DEEPLINK Custom Metal Processing Practice: Overcoming Precision Forming Challenges for Special-Shaped Stainless Steel Wine Glasses

I. Project Background & Challenges

Our client, a brand specializing in high-end household products, intended to develop a seamless, one-piece formed stainless steel wine glass targeting the light luxury consumer groups in Europe, America and Russia.

Core Requirements

• Structure: The cup body features a wavy special-shaped curved surface, with 6 positioning pits on the bottom; the whole product is a seamless one-piece structure without welding or splicing.
• Material: Food-grade 304 stainless steel, ensuring safety and non-toxicity.
• Appearance: Mirror-polished finish for a premium metallic texture with no obvious processing marks.
• Precision: Position tolerance of the bottom pits ≤±0.2mm, with smooth and burr-free rim.

II. Process Solution & Implementation

We finally adopted a combined process of multi-pass deep drawing (deep stamping) one-piece forming + local coining + mirror polishing to fully meet the client’s requirements.

1. Core Process: Multi-pass Deep Drawing One-piece Forming

Instead of the traditional tube hydroforming process, we started with stainless steel flat blanks and completed the cup body forming through 4 progressive passes of deep drawing. The details of each procedure and the problems solved are as follows:In the blank preparation stage, we selected 2mm-thick 304 stainless steel sheets, blanked them into round pieces with a diameter of 120mm, and deburred the edges to avoid stress concentration at the edges and prevent cracking during subsequent drawing.In the 1st drawing pass, we adopted a large-fillet mold to initially draw the blank into a shallow cup with a height of 40mm, controlling the drawing coefficient at 0.55 to release initial stress and prevent instantaneous tearing of the material.To restore material plasticity for subsequent deep drawing, we performed solution annealing at 1050°C after the 1st drawing, followed by rapid water cooling to effectively eliminate work hardening.In the 2nd to 3rd drawing passes, we gradually reduced the mold fillet, drawing the cup body to the final height of 65mm, with the drawing coefficient controlled at 0.7 for each pass. By evenly distributing the deformation, we ensured the wall thickness difference was within 0.2mm.Finally, in the 4th shaping pass, we used a shaping mold with a wavy contour and precisely formed the special-shaped curved surface of the cup body via hydraulic press coining, avoiding springback of the cup and perfectly restoring the designed wavy shape.

2. Detail Finishing: Local Coining Process for Cup Bottom

After the main cup body was formed, we used a custom precision mold for local coining of the cup bottom:

• Fix the cup body upside down, and apply pressure synchronously on a hydraulic press with a 6-point linkage punch.
• Adopt a step-by-step pressure application strategy: first light pressing for positioning, then gradually increasing pressure to the final depth to avoid overall deformation of the cup body.
• Conduct low-temperature stress relief tempering after coining to eliminate local stress and prevent deformation during use.

3. Surface Treatment: Food-grade Mirror Polishing

To achieve a high-end visual effect and meet food safety standards, we implemented a 3-stage polishing process:

• Rough polishing: Remove stamping marks and oxide scale with an 800-mesh abrasive belt.
• Medium polishing: Improve surface gloss with a nylon wheel paired with chromium oxide polishing paste.
• Fine polishing: Achieve a mirror finish with a pure cotton cloth wheel paired with diamond polishing paste.

III. Project Results & Client Feedback

After 3 rounds of mold iteration and process optimization, we successfully delivered stainless steel wine glass samples meeting all requirements:

• ✅ Structural Integrity: 100% seamless one-piece forming with uniform wall thickness.
• ✅ Precision Compliance: Position tolerance of the bottom pits controlled within ±0.2mm.
• ✅ Perfect Appearance: Transparent mirror effect without any processing marks, matching the light luxury positioning.
• ✅ Safety Certification: Passed EU Food Contact Materials (FCM) testing and complies with LFGB standards.

IV. DEEPLINK Core Advantages: Why Choose Us?

1. Technical Barriers in Complex Special-shaped Component Forming

With 10+ years of expertise in precision metal forming, we master core processes such as multi-pass deep drawing, local coining and internal high-pressure forming. We realize one-piece forming from flat blanks to seamless special-shaped parts, perfectly solving the problems of insufficient strength and leakage risks caused by traditional welding processes, making us a reliable partner for high-end custom metal parts.

2. Full-chain Customized Service Capability

We provide a one-stop customized solution from product design optimization, mold development and small-batch trial production to large-scale mass production:

• Design stage: Assist clients in optimizing structures, balancing process feasibility and appearance effects, and reducing mass production risks.
• Mold development: Independently design and manufacture precision molds with an iteration cycle shortened to 7–10 days, responding quickly to client needs.
• Quality control: Full-process inspection (dimension, surface, material) to ensure every product complies with design and safety standards.

3. High-quality Metal Materials & International Certification Assurance

All metal materials are selected high-quality metal materials. The production process strictly follows the ISO9001 quality management system, and finished products pass international quality certifications such as EU CE and American ANSI, meeting the access requirements of overseas markets and reassuring overseas buyers.