Intralox, METTLER TOLEDO Help Stemilt Growers Increase Throughput by 5–6 Tons Per Hour

Customer Objectives

Stemilt Growers, a leading cherry packer and provider founded over 55 years ago, was facing challenges packing the volume of cherries their customers were demanding. The challenge was that key parts of the process—including clamshell filling, weight checking, and over- and underweight clamshell rejecting—were manual. This limited the volume of cherries that could be packed and resulted in orders not being fulfilled.

To address this challenge, Stemilt chose to automate their key processes. They installed automatic fillers to pack cherries into clamshells and C33 PlusLine WD (washdown) checkweighers from METTLER TOLEDO to check each clamshell’s weight after it was filled, increasing the volume of cherries they could pack. The C33 PlusLine WD checkweighers efficiently weigh clamshells coming from the filler at high speeds with very high accuracy. In addition, the METTLER TOLEDO systems were quoted with a weighing accuracy of +/- 1 g at 2 sigma accuracy and were configured to work with four different package sizes ranging from 1–4 lb. Depending on the sizes of the packages, the line speed also changed, with the fastest line running at 120 clamshells per minute. However, Stemilt needed a system that could reject and separate clamshells that were over- or underweight at the same speed and rate as the filler and checkweigher.

Intralox Execution

Stemilt worked closely with METTLER TOLEDO to ensure that a solution for rejecting over- and underweight clamshells would maintain product and package quality. METTLER TOLEDO contacted Intralox layout optimization specialists to evaluate and test in-house the best available solutions for gentle rejecting to pair with their checkweighers.

The Intralox solution included four Active Integrated Motion (AIM) Switches for rejecting—on two cherry packing lines—installed after METTLER TOLEDO’s checkweighers. The AIM Switch provides gentle, efficient diversion of the clamshell to a holding or rework lane parallel to the main line. This configuration was optimized for the existing layout, and would be difficult to accomplish with traditional technologies such as air blast rejects or plow-style rejects. The Intralox solution was installed in tandem with the METTLER TOLEDO checkweighers after successful testing. It eliminates the potential for product damage as well as non-valueadded labor, maintenance, and production downtime.

Results

The optimized layout allowed Stemilt to increase throughput to 12 T (10.9 t) per hour while producing 100% consumer packages—an increase of 5–6 T (4.5–5.4 t) per hour—through the entire season and reduced the cost per pound by $0.04–$0.06. Stemilt increased their capacity by 57% from 35 clamshells per minute to 55. The combined system of the automatic clamshell fillers, METTLER TOLEDO checkweighers, and Intralox AIM Switches has run reliably and consistently since 2018. No repairs have been needed, allowing for a labor reduction in the reject process from 10 people to four—a 60% decrease. In addition, neither the checkweighers nor the AIM Switch reject system has experienced any unplanned downtime. With this project’s success and having used Intralox Dual-Stacked Angled Roller Belt (DARB) Sorters and Activated Roller Belt (ARB) Sorters S7000 for sorting packed cartons in their palletizing area, Stemilt is interested in working with Intralox again in the future.