Why Maximum Opening Is Not Enough When Selecting a Pneumatic Clamp: The Importance of a 41.15 mm Resting Opening

Problem | Why Can Maximum Opening Alone Lead to the Wrong Clamp Selection?

When selecting a pneumatic clamp for aluminum profiles, many buyers and engineers first ask:

“What is the maximum opening?”

This is an important question, but maximum opening alone does not provide enough information for accurate clamp selection.

The KRT-110 has a 90 mm maximum opening, a 41.15 mm resting opening, and an overall length of 112 mm.

If users focus only on the 90 mm value, they may assume that any aluminum profile below 90 mm will automatically fit.

In practice, the clamp does not remain fully open during the entire loading process.

How the workpiece enters the jaws, the initial position of the clamp, the actual clamping section, and the available installation space all influence compatibility.

Therefore, pneumatic clamp selection should consider:

resting opening + maximum opening + actual clamping point + installation space.

Cause | Why Is Resting Opening Often Overlooked?

1. Maximum opening is an extreme position, not the starting position

The 90 mm value represents the maximum opening capability of the KRT-110.

The 41.15 mm resting opening, however, represents the clamp’s initial opening condition.

The dimensional difference is:

90 − 41.15 = 48.85 mm

This means the clamp moves through a defined opening range from its resting condition to its fully open position.

If the workpiece needs to enter before the clamp reaches its maximum opening, the resting opening becomes an important selection parameter.

2. “Can be clamped” and “can enter the clamp” are different questions

A profile may be well below 90 mm at its final clamping position.

However, ribs, raised edges, or irregular geometry may require additional clearance during loading.

In this situation, the maximum opening may be theoretically sufficient, while the actual loading process is still difficult.

Engineers therefore need to answer two separate questions:

Can the profile fit within the final opening range?

and

Can the profile enter and position correctly during the actual loading process?

3. Irregular profiles make resting opening more important

Regular square or rectangular profiles are relatively easy to measure.

Irregular aluminum profiles may contain grooves, ribs, steps, or raised sections that make the loading path more complex.

For these profiles, checking only the 90 mm maximum opening can miss important positioning issues.

Solution | How Should 41.15 mm and 90 mm Be Used Together?

The confirmed KRT-110 dimensions are:

Step 1: Measure the actual clamping point

Identify the exact section where the jaws will contact the aluminum profile.

Do not rely only on the nominal overall width.

Step 2: Check the 41.15 mm resting opening

Determine whether the workpiece has suitable initial clearance and positioning conditions.

If the required dimension is larger than 41.15 mm, the actual pneumatic opening and loading sequence should be reviewed.

Step 3: Check the 90 mm maximum opening

Use the maximum opening to confirm whether the clamp has enough final opening capability.

If the required dimension is close to 90 mm, local ribs, jaw contact position, and clamping direction should also be checked.

Step 4: Check the 112 mm overall length

Even when the jaw opening is suitable, the clamp body must fit within the available fixture or equipment space.

Application | When Is Resting Opening Especially Important?

The 41.15 mm resting opening is particularly relevant in:

Multi-size aluminum profile production

Different profiles may require different loading clearances even when they use the same clamp.

Irregular aluminum profiles

Complex cross-sections can affect how the workpiece enters the jaws.

Limited installation spaces

The 112 mm overall length and available jaw movement should both be considered.

Frequent profile changes

When several products are processed on the same line, both resting and maximum opening conditions should be compared before standardizing one clamp model.

How to Choose

1. Measure the real clamping section

Use the jaw contact position as the main reference.

2. Evaluate the resting condition

Compare the workpiece with the 41.15 mm resting opening.

3. Evaluate the maximum opening

Confirm that the required opening does not exceed 90 mm.

4. Verify the clamping direction

The same profile may require different openings depending on orientation.

5. Check installation space

Use the 112 mm overall length to evaluate fixture compatibility.

FAQ

What does the 41.15 mm resting opening mean?

It is the initial jaw opening of the KRT-110 when the clamp is in its resting condition.

Why is the 90 mm maximum opening not enough for selection?

Because maximum opening only defines the upper opening capability. Loading clearance, initial positioning, and clamping direction also matter.

What is the opening difference?

The difference between 41.15 mm and 90 mm is 48.85 mm.

Will every profile between 41.15 mm and 90 mm fit?

Not automatically. Profile geometry, actual clamping point, loading method, and installation space must also be evaluated.

Conclusion

Maximum opening answers only one question: how far can the clamp open?

It does not fully answer whether a workpiece can be loaded and clamped correctly.

For the KRT-110, the 41.15 mm resting opening and 90 mm maximum opening should be evaluated together. Combined with the 112 mm overall length, profile geometry, and actual clamping point, these dimensions provide a more reliable basis for pneumatic clamp selection.