Installing a resin dryer will often be determined by the processing being performed, either on the machine or centrally located in the facility. Often, a mezzanine is used as a central location, freeing up valuable floor space.
There are, of course, reasons why press-side dryers may be best for some processors. But more and more are converting to central systems because their production requirements have changed over the years.
Injection molders often use a range of resins, with material and color changes happening often. In these shops, central location often is the best choice.
For extruders, blow molders and long-run injection molders, a dryer located within close proximity to the throat of the machine is often preferred. Press-side or press-mounted dryers are commonplace where processors have fewer than 10 process machines and have low throughputs on those machines.
If you are processing highly hygroscopic material, the dryer will be installed close to the feed throat. A shop also may want to use a dryer to convey the material.
It also is important to insulate the hopper when the dryer is installed on the machine. Insulation also can be placed on the sides, access doors and cone of the hopper. The insulation does not need to be placed above the general material level in the hopper.
A shop also can insulate the high-temp flex hose that carries hot air to the hopper cone and dryer cabinet, with duct work transferring hot air to the cone.
Central drying allows one dryer to provide -40° dew point air to multiple material hoppers of different sizes. An adjustable heater and blower are mounted on each hopper so the heat and air flow can be adjusted to the material in that hopper.
When the central resin handling area is set up a significant distance from the machine’s supply hopper or silo, it is important to make sure that the transfer lines are insulated to help maintain the required temperature in the transfer pipes and the handling air is properly desiccated. This will prevent re-introducing moisture to the resin during transfer.
The benefits of central drying include space savings, fewer material handlers, energy savings, increased machine uptime, increased material control, improved part quality, and fast return on investment.
The process heater location can vary, depending on the size of your system and the distance between the dryer and the machine hopper.
If a shop has a small system, it can be located in the dryer cabinet. If a shop employs a larger system, the process heater should be situated on the dryer to keep heat loss to a minimum.
Additional drying capacity can also be installed at the press. Microprocessor-based controls allow processors to monitor moisture levels throughout the process to ensure the highest part quality.
There are so many scenarios that can arise, and shops must consider each application individually to determine installation.
Installation also may change depending on application setup. When processing materials that need to be blended, then dried, that can impact the location of the dryer.
Resin drying is a vital part of plastic molding processes. Without reliable drying, scrap rates of end products can result in lost revenue and lost opportunity.