Switch to AC Drives & Save Energy, Maintenance Costs

Extrusion processors are fast taking advantage of the energy-saving opportunities provided by switching to AC drive technology. Major suppliers like Davis-Standard, Pawcatuck, Conn., are furnishing new extruders with AC drive and motor packages on almost every machine they ship. And now there are established options for processors who want to retrofit existing DC-driven extruders to AC technology.

“DC motors are expensive to rewind and require a lot of maintenance to keep them operating,” remarks Scott Barlow, president and co-owner of Integrated Control Technologies (ICT), Carrollton, Tex. “This is compounded by the fact that they are very inefficient. For many plants, the greatest hidden cost is energy loss from using DC motors.”
ICT  was launched in 2008 to upgrade extruder motors and controls, helping processors understand the costs and providing an alternative solution. The company designed a standard product offering called the ACPAK (AC Extruder Drive Package) to replace obsolete DC extruder drives and inefficient motors. ICT stocks this product in ranges from 75 to 500 hp.

Barlow says he has conducted a large number of energy studies and advises extrusion plant owners and managers to develop an action plan to make AC drive conversions a priority. This should include conversion dates to budget for the upgrades and ensure a practical balance of workloads. Why switch? Barlow says there are four main reasons:
 1.  Payback takes as little as two years.
 2.  Savings are permanent, making the processor’s bottom line healthier over time.
 3.  Monthly utility bills are lower, freeing up cash for other purposes.
 4.  The cost of an AC drive and motor combined is less than that of a new DC motor.

TIMING IS EVERYTHING 
When should a processor make the move to AC drives and motors? Compelling as the savings are, many manufacturers wait until the DC motor fails before making the switch, which Barlow refers to as “a ticking time bomb” for production deadlines. Once the motor fails, the processor realizes that the savings in upfront cost of an AC drive and motor is an additional benefit besides energy savings. 

While this may seem a reasonable strategy, the problem most companies encounter is the long lead time and lost production, according to Barlow. Historically, delivery of a new AC drive-package and motor can take as much as six to eight weeks.

“For this reason, we recognized the need to move fast, so we developed our solution to address emergencies with the ACPAK extruder drive packages shipped out in as little as one business day,” Barlow notes. 

ICT uses industry-leading components like Baldor motors and the Yaskawa A1000 drive, made in the U.S. “The Yaskawa drive in the ACPAK is a reliable design that operates in places as hot as South Texas in August,” Barlow maintains.

HERITAGE BAG CONVERTS
Three years ago, leading blown-film processor and bag maker Heritage Bag in Roanoke, Tex., embarked on a project with ICT to convert its 100+ extrusion lines at six plants nationwide. “We had been using ICT before this project to troubleshoot electronics
issues that were a bit beyond our maintenance capabilities, but for the last three years the focus has been on extruder conversions,” states Cray Quinn, v.p. of major projects at Heritage Bag. The company is about two-thirds of the way through the conversion process now, and Quinn reports energy savings of about 15% on those lines that have already made the switch. “Energy is a huge part of our cost structure, second to materials,” Quinn notes.

Quinn said the total cost to convert is roughly $30,000 per extruder, and payback has ranged from 12 to 18 months. “The higher the output on a line, the quicker the payback,” he states. Heritage runs monolayer lines from Gloucester Engineering, Gloucester, Mass., and Hosokawa Alpine American, Natick, Mass., in sizes from 2.5 to 4.5 in. Heritage has about 30 drive and motor packages in-house. 

“We do some of the preliminary wiring and a few other things ourselves, then ICT helps with the start-up,” Quinn says. “The whole process takes about two days.” Because AC motors are smaller, Quinn says Heritage has had to make some minor modifications to its extruder bases and couplings. Heritage uses Yaskawa drives, and 100-, 150- and 200-hp motors from Baldor.

“In the three years since we started this project, we have not had a single failure,” Quinn adds. “The motors are smaller, freeing up room on the production floor. They also run cooler and are very maintenance friendly.”