The original for reliable thin sheet metal joints with pilot hole
Less material = less costs. This is noticeable in many areas of application also in the used material thicknesses. For sheets thicker than 1 mm, it used to be possible to apply common sheet metal screws, but an increasing reduction of sheet thicknesses, due to the cost saving potentials, prevents this today. In particular the process-reliable assembly of pre-punched thin sheets is by no means trivial in the field of self-tapping fastening.Since the thickness of the components to be connected must at least match the pitch of the sheet metal screws, they quickly reach their limits due to the reduction of sheet thicknesses in many areas. In the application reality, a multiple repeat assembly is thus almost impossible, since only one thread turn is engaged in the screw-in sheet metal. Therefore, the so-called thin sheet metal screws established themselves in the market during the past few years. These screws have a metric 60° thread and are mostly made with cone-shaped points. The advantage of a metric thread is the smaller thread pitch in comparison to sheet metal screws, whereby more thread turns are engaged.
But for the most part, it is not the screw but the formed female thread which represents the actual weak point of the joint. The fastening technology experts at EJOT recognized the potential of this approach at an early stage and developed a special thin sheet metal screw for a process-reliable assembly in the pre-punched thin sheet. The innovative SHEETtracs® screw has a 45° (30°/15°) asymmetric flank angle and with less material displacement, it creates a stronger female thread in the screw-in sheet. This increases the torque level of the joint and facilitates multiple repeat assemblies.
In the lower, tapered area of the screw, the flank angle is reversed and the resulting through draught is formed into fastening direction. The non-circular thread-forming zone ensures an easy, centred application and the raised thread areas ensure a secure penetration of the sheet material. Contrary to non-circular thread geometries, the circular cross section in the upper, load-carrying thread results in higher thread engagement. The metric pitch of the SHEETtracs® ensures a problem-free interchangeability with metric screws, for example in case of future maintenance or repair.
This innovative fastening element also supports the implementation of individual lightweight design strategies, not only in the automotive sector. For example, a reduction of the sheet thickness of casing walls of "white goods" become possible with the SHEETtracs® - an important factor for the weight and also cost optimisation in this product category.
EJOT SHEETtracs® at a glance:
- High strength of the screw joint
- High vibration resistance
- Simple and reliable assembly due to good alignment and low installation torque
- High stripping torque thanks to a strong female thread
- Metric compatibility
