On semi-tubular rivets, the grip range refers to the thickness of the material or the depth that the rivet can effectively hold together. It's the range of material thickness the rivet is designed to join, and it's crucial for proper installation and the strength of the joint. The grip range is not the same as the rivet's length. Here's a more detailed explanation:

What it means:
The grip range represents the range of material thickness that the rivet is designed to hold securely after being set.

Why it's important:
Choosing the correct grip range is essential for a strong and reliable joint. If the grip range is too low, the rivet may not grip the material adequately, and the joint may fail. If the grip range is too high, the rivet may not set properly, and the joint may be compromised.

How to determine the correct grip:
You'll need to measure the total thickness of the materials you're joining. Then, select a semi-tubular rivet with a grip range that encompasses that thickness.

Relationship to rivet length:
The rivet length is determined by the grip range plus an allowance for clinch or forming of the rivet's body.

Example:
If you're joining two sheets of metal that are 1.5 mm thick, you'd need a semi-tubular rivet with a grip range of at least 2-5 mm.