1. Process difference: Welding vs. Integrated Forming
(1) Seam inner liner: It is formed by welding metal sheets after curling, and the seams are usually laser or high-frequency welded. The advantage is that the production cost is low (about 30% lower than seamless inner liner), but the weld seam is prone to residual metal shavings or oxide layer, and long-term use may breed bacteria.
(2) Seamless inner liner: Using the “integrated stamping and stretching process”, the stainless steel sheet is directly stamped into the cup body without any seams. The process difficulty is high, but the inner wall is smooth without dead corners, avoiding the accumulation of dirt. According to the China Light Industry Standard (2022), the corrosion resistance of seamless inner liners is over 40% higher than that of seamless inner liners.
2. Performance comparison: insulation, долговечность, and safety
(1) Thermal insulation effect
The seamless inner liner has a complete structure and less heat loss. Laboratory testing (referring to GB/T 29606-2013) shows that under the same conditions, the 24-hour insulation temperature of seamless inner liner is 65 ℃± 3 ℃, while that of seamless inner liner is 55 ℃± 5 ℃.
The high thermal conductivity at the seams can result in a 1-2 hour reduction in the insulation time of the inner lining with seams.
(2) Service life
The welded seams of the seamless inner liner are prone to cracking under frequent cold and hot alternation, with an average lifespan of about 2-3 годы;
The seamless inner liner has a compressive strength of 0.8MPa (data source: SGS testing report) and a lifespan of over 5 годы.
(3) Security
The welding of seamless inner liners may use solder materials containing cadmium and lead (with higher risks for inferior products), while seamless processes completely avoid this problem.
3. Selection suggestion: Choose according to your needs
(1) Budget limited: optional seamless inner liner, but must identify food grade 304/316 stainless steel and lead-free solder markings.
(2) Long term use: Prioritize seamless inner liner, especially for sensitive populations such as children and pregnant women. Mainstream brands in the market, such as Food Demon Master and Elephant Print, use seamless craftsmanship for their high-end lines.
