Manufacturing Process Of Vacuum Insulated Stainless Steel Bottles
The Principle of Thermal Insulation
Thermal insulation refers to the technology and measure of reducing the transfer of heat between a target object (or space) and its surrounding environment, thereby maintaining the temperature stability of the object (or space). Its core principle is to weaken the three basic ways of heat transfer in nature: heat conduction, convection, and thermal radiation. Below is a detailed explanation of the principle, categorized by the three heat transfer modes.
1. Inhibiting Heat Conduction
Heat conduction is the transfer of heat between adjacent molecules (or atoms) in a substance due to collisions, without the macroscopic movement of the substance itself. For example, the handle of a metal spoon becomes hot when the spoon is placed in boiling water—this is heat conduction.
The key to inhibiting heat conduction lies in using materials with low thermal conductivity (λ). Thermal conductivity is a physical quantity that measures the ability of a substance to conduct heat; the smaller its value, the weaker the heat conduction ability, and the better the insulation performance.
• Using vacuum insulation: In vacuum insulation panels (VIPs), most of the air in the insulation layer is pumped out to form a high vacuum. Since there are almost no molecules in a vacuum to collide and transfer heat, heat conduction is minimized to an extremely low level. This is why vacuum flasks can keep liquids hot or cold for a long time.
The key to inhibiting heat conduction lies in using materials with low thermal conductivity (λ). Thermal conductivity is a physical quantity that measures the ability of a substance to conduct heat; the smaller its value, the weaker the heat conduction ability, and the better the insulation performance.
Common Mechanisms to Reduce Heat Conduction:
• Using porous materials: Most insulation materials (e.g., foam plastic, rock wool, glass wool) are porous. The air (or inert gas) sealed in the pores has an extremely low thermal conductivity (air λ ≈ 0.026 W/(m·K) at 20°C, much lower than that of metals like iron λ ≈ 80 W/(m·K)). These pores block the direct contact between the solid components of the material, significantly reducing heat conduction through the solid.• Using vacuum insulation: In vacuum insulation panels (VIPs), most of the air in the insulation layer is pumped out to form a high vacuum. Since there are almost no molecules in a vacuum to collide and transfer heat, heat conduction is minimized to an extremely low level. This is why vacuum flasks can keep liquids hot or cold for a long time.
2. Suppressing Convection
Convection is the transfer of heat caused by the macroscopic flow of a fluid (gas or liquid) . When a fluid is heated, its density decreases and it rises; the colder, denser fluid sinks to fill the gap, forming a"convection current" that continuously transfers heat. For example, the air near a heater rises, and cold air near the ground flows toward the heater—this is air convection.
Thermal insulation materials and structures suppress convection bypreventing the free flow of fluids:•Sealing porous structures: The pores in insulation materials (e.g., expanded polystyrene, EPS) are small and closed. This prevents the air inside the pores from forming large-scale convection currents; only minimal"micro-convection" occurs in tiny pores, which has a negligible effect on heat transfer.
Thermal insulation materials and structures suppress convection bypreventing the free flow of fluids:•Sealing porous structures: The pores in insulation materials (e.g., expanded polystyrene, EPS) are small and closed. This prevents the air inside the pores from forming large-scale convection currents; only minimal"micro-convection" occurs in tiny pores, which has a negligible effect on heat transfer.
3. Reflecting or Absorbing Thermal Radiation
Thermal radiation is the transfer of heat in the form of electromagnetic waves (infrared rays are the main form), which does not require a medium and can occur even in a vacuum. For example, the sun’s heat reaches the Earth through thermal radiation, and a person feels warm when standing near a hot stove—this is thermal radiation.
Thermal insulation for radiation mainly relies on reflectingorabsorbing radiant heat: •Reflecting thermal radiation: Materials with high reflectivity (e.g., aluminum foil, metalized film) are used. These materials can reflect most of the incident infrared radiation (reflectivity > 90%) back to the heat source, preventing radiant heat from entering the insulated space. For example: ◦The inner layer of a vacuum flask is coated with a thin metal film (usually silver) to reflect the thermal radiation of the liquid inside, reducing heat loss.
