Diamond tooling is used to produce polished concrete floors. Diamond cutting and grinding tools are attached to a rotary polishing machine which moves the diamond tools across the concrete floor up to 800 RPM. By using tooling with progressively finer grit, the concrete is eventually brought to a polished state.
Here is an overview of diamond tooling used in a concrete polishing system:
The word “diamond” in “diamond tooling” is not a metaphor. Actual diamonds are built into the surface of the tooling as an abrasive. Diamonds are used for very specific reasons:
- Hardness. As most of us learned in science class, diamonds are the hardest natural substance on Earth. This means that diamonds can cut every other substance, including itself.
- Thermal transfer. Diamonds are excellent thermal conductors, which means that heat passes through diamonds rather than being retained in the diamond. Glazing of a tool happens when the tool surface melts and re-hardens as a smooth surface. Since diamonds are such good thermal conductors, they are less susceptible to glazing.
- Chemically inert. Diamonds do not react with most other chemicals, including acidic and alkaline substances. This means that the diamonds exposed on the surface of tooling are not affected by chemicals used for grinding.
There are two ways that diamonds are integrated into diamond tooling: resin diamond abrasives and metal bond diamond abrasives. The difference between them is the bond used to secure the diamonds into the surface of the tooling.
The bond is intended to perform two separate and contradictory functions. The bond must hold the diamonds on the tooling surface. However, the bond must gradually and evenly wear away so that new diamonds are exposed to the surface as the surface diamonds dull.
Resin Bond Diamond Abrasives
Resin diamond abrasives use a resin bond to hold the diamonds to the tooling. The “resin” of resin diamond abrasives is a plastic called phenol-formaldehyde resin or phenolic resin. This plastic resin is familiar to many people as the hard plastic used to make billiard balls and quartz counter tops.
Tools with resin diamond abrasives are made by combining powdered phenolic resin with industrial diamonds. Phenolic resins polymerize under heat and pressure, so the mixture of diamonds and resin powder is compressed and heated.
The resulting tool has good thermal properties since plastic is a thermal insulator, but diamonds are the most effective naturally occurring thermal conductor. Moreover, tools with resin bonds are considered self-sharpening because the resin wears away and exposes new diamonds on its surface as it is used.
Metal Bond Diamond Abrasives
Metal bond diamond abrasives use a metal bond to hold the diamonds to the tooling. The metal is typically a mix of powdered metals that may include iron, cobalt, nickel, bronze, copper, tin, silver, or tungsten. Similar to the process for resin bond, a metal bond is formed by sintering (heating and compressing) a mixture of diamonds and metal powder.
Metal bond tools have different properties depending on the mixture of metals sintered. For example, harder metals are better for softer concrete because softer concrete tends to be more abrasive on the tool surface. Conversely, softer metals are better for harder concrete so that the metal bond wears away quickly to continually expose a fresh layer of diamonds.
Because metal is a thermal conductor, metal bond tools are designed to conduct heat from the surface toward the core where it can be dissipated. This reduces glazing by keeping the temperature below the melting point of the metal bond.
Grit is the metric for describing how coarse or fine the diamond tooling is. When dealing with diamond tooling, the grit is determined by a number of factors, including the size of the diamonds and the arrangement of the diamonds. If the diamonds are larger and have greater gaps between them, the tool will tend to have a coarser “grit.” On the other hand, smaller diamonds with small gaps between them will produce a tool with a finer “grit.”
Generally speaking, polishing concrete proceeds from coarser to finer grits. Once the grit reaches 400 or higher, the concrete is considered “polished.”
Both metal bond and resin bond diamond tools have material properties to make diamond tooling an effective and efficient tool for polishing concrete. When you’re ready to transform the appearance of your concrete floors, rely on Eco Guard today.