How to Measure PET Strapping Thickness Correctly

Why Thickness Measurement Matters

Thickness is used in:

• product specifications;
• machine compatibility;
• material comparisons;
• tensile-stress calculations;
• supplier qualification.

An inconsistent measurement method can therefore create false conclusions across several different technical decisions.

Step 1: Identify the Strap Surface

First determine whether the strap is:

• smooth;
• embossed;
• otherwise textured.

This matters because the instrument may contact different surface features.

Step 2: Define the Instrument

The measurement procedure should specify the instrument or gauge.

Important considerations include:

• contact geometry;
• resolution;
• calibration;
• repeatability;
• applied measurement force where relevant.

Newton-specific dimensional SOP:

Please ask Newton to confirm the approved method or grade-specific value.

Step 3: Define the Measurement Location

Do not rely on one convenient point.

A supplier specification should define how samples are selected across:

• width where applicable;
• length;
• coil position;
• batch.

The purpose is to understand the product distribution rather than produce one favorable number.

Step 4: Measure Without Damaging the Strap

The measurement itself should not crush, distort or artificially flatten the specimen.

This is particularly important for textured surfaces.

Step 5: Record the Surface and Method

A useful record should state:

• strap ID;
• batch;
• smooth/embossed;
• instrument;
• method;
• measurements;
• operator/date where required.

Without the method, the number has less value.

Why Embossed PET Is Different

Embossed PET contains peaks and valleys.

A peak-to-peak caliper reading can be larger than the effective solid thickness.

Therefore:

Peak caliper is not equivalent solid thickness and cannot alone establish the effective load-bearing cross-section.

This distinction is important when using thickness to calculate nominal tensile stress or compare material efficiency.

Read PET strapping embossing.

Can g/m Be Used as a Cross-Check?

Yes, but only as a cross-check.

Mass per unit length can help identify whether the total material quantity appears consistent with the dimensional picture.

However, g/m cannot prove:

• local thickness;
• thin spots;
• edge shape;
• width distribution.

For the broader control problem, see PET strapping width and thickness consistency.

Thickness and Machine Compatibility

A PET strap can be mechanically acceptable but still interact poorly with the machine if its actual thickness distribution is outside the machine's operating window.

Read PET strapping machine compatibility.

Thickness and Tensile Strength Calculations

If tensile stress is calculated from force divided by nominal width × thickness, the dimensional definition directly affects the result.

This is especially important for embossed strap.

See breaking force vs tensile strength.

How Should Buyers Compare Supplier Thickness?

Use the same:

• surface type;
• method;
• instrument principle;
• sample conditioning;
• sample locations;
• specification basis.

A decimal number with more digits is not automatically a more accurate measurement.

FAQs

Can I use a normal caliper to measure PET strap?

An appropriate calibrated instrument and defined method should be used. The correct method depends on the required specification and surface.

Where should I measure embossed PET?

The method must define how surface peaks and valleys are handled.

Is the thickest reading the real thickness?

Not necessarily.

Can I calculate tensile strength from embossed peak thickness?

Use caution because peak caliper may not represent effective solid cross-section.

Can g/m replace thickness measurement?

No.

Why do two suppliers report different thickness on similar straps?

Possible reasons include actual product difference and different measurement methods.

Discuss Your Requirements With Newton

If you are comparing supplier thickness data, send Newton the existing measurement method, strap surface and machine requirement so the comparison can use the same basis.

Record the agreed size, coil format and test definitions in your PET Strapping Sizes & Specifications brief.

Discuss your specification or application with Newton →