Secure, Firm Closures with Flexible Operation

The closure device (封闭器) is the most operationally critical part of the drum. During production it must be:

• Firmly connected — the closure should be attached to the drum body in a way that will not loosen or detach during handling and transport.
• Easy to open and close — the mechanism must operate flexibly without excessive force, binding, or jamming.
• Well sealed when closed — once the lid is pressed down, the contact between the lid and the bottom (chime) must form a tight, gap-free seal to protect the contents from moisture and contamination.

A closure that is loose, hard to operate, or leaks when shut is a direct failure of the drum's core function.

2Bright, Intact Galvanized or Painted Hoops & Closures

The metal components — the hoops (桶箍) and the closure fittings — are usually galvanized or painted for corrosion protection. After surface treatment they should be:

• Bright and clean in appearance — galvanized or painted surfaces should present a uniform, lustrous finish.
• Free of flaking or peeling — the coating must not show spots where the zinc or paint has fallen off, as bare metal quickly rusts.

Any dull, patchy, or peeling surface is both a cosmetic defect and a sign of weakened corrosion resistance.

3Smooth Rounded Curl Edges & Clean Interior/Exterior

The rounded curl edge (圆卷边) at the top and bottom rims must be:

• Smooth and clean, with no protruding paper tongue (纸舌) — stray paper fibers caught in the curl indicate poor rolling quality.
• The drum should be clean inside and out, with no oil stains or other contamination that could affect the packaged product.

4Clear, Even, and Durable Printing

When the drum body carries printed graphics or text, the printing must be:

• Clear and legible, with sharp lines and characters.
• Even in coverage — ink density should be consistent across the design.
• Firmly adhered — the print should not rub off easily during normal handling.
• Free of ink running (跑墨) — no smudging, bleeding, or blurred edges.

5Firm, Flat Hoop Welding

The welded joints on the metal hoops are points of structural stress. Welding quality must satisfy:

• Firm and flat weld beads that sit flush with the hoop.
• No burn-through and no false (incomplete) welds — the joint must penetrate fully.
• No obvious rust, delamination (剥层), or cracking (龟裂) on or around the weld.

6Smooth Drum Body Free of Defects

The drum body itself should be smooth and free from manufacturing flaws:

• No mechanical damage — scratches, dents from tooling, or impacts.
• No wrinkles (皱褶) and no delamination / open glue (开胶) between the kraft plies.
• The waterproof paint must be applied evenly: no missed spots (漏涂), no bubbles (起泡), and no obvious running / sagging (流挂).

7Shape Retention After Processing

Once processing is complete, the drum must hold its intended round, regular shape. It should:

• Remain circular and upright, not losing the shape it is supposed to have.
• Show no obvious dents (瘪), leaks (漏), or other defects that could compromise later use.

Loss of shape, dents, or leaks are not minor cosmetic issues — they can directly cause failure during filling, stacking, and transport.

8Surface Finish & Fitting Integration

Two final but important aspects:

Surface finish. The product surface should be smooth, with no marks left by machining. There should be no wrinkles and not a single spot of open glue (开胶). The material treatment must be uniform, free of bubbles, and properly waterproof.

Fittings. Attached hardware should be securely fixed and naturally integrated with the product, lying flat and flush. There must be no corrosion or rust, and the opening/closing action must remain flexible.

Production Quality Checklist