Checkweighers

Checkweighers are a type of scale or weighing device that weighs an object as it passes through a production line, where it is weighed, classified, transported, accepted or rejected according to predetermined limits. Also referred to as in motion or tolerance weighing, a checkweighing device can do all of this at an extremely high speed. Called high or low speed checkweighers, they are often used to guarantee that filling and packaging machines are producing packed goods at the correct weights. This is not only required by law, but to obtain greater efficiency and lower costs. Inline checkweighers that fit into an assembly line or conveyor system are becoming increasingly popular.

Checkweighers

Description
While checkweighers are different in both use and design, a standard checkweigher consists of four parts: 1) an infeed section, 2) scale 3) discharge area and usually 4) a rejector or line divider They indicate their preset limits using either visual (lights or bar graphs) or audible signals. And while most manufacturers claim that their scales are 100% stainless steel, most are made with aluminum load cells featuring stainless steel shrouds and platforms.

Accuracy vs Cleanliness
The need for more checkweighers that are more accurate, hygienic and easy to clean has never been greater. Checkweighers are often used in the food processing industry and are in constant contact with the end product. New regulations such as the Hazard Analysis and Critical Control Points (HACCP), and GMP make it important for checkweighers are easy to clean so that there is no chance of contamination. This not only means that they be easy to clean, but are capable of being cleaned using extremely corrosive cleaning agents. In some cases, the scale will be completely submerged in a cleaning solution. Unless the scale is constructed properly, it won't last long. This type of cleaning requires more than the standard IP65 or NEMA 4 washdown rating that traditionally has been the only option in harsh environments. Scales are entering into the market with higher ratings, up to IP 68, that allows for total submersion without negative effects on the scale.

Selecting the Right Checkweigher

Washability Rating: try to choose a checkweigher with a washdown rating greater than the standard IP65 or NEMA 4 rating especially if the scale is going to be cleaned using extremely corrosive cleaning solutions.
Construction Material: 304 Stainless Steel. Make sure that the scale is as close to 100% all stainless steel as possible. Stainless steel scales with titanium are capable of handling corrosive material that will deteriorate under ordinary 304 stainless.
Readability: while the average checkweigher has a readability of 10,000 digits, look for scales with a rating as high as 30,000 digits to get more accurate readings, i.e., 0.0002 rather than just 0.0005.

Interweigh Systems Inc. 51 Bentley Street, Markham, Ontario, Canada, L3R 3L1
Phone: (416) 491-7001 ~ Toll Free: (800) 268-3269 ~ Fax: (905) 940-1711
Or contact us at one of our four locations: Markham, Mississauga, Woodstock and Montreal