In the heart of Thailand, a colored-cement and grout manufacturer needs the fastest and most accurate customized mixing system in the world. Where other mixers take 20 minutes or more they need a system that takes under five. In an 8,000-pound batch they need five 30-gram samples to be within Cv. 5%. They also need the system to be automated yet foolproof; sophisticated yet user-friendly; fast, accurate, and repeatable.

Meanwhile, in Pennsylvania, a sales representative is starting a follow-up call to a recently installed system. As he waits in the lobby toward the exit he is stopped by a tap on his shoulder. “Hey, are you the guys who did the mixer?” a curious stranger politely asks. “I saw the logo on your shirt—A & J Mixing. We might have a project for you.” They exchange pleasantries, business cards, and a handshake.

Jon Prenger, a veteran designer with A & J Mixing, suggested Rice Lake’s 720i indicator to handle the individual scales beneath the mixing system and a 920i indicator interfaced with a PLC & PC to control the weigh hoppers and load-cell-based mixer. But it doesn’t end there; where product is discharged sit two 720i’s that monitor a pail-filling system resting on a bench scale. Since the product flows so quickly, its rate of flow is difficult to control. This is where Bliss’ auger design integrates into the system to achieve unmatched results. Calculations for flow are based on the attributes of the material being used which is stored in Rice Lake’s ProAction PCEE database. From there an automated roller conveyor sends filled pails to a pail closer.

“This was a brand new installation,” Jon remembers. “In the past, systems like this were hand-filled or not controlled in conjunction with a PLC and programmed indicator. They would just have an indicator, fill, stop, and it would be a manual top-off to get to weight. Today, with our system there’s none of that going on and the element of human error is minimized as much as possible. The operator just puts the pail in place and hits START. It fills and is taken away.”

The 720i triggers relays in a separate control panel which then goes back to the main control panel where the VFD is located. It’s not actually controlled by the PLC. Because the PLC is a separate system, they can keep mixing or run a parallel system at the same time. Everything fills into the mixer, which is also on load cells for checkweighing so the PLC knows when the material has actually been added to the mixer. Any hand-adds (small requirements of 10 pounds in a 5,400-pound batch) can be seen by the indicator. Through touchscreen interaction, the operator verifies the hand-add has been done. Floor scales are used alongside the mixer. The operator puts a container on one of these floor scales and the PLC will see the extra 10 pounds. Once the operator confirms it has been added, the indicator commits the weight and the mix begins. When everything is mixed, it is discharged into the hopper above the small screws A & J Mixing designed. From there everything is mixed together and pails are filled as required based on weight. However, some materials flow so quickly that aeration is impossible to avoid. This aeration results in the system not necessarily seeing the exact flow rate all the time but the scale’s high accuracy compensates for this.

“We also had to look at how many different recipes and weights that we had to incorporate into this,” Jon continues. “We used ProAction PCEE and DBE to create our own custom input system where the operator looks at the work order to see which product is being made that day. The operator will input that product code in the 720i where a confirmation system in the database double-checks the proper code has been input. After that, it’s semiautomatic. When the operator presses START, the batching program has preset points set so it automatically fills when setpoint relays are reached, which is controlled by the digital I/O of the 720i and slows down the screw to achieve high-end accuracy. When we do a 60-pound pail, we can be no more than plus or minus half a pound, and can never be under weight. We were filling six-gallon pails in approximately thirty seconds! The benefit of the 720i is flexibility and reliability. The entire system is controlled with Rice Lake equipment. The customer has never had a problem with it and is extremely happy.”

A & J Mixing’s attentiveness to customer needs is reciprocated in its relationship with Rice Lake. “Working with Rice Lake is great,” Jon reports. “Any time we have customer questions or need something shipped overnight they always come through. Their support is unmatched. Our customers don’t necessarily have a scale company in place. This is something new for them; they’re used to just mixing and bagging off a system and haven’t used scale controllers and technology to control and run the whole system, so they don’t have those contacts. Rice Lake is able to provide local distributors or scale companies. My customer now has a local contact so if there’s anything physically wrong onsite someone can show up right away. I can help them only so much from the phone, so it’s nice to have someone local. We provide a lot of support, and it’s important that everything—from indicators and scale bases and load cells to the cabling—holds up.”

A & J Mixing is pushing the envelope in their niche industry. The first pail-filling system they completed was in 2005 and had only one target weight and one product/bucket size. Subsequent systems go leaps and bounds beyond that. The framework of one system that works this well allows A & J to use it as a template for similar solutions in different industries. The flexibility and reliability of Rice Lake equipment is there every step of the way, and support is only a phone call away. Rice Lake and A & J Mixing work well together to provide the perfect mix.