Thermal insulation for radiation mainly relies on reflectingorabsorbing radiant heat: •Reflecting thermal radiation: Materials with high reflectivity (e.g., aluminum foil, metalized film) are used. These materials can reflect most of the incident infrared radiation (reflectivity > 90%) back to the heat source, preventing radiant heat from entering the insulated space. For example: ◦The inner layer of a vacuum flask is coated with a thin metal film (usually silver) to reflect the thermal radiation of the liquid inside, reducing heat loss.
Summary: Comprehensive Insulation = Synergy of Three Mechanisms
Practical thermal insulation products rarely rely on a single mechanism; instead, they combine multiple methods to achieve the best effect. For example:
•A vacuum flask uses a vacuum layer to inhibit conduction and convection, plus a metal coating to reflect thermal radiation—three mechanisms work together to achieve long-term temperature retention.
In short, the essence of thermal insulation is to target the three pathways of heat transfer, using material selection, structural design, and process optimization to weaken or block heat flow, ultimately maintaining the temperature stability of the protected object or space.
•A vacuum flask uses a vacuum layer to inhibit conduction and convection, plus a metal coating to reflect thermal radiation—three mechanisms work together to achieve long-term temperature retention.
In short, the essence of thermal insulation is to target the three pathways of heat transfer, using material selection, structural design, and process optimization to weaken or block heat flow, ultimately maintaining the temperature stability of the protected object or space.
Production Process
The production process of stainless steel vacuum flasks combines metal processing, vacuum technology, and quality testing. It begins with selecting food-grade stainless steel (304/316), then forms inner/outer shells via stamping and deep drawing. Welding (argon arc for bottom, laser for neck) ensures sealing, followed by core vacuum processing (creating a high-vacuum layer to block heat conduction/convection). A reflective coating (Cu/Ni/Al) reduces radiant heat loss, then surface treatment, accessory assembly, and strict inspections (insulation, safety, appearance) are done. Vacuum degree and welding precision are key to its heat preservation performance.
Raw Material
Tube Cutting Line
Water Swelling Line
Drawing Line
Welding Line
Welding Line
Vacuum Forming Line
Vacuum Machines
Ultrasonic Cleaning Line
Inspection Process
Polishing Line
Polishing Line
Automatic Painting Line
Powder Coating Process Line
Drying Line
Vacuum testing
Laser Engraving
Laser Engraving
Injection Molding Line
Mold processingproduction line
Mold processingproduction line
Product testing room
Sample room
Sample room
Design and Development Cooperation Process
01. Initial Requirement Alignment
The client communicates core demand directions: target market positioning (e.g., premium/home use/outdoor), key functional preferences (e.g., one-click lid, double-wall vacuum, large capacity), budget range, and brand customization needs (e.g., logo placement, color palette). Soniu proposes preliminary design directions (e.g., 2-3 conceptual styles) and technical feasibility assessments (e.g., whether outdoor-use insulation requirements match existing design capabilities).
02. NDA (Non-Disclosure Agreement) Signing
Both parties execute an NDA to protect sensitive information throughout the design collaboration. The agreement specifies:
• Confidential scope: Soniu’s proprietary design schemes (e.g., innovative vacuum layer structures, ergonomic lid designs), technical parameters (e.g., material ratios, production process parameters); client’s market research data, brand strategy, and unannounced product launch plans.
• Confidential period: Typically 3–5 years (extendable by agreement) to prevent post-cooperation leakage of Soniu’s unique designs or client’s business information.
• Purpose: Safeguard Soniu’s design intellectual property and the client’s market competitiveness, enabling open exchange of design feedback.
• Confidential scope: Soniu’s proprietary design schemes (e.g., innovative vacuum layer structures, ergonomic lid designs), technical parameters (e.g., material ratios, production process parameters); client’s market research data, brand strategy, and unannounced product launch plans.
• Confidential period: Typically 3–5 years (extendable by agreement) to prevent post-cooperation leakage of Soniu’s unique designs or client’s business information.
• Purpose: Safeguard Soniu’s design intellectual property and the client’s market competitiveness, enabling open exchange of design feedback.
03. Soniu-Led Design & Development
• Soniu’s R&D team develops detailed design solutions: 3D models of the vacuum flask (body shape, lid structure, base design), structural drawings (vacuum layer thickness, weld seam optimization), and BOM (Bill of Materials, e.g., 316 stainless steel for premium lines, food-grade silicone for gaskets).
