There are two types of drilled-in anchors: mechanical and adhesive anchors. Mechanical anchors secure themselves by screwing/wedging into the object at the tip. Adhesive anchors require a hole to be drilled, cleaned, filled with an adhesive, and then the anchor can be inserted.
Mechanical anchors are generally easier to both install and uninstall. This type of anchor should be used only with solid, strong concrete. If the concrete is weak the anchor will not properly tighten and won’t function to its’ potential. Because all the weight and stress is concentrated at the tip of the anchor it has been known to cause cracks in the cement, especially with weaker concrete. You must make sure that the size of the hole is no bigger than the anchor, or it will not properly stick in place. While sometimes unavoidable, make sure not to drill the anchor into any air or powder pockets as this will cause a larger hole than the anchor itself. If this were to happen your only option is to create a new hole nearby; do not continue with the original hole. Another major precaution when using mechanical anchors is to stay away from the edges as this will induce cracks much easier. While they are much easier to install they are also dislodged much easier. Mechanical anchors can often loosen due to vibrations and can easily rust.
Adhesive anchors are fastened chemically and are not only more difficult to install, but the process is more expensive as well. You don’t have to worry about the strength of your concrete when using adhesive anchors as they will work even with low strength concrete. In order to install an adhesive anchor you must first drill and clean the hole. Once the hole is cleaned you fill the hole with your adhesive material. It is very important that you clean the hole thoroughly as any leftover dust or particles will greatly reduce the effectiveness of the adhesive. Adhesive anchors are known to be more secure and reliable because the adhesive allows the stress/weight to be spread throughout the anchor instead of placing it all at the tip. This allows for much fewer cracks as well as reduces harm to the surface paint of the wall. Besides being a bit more expensive and a lengthier process, adhesive anchors are criticized for not functioning properly under high temperatures.
Two Method Approach
Most prefer to complete a project using either mechanical or adhesive, staying consistent for both purchasing and building. If equipped with the time and money, some like to use a two method approach where the adhesive anchors take most of the weight and the mechanical anchors act primarily as a backup.
George Tobin is the Online Strategy Manager for Mutual Sales Corporation. MSC offers a variety of specialized Anchors and Fasteners nationwide.
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