Pull Out Force Calculator

Calculator Inputs

Calculation method

Diameter or equivalent diameter (mm)

Embedment length (mm)

Bond or shear strength (MPa)

Contact area override (mm²)

Normal force for friction (N)

Coefficient of friction

Number of fasteners

Edge distance factor

Installation quality factor

Temperature or environment factor

Safety factor

Entered pull load (N)

Output unit

Notes

Formula Used

For a bonded cylindrical part, contact area is:

A = π × d × L

For a flat circular contact, contact area is:

A = π × d² ÷ 4

For a threaded insert estimate, the calculator uses:

A = π × d × L × 0.75

The ultimate pull out force is:

F_u = A × τ × C_e × C_i × C_t × n

The allowable force is:

F_allow = F_u ÷ SF

For a friction pull fit, the base resistance is:

F = μ × N

Here, d is diameter, L is embedment, τ is strength, n is fastener count, and SF is safety factor.

How to Use This Calculator

Select the pull out model that matches the joint.
Enter diameter, embedment length, strength, and correction factors.
Use contact area override when tested area is already known.
Enter normal force and friction coefficient for a press or friction fit.
Add the expected pull load to check margin and utilization.
Press Submit to view the result above the form.
Use CSV or PDF buttons to download the same calculation.

Example Data Table

Example	Method	Diameter	Embedment	Strength	Safety Factor	Estimated Allowable Force
Small bonded pin	Bonded cylindrical	8 mm	40 mm	5 MPa	3	1,675.5 N
Threaded insert	Thread approximation	12 mm	60 mm	8 MPa	3	4,523.9 N
Friction sleeve	Friction pull fit	Not used	Not used	Not used	2	210 N

Pull Out Force Basics

Pull out force is the axial force needed to remove an anchor, pin, screw, insert, or bonded part from its seat. It is important in physics, design, construction, fixtures, and test planning. The value depends on contact area, material strength, embedment length, friction, installation quality, and load direction.

Why the Calculation Matters

A part may look strong, yet fail when the load is concentrated. Pull out failure can happen through bond rupture, thread shear, cone breakout, bearing crush, or slipping. This calculator gives a structured estimate. It helps compare several assumptions before a physical test is performed. It also helps choose a safer embedment length or stronger material.

Key Inputs

Diameter and embedment length define the contact surface for a cylindrical anchor. Bond or shear strength defines how much force each square millimeter can resist. Correction factors adjust the result for edge distance, installation quality, heat, moisture, or imperfect curing. A safety factor then reduces the ultimate value into a working value.

Interpreting Results

The ultimate force is a calculated maximum before safety reduction. The allowable force is the recommended working resistance after the safety factor is applied. Utilization shows how much of the allowable value is used by the entered pull load. A value below 100 percent means the selected setup passes the entered demand. A value above 100 percent means the design needs review.

Practical Notes

Use tested data when it is available. Published strengths may assume clean holes, correct curing, ideal temperature, and proper installation torque. Real parts may have dust, gaps, corrosion, vibration, or uneven loading. For critical lifting, medical, aerospace, or public safety work, use certified testing and qualified engineering review.

Improving Resistance

Pull out resistance can be improved by increasing embedment length, increasing diameter, using stronger adhesive, improving surface preparation, or adding more fasteners. Reducing edge effects also helps. A lower safety factor may increase the displayed allowance, but it does not make the joint stronger. Choose conservative values when conditions are uncertain.

Common Applications

Typical uses include anchor selection, glued dowel checks, insert testing, press fit review, and lab demonstrations. Students can also study how area and strength combine to produce measurable resistance. It supports careful early design choices.

FAQs

What is pull out force?

Pull out force is the axial force needed to remove a fastener, insert, or bonded part from its installed position.

What units does this calculator use?

The main calculation uses millimeters, megapascals, and newtons. It can also display the final result in kilonewtons or pound force.

What strength value should I enter?

Use tested bond strength, adhesive shear strength, material shear strength, or a certified product value. Use conservative values when exact data is unknown.

Why is embedment length important?

Longer embedment increases contact area. More area usually gives more pull out resistance, if the material and installation remain sound.

What does safety factor mean?

The safety factor divides the ultimate estimate. It creates a lower allowable force for working design and uncertainty.

Can this replace a lab test?

No. It is an engineering estimate. Critical systems need testing, standards, and review by a qualified professional.

Why are correction factors included?

They account for edge distance, poor installation, temperature, curing, moisture, or other real conditions that reduce capacity.

What happens if utilization exceeds 100 percent?

The entered pull load is greater than the allowable result. Increase capacity, reduce load, or review the design.