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

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-10532.htmlAmong these projects, achieving the same cup design in both plastic and stainless steel is particularly special. This stems 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-10532.htmlI hope my following insights can provide some help, especially to those newly acquainted with the cup industry.

In our factory, some cup styles can be produced on both plastic and stainless steel production lines, such as classic straight-walled cups or sport cups with slight contouring. Why are these feasible?

Plastic Process (Injection Molding/Blow Molding):

These shapes have relatively simple mold structures. They can be mass-produced efficiently with high yield rates via injection molding (for one-piece forming) or blow molding (for hollow forming). https://www.umbottle.com/ProductsDetail-VB-10532.htmlA precision mold is key, and selecting the appropriate injection molding machine tonnage enables fast, high-quality production.

Stainless Steel Process (Drawing/Welding):

For straight-walled cups, we use stainless steel sheets drawn multiple times on a drawing machine to form the body, with the base laser-welded on. This process is mature and stable, with yield rates controllable above 95%. https://www.umbottle.com/ProductsDetail-VB-10532.htmlWhile vacuum evacuation is also technical, for regular shapes, vacuum furnaces operate very efficiently.

For such cup styles, the purpose of material interchangeability is clear: to meet different consumer needs regarding material (lightweight vs. insulation) and price. Switching materials for production uses existing equipment and processes, https://www.umbottle.com/ProductsDetail-VB-10532.htmlkeeping costs controllable and market acceptance high. This is what we call "meaningful development."

Let's first look at a successful example to establish a baseline for comparison.

Product Structure: A classic straight-walled cup with a simple threaded mouth, 500ml capacity.

Plastic (PP Material) Implementation:

Process: Injection molding, 4-cavity mold (producing 4 units per machine cycle).

Mold Cost: Approximately ¥80,000 - ¥100,000 RMB (high precision required, including mirror polishing).

Unit Cost (Pure Production Cost): About ¥2.5. This includes ¥1.2 for raw materials and ¥1.3 for utilities, labor, https://www.umbottle.com/ProductsDetail-VB-10532.htmland equipment depreciation.

Production Efficiency: Injection cycle time is 25 seconds. One shift (8 hours) can produce about 4,600 units. The yield rate remains stable above 98.5%.

Double-Walled Stainless Steel (304 Material) Implementation:

Process: The cup body is formed from a single steel sheet through 3 drawing steps, with the base laser-welded and the cavity vacuum-sealed.

Equipment & Tooling: Progressive drawing dies, laser welding machine, vacuum furnace.

Unit Cost: Approximately ¥12. This includes ¥6 for sheet metal and ¥6 for energy consumption and labor in processes like welding and vacuum evacuation.

Production Efficiency: https://www.umbottle.com/ProductsDetail-VB-10532.htmlThe fully linked production line can produce about 2,000 units per shift. The comprehensive yield rate is about 95% (with primary losses in the vacuum evacuation step).

My Comment:

For this cup style, the marginal cost of switching between plastic and stainless steel is very low. This is because the production systems for both are highly optimized for this "rotationally symmetric" regular shape. https://www.umbottle.com/ProductsDetail-VB-10532.htmlSwitching materials primarily serves different market demands and requires almost no production line adjustments, making this "implementation" straightforward.