RAW MATERIALS HANDLING: The KISS formula for materials handling
Not everything that's new has microprocessor control, is Internet-ready and has a list of features as long as your arm. Simple, low-cost materials handling equipment still does the job quite nicely.
July 1, 2001 by Cindy Macdonald, associate editor
While “keep it simple” is gaining popularity as a mantra for personal life, it also works as a workplace philosophy. Newer raw materials handling equipment has the benefit of being designed for ease-of-use, emphasizing simplicity and low maintenance. In addition, the keep it simple principle often means cost savings for the processor, although it also usually means a compromise on versatility and flexibility.
The basics of conveying
At its most basic, materials handling simply means moving resin from point A to point B. That can be accomplished without even a single hopper-mounted loader. IMS and Anver both offer in-line vacuum units that use compressed air to convey materials through a hose. IMS’s Line-Vac is specifically designed to move large volumes of plastic pellets, regrind or even small parts over long distances. It is compact and lightweight, and has no moving parts, so maintenance is minimal. Three sizes are available to fit 1-1/4 in., 1-1/2 in. or 2 in. ID hose. Each unit costs less than US$200.
Anver’s Adjustable Flow and Transfer Tubes use compressed air to create a venturi vacuum and have a straight-through bore that lets materials pass without clogging.
For material storage, Spaltech International offers Vacu-Bin self-emptying material handling bins. These allow material to unload without creating starvation holes at the vacuum wand pick-up point. The bins are designed to allow material to flow freely to the lowest point in the bin, where it can be easily picked up by the wand. Rosanne Palmieri of Spaltech explains that Vacu-Bins help processors save money by keeping material clean, keeping the plant clean through less spillage and dust, and by reducing machine down-time due to material starvation.
Even central loading can be simple
The new SPP Vacuum Pump from Conair provides the benefits of central vacuum conveying systems in a low-cost, low-maintenance package designed for small-volume conveying applications. The unit has a brushless motor, eliminating the brush monitoring and replacement problems normally associated with single-phase vacuum motors.
The compact SPP Vacuum Pump provides enough power for up to 600 pounds per hour of material transfer. The Single-Phase SPP is priced as low as US$1000, and it conveniently plugs into a standard 115-volt outlet.
Nucon’s PDV vacuum pumps use TEFC motors and a pneumatically actuated breaker valve that prevents the pump from reversing during shutdown and allows for continuous run/idle. This saves wear and tear on the pump and motor by eliminating stop/start situations. An absorptive reactive exhaust silencer is used for maximum noise reduction.
Process Control Corp. has redesigned its RN series of vacuum receivers to offer easier cleaning and replacement of the pellet screen and a more reliable check valve for use in common material line applications.
The lid incorporates two side latches that hold a small pellet screen which prevents pellets or angel hair from entering the vacuum line. The screen can be removed without removing the lid.
With Dega’s Ready central vacuum loading system, one motherboard controller can accommodate up to 64 “daughter boards” for easy expandability. Each loader can be programmed from the machine or from the remote motherboard. Six sizes of hopper- mounted cyclones are available, and each may be equipped with a proportional valve to assure differentiated feed of virgin and reground material.
Take control of minor ingredients
Mould-tek has taken the successful pinch valve design used for major ingredients on its GXB blender and applied it to minor ingredients as well. The pinch valves replace auger feed for minor ingredients, and provide higher accuracy and throughput. The modified GXB blenders are said to achieve accuracy as low as 0.1% consistently for minor ingredients.
For color feeding directly to the machine throat, Comet Automation Systems has introduced a new weigh feeder, the Color Exact 1000. It is a screw metering unit for free-flowing powders and color concentrate, available with either a step motor for injection machines or a DC drive motor for extrusion machines.
The material hopper is stainless steel, and is integrated with the metering screw so that the entire assembly is removed from the machine for cleaning or color changes.
AccuRate’s L Series MECHATRON minor ingredient feeders pack all the award-winning features of the larger M Series into a substantially smaller package, suitable for the gravimetric minor ingredient feeding applications common to compounding.
The simple side of dryers
Conair’s newest line of medium-sized carousel dehumidifying dryers, the CM Series, incorporates a standard, off-the-shelf controller that is a good choice for processors who want simple, reliable performance in an easy-to-operate, inexpensive dryer.
The CM Series includes models with throughput ranging from 100 to 350 lb./hr. Controls allow easy setting of process temperatures from 160 to 250F (71 to 121C), or 160 to 375F (71 to 191C) in high-heat models. High temperature alarms are standard.
The CM dryers can also be operated with the optional Conair Power Miser 2 energy saving system, which minimizes power consumption by regulating the process heaters and airflow when the dryer is operating at less than rated capacity.
Universal Dynamics’ Autodry line is another option for low-cost hopper dryers. The machine-mountable units have a solid cone hopper design that offers instant dry air, a low dewpoint and high air flow. Available hopper sizes are 20, 40, 60 and 120 lb. According to Una-Dyn, when compared with a nominal 30 pph electric desiccant dehumidifying dryer, Autodry consumes approximately 38% less energy.