The higher the coefficient of friction, the lower the additional securing force generally required. In practice, however, errors are rarely caused by the calculation formula itself. More often, incorrect table values are used, contaminated loading surfaces are overlooked, or anti-slip mats are not positioned correctly.
In this article, we explain how to determine the coefficient of friction correctly, which values a coefficient of friction table can provide, and which common load securing mistakes you should avoid.
What Is the Coefficient of Friction?
The coefficient of friction, also known as the friction coefficient or coefficient of sliding friction, describes the resistance to sliding between two contact surfaces. In load securing, it is represented by the Greek letter µ.
Put simply, a coefficient of friction of µ = 0.3 means that around 30 percent of the weight force can theoretically be taken into account as friction force. The basic formula is:
Friction force = weight force × coefficient of friction µ
Example: A load unit has a weight force of 1,000 daN. With a coefficient of friction of µ = 0.3, the calculated friction force is 300 daN. If suitable anti-slip mats increase the coefficient of friction to µ = 0.6, the calculated friction force rises to 600 daN.
This is precisely why anti-slip materials are so cost-effective in many applications. They increase the friction between the cargo and the loading surface and can therefore reduce the amount of additional securing equipment required.
Why Is the Coefficient of Friction So Important in Load Securing?
Cargo must be secured in such a way that it cannot slide, tip over, roll back and forth, or fall from the vehicle even during emergency braking, sudden evasive manoeuvres, or when driving on poor road surfaces. In Germany, this obligation is stipulated, among other provisions, in Section 22 of the German Road Traffic Regulations (StVO).
The DIN EN 12195-1 standard is particularly relevant when calculating securing forces. It describes methods for calculating securing forces on road vehicles. The coefficient of friction is a key input value because it directly affects how much additional securing force must be applied.
The coefficient of friction is particularly important for tie-down lashing. With tie-down lashing, lashing straps press the cargo onto the loading surface. This increases the friction between the load and the surface beneath it. The higher the friction, the more effective this type of load securing becomes.
Coefficient of Friction Table: Typical Practical Values
A coefficient of friction table helps identify suitable reference values for load securing. However, it is important to remember that table values do not replace an assessment of the actual conditions on site. The specific material combination, the condition of the surfaces, and the cleanliness of the loading surface must always be taken into account.
The values are intended as practical guidance. For reliable calculations, manufacturer specifications, test certificates, relevant standards, and the actual conditions on site should always be taken into account.
Determining the Coefficient of Friction: How to Proceed in Practice
Correctly determining the coefficient of friction does not begin with a table, but with an assessment of the actual contact surfaces. The decisive factor is always which materials are actually in contact with each other. It is therefore not just the cargo itself that matters, but the specific contact surface.
1. Check the Contact Surfaces
First, check whether the loading surface and cargo are dry, clean, swept clean, free of grease, and free from ice, snow, or oil. Even minor contamination can significantly reduce the actual coefficient of friction.
A contaminated loading surface is one of the most common mistakes in load securing. Sand, dust, wood debris, plastic film residue, moisture, or oil residue can prevent the assumed table value from being achieved under real-world conditions.
2. Determine the Material Combination
The next step is to determine the actual material combination. Typical examples include a wooden pallet on a coated plywood floor, a steel frame on a wooden loading surface, a mesh box pallet on metal, a big bag on an anti-slip mat, or a machine on rubber granulate.
Important: The actual contact area is what counts. For example, if a pallet rests partly on an anti-slip mat and partly directly on the loading surface, the higher coefficient of friction provided by the mat must not simply be applied to the entire load.
3. Select a Table Value or Tested Value
For simple standard applications, a coefficient of friction table can provide useful guidance. However, for anti-slip materials such as anti-slip mats, manufacturer specifications and test certificates are particularly important.
Sandax anti-slip mats (anti-slip mat rolls or anti-slip mat pads) are designed for professional load securing and can significantly increase the coefficient of friction between the cargo and the loading surface. In many applications, a coefficient of friction of µ = 0.6 is used for suitable, tested anti-slip mats.
4. Take Safety-Critical Factors into Account
Temperature, moisture, dust, grease, damaged mats, uneven contact surfaces, or high point loads can alter the actual coefficient of friction. If there is any doubt, a conservative value should be used or a specific friction test should be carried out.
Coefficient of Friction for Anti-Slip Mats: Why µ = 0.6 Does Not Automatically Apply
Anti-slip mats are one of the most effective ways to increase friction in load securing. They are placed between the cargo and the loading surface and help prevent the load from sliding.
However, the coefficient of friction of anti-slip mats is not automatically guaranteed. A value of µ = 0.6 should only be used when the mats are applied correctly.
To achieve this, the mats must be positioned under the actual load-bearing points, be clean and fully functional, be suitable for the material combination, and sufficiently separate the cargo from the surface underneath. If only a few small pieces are placed underneath while other parts of the cargo remain in direct contact with the loading surface, their effectiveness is reduced.
