Slow speed ahead for scrap granulation

Stephen Moore | Nov 12, 2019

Rapid Granulator has unveiled what it describes as the biggest innovation in slow speed granulation in years. The variable speed Rapid OneCUT PRO contributes to less dust, less noise, less energy consumption and significant operational benefits according to its manufacturer.

Variable speed granulation offers quality, energy and operational benefits to scrap recovery.

Amid growing demand for efficient and reliable recycling solutions, the OneCUT PRO allows injection molded plastic processors to adjust the rpm range when granulating at a slow speed from the standard 25 rpm to a bandwidth of 15–35 rpm (plus/minus 40 percent rotor speed), for optimal quality regrind.

With the vast majority of processors running at under capacity when it comes to regrinding, the new machine, which uses the new Rapid FlexiSPEED system, allows operation at lower speed when required. For processors facing capacity limitations, on the other hand, operating at a higher speed level will allow them to overcome capacity constraints, boosting operational output. The torque level of the machine is maintained, regardless of the speed at which it is running.

Further benefits of the new machine include the operator-friendly "Open Hearted" design through the patent pending QRR (quick rotor release) system and the use of an innovative energy saving technology.

While knife granulators are conventionally used for granulating softer materials and run at a speed of 200-250 rpm, processors of brittle materials such as glass-fiber reinforced plastics primarily rely on slow speed granulators. These processors have, until now, been limited to running their granulators at 25 rpm, regardless of the specific material that they are processing.

"Rapid is the leader in granulation and we wanted to know why the standard 25 rpm for slow speed granulators had never been questioned. This is why we started tests to optimize the speed according to specific plastic material characteristics. This has resulted in OneCUT PRO, the best of three worlds – less noise, less dust and less energy consumption," says Bengt Rimark, Rapid's CEO based in Bredaryd, Sweden.

Running the new machine at a lower speed of 15 rpm helps to improve the quality of ground highly brittle materials through minimizing dust generation. But there are noise reduction advantages too, as noise levels correlate closely with cutting speed. By reducing rotation speeds from 25 rpm to 15 rpm, noise levels can be reduced in many applications by 3-5 dBA. This means about a 50 percent reduction in actual noise pressure on the ears of factory workers.

A further advantage for low speed operation is the energy saving boost. "There is an almost 100% percent correlation between speed and energy consumption. If we reduce the speed by 40 percent, we have also reduced the energy consumption by up to 30 percent. That is a significant saving," says Rimark. For operators wishing to run the machine at a higher speed, moving from 25 rpm to 35 rpm, will allow them to increase the capacity with 30-40 percent in the granulator.

Besides the flexibility and improved granular quality, OneCUT PRO brings great operational benefits too. "One of the biggest disadvantages of slow speed granulators when compared to knife granulators is the gearbox design, which makes the rotor very difficult to turn by hand. What we have done for this machine is introduce the QRR (Quick Rotor Release), which allows the operator to easily disconnect the whole gearbox from the rotor so they can easily clean the machine for the next feed," notes Rimark. "When the gearbox is disconnected the whole cutter house can be opened up, providing the Rapid's unique Open Hearted design, that drastically simplifies cleaning, service and preventive maintenance," he adds.

A further advantage of OneCUT PRO is the implementation of EnergySmart, a new system that can lead to an about 80% percent reduction in energy consumption. This function allows the operator to stop the machine from running when accumulating materials, rather than having it run continuously. With Rapid Stop & GO mode, the granulator will stop and go in intervals, so there is zero energy consumption and no noise during pause mode. When EnergySMART is implemented together with running the machine at a rotor speed of 15 rpm the maximized energy saving is reached.

At the recent K Show, Rapid also presented its complete line of ThermoPRO machines, a new range of granulators specifically designed for in-line processing of skeletal waste from sheet and film thermoforming lines. "This machine needs to be flexible to handle different thermoforming speeds and thicknesses. It also must not have and moving parts exposed to operators on the plant floor," says Rimark.

The ThermoPRO is equipped with a new heavy duty rollerfeed system that also can handle the start-up cups up to 200 mm height in the web, eliminating any extra labor costs and material waste. ThemoPRO with integrated loop control is made in super soundproof execution in order to operate at noise levels below 80dBA, a level at which the use of ear plugs is not required. Rapid Granulator currently offers 15 different base configuration machines, depending on customer requirements.

Rimark believes that as a supplier operating in the circular economy field, Rapid Granulator has never been in a stronger position due to intensifying focus on plastic pollution. "We are very fortunate to be in a business that is part of the solution to reducing the environmental impact of plastics. Customers are desperate to get recycled materials in their product as that is what their consumers are demanding too. But we are not only helping customers recycle their materials, we are also making them more profitable when doing it," he concludes.

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