Fabric tensile strength and tear resistance describe different tests. When comparing materials, retain the full property name, unit, direction and method. A large number on a data sheet does not replace these details, even when both results are given in newtons.
What each test asks
In a tensile test, a specimen is stretched and a force result is determined using the relevant method. For rubber- or plastics-coated fabrics, ISO 1421 describes strip and grab methods. How the specimen is held forms part of the method and needs to be known when comparing results.
A tear test considers the force needed to initiate or propagate tearing. For example, ISO 4674-1 describes separate tongue-tear and trouser-tear methods for coated fabrics. A result from one type of test does not supply the result of the other.
How to read N and daN
N is the symbol for the newton, a unit of force. The prefix da represents a factor of 10 in the SI system, so 1 daN = 10 N. Accordingly, 40 daN = 400 N and 3 daN = 30 N.
Keep the rest of the notation when converting. A value of 40 daN/5 cm can be written as 400 N/5 cm. The prefix changes while the width notation and test method remain. This conversion does not justify scaling the result to an arbitrary component width or treating it as another test’s result.
Two entries for Sanwil B-575
The Sanwil B-575 listing at DELIM links to the manufacturer’s SKATEN B-575 material. The official Sanwil table gives two separate entries:
- tensile strength along / across, Method 2: ≥ 40 / ≥ 40 daN/5 cm;
- tear strength along / across: ≥ 3 / ≥ 3 daN.
Changing daN to N gives ≥ 400 / ≥ 400 N/5 cm and ≥ 30 / ≥ 30 N respectively. Comparing these as one strength scale is inappropriate: they describe different properties, and the first entry also retains a width notation.
The ≥ signs identify the stated minimum values, rather than measurements from a particular roll. Keep the manufacturer’s “along / across” direction labels. Relabelling them “warp / weft” requires confirmation of the material construction.
What to match across two technical documents
- The property name: tensile behaviour, tearing, coating adhesion or another measure.
- The complete value, including its inequality sign, unit and additional notation such as /5 cm.
- The test direction, with each result clearly labelled.
- The standard, edition and specific method, plus specimen geometry and test conditions where needed.
- The source of the number: a specification requirement, a typical value or a report result for a particular specimen.
Sanwil’s public table carries the label Method 2. For a meaningful comparison, obtain the exact standard reference and conditions from the manufacturer’s documentation. The same method number in two different documents does not establish the same procedure. Matching units alone is also insufficient.
From the data sheet to your product
A material’s data-sheet figure does not by itself establish an allowable load mass or the strength of a finished bag, cover or seam. A product has joints, openings, reinforcements and hardware. Define and verify the requirements for that assembly separately.
Send a DELIM manager the item code, assembly description and technical documents you are comparing. State the required property, direction and sample acceptance criterion. For general material selection, use the guide to polyamide fabrics; execution, availability and supply terms are confirmed for the specific enquiry.