There’s a lot going on throughout the floor of a plastics plant—primary processing machines, such as injection molding, extrusion, blow molding, or other machines. Then there’s the material, which is often stored at machine-side locations.
There are the auxiliaries needed for temperature control and cooling, including water supplies, pipe or hoses, chillers, and temperature control units.
There are more auxiliaries to move material, create blends or mixes.
And, in many cases, there are machine-side dryers essential to pre-conditioning the materials fed to primary processing equipment. With so much equipment and activity clustered around processing machines, the production floor can become congested and inefficient.
The Problem with Machine-Side Material Drying
Machine-side congestion can be bad enough when machines operate on long runs of a single part and material, but it becomes even more problematic when there are frequent changes in the production mix.
Such changes can require storing more than one material nearby, or if added drying capacity is needed, hoppers and dryers may need to be swapped out, which means maneuvering personnel, forklifts or pallet jacks in tight spaces.
The point is this: If your business relies on machine-side material drying, you don’t always have a lot of good choices, because you’ve got to respond to every situation at machine-side, even if it means increased congestion or reduced efficiency.
But, fortunately, there are alternatives.
Centralized Resin Drying Systems
One great alternative is to consider a centralized drying solution. These central drying systems can be assembled in a convenient location, away from the processing area. Discrete hoppers mounted on stands are serviced by one or more large dryers.
These systems have the benefit of removing dryers and hoppers – and, often, Gaylords or bins of material – from the area around the machine, significantly reducing congestion. If your drying hoppers are located on the machine or extruder throat this is also an opportunity to move them to safer, easier-to-clean location on the ground.
For even more flexibility and efficiency, it might be wise to consider an integrated system, such as Conair ResinWorks™ or the simpler Multi-Hopper Cart. Typically, these easy-to-install systems combine a single resin dryer supplying air to material hoppers mounted on stands. With the Multi-Hopper Cart – these stands are on casters, and are easily movable to wherever you need them.
A system may consist of a relatively small dryer serving just two or three hoppers on one cart, or a larger dryer supporting up to 16 hoppers on four interconnected carts. A wide variety of dryer and hopper sizes offer the flexibility to meet a range of throughput requirements, from 25 pounds to thousands of pounds per hour, delivering dried material to processing machines using a pneumatic conveying system. Being modular and expandable, they offer a lot of flexibility.
How centralized drying systems work
In operation, a ResinWorks system uses a single dryer to drive heated and dehumidified air through a manifold that is built into each ResinWorks cart. The manifold provides an individual air supply to each hopper.
Inside the inlet air hose that feeds each hopper is a tube heater, linked to the dryer’s control panel. An operator can set and manage different temperatures for each drying hopper, as needed, from the dryer control panel or from HMI panels at each hopper.
Handling Varied Requirements with Centralized Drying
Let’s say that you need to process multiple types of material with varied temperature requirements: nylon, polycarbonate (in two different colors), and PET.
The nylon in hopper 1, as well as the polycarbonate in hoppers 2 and 3, requires a drying temperature required of 200°F. However, the PET in hopper 4 requires a much higher drying temperature of 350°F. The large temperature difference is no problem: once the operator programs the required hopper temperatures into the dryer control, the tube heaters take over. Incoming dehumidified air from the dryer is heated to 200°F as it enters hoppers 1, 2, and 3, while the heater serving hopper 4 boosts air temperature up to the 350°F required to dry the PET.
Perhaps the best thing about a centralized drying solution like ResinWorks is that it multiplies the control and monitoring features of a typical dryer, distributing them over the number of hoppers being served. So, on a single dryer control, it is possible to monitor the overall system, manage the settings for every hopper, process data from Conair Drying Monitors (if they are being used to monitor hopper temperature profiles) and trigger temperature setback to reduce heat and prevent over-drying.
Benefits of centralized drying systems
Clustering material drying and preconditioning (drying, mixing/blending, material selection and routing) at a central location, and then linking these assets to a pneumatic conveying system through a resin selection system, yields a range of benefits:
- Single point of control for material drying and pre-conditioning operations: A centralized drying solution enables a single point of control for preconditioning material for multiple machine locations. It eliminates the need to move back and forth between machine-side dryer and hopper locations to change settings.
- Reduced installation cost. A centralized drying solution requires just one power drop, rather than multiple drops to serve multiple machine-side drying locations.
- Improved space efficiency/reduced congestion: Centralizing gets Gaylords, boxes, and bins of material out of processing areas and eliminates the extra machine-side floor space requirements needed to access, store, and move them. The reduced space requirements may allow for closer spacing of processing equipment or added room for part handling or secondary operations.
- Improved material changeover and hopper cleaning operations: Centralized, multi-hopper drying systems eliminate the need for operators to perform changeovers on machine-side dryers. They enable a single operator to rapidly isolate, empty, and clean any of multiple material hoppers in minutes, without any downtime for the rest of the multi-hopper system. .
- Improved plant-wide material handling efficiency: Instead of having to ensure material replenishment at machine-side, automated conveying can ensure a steady supply of pre-blended, pre-conditioned material from the central location to each machine, and operators can focus solely on production and quality. To meet high material demands, additional hoppers of the same material can be preconditioned so it is immediately available when needed.
Do you need to reduce changeover labor and machine-side congestion?
Depending on material consumption and production requirements, the configuration of centralized drying systems can vary greatly (as mentioned above, throughputs range from a little as 25 pounds per hour to thousands of pounds per hour).
These systems can help your plant manage a range of materials to support many types of production, or be focused around delivering high throughputs of a few materials processed in very high volumes.