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Material handling system grows with molder

May 15, 2001

6 Min Read
Material handling system grows with molder

When Spectrum Plastics Molding Resources (Ansonia, CT) began approaching suppliers for a centralized resin conveying and drying system, one of its goals was a system that would allow continual upgrades and enhancements over time as business needs grew. However, the custom molder of small medical, electronics, and consumer products soon found itself at a crossroads, struggling to find a supplier that could fulfill its needs. Eventually, one company did step up with a solution and today Spectrum is still reaping the benefits of a journey that first began eight years ago. 

"We wanted to upgrade our system for efficiency of use, as well as to get a better quality of dried product from the high-tech engineering materials we were using," says Ed Flaherty, vp of manufacturing and engineering at Spectrum. Specifically, he says the company, which at the time had 60 employees and 47 presses, was looking for a small-footprint material handling system that could reduce energy consumption and maintain precise dryness throughout the entire system. 

Spectrum was initially unsuccessful finding a drying equipment supplier for several reasons, according to Flaherty. One is that Spectrum uses small shot sizes that consume only 3 lb/hr; at that time suppliers were not accustomed to dealing with multiple hoppers that have small volumes of per-hour capacity. "Usually, manufacturers centrally dry in 200- to 500-lb hoppers, but we were talking about a 60-lb hopper," Flaherty explains. 

Another factor concerned the kind of materials Spectrum uses, such as LCP and PPA, because such ETPs generally have very specific drying requirements. The PPA at that time, for instance, required dewpoints of less than ­20F. (Eventually, the molder went to the manufacturer and had a PPA with less sensitive drying requirements developed just for Spectrum.) While many dryers on the market had such dewpoint capabilities, Spectrum wanted a system that would ensure proper airflow through the hopper without using balancing valves, and most suppliers did not manufacture such a machine. Spectrum also wanted a dewpoint monitor, another feature not readily available from most suppliers. 

A Customized Response 
The search ended when Spectrum approached Baltimore, MD-based Novatec with its case. Though Novatec did not have a system to offer, the company agreed to work with Spectrum to design a customized system. "From an engineering standpoint, Novatec came back with the best solution," Flaherty says. The solution, which Novatec refers to as its bread-board model, consists of eight drying hoppers banked together and connected to one small drying unit. 

Novatec's system maintained dewpoint at -40F throughout the entire system, and by installing each hopper with its own heater blower, proper temperature and airflow was maintained. The system also has a regenerative cycle that allows the user to select whether to change over on dewpoint or on a timed cycle. On changeover the dryer will not go into regeneration until the dewpoint is reached, which saves energy, another of Spectrum's goals. In addition, the dryers have constant dewpoint readout. 

After a year of monitoring the original system a further reduction in energy consumption was achieved with the installation of two central dryers, in addition to the one from the bread-board model. The three central dryers replaced 34 smaller individual dryers Spectrum had before the Novatec system, which used more energy. Insulated hoppers also reduced heat loss and boosted efficiency. As a result, Spectrum was eligible for energy conservation credits as the plant's efficiency improved dramatically. "We were saving about 50 percent on power consumption compared to the old system," says Flaherty. 

Another one of Spectrum's goals was a smaller footprint. By placing a central vacuum loading area on a mezzanine above the materials being used, the company cut floor space requirements in half, in addition to making the process more efficient. When a molding job is completed, material can be gravity fed back to the material container below. Material handlers load the hoppers, set the drying temperature, and log the material in and out of the warehouse where it's stored. 

The system's design also has provided some unforeseen benefits. "We have a closed loop dry air system so the conveying system as well as the dryers are all using dry air," says Flaherty. "It is all kept at a low dewpoint so we don't need the drying hoppers at the machine." In addition, Spectrum found the closed loop system left no residue in the pipes. "When you go from one material to another there's always a chance of cross contamination, but we've had no problem as this system has a purge cycle at the end of each material pull." 

Growing with the System 
It's been eight years since Spectrum first ventured into closed loop central drying and the company has grown to 184 employees and 64 presses. Over the years, several refinements have been made to the system. "We have reengineered Spectrum's existing equipment to integrate with three more phases, and the company is still using the original stuff from way back, carrying it over with each new phase," says Ed Rondeau, Novatec's regional manager. 

After the first two years, Spectrum added another bank to the original eight hoppers. Eventually, two banks of five and one bank of four hoppers were added to that system. Spectrum now has 38 drying hoppers and most of the plant runs on drying hoppers from the central systems. The plant has four manufacturing cells but the material preparation and drying system is in an area in the rear of the plant. 

A quick-change manifold system and overhead conveyance lines pneumatically move resin to individual presses after it has been adequately dried. The presses served by this system include 34 Arburgs, 17 Nissei verticals, six Cincinnati horizontal electrics, one Cincinnati horizontal hydraulic, three Cincinnati shuttle presses, and three Van Dorn hydraulics. 

Over the years Novatec has reduced the footprint of the material handling system by 30 percent and added backup systems, including an extra vacuum pump and drying capacity. 

"Spectrum actually has more dryers than it needs at any given time," says Rondeau, "but it needed the flexibility to be able to have everything running at once if it needed to, and it has that capability." 

In addition to energy savings, Flaherty touts Spectrum's return on investment. He says the company's return was about a year and a half, but notes that it was replacing equipment already on the floor. "Since we were replacing equipment we had to justify the cost variance. But if you're putting in brand-new equipment there isn't any question. You should go central," he says. 

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