Unveiling What Kind of Cup Can Achieve Both Plastic and Stainless Steel? Part Four

There's a story in every cup, warmth in every life. Hello everyone, "Dong Dong's Cup Talk" is here. Throughout my years in this industry, I've had the privilege of being involved in the design and development of over 500 cups across different materials, shapes, and functions. https://www.umbottle.com/ProductsDetail-VB-10534.htmlAmong these projects, achieving the same cup design in both plastic and stainless steel is particularly special. Thisstems from numerous complex considerations, including: Is material interchangeability feasible? Would implementation lead to prohibitively high costs?

Today, I'll use some case studies to analyze this. While I have many years of experience, my personal expertise has limits. If anything I share seems incorrect or mistaken, please don't hesitate to point it out. https://www.umbottle.com/ProductsDetail-VB-10534.htmlI hope my following insights can provide some help, especially to those newly acquainted with the cup industry.

Finally, I've compiled a structural and process analysis comparison to make the differences clearer.

1. Production Stage: Cup Body Forming

Specific Challenges & Data Analysis:

Plastic uses injection molding.

Stainless steel requires separately drawing/deep drawing the two halves. However, this irregular, non-rotationally symmetric shape rules out continuous drawing dies. https://www.umbottle.com/ProductsDetail-VB-10534.htmlIt necessitates expensive hydroforming or segmented drawing followed by welding, leading to poor consistency.

Impact on Cost & Yield Rate:

Equipment investment increases by over 1 million RMB.

Unit forming time stretches from seconds to nearly a minute.

Dimensional tolerance widens from ±0.1mm to over ±0.5mm, https://www.umbottle.com/ProductsDetail-VB-10534.htmlcreating issues for subsequent steps.

2. Production Stage: Inner Wall Welding

Specific Challenges & Data Analysis:

Assume the two inner half-shells are welded separately. The major difficulty is welding these two halves along the complex curve into a complete inner shell. https://www.umbottle.com/ProductsDetail-VB-10534.htmlThis requires robotic trajectory welding, with a seam length multiple times that of a standard cup.

Impact on Cost & Yield Rate:

Significant thermal deformation occurs during welding, causing severe out-of-tolerance issues in roundness and straightness post-weld.

Our factory tests showed a first-pass qualification rate below 30% for such long, curved seams; 70% required manual rework or were scrapped.

3. Production Stage: Outer Wall Welding

Specific Challenges & Data Analysis:

Faces the same problems as inner wall welding.

More critically, inconsistent welding deformation between the inner and outer walls causes an uneven vacuum layer gap during final assembly, https://www.umbottle.com/ProductsDetail-VB-10534.htmlsometimes even causing them to touch.

Impact on Cost & Yield Rate:

Directly leads to vacuum failure or extremely poor thermal insulation performance.

4. Production Stage: Vacuum Evacuation

Specific Challenges & Data Analysis:

This is the most critical failure point. Standard cups undergo vacuum evacuation in a single, complete, regular annular chamber.

This cup's vacuum chamber is split into two complex, irregular halves connected by a long weld seam. https://www.umbottle.com/ProductsDetail-VB-10534.htmlDuring evacuation at 400-500°C, any minor flaw in the weld (pinholes, cold welds) will rupture under the pressure differential, causing vacuum loss.

Impact on Cost & Yield Rate:

Based on our experience with similarly complex structures, the yield rate for vacuum evacuation in this design would not exceed 10%.

This means 9 out of 10 semi-finished units would be scrapped, with material loss alone exceeding 100 RMB per unit.

5. Production Stage: Reshaping & Correction

Specific Challenges & Data Analysis:

After the aforementioned "ordeal," the cup body is severely deformed, requiring extensive manual reshaping and correction.

Impact on Cost & Yield Rate:

Production efficiency plummets, and labor costs soar.

The reshaping process easily causes surface scratches, https://www.umbottle.com/ProductsDetail-VB-10534.htmlleading to secondary defects.