Points to consider in choosing the right checkweigher
If you’ve determined that you need a checkweigher as part of your quality control, how do you go about choosing one?
Like many things, checkweighers vary considerably. Although all check product weight to ensure that only what goes out your doors is within specified limits, their robustness and accuracy varies. There is also the consideration of automatic or manual. So what else should you consider when thinking about the equipment that will remove products outside specs to keep your quality and costs in check?
There are five main points: the required accuracy, your line rate, the environment the system will operate in, package specifications and integration.
1. Required accuracy
This is the first point to consider: what degree of accuracy do you need? Some modern checkweighers have the technology to allow you to be very precise, for instance accurately weighing right down to just 10-gram items. The latest technologies can also accurately check the weights of moving products, not just static.
2. Line speed
How fast is your line? Developments in checkweigher technology mean that certain models can be used on high-speed lines without creating a bottleneck as product builds up. It’s also worth keeping in mind that the longer an item is, the faster the checkweigher conveyor has to move to maintain the item-throughput rate. Talk with your supplier about the balance between line rate and accuracy.
3. System environment
The third area to consider is the environment your checkweigher will operate in. Unlike some other systems in your process, temperature won’t necessarily affect your checkweigher, so it won’t generally matter whether you’re weighing chilled, frozen or heated items. However, major extremes or fluctuations could have an impact, such as causing condensation (a tip here is to insulate or seal controls etc. to protect them). Extremes may also mean you need special belt materials. Naturally if you wash down your checkweigher or have to use caustic cleaning products, you need one rated for that. You will also have to give special consideration if your environment is hazardous (explosive gas or vapour, dust particles mixed with air in ignitable concentrations). Air movement is another factor: a draft shield could be useful in high-precision applications, but is unlikely to be needed in reasonably still environments.
4. Package specs
Some checkweighers are designed for certain types of packages, say heavy or light items, cans or bags, cartons, cases, weight-unbalanced items, etc.. Do you need guiderails to stabilise and direct items? What about addressing spacing small or unstable items? Do your packages cause much friction? Also, only one package must be on the checkweigher at a time.
The final consideration is whether your business needs an automatic or manually operated checkweigher. You can find good quality models in both stand-alone, manual checkweighers and fully automatic systems. What is the space available to integrate a check weigher into the production line? Is a reject system needed? What does the check weigher need to do if a package is over or under filled? Does it need to communicate with any other line equipment?
When choosing your checkweigher, all the points above are worth mentioning to your supplier. Good equipment suppliers will be able to guide you through to result in the best machine for your QC and quality assurance.
If you’d like some guidance on choosing a checkweigher that’s right for your business, the iQvision team can help. Please contact us via email or call 1300 IQVISION (1300 478 474). We have years of experience customising applications from the simple to the complex.
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