The term “lapping” refers to a machining process. Two surfaces are rubbed together. Set in between the two surfaces is an abrasive. This can be done by hand or with a lapping machine. Often, lapping table machines are used. This process is often done to get a surface to a desired level of roughness. In other cases, it is done to achieve a specific level of flatness. Often the two concepts (flatness and roughness) are confusing to novices.
Surface roughness can be measured in the small differences in the height of a surface. It is most often measured in microinches. If a surface is found to have an Ra of 8 has valleys and peaks that have an average height or depth of no more than 8 micro inches across a given area. By contrast, surface flatness is most often measured in Helium Light Bands (HLB). One HLB equals about 0.000011 inches. A typical accuracy is between one and three HLB. Total flatness is often the goal of lapping but other levels can be achieved as well.
There are several kinds of work done on lapping table machines. Traditional lapping is where wet abrasives such as slurry are used to slowly finish a surface to the desired flatness. This is a long and tedious process. In order to keep all of the surfaces free of grit, everything has to be cleaned often during the process. This increases the time it takes to get to the desired finish. In the 1990s, speed lapping was developed. This form of lapping replaces the wet slurry with a fixed abrasive wheel. High speed lapping can get the same results as traditional lapping in about one twentieth of the time spent. High speed lapping can be very cost effective and can save up to 40% from traditional lapping methods.
In terms of what materials can be worked on, high speed lapping with lapping table machines works well for a wide variety of surfaces. It is great for metals (steel, aluminum, brass, etc.) but also on ceramics, plastics and glass.
If you are looking for the best way to get your ceramics to the right surface roughness, diamond lapping is the best method. Using diamond lapping methods you can:
- Get a better surface finish down to the sub-micron level.
- Reduce the amount of waste produced.
- Improve your parts productivity.
- Create a uniform edge to edge flatness level.
- Improve the consistency level across the entire surface.
Given the importance of consistency, diamond lapping table machines offer your best bets when dealing with ceramic lapping. Diamond table lapping machines give you control over the groove and land pattern. This increased control means you have more control over the unit load and bearing ratio, giving you a more consistent finish. Using these machines gives you a better product and results in happier customers.