Pro's Corner

Understanding Concrete Floor Grinders: What is Best for You?

If you have ever done any research into the surface prep and concrete polish market, you will know that concrete grinder machines do not come cheap. As with many things in life we need to do our research to make sure we are getting exactly what we need, getting a valuable purchase, and getting the best quality we can. We want to help you be confident in your purchase.

First, we will discuss the two head configurations of grinders, planetary and rotative. Next, we discuss the power options. This might sound simple, but when it comes to voltage, phases, and propane there are lots to discuss. Finally, we will break down what to look for in the size and weight of these powerful machines.

Planetary vs. Rotative

One of the first things you need to be aware of is choosing between a planetary or rotative machine. Planetary or Rotative refers to how the discs move to get the job done. Each configuration is capable of a complete floor polish or grind with its own specifications. 

Planetary Grinders

planetary

A planetary grinder has one large disc with three smaller discs mounted on it. A good way to visualize a planetary grinder is the large disc is similar to the sun, with smaller planets/discs rotating on their own axis around that sun/bigger plate. This larger disc will never come in contact with the ground, as it acts as the main motion drive to rotate the smaller discs.

A planetary grinder is typically a lighter weight machine compared to rotative machines which in some cases can make them more maneuverable and easier to work with. Concrete Grinders are either belt-driven or gear-driven. Planetary machine configurations are often made to be belt-driven.  

Rotative Grinders

A rotary or rotative grinder turns from a fixed axis, allowing them to have multiple heads. The main limitation of this type of grinder is how wide it can be. Some machines have as many as 8-10 heads, although the most typical arrangement is the 2 and 4 head configuration.

rotative

When you have multiple heads on a rotative grinder, you will most likely have a counter-rotating machine. This means the different heads rotate in opposite directions, making them easier to use for the operator and allowing the machine to go in a straight line. 

Rotative Grinders are always gear-driven and heavier than planetary machines. This can make them a better option for removing thick glues or paint. 

Power Options:

A machine can come in a variety of power options such as electric or propane. Each of these options has factors that make them ideal for the type of work you are doing. 

Electric machines typically come in 110, 220-240, or 380-480 volt machines. They are also in single-phase and three-phase configurations. 110 volt come in only a single phase. 220-240 volt are often offered in single-phase and three-phase. 380-480 volt are typically always a three-phase machine.

Here is what you need to know about single-phase vs three-phase:

Single-phase: is a two-wire alternating current (AC) power circuit. This is what is common in most residential homes. If you plan on doing only residential jobs a single phase will be the way to go. The main advantage of a single-phase machine is the equipment is typically smaller, costs less, and power is more available to use.

Three-phase: is a three-wire of alternating current power circuit. Each leg of alternating current reaches a maximum voltage. This can get complicated, but basically, you have more consistent power that never drops to zero. These machines are large and powerful machines requiring them to consume more power. Three-phase motors will cost more, but they will be generating more power making them worth the investment.

phase perfectIf you're wondering what to do if you don’t have three-phase on a job site, and want to know how to use the machine, good question!

It is a simple fix for contractors looking to take advantage of this option. A phase converter can be used to convert single-phase power to three-phase power. A phase converter creates the third line of voltage enabling three-phase power when you are in a single phase area.

Propane machines: These machines are powerful and come with the added convenience of not having to worry about finding a power source. They have the added benefit of being often more powerful than their electric counterparts. Running on propane provides great benefits to not worrying about power, additional power cables, etc. 

There are some drawbacks and challenges of propane, though. Propane grinders are loud machines. They will need to be used in areas where loud noises are permitted. Therefore, if your plan is mostly commercial this will be a great option but if you plan on doing more residential a quieter electric machine might be best.

Size and Weight 

Is size an important factor when choosing a grinder? The answer is a bit complicated. A larger machine will get the job done faster than a smaller machine if they have a larger grinding head to complete concrete passes. A smaller machine will complete everything a large machine can, but will fit in smaller spaces such as a doorway or a hallway. Therefore, what you need will depend a lot on the jobs you plan on doing. 

Weight is also important to consider. We have discussed how rotary grinders are often heavier than planetary. When grinding concrete that extra weight can be useful in removing those hard-to-remove surfaces. To combat this in both types of machines, many have a weight system that can be added and removed so that you have the right downward head pressure for the job. Therefore, in the past, a rotary might have been your only solution for a heavier machine. Today though you have many options that ultimately will come down to what the contractor wants. 

concrete surface preparation, Concrete, Surface Preparation