Tri-Ply Circles
Peel Strength in Tri-Ply Circles: What N/mm Tells You
Peel strength - measured in N/mm - is the single number that predicts whether a tri-ply circle will delaminate on your press line. Here is what it means and what to demand.
What peel strength measures
A lab specimen of the bonded sandwich is pulled apart; the force per mm of width is the peel strength. Higher = stronger bond. Reputable mills report values like 28-45 N/mm per interface (304/Al and 430/Al tested separately).
Test standards
Common references: GB/T 2792 and GB/T 6396 (China), ASTM D903-style peel methods adapted for metals. Ask your supplier which standard their number follows - an N/mm without a standard is just a number.
What to demand
- MTC per lot showing peel values for both interfaces
- Minimum threshold agreed in writing (e.g. ≥25 N/mm)
- Test specimen photos on request for large orders
Low peel strength is the #1 predictor of blisters and delamination after deep drawing.
Frequently asked questions
What is a good peel strength for tri-ply?
Values of 25-45 N/mm per interface are typical of well-bonded material. Agree a minimum in your spec.
Which standard covers peel testing?
GB/T 2792 and GB/T 6396 are commonly cited; ASTM peel methods are also used. Always ask which standard applies.
Have a cookware project in mind?
We manufacture triply cookware and supply tri-ply circles for OEM, private label and distribution. Tell us your specs - we reply with a quote.