• Soniu presents the design package to the client for review; revisions are made based on client feedback (e.g., adjusting lid opening force, modifying body curvature) until the design is finalized. Compliance checks (e.g., FDA, EU LFGB food safety standards) are integrated into this stage.
• Soniu presents the design package to the client for review; revisions are made based on client feedback (e.g., adjusting lid opening force, modifying body curvature) until the design is finalized. Compliance checks (e.g., FDA, EU LFGB food safety standards) are integrated into this stage.
04. Prototype Fabrication & Validation
Soniu produces 2–5 functional prototypes based on the finalized design, conducting rigorous testing:
• Performance tests: 12-hour heat retention (≥55°C for 12h with 95°C hot water), cold retention (≤10°C for 12h with 4°C cold water), lid leak-proof test (inverted for 24h).
• Safety & usability tests: Surface burr detection, temperature resistance of outer coating, ease of lid operation.
The client confirms prototype approval (for function, appearance, and usability) to greenlight mass production.
• Performance tests: 12-hour heat retention (≥55°C for 12h with 95°C hot water), cold retention (≤10°C for 12h with 4°C cold water), lid leak-proof test (inverted for 24h).
• Safety & usability tests: Surface burr detection, temperature resistance of outer coating, ease of lid operation.
The client confirms prototype approval (for function, appearance, and usability) to greenlight mass production.
05. Production Preparation & Contract Finalization
• Soniu optimizes production processes (e.g., adjusting deep drawing speed for flask shells, calibrating vacuum pumping equipment) and sources raw materials per the approved BOM. Pre-production trials (10–30 sample units) are run to verify process stability.
• Both parties sign a formal cooperation contract, clarifying: design ownership (whether Soniu retains design rights or transfers them to the client), mass production quantity, quality acceptance criteria (defect rate ≤0.5%), delivery timeline, and payment terms.
• Both parties sign a formal cooperation contract, clarifying: design ownership (whether Soniu retains design rights or transfers them to the client), mass production quantity, quality acceptance criteria (defect rate ≤0.5%), delivery timeline, and payment terms.
06. Mass Production & Quality Control
Soniu initiates batch production, with multi-stage quality checks:
• In-process inspection (IPQC): Random sampling to verify shell forming precision, vacuum layer sealing integrity, and coating uniformity during production.
• Final inspection (FQC): 100% testing of insulation performance and lid functionality; sampling (1% of batch) for material safety analysis (heavy metal detection).
The client may send representatives for on-site quality audits or appoint a third-party inspection agency.
• In-process inspection (IPQC): Random sampling to verify shell forming precision, vacuum layer sealing integrity, and coating uniformity during production.
• Final inspection (FQC): 100% testing of insulation performance and lid functionality; sampling (1% of batch) for material safety analysis (heavy metal detection).
The client may send representatives for on-site quality audits or appoint a third-party inspection agency.
07. Delivery & Post-Sales Support
Soniu arranges logistics (e.g., container shipping, air freight) as contracted, accompanying products with quality certificates (insulation test reports, material compliance documents). Post-delivery support includes:
• Technical assistance (e.g., troubleshooting production-related issues if the client needs secondary processing).
• Design iteration support (e.g., minor design tweaks for subsequent orders) and replacement of defective units within the warranty period (usually 12 months).
Key Note: Clear definition of design ownership in the contract and timely documentation of design revisions are critical to avoid intellectual property disputes—distinct from OEM, where design rights typically belong to the client.
• Technical assistance (e.g., troubleshooting production-related issues if the client needs secondary processing).
• Design iteration support (e.g., minor design tweaks for subsequent orders) and replacement of defective units within the warranty period (usually 12 months).
Key Note: Clear definition of design ownership in the contract and timely documentation of design revisions are critical to avoid intellectual property disputes—distinct from OEM, where design rights typically belong to the client.
Customization Unlimited
Competitiveness High
Premium Outlook
Product Quality
Pioneer & Leader in Water Bottle Ceramic Coatings
Soniu holds a landmark position in water bottle innovation—it is the first company globally to develop ceramic coatings tailored for water bottles, and today stands as the undisputed leader in this field. What began as a quest to elevate daily hydration has evolved into a legacy of technical advancement, blending user-centric practicality with cutting-edge science.
