Nip microburrs in the bud

If you have ever heard the saying, “the only things certain in life are death and taxes,” you know there is truth in those words. But it is obvious that the person who coined that phrase was not a machinist – otherwise the adage would have included burrs.

Every machined part will have burrs, it’s a fact. While some industries and parts have a larger tolerance for what is acceptable, machined parts are never 100% burr free after turning, milling, drilling or grinding. It is the nature of what we do.

For the vast majority of parts, the burrs can be removed, when necessary, by filing, scraping, sanding and other similar methods. In other cases, a machined chamfer, fillet or radius will provide an adequate edge with no further treatment. Minor imperfections that remain usually go unnoticed and the customers are content.

Then there are those parts that have very precise geometry, fine finish surfaces or the user cannot risk a microscopic chip coming free and contaminating a system. These types of parts usually have very stringent geometric requirements and fine features. Deburring processes for these types of parts must preserve the fine geometries and guarantee that microscopic burrs are removed so there is no possibility of contamination.

Removing burrs from small parts while they are in the machine is the best option. Adding small chamfers or fillets is by far the most common method to remove or prevent burrs. For high volume parts a special insert or tool geometry might be a good choice. It is common to see special drills and reamers with inserts included to break the edge of a hole.

When a cutting tool cannot be used there are numerous abrasive brushes on the market designed to be used inside the machine. Brushing is an effective method of deburring so long as the burs are not heavy. Brushing is also low risk as the abrasive action is not aggressive and there is little chance of changing the part geometry.

Burs (small cutting tools) are most often used with pneumatic tools for hand deburring, but I have seen creative programmers and machinists mount them in machines. Burs are a great choice in both scenarios because they come in an almost endless variety of shapes and sizes. Because they are typically small and the cutting action is much like that of a file they can be used on very small details. When applied with a machine they can be used on very delicate parts with precision. The only drawback is they often require very high RPM to cut effectively, so using them in a machine can pose some challenges.