Consistent Flow

Crucial for quality

Published: Monday, April 9, 2007 - 22:00

In the old days at Soliant LLC in Lancaster, South Carolina, employees pushed 275-lb drums filled with acrylic resin powder to a scale for weighing and adding to a mix. Once the powder was weighed out, two employees manually scooped 1.5 lb at a time from the drums to the mixing vessel, the beginning stage of the 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. In the vessel, the powder was stirred into a mixture about the thickness of mayonnaise.

This typical aero mechanical conveyor system with an integral sack tip hopper was instrumental in ensuring a dependable and consistent flow of soft acrylic powder without lumps or sticking.

Before scooping into the mixing vessel, employees first had to manually 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 man hour for each operation.

“The manual system was time consuming and didn’t provide the quality control we needed,” notes 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 AMC based on an advertisement he saw in a trade journal.

The aero mechanical conveyor (AMC) from Spiroflow Systems Inc. was instrumental in assuring a consistent flow of soft acrylic powder into a large cylindrical mixing vessel without lumps or sticking in the production of Soliant’s Fluorex thermoplastic paint.

Fluorex is an alternative to traditional paint and plating systems and, with a current production palette of more than 140 different colors, is used by a variety of industries from automotive to marine, architectural, signage, appliance, electronics, telecom and others.

“We had no knowledge of Spiroflow’s capabilities, even though they were in our backyard,” says Beard. “After visiting their facility, we were convinced that Spiroflow had the know-how and expertise we were looking for. A demonstration using our powder convinced us that their equipment was right for the job.”

Aero mechanical conveyor operation
Designed and custom built for Soliant, the all stainless steel conveyor and distribution system consists of an inclined 90-in. long, straight-line AMC with a sack tip hopper at the inlet.

The Spiroflow 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 required to add material to the mixer, the mobile conveyor is positioned on a 4 x 4 ft weigh platform whose top is flush with the factory floor.

Once on the weigh platform, the weight of the conveyor 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 ensures 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-degree angle. An air motor powers both the conveyor and rotary valve. This 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 at a consistent high speed in a continuous loop within parallel steel tubes. At each end, the rope assembly runs from one tube to the other around specially designed sprockets. One of the sprockets 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 conveyance allows production capacities from high to low with low energy requirements and minimal production degradation and separation.

According to Spiroflow, the AMC 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. The system can handle up to 120 tons of material per hour.

“It’s a quality, worry-free piece of equipment we are glad to have,” noted 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.”

Beard added that the system is virtually maintenance free. In more than five years since installation, the only routine maintenance required relates to cleaning and rope tensioning, he says, and Spiroflow’s after-sales team has been excellent in providing the required support.

Besides horizontal straight-line aero mechanical conveyor systems, Spiroflow offers a multitude of conveyor configurations, distances and angles. It can also be used with other process equipment such as bulk bag dischargers and flexible screw assemblies, and it is PLC friendly.

In addition to free-flowing powders such as acrylics, flour and carbon black, the system has no problem with granules, flakes or chips and can also convey difficult materials such as titanium dioxide.

About The Author

Michel Podevyn

Michel Podevyn has been in the powder-handling industry for more than 30 years. He has extensive experience in equipment development and was integral in the development and deployment of the flexible screw conveyor. Podevyn is the CEO and president of Spiroflow Systems Inc.