Extraordinary times, extraordinary dryers
Even in the middle of a pandemic, the science behind molding plastic parts doesn’t change. Which means it’s just as critical now as ever to dry plastics in the processing phase. These new technologies really bring the heat.
The COVID-19 pandemic is wreaking havoc on almost all aspects of plastics processing – supply chain, factory production, delivery times – but the actual science behind part molding remains unchanged. Which means that drying resin in the processing phase is still vital. So whether you’re dealing with hygroscopic polymers such as nylon, ABS, acrylic, PET, PBT, polyurethane, and polycarbonate that absorb moisture internally and release it through the air, or non-hygroscopic resins like PVC, polypropylene, polystyrene, and polyethylene that merely collect moisture on the surface of the pellet, the importance of dryer selection to meet your process requirements is still hugely important.
Here’s some of the latest drying technologies for your consideration.
Industry 4.0 is now everywhere in plastics manufacturing, including many of the newest dryers. Dri-Air Industries Inc. recently introduced the Industry 4.0-compliant SmartTouch control, which gathers data from the dryer and shares it with the injection molding machine and other pieces of equipment, and which is compatible with all DriAir dryers. With OPC/UA open platform and communication via an optional Ethernet switch or WiFi bridge for wireless communication, the SmartTouch control is driven by thermocouples strategically located in the towers, hoppers, and other locations to properly control the operation of the dryer for maximum energy efficiency. “The OPC/UA open platform allows users to add new sensors, communications devices or protocols that may become available in the future,” said Dri-Air president Jason Sears. “The control features a seven-inch colour touchscreen with easy to use prompts for temperature, time, and dewpoint display; and comes standard on our HP series dryers and dual-hopper dryers, and is optional on our Arid-X series dryers.”
Maguire Products Inc. is rebranding its VDB vacuum resin dryers as the Ultra series, reflecting its ability to pay for itself by saving in energy costs. In a typical material drying example for a process running at 220 lbs per hour for 6,000 operation hours per year, an average desiccant dryer might run at 60 watts per lb of material, versus the Ultra low energy dryer that would run at 19 watts per lb. Each system uses the same amount of energy but the energy used to dry is dramatically different: a comparable desiccant dryer would use almost 45 watts to dry the material so it can be processed, whereas to the same level the Ultra would only use four watts. Additionally, the use of data provided by the load cells allows the dryer to achieve many functions automatically — such as automatic starts and stops — and also makes possible automatic adaptive drying, so that only the material that’s required for a process is dried. Ultra dryers are available for throughputs of 150, 300, 600, and 1,000 lbs per hour.
SLEEP WHEN NECESSARY
The new PowerSmart optional control system from Novatec Inc. manages the energy used by the company’s central dryers based on data collected during drying, and not only provides the user with data such as the temperature and dewpoint in a hopper and dryer, but it also automatically adjusts the process to maximize efficiency. PowerSmart ensures resins are dry enough to avoid surface defects in the final product — but not too dry, company officials said, since overdrying can cause parts that are made of nylon, TPU or PBT to become brittle or inflexible. “PowerSmart monitors the material usage rate in the drying hoppers and then adjusts the machine’s energy use to match the actual moisture level, resin demand, and inlet temperature,” said Mark Haynie, Novatec’s dryer product manager. Additionally, PowerSmart automatically puts the hopper into a “sleep” mode once the resin is dried so that it doesn’t waste energy by running all the time, and then reactivates the drying process when more resin is needed. “In sleep mode, the hopper uses about as much energy as a 200- watt lightbulb, while maintaining the moisture level of already-dried resin,” Haynie said.
A new series of twin-tower or twin-bed desiccant dryers increases energy efficiency and decreases desiccant regeneration times without impacting drying performance, according to manufacturer AEC. The NGX dryers reduce electrical energy consumption by more than 25 per cent compared with competitors’ wheel-drying technologies, company officials said. NGX dryers are available in six sizes, ranging from 25 to 300 pounds per hour of processing capacity. The models are the NGX-25, NGX-50, NGX100, NGX-150, NGX-200, and NGX300, with the numbers designating the maximum number of pounds per hour of resin they can process. The dryers are available as stand-alone units; as portable units with a dryer and hopper on a cart; on a Nomad cart that takes the portable dryer/hopper combination and adds integrated conveying for beside-the-press use; and as part of a small, central dryer system that can feed multiple drying hoppers and multiple processing machines.
USE YOUR INTUITION
Plastic Process Equipment’s new FX series of Max-Dry honeycomb desiccant wheel dryers feature intuitive touchscreen microprocessor controls that make it easy to change settings and view process temperatures and dewpoint values. Offered as a replacement to the company’s MD series dryers, the FX dryers’ honeycomb matrix desiccant wheel has a series of channels that are coated with molecular sieve and silica gel that are permanently bonded to ceramic fibres inside the rotor. The desiccant wheel has a larger drying surface than a twin-tower desiccant dryer three times its size, company officials said. The wheel should last five years or longer. The FX dryers are available in seven sizes, with drying capacities ranging from 45 to 530 pounds of resin per hour. The beside-the-press units are available in 230- or 460-volt models.
The GenesysNext dryer line from Piovan has been optimized for the processing of recycled PET. Featuring self-adaptive technology, the new dryers can automatically manage the drying process by setting all the critical parameters – from the process air flow rate to its dewpoint value, from the residence time to the temperature – while maintaining optimum operating conditions even as hourly production and initial temperature and humidity conditions of the plastic granulate vary. According to Peter Dal Bo, Piovan’s chief commercial officer, the innovations that this new generation machine brings include more intuitive control and improved self-regulation. The GenesysNext dryers also use Piovan’s AIPC technology – short for automatic injection pressure control – which connects drying to injection molding and preform production. “This ensures the lowest production cost for each preform, not just in terms of energy savings but also in terms of optimization of the entire preform production process, with increased end product quality and reduction of rejects,” Dal Bo said.
With its recent acquisition of Austrian company FarragTech, Wittmann Battenfeld has expanded its dryer portfolio range to include new models of the CARD – which stands for compressed air resin dryer – series. CARD dryers can cover all drying applications, Wittmann officials said, from material throughputs of 0.16 to more than 1,000 kg of resin per hour, regardless of the material being dried, without water coolers. The drying containers are made of stainless steel and come with at least one sight glass window for visual inspection. Depending on their size, the drying containers also have a cleaning door. For filling the dryers – all the way from the CARD 1G with a volume of one litre up to the CARD 3500XL with a volume of 3,500 litres – Wittmann offers material loaders to match each appliance.