In-Depth Analysis of Stainless Steel Water Bottle Stretching Process --- Q&A Session

Every cup holds a story, and life has its warmth. Hello everyone, and welcome to "Dong Dong's Cup Talk" As I've shared more and more content with you all, writing these pieces has become increasingly challenging. So today, I've invited a true expert, Engineer Zhang. He is the technical authority in our factory and holds a deep affection for our work. https://www.zhanyict.com/en/ProductsDetail-VB-10503.htmlHe's here today to share insights about the stretching process for stainless steel water bottles. Let's give a warm welcome to Engineer Zhang!

Hello everyone! I'm Old Zhang, and I've been in the stainless steel water bottle industry for a full twenty years. For these two decades, I've focused on practically nothing else but grappling with the craft of "stretching." From the earliest manual punch presses to today's intelligent multi-station continuous stretching machines, https://www.zhanyict.com/en/ProductsDetail-VB-10503.htmlfrom watching seasoned masters rely on experience and "listening to the sounds" to the current era of digital, parametric precision control – I've witnessed with my own eyes and worked hands-on with every evolutionary step of this process. Today, I want to talk systematically with you all about the ins and outs of the stainless steel water bottle stretching process. I hope to offer some inspiration to those new to the field and also exchange ideas and learn from the veteran masters. [Cue applause here!]

III. Industry Limits & Common Questions Answered

Material & Final Thickness Limits:

Raw Material Thickness: In the general water bottle industry, deep drawing becomes very difficult and risky with raw sheet metal thicker than 1.5mm. Excessive thickness leads to poor material flow, requires immense tonnage, and makes tearing extremely likely.

Final Thickness Limit: Theoretically, through multiple draws and annealing, one can achieve 0.2mm or even thinner. However, the practical limit for stable commercial production currently sits around 0.3mm. https://www.zhanyict.com/en/ProductsDetail-VB-10503.htmlGoing thinner causes costs to skyrocket and yield rates to become unacceptably low, negating practical value. Conversely, very thick walls (e.g., >1.5mm) are almost never seen in the market due to weight, cost, and processing difficulty.

Lubricant (Drawing Oil) Selection:

Lubricating oil is the material's "protective talisman."

Standard Thickness (1.2mm - 0.8mm): Mineral oil-based drawing oils can be used; they are cost-effective.

Thin-Wall & Deep Drawing (Below 0.8mm): Must use specialized drawing oils containing Extreme Pressure (EP) additives like chlorine or sulfur. https://www.zhanyict.com/en/ProductsDetail-VB-10503.htmlUnder high pressure and temperature, these react with the metal surface to form a robust lubricating film, preventing direct die-to-workpiece contact and thus avoiding scratches and tearing. Thorough cleaning processes afterwards are essential to completely remove these oils and any residues.

Dimensional Limits for Cup Stretching:

Maximum Diameter: I have seen barrel-like products over 600mm in diameter made using segmented stretching and welding processes. However, for a single-piece, monolithic stretch, the current technical limit with mainstream equipment is around 400mm in diameter. Beyond this, the requirements for press tonnage (thousands of tons) and sheet metal quality become extremely stringent.

Minimum Diameter: This depends more on mold manufacturing precision and the capabilities of small-scale stamping presses. https://www.zhanyict.com/en/ProductsDetail-VB-10503.htmlCup-shaped objects with diameters of 20mm or even smaller (e.g., medicine cups, test cups) are possible, but this falls under precision stamping, not the traditional water cup industry.