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Scorpion PLC pugmill makes selecting material blends easier

Selecting material blends has never been easier with the Scorpion PLC pugmills from Precisionscreen

The Scorpion PLC pugmill with additive bin

Brisbane-based Precisionscreen began manufacturing its Scorpion pugmills in the 1980s when the business was established, and nearly 40 years later the mixers remain popular at quarry sites across the country.

But while the market appetite for the pugmills has remained strong, the equipment has undergone significant development and refinement over the years in a bid to provide operators with more automation than ever before.

First introduced on the Scorpion pugmill eight years ago, the PLC control system is designed and built at Precisionscreen’s Wacol facility in conjunction with control systems and sensors manufacturer ifm – making mixing materials an easier and faster process.

“The PLC system enables you to electronically control the functionality of the machine. It’s essentially ease of operation for the on-site operator,” says Precisionscreen senior sales executive Jonny McMutry.

“You can have either an auto or manual running function for the machine, but what that can also do is enable you to preset a particular volume of water or a particular volume of cement.

“The idea for the PLC system is just to create a greater sense of automation for the machine, a greater sense of reliability for less calculations or less difficulty for the on-site operator.”

Using the PLC system, the Scorpion pugmill is a single operator machine, meaning the operator who is loading the pugmill simply needs to turn on the machine each morning and select which function or blend they are trying to achieve.

“The machine takes care of itself to some degree,” McMutry says.

On the Scorpion pugmill, configurations can be changed with the touch of a button via the ifm CR1081 control panel.

Of course, the technology of pugmills hasn’t always been like this. Up until the introduction of the PLC system eight years ago, Precisionscreen’s offering was far more limited.

Older iterations of the Scorpion pugmill required operators to do the calculations themselves – constantly stopping and starting the machine to calculate and achieve the desired speed and tonnage.

“If you go back 10 years ago, we used to have almost like a sticker chart on the machine based on what you’d have to calculate off of the loader scales, how much materials you were putting through the machine and adjust the speeds on the water pump,” McMutry says.

“Since then, we designed an additive bin but again it was screw controlled, which meant you would have to speed up and slow down the screw conveyer based on what tonnage you estimated was going off the belt.

“We’re now able to use the PLC system to calculate quickly how much material is going up the belt and what speed the water pump needs to run out to get the right percentage of water base.”

The Scorpion pugmill can be adapted to a customer’s needs

The PLC control system’s automation not only results in a less stressful day’s work for the operator, but it also allows for a longer and more productive day. Given there’s no setup or calculation time, the Scorpion pugmill can hit more than 10 hours day, according to McMutry – something that would have been unlikely with older models.

The fact that the Scorpion pugmill and the PLC control system are both designed and manufactured in Australia is also an advantage. Several in-house technicians employed
by Precisionscreen are tasked with adjusting the control systems, as well as working on the latest developments with ifm.

“It has developed over time and over the years and again that’s the benefit of us fully manufacturing and developing the system within our Brisbane factory,” McMutry says.

“We can design, develop and adjust based on both customers’ expectations and industry standards.

“Bringing it all in-house and having a couple of in-house technicians looking after it means that if we do need to make adjustments, which we have done over the past eight years since we’ve introduced a system, we can do it pretty quickly.”

Precisionscreen can also remotely plug into machines to conduct maintenance and check pressure settings via Wi-Fi connectivity – which is an optional extra on the pugmills.

The Scorpion pugmill itself is powered by a 162kW engine, which can produce up to 300 tonnes per hour of road base with optimum moisture content.

The pugmill can also conduct cement-stabilised applications when cement or similar materials are loaded into the additive bin through an inlet chute via solos or an additive bin feeder.

In the pughead twin auger shafts that feature 50 reversible wear paddles and a 3,500mm-long pug head chamber with two speeds ensure material can mix adequately.

Other features of the Scorpion pugmill include wind down legs for added stability whilst in operation and additional safety features such as galvinaised guarding, rock guards, a safety warning beacon and siren and pughead guards are all fitted.

Precisionscreen offers the Scorpion pugmill in two configurations – the PLC and OMC – the latter of which does not feature the electronic PLC system.

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