A common practical mistake is what could be described as symbolic placement: an anti-slip mat is used, but not underneath all load-bearing contact points. For reliable load securing, all relevant contact points must be taken into account.
Common Mistakes When Determining the Coefficient of Friction
Mistake 1: Using Table Values Without Verification
A coefficient of friction table is helpful, but it does not replace an assessment of the actual conditions. The same table value can vary significantly in practice if the surface is damp, dusty, damaged, or contaminated.
Mistake 2: Ignoring Contamination
A swept-clean loading surface is not a minor detail, but a prerequisite for accurate calculations. Oil, grease, ice, snow, or loose material can drastically reduce friction. Anyone who still calculates using high coefficients of friction risks unsafe load securing.
Mistake 3: Positioning Anti-Slip Mats Incorrectly
Anti-slip mats are only effective where the load is actually transferred. If part of the cargo rests directly on the loading surface next to the mat, this area must be assessed separately.
Mistake 4: Continuing to Use Damaged Mats
Heavily soiled, torn, hardened, or permanently deformed anti-slip mats may lose their effectiveness. Mats should therefore be inspected regularly and replaced if there is visible damage.
Mistake 5: Confusing Friction with Positive Locking
Friction and positive locking are two different load securing principles. Friction prevents sliding through resistance between contact surfaces. Positive locking prevents movement by positioning the cargo without gaps, blocking it, or filling empty spaces. Both methods can be combined, but they should not be confused with one another.
Practical Example: How Much Difference Does the Coefficient of Friction Make?
Assume a load has a weight force of 2,000 daN. With a coefficient of friction of µ = 0.2, the calculated friction force is 400 daN. With a coefficient of friction of µ = 0.6, it increases to 1,200 daN.
The difference is 800 daN. This demonstrates how significantly the correct coefficient of friction affects load securing. A suitable anti-slip mat can substantially reduce the amount of securing required, but it does not automatically replace all other securing measures.
Depending on the cargo, weight, center of gravity, direction of travel, tipping risk, and securing method, additional equipment such as lashing straps, edge protectors, locking bars, dunnage bags, or positive load securing may also be required.
Checklist: How to Determine the Coefficient of Friction Correctly
- Which materials are actually in contact with each other?
- Is the loading surface dry, clean, swept clean, and free of grease?
- Is there any ice, snow, oil, dust, sand, or packaging residue?
- Are anti-slip mats positioned under all load-bearing contact points?
- Are manufacturer specifications or test certificates available for the coefficient of friction?
- Has the coefficient of friction been selected conservatively enough?
- Are additional securing measures such as lashing straps or positive locking required?
Conclusion: Determining the Correct Coefficient of Friction Means Safer and More Efficient Load Securing
The coefficient of friction is a crucial factor in safe and efficient load securing. Determining it correctly makes it possible to calculate securing forces realistically, use lashing equipment more effectively, and reduce transport risks.
However, the decisive factor is not the highest value in a table, but the value that matches the actual conditions. Contact surfaces, cleanliness, material combinations, and the condition of the equipment used must always be taken into account.
Tested anti-slip mats in particular can significantly reduce the amount of securing required. The key requirement is that they are correctly positioned under all relevant load-bearing points and are suitable for the specific application.
Discover suitable solutions for professional load securing in the Sandax Shop: anti-slip mats for load securing.
FAQ: Frequently Asked Questions About the Coefficient of Friction
What Is a Coefficient of Friction?
The coefficient of friction µ describes the resistance to sliding between two contact surfaces. In load securing, it indicates what proportion of the weight force can theoretically be used as friction force.
What Coefficient of Friction Applies to Anti-Slip Mats?
In practice, a coefficient of friction of µ = 0.6 is often used for suitable, tested anti-slip mats. This requires the mats to be used correctly and the contact surfaces to be clean.
What Does a Coefficient of Friction of µ = 0.6 Mean?
A coefficient of friction of µ = 0.6 means that 60 percent of the weight force can theoretically be taken into account as friction force. With a weight force of 1,000 daN, this would correspond to 600 daN of friction force.
When Should a Low Coefficient of Friction Be Used?
If the loading surface or contact surfaces are dirty, icy, oily, covered with snow, or greasy, a significantly lower coefficient of friction must be used. In such cases, the loading surface should first be cleaned and the situation reassessed.
Does an Anti-Slip Mat Replace a Lashing Strap?
No. Anti-slip mats increase friction, but they do not automatically replace lashing straps or other securing equipment. Whether additional securing is required depends on the weight, center of gravity, direction of travel, tipping risk, and securing method.
How Is the Coefficient of Friction Determined?
The coefficient of friction is determined using table values, manufacturer specifications, test certificates, or specific friction tests. In practice, the key factor is ensuring that the selected value matches the actual material combination and the condition of the contact surfaces.