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Scrubber dryers - a brush with technology27th of March 2015
How important is the type of squeegee and the size, shape and position of the brushes in determining a scrubber dryer’s performance? Ann Laffeaty finds out.
Scrubber dryers come in all shapes and sizes and the average customer will consider the size, comfort, cost and ease of use of the machine when considering which model to purchase. All these factors have a major impact on the performance of a scrubber dryer. But what about the tools that actually perform the scrubbing and drying tasks, namely the brushes and squeegees? How much of an impact do these have on the productivity or otherwise of a machine?
According to Hako marketing director Klaus Serfezi the brushes and squeegees are the most important components of any scrubber dryer in terms of cleaning results. “It is always essential to choose the right kind of brushes or pads for the type of floor to be cleaned,” he said. “Once that is done, step one – namely, removing the dirt from the surface - has been taken care of.
“The next step, however, is just as important: sucking up dirt and water with the squeegee. The more efficient the suction performance, the better the cleaning result. This is the one big advantage of scrubber drying compared with manual cleaning where the dissolved dirt is not removed from the floor sufficiently if at all.
It is important, however, that the operator carries out regular checks on the state of the brushes or pads and the squeegee. The sealing strips of the squeegee in particular need to be monitored and any dirt deposits removed.
He says the size and shape of the brushes and squeegees play a part in the machine’s performance and efficiency. “Naturally the actual working width of these tools needs to match the size of the building to be cleaned. That’s why it is important to advise customers on site. Before the customer decides to use a machine with a wider working width, we have to ensure that the machine will be able to access all areas of floor space and that any doors or ramps do not become insurmountable objects.
“More often than not, however, customers make the mistake of choosing a machine that is too small in order to save costs. What they don’t take into account is the fact that daily working time will increase significantly, resulting in unreasonably high labour costs.”
He adds that the shape of the squeegee is key to good suction performance. “Parabolic or V-shaped squeegees offer huge advantages over straight, standard squeegees,” he says. “This becomes obvious when cleaning uneven surfaces or tiled, jointed floors. The same applies to working in curves where the difference becomes clearly visible.”
And he claims that the materials used to make the brush heads, squeegees and fittings are also significant. “Brush heads and squeegees are particularly exposed to collisions which means they need to be very robust. Scrub decks and squeegees made from pressure-casted aluminium are extremely durable and can withstand a fair amount of rough treatment.
“In addition, millimetre-thick metal fittings on a full metal frame allow for heavy-duty operation. Naturally these elements initially make a machine more expensive, but the investment pays off quickly as customers save costs in the long run. The aim is to ensure the machines are constantly in service.”
He says Hako is continually working on improving its scrubber dryers. “We only act as consultants for brush and pad manufacturers, but squeegees are our domain and we are continuously working on improving them further. New types of flooring come on to the market all the time and this creates new challenges for the cleaning industry.”
Kärcher’s environmental matters public relations officer Linda Schrödter agrees that the cleaning result is greatly dependent on using the right brush for the job. “The brush must be suited to the particular type of floor - whether it has a smooth surface, indentations or a porous structure - since the brush needs to be able to reach the dirt in all areas,” she said.
“The suction lips should also be able to pick up water reliably even when turning so that the surface can be walked on soon after cleaning without any risk of slips.”
She adds the size and shape of the tools is important. “The first thing to decide is whether a disk or roller brush should be used,” she said. “For textured floors, heavy dirt or where there are many crevices, a roller brush is recommended since it maintains contact with the floor very well when higher contact pressure is exerted on a smaller contact area. Scrubber dryers with roller brushes can also include a pre-sweep unit which makes the important task of pre-sweeping redundant.
“Corners can also be cleaned more effectively using roller brushes since the distance between the roller and the brush enclosure is smaller than for disk brushes.”
According to Schrödter, the rotation speed and contact pressure of the brush will also affect the cleaning result. “The working width of the scrubber dryer is determined by the size and width of the brushes,” she said. “The squeegee is generally a little wider than the brushes to ensure that water is picked up reliably, even in corners.
"Whether straight or curved, the results are identical in terms of suction. Curved squeegees are mainly used on flatter surfaces whereas straight squeegees are more often used on textured floors where adjusting the tilt of the squeegee may be necessary.”
Even the position of the brushes and squeegees on the machine can make a difference, she adds. “In principle the greater the distance between brushes and squeegees, the longer the cleaning agent has to take effect and therefore the better the dirt will be removed,” she explained.
