Global VersaWeigh™ Checkweigher

For pet food products in cartons, cans, bottles, or pouches, a chain checkweigher offers line speeds up to 700 packages per minute. It is appropriate for both dry and wet environments.

To ensure that pet food processors are not under or overfilling packages, checkweighers are used to verify the correct weight of each package. Accurate weight avoids giving away costly product or from receiving hefty fines from regulatory bodies for underfilling.

Checkweighers do not detect physical contaminants but they can be combined with food metal detectors and X-ray inspection systems that do detect contaminants. Food metal detection systems provide reliable, cost-effective protection from even the smallest metal contaminants found anywhere in a food production process. Food X-ray inspection systems provide protection from metal, glass, stone and other dense foreign objects for almost any type of packaged, bulk, or piped product.

Food manufacturers can find metallic and non-metallic foreign objects and eliminate “wet” product effects common with metal detectors with the Thermo Scientific NextGuard X-ray Detection Systems (https://www.thermofisher.com/order/catalog/product/NEXTGUARDPRO). Designed for a wide variety of food applications, NextGuard systems offer enhanced capabilities to inspect packaged products for missing pieces or components, under and over-fills, and other quality problems.

Checkweighers can sometimes come in contact with food products that can leak or spill. The equipment has to get washed down regularly to prevent contamination so it must meet IP65 Washdown requirements. Therefore, checkweigher components require materials that can withstand washdown using chemicals. The metal should be fully constructed of ANSI Type 304 SS (stainless steel), which is an austenite steel. For even harsher situations, ANSI 316 stainless is used; it is more impervious to corrosion than 304 SS. Equipment should meet American National Standard ANSI/IEC 60529-2004 for equipment with electrical components. This standard describes a system for classifying the degrees of protection provided by enclosures of electrical equipment for two conditions:

- The protection of persons against access to hazardous parts and protection of equipment against the ingress of solid foreign objects
- The ingress of water

Equipment should be designed with minimal flat, horizontal surfaces and slots to reduce food buildup, and use stainless steel conveyor beds. IP65 enclosures provide basic waterproof protection from water, including jet sprays used during washdown.

Proper design of the in-line checkweigher can influence accuracy. Here are some of the design factors:

- Product speed
- Product weight and size
- Product transfer onto and off of the checkweigher
- Reject method and design

In addition, conveyors must be level and aligned, belts and chains should be inspected regularly for wear or product buildup, gaps between conveyors should be minimized and infeed and weigh table belts or chains should be running at the same speeds. Other factors include the spacing between products' centers to ensure that more than one product is not on the weighing table at any one time, and calibrations should be done regularly.