Maintaining a consistent flow of soft acrylic powder into a large cylindrical mixing vessel, without lumps or sticking, is critical in the production of Fluorex™ thermoplastic paint. An Aero mechanical conveyor (AMC) from Monroe, NC-based Spiroflow Systems Inc has been instrumental in making this happen for Soliant LLC, just 35 miles away in neighboring Lancaster, SC.
An alternative to traditional paint and plating systems, Fluorex™ is more durable, cost effective, and environmentally friendly. With a current production palette of over 140 different colors, Soliant thermoplastic decorative film and coating is used by a variety of industries from automotive to marine, architectural, signage, appliance, electronics, telecom, and others.
A Laborious Procedure, Prone to Error
Before purchasing the Spiroflow Aero mechanical conveyor in the early 2000s, Soliant employees manually pushed 275 lb drums filled with acrylic resin powder to a scale for weighing and adding to the mix. Once weighed out, two employees manually scooped 1.5 lb of powder at a time from the drums to the mixing vessel, the beginning stage of the Fluorex™ process. The scale was used to ensure that only the amount of powder specified in the mixing process for that particular paint be added to the mixing vessel. Once in the vessel, the powder was stirred into a mixture about the thickness of mayonnaise.
Before scooping into the mixing vessel, employees first had to hand inspect the contents of each drum and physically break up any lumps or sticky powder. Speed and consistency varied from application to application. Each application required an average of 25 minutes per employee, or almost a manhour for each operation.
"The manual system was time consuming and didn't provide the quality control we needed," noted Mark Beard, staff product development engineer for Soliant. "We needed a dependable, hands-off system that assured batch-to-batch consistency and automatically provided a consistent speed and material flow."
Beard researched and ultimately recommended the portable Spiroflow Aero mechanical conveyor based on an advertisement he saw in a trade journal.
"We had no knowledge of Spiroflow's capabilities, even though they were in our backyard," noted Beard. "After visiting their facility, we were convinced that Spiroflow had the knowhow and expertise we were looking for. A demonstration using our powder convinced us that their equipment was right for the job."
How the Operation Works
Designed and custom built for Soliant by Spiroflow Systems, the all stainless steel conveyor and distribution system consists of an inclined 90 in. long straight-line Aero mechanical conveyor with a sack tip hopper at the inlet. The system is mounted on a mobile frame complete with two fixed and two swivel casters. The casters assure easy positioning and have locking brakes for maximum safety.
When it's time to add material to the mixer, the mobile conveyor is positioned onto a 4 x 4 ft weigh platform that is sunk into the floor so that its top is flush with the factory floor. Once the conveyor is located on the weigh platform, its weight is tared so that the precise amount of acrylic powder can be loaded into the conveyor feed hopper.
The powder is tipped into the hopper through a plastic strip curtain located at the front of the dust hood above it. The dust hood is connected to a dust extraction system that assures an environmentally safe dust-free operation. A grid across the top of the hopper is used to break up any agglomerates of material, a main concern with the previous procedure.
A rotary valve controls the rate of flow from the hopper to the conveyor. Six air-operated vibratory pads strategically placed around the hopper ensure a consistent flow of powder into the rotary valve at the hopper outlet without bridging.
The conveyor has 3 in. conveying tubes and operates at a 45 deg angle. An air motor powers both the conveyor and rotary valve, as is common in hazardous environments. An inner-locked access panel facilitates cleaning of the internal conveyor components and a vision panel in one of the conveying tubes enables operators to determine when cleaning is required.
The conveyor systems consist of several evenly spaced polyurethane disks attached to a wire rope. The rope and disks travel in a continuous loop fashion at a consistent high speed within parallel steel tubes. At each end, the rope assembly runs from one tube to the other around specially designed sprockets, one of which drives the rope and disks while the other provides tension to the rope. By maintaining the rope and disk assembly at a constant high speed, the conveyor produces an air stream that fluidizes and conveys product to the mixing vessel where the powder is centrifugally ejected. This method of conveying action allows varied production capacities from high to low with low energy requirements and minimal production degradation and separation.
According to Spiroflow, the Aero mechanical conveyor has proven to be one of the most cost-efficient methods of conveying materials in terms of its high productivity and dust-free operation. Features include total batch transfer, flexible operation at any angle without loss of capacity, dust-free sealed system for contaminant-free delivery, and removable housing around the conveyor for easy cleaning. Capacity of material handled varies up to 120 tons per hour.
The problem of lumpy, sticky powder has been eliminated, according to Beard, making it a virtually worry-free operation.
"It's a quality worry-free piece of equipment we are glad to have," said Beard. "Pouring into the vessel is consistent and we find the system extremely dependable. Instead of over an hour in labor required under the old method, the same process takes under 20 minutes, is totally automatic, and requires little or no supervision."
In addition, Beard pointed out, the system is virtually maintenance free. In over five years since installation, the only routine maintenance relates to cleaning and rope tensioning, he said, and Spiroflow's after-sales team has been excellent in providing required support.
