For large jobs, contractors may want to consider a ride-on unit for grinding, honing and polishing concrete floors.
Two smaller, walk-behind machines can be used in tandem for increased productivity.
Grinders are available in a variety of power souces, including cord electric, battery electric, hydraulic motors and, as shown above, propane.
When choosing a grinder, remember to size your equipment according to the size of your typical jobs.
In our last issue, we introduced the idea of concrete polishing as a potential new revenue stream for rental businesses looking to break into this burgeoning market. While it’s true the majority of concrete contractors currently serving this market own their own machinery, there are tools and systems available to assist smaller contractors and even DIYers in trying their hand at polishing concrete.
There’s no doubt this market is not for everyone. Some of the equipment requires a significant investment, it’s not easily transported and it requires expensive tooling and a certain expertise to achieve the desired effect. That being said, with enough knowledge and the right frame of mind, serving the concrete polishing market could open up profit potential for rental businesses that wish to pursue it.
There are several factors to take into consideration when selecting concrete grinding equipment for your rental inventory, among them the equipment’s power requirements, weight, motor size, overall size, working dimensions and direction or directions the abrasives rotate. Following are some of the key selection factors, according to Jim Cuviello, owner of Cuviello Concrete in Stevensville, MD and one of the founding members of the Concrete Polishing Association of America.
Power requirements. Equipment is either powered by cord electric, battery electric or propane, and in some cases hydraulic-driven motors are used. With propane power there are no cords and no electrical requirements other than the battery used for starting the machine. Electrical requirements for cord electric equipment are typically 110-volt single-phase, 220-volt single-phase or three-phase, and 460-volt three-phase. Some 220-volt pieces of equipment allow you to run them single- or three-phase. Amperage requirements can range as low as 20 amps and as high as 60 amps.
Weight. Walk-behind equipment ranges in weight from 110 pounds to over 2,000 pounds before optional weights are applied. Ride-on equipment can weigh over 13,000 pounds. Equipment weight is important from a transportation point of view, but more important is the actual weight or head pressure over the abrasives.
Motor size. Motors range from 1 hp on a small, single-head rotary machine to 40 hp on a walk-behind machine with a multi-rotary head. There are three variables that affect the amount of power required for a machine to efficiently operate — how much contact area there is between the abrasives and the concrete surface, the grit designation being used, and the weight of the machine. These variables contribute to friction between the abrasive and concrete. The higher the friction, the more power required to drive the abrasives.
Overall dimensional size. You can find equipment small enough to fit in the back of a small hatchback and equipment so large it will only fit on a flat-bed tractor trailer. Equipment comes in all shapes and sizes. Some break down into multiple pieces for easier transportation and some are all one piece.
Working dimensions. This is defined as the overall area of the abrasives effect when the machine is running. Equipment working dimensions can range from square and 14 inches to round and 15 inches to 98 inches with multiple planetary heads.
Push, propel or ride on. Some machines are designed to be pushed, pulled or moved side to side while others are propelled with motor-driven wheels or come as ride-on units.
Belt/chain, gear or direct drive. The rotating heads of the machine are most often driven by a main or centralized motor that uses a belt or chain in conjunction with a pulley system. Some equipment eliminates all belts or chains and uses a gear system. Small, single rotating head machines are usually driven directly from the motor.
Abrasives drive. There are machines that have a large fixed single-rotating head that could measure 15 to 20 inches, fixed dual-rotating heads that are positioned side by side, machines that have two to eight rotating heads that intertwine in a gear-like fashion whose working width is up to 56 inches, and then there is planetary equipment where one large head rotates in one direction in addition to smaller satellite heads that rotate in the opposite or same direction.
What equipment is right for you?
How do you decide what equipment is right for your rental invetory? Below is a guide to help narrow down your decision.
First you need to decide the immediate market you are going to service. Is it residential, commercial or a combination of both? If you are going to service the residential market, it will be rare to find three-phase power, so you will have to choose equipment that runs on 110 volt or 220 volt single-phase power. Also, keep in mind that your equipment will have to fit through residential doorways and be able to be moved up and down stairs.
If you service the commercial market there will be times when three-phase power will not be available. When it is available it is usually only 220-volt three-phase, not 460-volt three-phase. Motors that run off of 220-volt three-phase power have high amperage requirements. When running 220-volt three-phase equipment with long runs of power cord, you will need four-gauge wires. Four-gauge, four-wire cable not only gets very heavy but also the cost of 60 amp plugs is considerable.
Will you offer surface preparation, polishing or both? If your customers perform heavy surface preparation, you will need a machine that has adequate weight and horsepower. Remember, the heavier the machine and the larger the motor, the more power you’ll need. When performing light to medium prep work with a lighter machine, the proper abrasives play a key role and the same is true when polishing with heavy equipment.
How big are the jobs your customers are trying to tackle? Are the jobs 2,000 square feet and under? If so, a 22- to 25-inch machine can tackle this size job in a timely manner for most processes, including polishing. For larger areas you will need multiple pieces of the same size equipment or make the decision to choose larger equipment. When making this decision, take into consideration the ability to put multiple machines on one job for increased production or on separate jobs to have the ability to tackle multiple jobs at the same time.
Are your jobs in open areas or broken into smaller areas? Large equipment works well in open areas but when having to work in areas with lots of rooms and tight corners, smaller equipment might be the better option. If your customers are consistently working in open areas of 1,000 square feet and over with doors that are 36 inches wide or larger, a 32-inch machine will significantly increase production. Remember that smaller machines offer a lot of versatility but require more manpower, whereas larger machines have less versatility but increased production.
There are many issues to consider when choosing the grinding, honing and polishing equipment that’s right for your company. Educate yourself on the options in the industry and consider how the machine characteristics will help your customers produce the floors they want.