Knowledge and experience actualized by powder processing technology

The fine art of automating powder processing with vacuum conveyors

By Doan Pendleton December 3, 2023
Courtesy: Vac-U-Max

Powder processing insights

  • Companies specialize in automating powder processing using vacuum conveyors, improving efficiency, safety and quality while reducing labor and contamination risks.
  • There are several tailored solutions for varying powder processing needs, including unique applications like systems for the visually impaired and handling challenging materials like sticky powders.
  • By integrating vacuum conveying systems, it can significantly reduce material loss, eliminate health hazards and increase overall productivity in powder processing facilities.

Integrating vacuum conveying systems with powder processing equipment demands more than control systems to coordinate material movement, batching and processing. It requires tribal knowledge of material behavior, and a history of field-proven solutions.

Powder processing is a specialized field, with more than 10,000 powders available, each with distinct characteristics and behaviors. In addition, each production line has its vagaries. Expertise in vacuum technology, production and process knowledge, and understanding of material characteristics are essential to designing powder transfer systems.

Automating manual transfer of powders via pneumatic, aero-mechanical or flexible-screw technology, is a common capital investment in industry today due to its high return on investment (ROI) following from increased efficiency, reduced labor, elimination of respiratory and ergonomic liabilities and ingredient preservation, as well as bolstering product quality and boosting safety and cleanliness.

Expertise in technology, production and proves knowledge are essential to successful systems integration projects. Courtesy: Vac-U-Max

Expertise in technology, production and proves knowledge are essential to successful systems integration projects. Courtesy: Vac-U-Max

Detailed considerations

Vacuum conveyors are the most hygienic method for powder and bulk solids transfers. Conveying systems are fully enclosed, protecting materials from air, dirt, and waste. Because product does not escape from a vacuum conveying system, particulates that can endanger worker health, jam expensive equipment, or result in cross contamination do not escape into the environment.

The simplicity of vacuum conveying systems, consisting of only four components, sometimes leads to the misconception that vacuum conveying systems are just fancy heavy-duty vacuum cleaners. While based on similar vacuum technologies, transferring powders and bulk solids is considerably more challenging than sucking up waste and debris.

Vacuum conveyor design is influenced by factors such as material size, bulk density, and characteristics, as well as conveying distance, upstream and downstream equipment, plant layout, overhead clearances, and even environmental factors.

Fit to purpose

For any given company or processing line, automation looks different. Sometimes, automating powder transfer is a response to growth, e.g., when manual transfer no longer meets demand. Often it addresses a safety hazard that is costing money in disability claims (commonly musculoskeletal) or in number of workers needed.

Whether it is a complex PLC-controlled, computer-compatible, multi-ingredient storage batching and processing system, or a simple “up and in” material transfer system, powder transfer with vacuum conveyors often needs some level of customization to avert issues that might interrupt operations.

Even with seemingly simple applications, like a pre-engineered “up and in” conveying system for materials easily conveyed, like wax chips, the first step is a detailed dialogue with the customer to delve beyond basic material considerations, conveying speed and conveying distance. This dialogue informs the conveyor manufacturer of potential issues that call for ancillary equipment or a custom solution to guarantee integrated systems.

Sometimes conveyor design is uncomplicated, and the control system is what sets the installation apart. Note that some conveyor manufacturers are also U.L. listed builders and suppliers of electrical control panels and PLCs.

Powder processing is a specialized field, with more than 10,000 powders available, each with distinct characteristics and behaviors. Courtesy: Vac-U-Max

Powder processing is a specialized field, with more than 10,000 powders available, each with distinct characteristics and behaviors. Courtesy: Vac-U-Max

Interesting example

An organization that employs blind and visually impaired individuals needed a conveyor system to deliver detergent from 2,000-pound super sacs to an auger filler. The customer wanted the two control systems integrated with each other. Factory acceptance testing of the vacuum conveyor was done at the auger filler manufacturer’s facility to demonstrate.

The filling system allowed the blind or visually impaired to operate the line. The operator inserts a wand into the super sac, pulling material from the conveying line into the filling machine. An audible signal alerts the operator to move the wand within the bag whenever the wand fails to suck detergent into the hopper. When boxes are full, another audible signal alerts operators to move it from the filling station to where boxes are sealed. Audible callouts confirm process status.

Options available

Using a wand to feed conveying systems is a common low-cost option for lower volume applications, while still reducing manpower needs and ergonomic hazards. Other options are fully automated super sac unloading equipment or bag dump stations with integral dust collection that stops dust from entering the environment during dumping.

In difficult situations seasoned manufacturers with tribal knowledge of applications, and experience with tens of thousands of materials often select standard equipment that is an 80% fit and then engineer and fabricate the other 20% to fit the application.

What seems a complicated procedure to the layman can be simple for pneumatic conveying experts, as was the case at a cable producing facility when super-absorbent polymer was escaping into the environment. The goal was to eliminate polymer dust entering air around the operator during cable manufacture, reclaim excess material from the coating chamber and eliminate bag dump station clogging.

A dual conveyor system, with automatic changeover, programmed to work much like a pumping heart, was the answer. First, cable enters a chamber at about 400-600 feet per minute while an atomizer simultaneously injects positive air and the polymer into the chamber wherein it coats the cable fibers. At that same time, the dual conveyor system sucks air out of the chamber faster than it enters the coating chamber, creating a negative pressure wherein the polymer cannot escape from the coating chamber.

Material enters the first of two valved chambers for a specified number of seconds, after which the first valve closes while the second valve and chamber open. When the first valve closes, air is blasted into the filter to release particulates to the bottom of the system where another routing system returns the polymer back into the hopper for reuse. The filtration cleaning process repeats for a few seconds until the first filter is clean, and the second valve closes to clean the filter for the second chamber.

Now, instead of losing 7% of material per shift, material loss is nearly zero. Workers exposed to fugitive polymers experienced sensitivity in their eyes and nasal passages and led to high turnover in the department. The hazard was eliminated with the new vacuum conveying system.

Other new powder compounds can seem impossible to convey with vacuum conveyors. Typically, getting material through the tube isn’t a problem, but getting it to automatically feed into the conveying tube can be.

Working with sticky stuff

Such was the case for a global leader in optimized heat management systems and its development of two custom vacuum conveying systems from the ground up for a new compounding facility. Due to the dense, sticky characteristics of its exotic powders, the seemingly simple process of transferring materials into the compounding extruder presented challenges. The materials clumped together and wouldn’t convey. Using conventional equipment wasn’t an option.

Part of the solution to get material to automatically feed into the conveying line was derived from a previous application in a very different industry. Although the makeup of the materials was completely different, the characteristics were similar, and knowing that led to its application for the exotic powders, resulting in a custom design bag dump station influenced by a bulk bag unloader fabricated for dense sticky powder that could be either a supersac or 50-lb. bags.

Integrating powder processing systems with automated powder transfer calls for knowing how powders behave and interact with upstream and downstream equipment. This tribal knowledge allows precision engineering of vacuum conveying systems that eliminate safety hazards, prevents dust from entering the environment, reduces labor costs; and when designed properly, becomes a “set it and forget it” system that generates productivity improvement.

Author Bio: Doan Pendleton is is the President of Vac-U-Max.