Counterbores are mostly used to create the recess for a screw head. This allows the screw head to sit flush with the surface, which is both aesthetically pleasing and functional. Such precise countersinking tools are particularly in demand in the woodworking and metalworking industries.
Depending on the application and the desired shape of the counterbore, a different tool is used. Another important criterion for tool selection is the position of the counterbore: is it on the front or back of the bore, or should both bore edges be machined simultaneously?
Below, we list the different types of counterbores and their areas of application.
Backspotfacers, also known as flat countersinks, have a cylindrical shape and straight blades that create a flat counterbore, usually perpendicular to the bore axis. This allows precise recesses for screw heads to be made, ensuring a flush and secure screw connection. Another area of application is cast parts with tolerances. Machining with a backspotfacer creates a smooth surface, which is essential for screw attachment. Spotfacers are indispensable, especially in the machining of metal workpieces – e.g., in mechanical engineering or the automotive industry.
If the required counterbore is on the front side of the workpiece, creating it is much simpler than if it is on the back side. In these cases, tools are needed that enable back bore machining. Such a backspotfacer passes through the bore, the blade deploys on the back side, and the countersink is machined on the back. The biggest advantage: The workpiece does not need to be turned over for backspotfacing, which significantly reduces process times.
Another challenge for spotfacing is interrupted cuts, which can often lead to tool breakage. HEULE offers solutions that can also handle interrupted cuts.
The selection of the right backspotfacer is crucial for a perfect result. Selection criteria include the material to be machined, the location of the counterbore, screw size, and production volume. With the BSF, HEULE offers an extremely reliable and economical backspotfacer that allows a bore-to-countersink ratio of up to 2.3x the bore diameter. The SOLO, on the other hand, machines both bore edges in a single operation.
A form countersink is designed to create special shapes or profiles. These match specific screw heads, such as countersunk screws with a conical head.
The shape of the cutting edge determines the shape of the counterbore (e.g., conical, round, or spherical). The often individually adapted tools or cutting edges result in high precision in terms of fit and great repeatability. There are form countersinks that are used for machining the front and/or back side of the bore.
HEULE offers the possibility of individually adapted blades for the BSF and SOLO. This allows the creation of a wide variety of countersink forms.
Conical countersinks are used for machining the front bore edge. They are available with various defined point angles (e.g., 60° or 90°) and different diameters. Countersinks with an odd number of blades feature smoother and chatter-free operation during the countersinking process. This reduces the load on the tool and thus extends its service life.
Conical countersinks are used in various application scenarios. On one hand, burrs can be easily removed from drilled holes; on the other hand, the bores can be prepared for the use of screw heads. This creates conical countersinks into which the screw head fits.
By using drill-countersinks (or countersink drills), the two operations of drilling and counterboring can be performed in a single pass. This is even possible if the counterbore is to be applied to the back side of the bore. These combination tools save time and ensure that the bore and the countersink fit together perfectly. Whether in metalworking or other areas – drill-countersinks are the perfect solution for anyone looking for an economical and precise method of machining workpieces.
Usually, countersink drills are individually adapted to the application situation. Examples of drill-countersinks: Customised tool from HEULE or step drills.
HEULE offers further combination tools for integrating multiple work steps into a single pass.
When looking for a countersink for your own production, there are several criteria to consider. The main criterion is the desired shape of the countersink, which determines the type of countersink. Furthermore, the material, the series size, and also the location of the counterbore (inside, outside) play a decisive role.
HEULE counterbore tools are primarily used for back bore machining; they are so-called backspotfacers. If spotfaces or form countersinks are required on the back side or on both sides of the bore, you should contact the deburring specialist from Switzerland. HEULE also offers solutions for counterboring with interrupted cuts and optimises process times through customised tools.
To achieve perfect counterbores in metal, some basic application tips should be followed. Adequate cooling (e.g., air or coolant) is necessary, as frictional heat is generated during counterboring, which could lead to overheating of the counterbore. Proper cooling extends the tool's service life. Cutting speeds should always be adapted to the material properties.
If backspotfacers are well cared for, their service life is extended and the counterboring result is improved. Countersinks should be stored in a dry place to prevent physical damage to the cutting edges. Below are some important points for storing and caring for your backspotfacer:
There are various errors in counterboring that affect the quality of the result. If the countersink is not set optimally, burrs can form, which then have to be laboriously removed. It is important to adapt the cutting speed to the material properties and the thickness of the workpiece. The cutting edges used with the countersink should always be adapted to the material, which leads to precise results.
