Application of Metal Double-Sheet Detection in Metal Packaging (Cans)

The materials used to manufacture metal beverage cans are mainly two types:

1. Aluminum

Aluminum is commonly used for two-piece cans due to its excellent ductility; the can body and lid are formed by stamping and the structure consists of two metal sheets: body + lid. Typical applications include soft drink cans.

Type: two-piece can

Structure: lid + body (two stamped metal sheets)

Features: made from aluminum, formed integrally, lightweight

Use: beverage cans

2. Tinplate

Tinplate is used for three-piece cans; unlike two-piece cans, a three-piece can consists of body + bottom + lid, typically used for products like powdered milk where higher structural strength is required.

Type: three-piece can

Structure: lid + bottom + body (three stamped metal sheets)

Features: made of tinplate, higher structural strength

Use: milk powder cans, large-capacity containers

Can lid production process

Riveting installs the pull-tab on can lids. If duplicate lids are fed, the pull-tab may be embedded in two lids, wasting two lids and one pull-tab. The resulting scrap, when transferred to the collection basket, can disrupt subsequent production stages.

To avoid double lid feeding, a Metal Double-Sheet Detector is used before riveting to detect single or double lids. When double feeding is detected, the detector sends a signal to the PLC and the duplicate piece is skipped and sent to the scrap collection basket.

(Can lid/body production process)

Can body production process

Processes such as cupping, ironing, seam welding and printing are widely used in two-piece and three-piece can production. The most common issue during operation is material overlap at feeding, resulting in scrap and defective products.

Atonm Metal Double-Sheet Detectors are specifically designed for detecting single/double sheets in can manufacturing. They accurately identify double feeds and output signals to PLCs so that machines can remove duplicates or skip processing.

(Two-piece can production)

Atonm Metal Double-Sheet Detector Working Principle

The detector is based on electromagnetic principles: the upper probe (transmitter) generates an alternating field; the lower probe (receiver) senses induced signals. The thickness of the metal between probes affects induced current strength. By comparing sensed signals with stored single/double parameters, the system determines single or double sheets.

(Detection principle)

System workflow

Single/double sheets enter probe area; controller compares induced current to reference voltages, outputs single/double signals to PLC, PLC instructs actuators to remove duplicates and re-feed production.

(System workflow)

Advantages in can manufacturing

Strong product performance to meet fully automatic feeding requirements:

1. Non-damaging to material: non-contact detection avoids scratching;

2. Easy tuning: intelligent chip supports automatic learning of material parameters;

3. Wide detection thickness range: tinplate 0.05–4.5mm, aluminum 0.1–40mm;

4. High efficiency: probe refresh interval 5µs, detection speed up to 1200 pcs/min;

5. Dual anti-interference design: modular SMD components, 4-layer PCB for strong EMI resistance;

6. Stable detection with high sensitivity and minimal false positives/negatives.