“There is also the ever-present challenge of dealing with wheel tracks left on the floor by larger walk-behind machines where the squeegees are located directly behind the brushes. This is why squeegees are best placed behind the traction wheels in order to avoid wheel marks.”
Kärcher has recently developed a new squeegee with a suction bar that has a trapezoid shape, the side elements being angled towards the front of the machine. “It is therefore literally wrapped around the machine,” said Schrödter. “When cornering, the suction bar swings sideways almost as far as the drive wheels. This means even when turning sharply the design ensures that water is reliably collected.”
She says the company is always working to increase the lifespan of its rubber blades and to adapt them to different cleaning tasks. “Lifespan is the main cost factor since the longer you can use the blades and brushes, the happier the customer,” she said. “But you can also influence lifespan by adjusting the contact pressure of brushes using a proper cleaning agent; by recommending the perfect brush for the application and by adjusting the speed of the brush.”
A scrubber dryer is only as good as its pick-up according to global marketing manager for machines at Diversey Care Laurent Ryssen. “If the pick-up is not efficient, any dirt loosened by the brushes, pads, chemicals and water will simply be redeposited back throughout the facility where it will be redistributed and smeared,” he said. “This will reduce cleaning quality while also increasing the risk of slip and fall accidents.”
The company claims its own W-Shape squeegees offer superior water pick-up while reducing the number of stops during a cleaning operation. “We also offer self-levelling squeegees and polyurethane blades for longevity and consistent pick-up, along with diamond pad technology.”
However, he adds that brush and squeegee technology is evolving slowly compared with other products on the market. But they are still definitely evolving according to Wetrok’s machine product manager Mark Meng.
“Previously tried and tested technologies are continuously being improved upon,” he said. “Product development focuses specifically on the shape, contour, and material of the squeegee.”
He claims brushes and squeegees play a central role in the workings of a scrubber dryer. “Good cleaning results and a dry floor are largely dependent on these components.” Wetrok has introduced a dual scrubbing brush system on its Discomatic Tango and Mambo compact scrubber dryers. “This has the advantage of a self-drive forward propulsion by means of the brush motion as well as greater surface pressure; improved reach into corners and more revolutions per minute for a better cleaning result,” says Meng.
He says factors like materials and design also have an impact on scrubber dryer performance. “The type of brush movement and the shape of the brush have a significant impact on cleaning results while the geometry of the power nozzle plays an important role in suction performance. A curved design with a central suction system has proven to be most successful.
“The choice of materials used to make the brushes and squeegees is important. Selecting the right material will ensure a good result and will optimise the service life of the squeegee.”
According to Nilfisk-Advance’s floor care group product manager Anders Sandstrom, the correct brush and pad tools are essential for achieving optimum cleaning results without damaging the floor.
“These tools can help preserve the flooring and keep it in top-level condition while extending its life and helping to drive down costs for the future,” he said. “The squeegee needs to perform in different environments and a high level of suction performance is essential for removing
the dirty solution while leaving the floor safe and dry and capable of being accessed immediately.”
He too feels the size and shape of the tools is significant. “A squeegee that is too large but has insufficient suction will leave dirty solution and detergent on the floor,” he explained. “This will incur the risk of slips and falls and over a period of time, the floor condition will deteriorate.
“A straight squeegee will perform well on a flat, even surface but may have jumping issues on tiles and uneven floors. A curved squeegee will always direct the water into the centre of the squeegee where the suction point is located and will therefore lead to higher performance and create fewer jumping issues.”
He says larger brushes can offer advantages over smaller models. “A larger disk brush will maintain contact with the surface for longer and will offer a higher level of cleaning efficiency. But a smaller brush combined with higher pressure will increase the risk of too much mechanical pressure which could cause floor damage.”
According to Sandstrom, cleaning tools vary from one model to the next. “A cylindrical brush will have contact with a smaller section of the floor than a disk brush, but unlike a disk brush may offer the advantage of being able to sweep away small items. So a cylindrical brush would be an advantage in a small warehouse with a concrete floor where there is some minor debris from pallets, for example, since no pre-sweeping is required.
“However in a supermarket or a shopping area where a high cleaning performance and floor finish is needed, the disk brush or pad solution would be a better choice depending on the flooring.”
Suppliers are constantly working on new designs and materials to achieve higher levels of performance, says Sandstrom. “The types of flooring available are endless and new types of floors are constantly being introduced,” he said. “Also, new tools for our scrubbers are hitting the market all the time and we are always expected to have machines that match these new tools. So we are always having to compromise since the ‘one size fits all’ concept never really seems to work.”