Types of Polishing Pad Bonds
In the realm of polishing pads, there are a number of types. The variations in size, numbers of steps, and even the materials a pad is made of contribute to the performance of the pad. One of the key aspects of a polishing pad is the type of material that bonds the diamonds to the pad. What are the different bonding materials? Why are there so many bond types? And Does it really matter which pad you choose?
The Role Of the Bond
The purpose of any diamond tool’s bond, including polishing pads, is two-fold. First, the bond keeps the diamond grit in place. This is a key to the cutting, shaping, grinding, and polishing processes. If it is not strong enough the process is ineffective. The other aspect of a bond’s purpose is to wear away and expose new diamonds. If the bond does not wear fast enough, this too can hinder the performance of the tool.
How the bond wears is central to the way a diamond tool performs. It is easy to think that the bond that wears longer is the “better” tool. But that is not actually the case. Diamond tools work by using very hard diamond grit to cut, or wear down, other hard materials. however, the diamonds get weak the longer they undergo friction from the process. As diamonds weaken they crack and disintegrate; falling out of the bond. This means that the bond must 1) have diamonds within it and 2) wear away so that the unused diamonds are exposed.
The Need for Many Types of Bond Material
If the bond of the diamond tool did not wear, when the diamonds cracked and fell out of the bond the tool would no longer perform. This is because the “cutting” material would not be able to operate on the stone to which it was being applied.
The key then is balance. The bond of the tool must wear at a rate that is commensurate which the rate at which the diamonds disintegrate. The rate at which the diamonds disintegrate depends upon the quality of the diamonds, the number of diamonds used, and the hardness of the material on which the tool is being used.
Polishing Pads Bond Types
Polishing pads differ in appearance. One line of pads may be very rigid, hard, and look like it’s made of metal. The next pad you see might look totally different. This one may be very flexible and look like it is made of rubber. One of the factors contributing to this visual difference is the bond material used for holding the diamonds of the pad, wheel, disc, or whatever other term you may hear it called. These various bonds have different strengths and wear rates. And as we have already discussed that makes each of them suitable for specific materials and tasks.
There are four basic diamond bonds that you will see on diamond tools. They are:
- Resin Bonding
- Vacuum Brazing
We are going to talk first about the last three in that list. Then, we will discuss in more detail the first in the list; namely resin bonding.
Electroplating is a process for bonding diamond to tools that is of the type single layer. The single layer type of diamond bond is one where the diamonds are fully exposed. Affixing the diamonds to the tool requires a process to get the diamonds to become part of the surface. One of the methods for this objective is the electroplating process. In electroplating, positively and negatively charged materials (the diamonds and the tool body respectively) are used in tandem to create the bond that holds the two parts together. The result is a single layer of exposed diamonds.
The process of vacuum brazing is also a single layer bond. Like electroplating, vacuum brazing results in the full exposure of diamonds. The fact that the diamonds are fully exposed makes tools with single layer bonds more aggressive than the matrix type bond. Vacuum brazing, like electroplating uses a process to cause the diamonds to bond to the body of the tool. However, the the method is a result of melting a filler metal that fuses the grit to the body of the tool.
So both electroplating and vacuum brazing are processes that produce a single layer bond that produces a diamond tool that is aggressive because of the amount of exposed diamonds. These bond types create a very dense layer of diamonds. However the diamonds used are different since the way they are bonded to the tool is different. So what about matrix bond diamond tools? Let’s look at those now.
Sintered Tool Bond
As mentioned above the final two bonds we are looking at here are of the matrix type. A matrix type bond is one that features diamond grit suspended in a matrix of some material. A sintered bond is one in which the diamonds are suspended in a material that is formed through a process known as sintering. We will not delve into the details of the sintering process in this article. However, Wikipedia has an extensive page about it here. The very short explanation is that metal powders are super heated and pressurized in a precise manner until they produce a mass of material. In the case of diamond tools,these masses contain diamonds. As the diamonds disintegrate, the sintered bond wears to expose more, new diamonds.
Some of the tools on which you will find sintered matrices are diamond blades, edge profiling bits, and edge polishing wheels. But a sintered matrix is not the only type. There are also resin matrix bonds.
Resin Bonded Tools
Most of the polishing tools on this website are of this type. Resin bonded matrix is one that you will see use for all sorts of materials. Although these polishing pads look very similar they are very different. In fact the number of diamonds, the hardness of the resin bond and the pattern in the surface all play a role in the performance of a stone polishing pad.
All sorts of variables play a role in the exact characteristics needed for stone polishing pads. For example, some stone is soft and other is hard. Hence, the a polishing pad is going to wear differently if it is used on marble than it will when it is used on quartzite or granite. Still yet, some man made material such as quartz has other characteristics that need to be taken into consideration. For example, creating too much heat during the polishing process can cause marking to occur on the stone.
For the reasons above and others, you will find many types of polishing pads. 3 Step Pads, 5 Step Pads, and 7 Step Pads are just a few of the processes for which polishing pads are offered. Then there are polishing pads designed for quartz and others made to give you the ability to dry polish. Each of these have different bond hardness, diamond count, and pricing levels. The idea is that you want to determine which pad(s) work the best on your machine(s).
As we have seen here, diamond tools come in many different forms. And there are a number of options when it comes to polishing pads. Which polishing pad yo choose will depend not only on your budget, but also on