Glass Bottle Manufacturing
Quality Control
Full-Process Quality Control for Glass Bottles
From raw material intake to finished goods delivery, we set quality checkpoints at every production step. Preventive process control guarantees consistency, sealing performance and safety batch after batch, suitable for automatic filling lines and long-distance sea transportation.
8 Quality Control Stages
THROUGHOUT PRODUCTION
Raw Material Incoming Inspection
First Checkpoint
Raw material incoming inspection is our first QC checkpoint. We sample each batch of silica sand, soda ash, limestone and colorants for purity, particle size and moisture. Unqualified materials are rejected to prevent bubbles, impurities and color defects.
Melting Process Monitoring
24/7 Furnace Control
During furnace melting, our QC team monitors temperature, pressure and melt homogeneity 24/7. Parameters are adjusted immediately on deviation to prevent internal defects such as stones and glass cords before forming.
Hot End Forming Inspection
Mold & Forming Control
Molds and forming directly determine bottle shape and neck finish. New molds are first-article inspected; mold wear is checked periodically and tracked by cavity number. Gob weight, blow pressure and forming time are monitored, and hot-end vision rejects chipped necks, severe deformation and large cracks.
Annealing & Stress Testing
Internal Stress Control
Freshly formed bottles retain thermal stress; poor annealing causes spontaneous cracking. We cool slowly and evenly in the lehr to release stress, and sample residual stress with a polarimeter to ensure impact and thermal resistance.
Cold End 100% Inline Inspection
Every Bottle Checked
Every annealed bottle passes the cold-end automatic line. 360-degree vision cameras, laser thickness gauges and neck finish gauges screen cracks, bubbles, black spots, burrs and dimensional deviation. Non-conforming bottles are rejected and recycled.
Physical & Chemical Sampling Test
Batch Lab Testing
Samples are picked per AQL standard for impact resistance, burst pressure, thermal shock and water resistance tests. These verify bottle safety during filling, transport and storage. All records are archived for traceability.
Surface Process Inspection
Decoration Quality
After coating, decal printing, silk screen and frosting, dedicated surface inspection checks coating adhesion, pattern clarity and color consistency. Peeling, missing print, scratches and particles are screened for durable decoration.
Pre-Shipment Inspection
Final QC Before Delivery
Before packing and shipment, final inspection samples the whole batch per AQL standard, rechecking specifications, quantity, packaging integrity and labels. Goods are loaded only after passing inspection.
Glass Bottle Quality Inspection Standards & Test Parameters
QC INSPECTION SPECIFICATIONS & ACCEPTANCE CRITERIA
The table below summarizes our routine, physical and chemical inspection standards for glass bottles, covering appearance, dimensional accuracy, annealing stress, impact resistance, internal pressure, thermal shock, sealing leakage and heavy-metal migration limits. Each production batch is verified against these criteria before shipment, ensuring consistent quality for automatic filling lines and long-distance sea transport.
| Test Category | Test Item | Core Requirement / Standard | Test Description |
|---|---|---|---|
| Routine Inspection | Appearance | No burrs, cracks, scratches, obvious bubbles or other appearance defects | Manual / equipment inspection |
| Dimensional accuracy | Bottle mouth / bottle body dimensional deviation ≤ ±0.3mm | Ensures filling-line compatibility and cap-sealing fit | |
| Capacity deviation | Full capacity deviation ≤ ±3% | Complies with industry requirements | |
| Wall / bottom thickness | Uniform with no obvious deviation; no risk of uneven thickness | Ensures structural strength and lowers breakage rate | |
| Physical Properties | Internal / annealing stress | Residual annealing stress ≤ Grade 4; no stress concentration | Prevents spontaneous bottle cracking |
| Impact resistance | Bottle-body impact energy ≥ 0.2J; no cracking | Simulates impact / collision scenarios | |
| Internal pressure resistance | No cracking or leakage under pressure | Simulates pressure scenarios during the filling process | |
| Thermal shock resistance | No cracking under hot-cold alternation with temperature difference ≥ 35°C | Simulates hot-cold rapid-change scenarios during bottle washing and filling | |
| Seal leakage test | No leakage or air leakage after pressure soaking | Ensures tight sealing after filling; no liquid leakage or evaporation loss | |
| Chemical Safety | Lead (Pb) migration | ≤ 0.5 mg/L | Enterprise internal control standard (stricter than the national standard limit of 1.5 mg/L) |
| Cadmium (Cd) migration | ≤ 2.0 mg/L | Enterprise internal control item; complies with food-contact glass safety requirements | |
| Inner surface water resistance | Reaches national standard HC3 grade or above | Prevents impurities from the inner glass wall from leaching into liquor during long-term contact |
Quality Promise
We do not rely only on final inspection to sort out bad bottles. Quality control is moved upstream into raw material, melting and forming stages to prevent defects and stabilize batch consistency. This reduces filling-line downtime, leakage and breakage complaints. Pre-production sample confirmation and third-party inspection are available.