Brush strips for scrubber-dryer machines

Lamellas for scrubbing, vacuum and cleaning machines

Vibraplast AG ensures streak-free results.

When working with scrubber-dryers, the cleaning result depends on a wide variety of factors. Have the brushes or pads appropriate for the type of soiling and the floor covering been selected? Is the cleaning agent used suitable and has it been dosed correctly? The working speed and the amount of cleaning solution also influence the cleaning result. However, the cleaning professional knows that the most important factor for a flawless end result is an optimally functioning suction nozzle with first-class suction lamellae. What at first glance looks to the layman like an ordinary piece of rubber or plastic is, in many cases, a piece of ‘hi-tech’ made from Aadorf, Switzerland. 

Vibraplast AG, founded in 1961, has built up expertise in the field of rubber lamellae for the cleaning industry over the decades and is now one of the world’s leading companies in this sector. The most prominent international manufacturers of scrubber-dryers are among the customers of the Aadorf-based company. Around 40 employees work for the specialist, whose business areas also include noise protection, vibration isolation, foam technology, elastomer and plastics technology. 

The company is a long-standing partner to the cleaning industry. Customers at home and abroad source components as well as complete assemblies for industrial cleaning machines. Customised solutions at every level of production are among the core competencies of this successful company.

The cleaning blade

Effective cleaning of floor coverings is achieved by completely collecting the dislodged dirt particles. This is accomplished using a vacuum nozzle fitted with appropriate cleaning lamellae. A distinction is generally made between two manufacturing processes. The stamping of molded parts has become established. For cost reasons, injection-molded parts are also used in some cases. However, manufacturing below 70 Shore A is problematic. Consequently, this method is only used to a limited extent. Vibraplast AG is able to offer both variants to the highest quality standards. Years of experience in the cleaning industry have shown that individual parameters (e.g. hardness) must not be considered in isolation.

A variety of complementary properties make up a high-quality lamella:

• Coefficient of sliding friction 
• Rebound elasticity 
• Microbial resistance 
• Ozone resistance 
• Abrasion properties 
• Angle of inclination
• Oil and alkali resistance
• Lubricity
• Thickness tolerance
• Shore A hardness

Selection criteria for practical use

On our specially developed lamella test bench, we simulate the use of various cleaning lamellae on a wide variety of floor coverings.

The configuration of the suction nozzle depends partly on the OEM and partly on the intended use case. In general, a distinction must be made between contact pressure applied via height-adjustable support wheels and that resulting from the suction nozzle’s own weight. Some equipment vendors also use additional weights to increase the pressure on the lamellae. If cleaning results are uneven, check the suction nozzle setting. Before making any adjustments, ensure that the lamella is not excessively worn and/or that the suction nozzle is not damaged.

The correct height setting is achieved when the scraper edge of the rear lamella rests across the entire width of the suction nozzle. The optimum angle of inclination is 45 degrees to the floor surface. A very important factor is the flawless cutting edge of the lamella—without any breaks or damage. The appropriate lamella combination must be selected depending on the surface condition, water volume and the oil and grease content of the contamination. The chosen hardness has a decisive influence on the ability to adapt to uneven surfaces. Relevant information can be found in the manufacturer’s operating manual.

Vibraplast AG is certified to ISO 9001:2000 and, using state-of-the-art measuring equipment, is able to maintain the tightest tolerances to ensure consistent quality and the fulfilment of customer requirements in collaboration with the machine manufacturer.

Polyurethane PUR

The raw material for cleaning lamellas consists of polyurethanes (PU, DIN abbreviation: PUR). However, this designation is only of a general nature (analogous to wood, steel or rubber) and says little about the technical properties.

Polyurethanes are plastics or synthetic resins produced by the polyaddition reaction of diols or polyols with polyisocyanates. Depending on the manufacturing process, the material can be hard and brittle, or soft and elastic. Elastomers in particular exhibit comparatively high tear resistance. In its foamed form, polyurethane is known as permanently elastic soft foam (e.g. for sports shoe soles) or as rigid assembly foam. Polyurethanes can exhibit different properties depending on the choice of isocyanate and polyol. The density of unfoamed polyurethane varies between approximately 1000 and 1250 kg/m³. Essentially, the resulting properties are determined by the polyol component.

Usually, to achieve the desired properties, it is not the isocyanate component that is adjusted, but the polyol component (chemically modified). Cleaning lamellas may therefore only be compared for quality purposes if the raw material mixture is identical. Otherwise, there is a risk of comparing “apples with oranges”. Manufacturing costs depend significantly on the additives used. However, precise details of the mixture are rarely available.

Test specifications

Polyurethanes can be tested relatively easily.

An unknown material can be identified or characterised using thermal or FTIR analysis. However, as measuring instruments are often lacking in practice, incoming goods inspection is limited to measuring thickness (mm) and hardness (Shore A). Whilst these test parameters are very important for the successful use of a cleaning lamella, they are not the sole determining factor.

Long-term tests have shown that particular attention must be paid to microbial protection as well as acid and oil resistance. The reliability and service life of cleaning lamellae depend largely on the raw material and the relevant additives. Visually flawless materials deform and disintegrate after a short period of use and are no longer suitable for cleaning. Cracks or deformations mean that collected dirty water cannot be fully absorbed. This results in air leaks and the resulting water and dirt residues. The cleaning result is unsatisfactory.

Stripping geometry

A key requirement for the proper functioning of a cleaning blade is the correct contact pressure and angle of attack. These are determined by the design of the cleaning machine. Optimal deformation results in a negative pressure (vacuum). The airflow draws the dirty water into the waste water tank. A rebound elasticity suited to the floor surface compensates for unevenness in different floor types.

Another factor influencing an optimal cleaning result is the correct selection of the appropriate blade combinations. The front and rear blades must be coordinated. The front blade is designed to collect the dirty water and direct it to the suction nozzle. The rear blade must be completely sealed to ensure that the floor covering is dry after cleaning.