Scale maintenance and repair is something that is brought up whenever someone is looking to buy a large industrial scale. Usually it is met with a question like “how often should I have my scale serviced?”, which generally is every 6 months, but depending on environment, frequency and other factors, scale service could be done every 3 months or every quarter.
It is important to consider the number of weigh-ins, climate and the value of the product being weighed, as these can all have an impact on the frequency of maintenance your scale needs.
Aside from the actual calibration, most of the inspection will consist of a visual inspection of the scale, foundation and surrounding area. Depending on the condition of the scale and the surrounding parts will determine what services will be needed.
Foundation
Like any structure if there is a poor foundation, then the entire structrue will be unstable. A truck scale foundation is no different. No matter how tough and durable a scale is, it will be at risk of failure if the foundation is not good. Cracked foundations can lead to movement or settling which causes chronic calibration errors, which in turn adds more profit loss due to downtime.
If there are any cracks in your foundation, then you should address it asap. Allowing small cracks to become bigger can possibly require you to remove part or all of the foundation, and force you to pour an entirely new foundation.
When a scale tech arrives at your site for service, cleaning or any type of maintenance, then they are going to give the scale a full visual inspection, and cracks in the foundation is one of the things that they search for.
Weighbridge
The weighbridge takes the bulk of the damage when weighing trucks. Generally truck scales are outside and are subject to the elements. It is a good idea to check for rust, on the surface and all around the weighbridge. Rust can cause the structure to not be as stable and can cause a lot of problems if it is not sorted in a timely manner.
Binding is also a common cause of inaccuracies in truck scales. With a lot of trucks being weighed daily, there is a high chance that rocks and other debris can fall off the truck and get itself lodged in between the foundation and the deck. It is a good idea to ask your scale tech about t-stripping. Installing t-strip molding between the two can help keep debris from getting caught or falling down into the scale. This may be a good precaution to take to help decrease binding incidents.
Checking Devices
Other than the foundation and weighbridge, the scale has other parts that need to be checked to ensure your scale is operating properly. Other aspects are the junction box, load cells, cable, indicator, etc. All of these devices need to be operating for the scale to get complete and accurate measurements.
If your scale has checking devices, make sure they are working properly. Inspect check rods to make sure the attachment points are solid. Inspect the bindings and hardware to ensure jam nuts are tight and that rods are level and free of debris.
Load Cells
Load cells are definitely at risk of getting debris and moisture in the electronic section of the load cell. The load cell area may contain dirt and debris that has built up since the scale’s last check. Load cells must have clearance to deflect through their capacity range. The same debris that can bind the scale deck can also keep the load cells and suspension components from moving freely. So it is a good idea to try and keep that area as clean as possible.
You will also want to check load cell cables for damage and if the seal has been degraded. To combat this problem, some manufacturers offer rigid or flexible metal conduit to run the cable through, providing a layer of protection that’s nearly impervious to damage from rodents.
One more thing to note is that during cleaning, if your load cell is electronic then you want to be careful about where you spray. It can cause damage to the internals of the load cell. If you are using a hydrostatic scale then you don’t have to worry since there are no electronics in a hydrostatic scale.
Junction Box
The junction box (J box) is one part of the scale that can surprisingly still get a lot of moisture and debris inside of it. If the J box is not operating correctly then you will get incorrect readings. This occurs from air exchanges, heating and cooling cycles, and over-aggressive washing that damages sealing components that haven’t been properly maintained. If left unchecked, wiring terminals and other components in the enclosure can corrode.
During the visual inspection, the scale tech will follow the aforementioned steps to check and be sure there is no moisture, debris or frayed wires in the J box.
Closing Words
At American Scale we strive to bring you informed and useful content on all things scale systems related, including products from the top scale manufacturers. Be sure to check out our truck scale articles about truck scale foundation or how much do truck scales cost. We even have a guide to warranties. To learn more about bench scales, it would be good to check out our other articles such as “Bench Scale Basics'' and “How Much Does A Bench Scale Cost?”. These articles will help with the basics of bench scale ownership. Also, take a look at our“Common Problems With Bench Scales'', to help prolong the lifespan on your scale.