When Soniu first launched its ceramic coating, it addressed two key user pain points: effortless cleaning and preserved beverage flavor. Unlike traditional metal or plastic linings that trap stains and metallic odors , Soniu’s initial ceramic formula featured an ultra-smooth, non-porous surface. Spills and residues wipe away with a simple rinse, no harsh scrubbing needed; more importantly, it keeps the unique notes of drinks, ensuring every sip of coffee,juice, tea, or water tastes exactly as intended—no"aftertaste" from the bottle itself.
Driven by a commitment to innovation, Soniu has since achieved remarkable technical breakthroughs, elevating its ceramic coating to deliver powerful antibacterial protection. Through refined material science and precision engineering, the latest iteration of its ceramic coating actively inhibits the growth of common harmful bacteria, including E. coli and Staphylococcus aureus, with a proven antibacterial rate of over 99.9%. This is a game-changer for daily use: whether the bottle is shared among family members, used in busy offices, or carried during commutes, it minimizes the risk of bacterial contamination, adding an extra layer of safety to hydration.
As the leader in ceramic-coated water bottles, Soniu’s journey—from pioneering easy-clean, flavor-preserving coatings to mastering antibacterial technology—reflects its dedication to making hydration safer, more enjoyable, and more reliable. For users worldwide, Soniu isn’t just a brand; it’s the gold standard for ceramic coating excellence.
With NIU Bottle
We NIU Bottle, a professional China OEM/ODM Manufacturer factory of stainless steel vacuum insulated water bottle tumbler bowl container offer one stop solution for your custom design project from concept design to prototype sample, tooling development, trial run production, mass production, inspection & tests, and final shipment with fast delivery, low MOQ, high-end quality, and reliability for long term business cooperation relationship. We always looking for and chasing GOOD REPUTATION for every customer.
What Do Our Customers Say
Lily
Our Customer
At NIU Bottle, we take our environmental impact seriously and are committed to reducing our carbon footprint as much as possible. We take pride in offering a selection of sustainable bottles that are crafted from recycled materials. We can make from a range of recycled materials including Recycled Steel, PP, PET, and Tritan Renew, with up to 90% recycling rates. Our production process is certified by RCS, GRS, GLF, and ISCC certificates. Furthermore, our bottles undergo antibacterial testing and FDA testing to ensure that they are safe for everyday use.
Jackson Reynolds
Our Customer
This cup is incredibly versatile. Whether I'm sipping on my favorite hot beverage or enjoying a refreshing cold drink, the cup maintains the ideal temperature. Its versatility makes it suitable for various beverages, adding convenience to my daily routine.
Fiona
Our Customer
As a Distributor and occasional final user on Clear tumbler and Steel Travel Coffee Mugs , Wine Tumbler and Growlers in USA, we really need: good quality, good price and on- time delivery. NIU Bottle and their Team helps us to make it realized! NIU Bottle has day by day...
Our Client Frequently Asked Questions
What is your MOQ?
For stock items, any quantity is available.
For OEM items, pls contact us for further discuss.
For OEM items, pls contact us for further discuss.
Can I get samples?
Sure. We usually provide exiting sample for free.
But a little sample charge for custom designs. Samples charge is refundable when order is up to certain quantity.
But a little sample charge for custom designs. Samples charge is refundable when order is up to certain quantity.
How long is the sample lead time?
For existing samples, in 1-3 days will be sent out.
If you want your designs, about 5 days will be ready, subject to you designs whether they need new printing screen, etc.
If you want your designs, about 5 days will be ready, subject to you designs whether they need new printing screen, etc.
How long is the production lead time?
For stocked colors, its fast delivery, can ship wintin 7days.
If customized OEM order, It takes 15-25 days after received deposit and all packing materials are confirmed.
If customized OEM order, It takes 15-25 days after received deposit and all packing materials are confirmed.
What documents do you need if I want my own design?
We have our own designer in company. So you can provide JPG, AI, cdr or PDF, etc. We will make 3D drawing for mold or printing screen for your final confirmation based on technique.
How many colors are available?
We match colors with Pantone card or your sample. So you can just tell us the Pantone number. We will match the colors. Or we will recommend some popular colors to you.
How do you ship the goods does it take to arrive?
Small order can delivery by express, for big order We usually ship by sea.
What is your payment term?
Our normal payment term is TT 30% deposit after order signed and 70% aganist copy of B/L.
For small order, it's 100% payment inadvance through alibaba.
For small order, it's 100% payment inadvance through alibaba.
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