Compounding efficiencies

For compounders of recycled resin, speed is key to keeping up with the competition. Contamination is one thing that can dramatically slow down a company.

Aaron Industries Corp., Leominster, Massachusetts, compounds recycled plastic. It manufactures about 1 million pounds of product per week, President Bob Tocci says, and it purchases a lot of regrind.

The company operates primarily 600-horsepower, 6-inch extruders that process 2,000 to 3,000 pounds per hour. “Until recently, all of our extruders have been equipped with slide-plate screen changers,” Tocci says. “A slide-plate screen changer can clog up pretty quickly if you even have slight contamination,”he says.

About a year ago, Aaron replaced the slide-plate screen changer on one of its six extruders with a CFO continuous melt filtration system from ADG Solutions LLC, Fairfield, Connecticut.

The switch has allowed Aaron to buy less expensive feedstock while avoiding shipping contaminated batches to other companies to be cleaned using a sink/float separator. “So, it simplifies our process,” he says.

It also has provided labor savings for Aaron. “With slide plates, you really need to watch your pressures; you need to have your operators close to the machines because, when the alarms go off, they need to slide the plates,” Tocci says. “Once you slide the plate, you have to go over to the other side of the machine and knock out the dirty screen pack and then install a new screen pack. And if you have really dirty material, you’re running back and forth, you can have an operator tied up on an extruder and just running one machine.”

ADG Solutions President Sandy Guthrie says filter technology and awareness of general technical advantages have grown greatly in the last several years, enhancing the potential of the ADG product. “The CFO is certainly capable of filtering up to 10 percent contaminants,” he says.

The ADG melt filter can handle difficult particles, such as stones, glass and metal pieces. The CFO filters onto a stainless-steel plate and is automatically wiped clean continually, so particles are unable to get lodged in it the way they can in the screen, he says.

Tocci says Aaron has seen quality improvements in its compounds with the new filter thanks to more consistent melt pressure.

“Because there’s constant pressure, and with a slide plate you get the varying pressure, that affects the pellet quality. And, inevitably, you always get a little contamination that makes its way through the moving slide plate. On more technical jobs now, we run on the machine with the CFO unit. So, we don’t have to worry about any contaminants sliding past the slide-plate screen changer.

“That’s really been a great benefit to us because that allows us to go after the higher-end accounts that we were a little bit apprehensive with in the past.”

Guthrie says another advantage of the CFO melt filter relates to cost. Most recyclers using mesh screens can spend as much as $90,000 per year on replacement screens. With ADG’s melt filter, the screens don’t need to be replaced as often. “All of the sudden, your screen cost diminishes hugely,” he says.

The CFOs run at lower pressure than traditional filters because they are self-cleaning. “So, now your vent doesn’t bleed because of excess pressure, your machine runs [at] higher rates because the pressure is something that’s controlled. So, we keep the extruder running very consistent, your pellets are consistent, your vent remains open and your rates are reliable.”

Much of the supply Aaron uses is polypropylene (PP) regrind, and the material has gotten dirtier in recent years. That means increased work for extruder operators.

“With the CFO, you don’t have to remember these things. It’s done automatically,” Tocci says. “The labor savings, the quality improvements, the ability to have confidence knowing that the material you’re manufacturing will have the highest quality possible” are benefits he says he has seen with the CFO. “Some of these molders require extremely high quality in a reprocessed compound; [with the CFO] you really can’t go wrong.”

Guthrie says the CFO systems start at $250,000, and Tocci says this initial investment presents the greatest challenge.

“We’d love to buy more, there’s just a financial aspect to these items where they are a lot more expensive than your average slide plate,” Tocci says.

Guthrie adds that his machine is basically plug and play.

He says process and labor efficiency gains are hard to quantify because of the number of variables, but he estimates them at 5 percent to 7 percent. Another benefit is that operators can run the extruder at a higher rate.

“A lot of machines that are capable of 2,500 pounds an hour may only be running at 1,800 because, at 1,800, they can’t filter any quicker,” Guthrie says. “So, if I take that filter off and I put one that’s got higher capability, and the extruder’s capable of pumping 25 [hundred pounds per hour], all of the sudden now I’ve got 2,500 pounds an hour.”

The ADG melt filter has been well-received by the handful of companies that have purchased the product so far, he says. The improvements made on the latest-generation of models, including a larger drive and gearbox and a more robust filter housing, have worked well.

Tocci is one of the filter’s satisfied customers. He says he wishes he had bought one earlier.

“When we jumped into this technology, we were a little unsure,” he says. But no more. “It’s a great help to have a unit that if you have a dirty or more contaminated material, you can throw it on this machine and not have to pack it all up, send it out, truck it to a cleaner, have them charge you a dime [per pound] to float/sink it, then put it back on a truck and freight it back into us. The money savings is substantial.”

The author is a correspondent for Plastics Machinery Magazine and can be contacted at agerlat@plasticsmachinerymagazine.com.

For more information: Aaron Industries Corp., 978-534-6135, www.aaroninc.com; ADG Solutions LLC, 203-255-9444, www.adgs.net