provides inherent strength and overload protection, while also providing accuracy and high reliability. A significant contributor for this is the positioning of the gauges on the outside of the Weigh Bar. More robust than a shear beam load cell for a given output – a shear beam load cell will reach its peak fatigue point much sooner than a Weigh Bar.
The unique design of the Weigh Bar allows simple calculations to be made by the indicator, eliminating several types of errors:
• End Loading – When an end load is applied to the Weigh Bar, it is subjected to a uniform compressive strain throughout its length – all sensors detect the same strain. • Torsion Effects – When torque is applied to the Weigh Bar, a uniform torsional shear strain is developed through the length of the bar – both sensors detect the same strain. • Side Loading – When a side load is applied to the Weigh Bar, it acts as a beam, but at a 90-degree angle. When this occurs, the neutral axis of the beam (the point in the beam where neither tension or compression occur) falls directly under the center of the strain gauges. No apparent strain is seen by the gauges. • Vibration –The fine grain structure of aircraft quality steel is resistant to vibration fatigue and induced error. The strain gauges and adhesive used are also vibration and fatigue proven.
Load Cells – The Avery Weigh-Tronix Weigh Bar® Weight Sensor
The exclusive Avery Weigh-Tronix Weigh Bar® is an extremely rugged, highly reliable, load sensing device. Over several decades, the Weigh Bar® has built a reputation for precision, reliability and durability that no other load cell can match.
Weigh Bar – Reduced cost of ownership
Precision machined from aircraft quality, alloy steel, the Weigh Bar® offers excellent repeatability and long-term durability, reducing cost of ownership and need for load cell replacement.
Rugged Weight Sensors
With up to ten times more steel content than shear beams or compression cells, it absorbs impact to minimize peak forces and is virtually fatigue-proof. The Weigh Bar® is proven to resist electrical surges and is protected by a limited warranty that includes coverage against lightning damage.
Accurate Weigh Bar
The sensor’s design automatically cancels the effects of side loading, end loading and twisting, resulting in quick, accurate readings which are achieved regardless of temperature change, vibration, and shock loads on the scale.
Sealed “Load Cell”
The standard alloy steel Weigh Bar® is well protected against harsh environments by an exclusive 5-layer, sealing process. For the most challenging locations hermetically sealed stainless steel weigh bars are available.