Have you ever tried Lulu? Do you know what tests that canister is actually performing? (Part 1)

You can't miss the national drink, Lulu, during holidays and festivals!

I remember as a kid, all I needed was to have a can of Lulu to drink.

You'll be able to stay happy all day.

That is a testament to childhood days.

We're not talking about drinks today.

Today, we're going to talk about it.

This kind of Can (easy-open, three-piece can)

What kind of testing projects are being done?

Next

You’ll understand it at a glance—no doubt about it.

Easy-to-Open Three-Piece Can

The easy-open three-piece can is a metal-coated container assembled by joining an easy-open lid, a bottom end, and the can body. It’s designed for filling non-carbonated beverages, food products, and other items that have been sealed and sterilized to meet commercial sterility standards.

1. Appearance Quality

Conduct visual inspection (by eye) of the can body, easy-open lid, and bottom cap under natural lighting, checking for any defects or imperfections. Checklist.

     Xiaomin on Inspection: The goal is to assess whether the can’s surface is smooth and free of pinholes by examining the sample’s physical appearance. Damage to the inner coating caused by bends or dents, missing edges or cracks without flanging, burrs, and uniformly smooth, even weld seals—among other issues.

2. Dimensional deviation

The main dimensions of the can body, easy-open lid, and bottom cap—such as height deviation and inner diameter deviation—must all fall within the specified tolerance ranges.     

Xiaomin on Inspection: You can check the specifications of the three-piece cans you produce and verify whether they meet the technical requirements of the sample part.

3. Double-crimped sealing

Double crimp sealing is a method used to seal products such as food, pharmaceuticals, and cosmetics. It works by rolling a layer of material over each of the two edges of the packaging material, then folding these two layers together to create a double-layered crimp.

Xiaomin Talks Testing: The double-seam sealing test can be used to evaluate the sealing performance of three-piece cans, determining whether they effectively prevent product leakage or contamination. It can also assess the strength and stability of the cans, ensuring they remain intact and undamaged during transportation and storage.

4. Internal and external coating quality

       Three-piece cans typically require special coatings applied to both their inner and outer surfaces. The coating on both the inside and outside of the tank should be fully cured and well adhered. After testing, there should be no defects such as flaking, discoloration, or blistering.

Xiaomin on Testing: The inner coating prevents food from coming into direct contact with the metal, while the outer coating protects the can from corrosion and damage—ensuring both food safety and consumer health.

5 • Internal coating integrity

The integrity of the three-piece can’s internal coating is actually assessed by measuring conductivity, which reflects the coating’s completeness and density through the determination of current values in the electrolyte.  

Xiaomin on Testing: If the internal coating integrity fails to meet standards, it can affect the product’s flavor and appearance; storage for one After a certain period, issues such as perforation or leakage may occur.

6 , Withstand Voltage Test

Under certain conditions, the ultimate load that a three-piece can withstand.

Xiaomin on Testing: During production and transportation, these products must withstand various forces—such as compression, impact, and collisions—so pressure resistance tests are conducted to ensure their quality and reliability.

7, Sealing Test

The can's sealing and barrier properties depend on the double-crimped closure design, the quality of the weld in the seam, and the heat-seal strength of the aluminum foil on the easy-tear lid.

Xiaomin on Testing: Ensuring that substances like food or beverages remain free from external contamination and oxidation, thereby safeguarding product quality and safety.

8. Sealant Dry Film Quality Testing

Weigh the dry film of the easy-open lid sealing adhesive.

      Xiaomin on Testing: The dry film of sealing glue can enhance the airtightness of three-piece cans, preventing moisture and oxygen from the air from affecting the contents inside.

9. Easy-open Lid Opening Force, Full-Open Force

The opening force is the amount of force required to "tear" the lid open at the moment it starts to lift, while the full-opening force is the force needed once the lid is fully detached.

Xiaomin on Testing: The opening force and ease of breaking the seal on three-piece cans directly affect the user experience. If the opening force is too tight, it becomes difficult to open; if it’s too loose, leaks and spoilage are more likely to occur.

10. Easy-Open Lid Reliability Testing

       Open the easy-to-open lid in the forward direction, and check whether the pull ring (or tab) has detached and if the lid is fully opened.

      Xiaomin on Testing: To avoid awkward situations—like the pull tab falling off yet still being unable to open the product.