What Is a Stacking Test?

Stacking Test, also known as Static Load Stacking Test or Compression Stacking Test, is a test to evaluate the ability of packages to withstand static pressure when stored in multiple layers during warehousing and transportation. By simulating stacking pressure in real logistics environments, this test assesses the compressive strength of packages and their ability to protect contents when subjected to static top loads under specified temperature and humidity conditions.

Core Objectives & Application Value of Stacking Test

The primary objectives of the Stacking Test are to ensure that product packaging can, throughout the supply chain (especially when stacked in multiple layers in warehouses, containers, or transport vehicles):

• Evaluate packaging structural strength: Verify if the packaging design can withstand stacking pressure
• Prevent packaging deformation or damage: Avoid product damage caused by packaging breakage
• Ensure transportation safety: Safeguard the safety of dangerous goods such as lithium batteries during transportation
• Meet international standard requirements: Comply with mandatory regulations of international transport organizations like IATA and IMO

Stacking Test is widely applied in lithium battery transport packaging, electronic product packaging, industrial equipment packaging, etc. In particular, it has become a mandatory safety assessment item for lithium battery products requiring air or sea transport.

Standard Basis & Requirements for Stacking Test

Stacking Test adheres to multiple international and national standards, mainly including:

• International Standard: ISO 2234 《Packaging - Complete, filled transport packages - Static stacking test method》
• Chinese National Standard: GB/T 4857.3 《Packaging - Transport packages - Static load stacking test method》
• Industry-Specific Standard: Special requirements for lithium battery transport packaging in IATA Dangerous Goods Regulations (DGR) Edition 64 and subsequent versions

According to IATA DGR Edition 64, effective January 1, 2023, all lithium battery packages transported under PI965 IB and PI968 IB clauses must pass the Stacking Test. IATA DGR Edition 65 (2024) further expanded the scope to more packaging types.

Specific Requirements & Testing Process of Stacking Test

Core Testing Requirements

Packages must withstand a force equivalent to the total weight of identical packages (including test samples) stacked to a height of 3 meters on the top surface for 24 consecutive hours. After the test, the following conditions must be met:

• No damage to battery cells/packs
• No leakage, deformation, or damage to the packaging that reduces its protective performance
• For paper/fiberboard packaging, preconditioning in specified temperature and humidity environments for at least 24 hours is required

Detailed Testing Process

1. Sample Preparation & Conditioning

   • Provide 3 complete packaged samples (containing batteries or simulants)
   • Measure the dimensions and weight of each package
   • Paper packaging must be conditioned in a standard temperature and humidity environment (e.g., 23±2℃, 50±5%RH) for more than 24 hours

2. Load CalculationCalculate the required stacking load using the formula:P = (H/h) × m × g × (n-1)Where:

   • P: Applied load (N)
   • H: Stacking height (usually 3 meters or as per actual requirements)
   • h: Height of a single package (m)
   • m: Mass of a single package (kg)
   • n: Number of stacking layers = H/h (rounded up)
   • g: Gravitational acceleration (9.81 m/s²)

3. Test Execution

   • Apply the calculated load using professional stacking test equipment
   • Maintain pressure for 24 hours (72 hours required by some standards)
   • Monitor packaging deformation in real-time

4. Result Evaluation

   • Check for permanent deformation or damage to the package
   • Evaluate if the contents are damaged
   • For battery products, additionally check if cells/battery packs are intact

Special Application of Stacking Test in the Lithium Battery Industry

In the lithium battery transport sector, Stacking Test is of special importance, mainly reflected in:

Mandatory Requirements under IATA Regulations

According to IATA DGR, the following lithium battery transport packages must pass the Stacking Test:

• PI965 Section IB (Lithium-ion batteries transported alone, cells <20Wh, battery packs <100Wh)
• PI968 Section IB (Lithium metal batteries transported alone, cells <1g lithium, battery packs <2g lithium)
• Newly added packaging types in 2024 such as PI966-II, PI967-I/II

Sea Transport Exemption

This test only applies to lithium battery packages for air transport; sea transport generally does not require it, but other packaging requirements must still be met.

Testing Equipment & Methods

Stacking Test requires professional testing equipment, mainly including:

• Electric/hydraulic compression testing machines
• Dedicated stacking test platforms (with horizontal adjustment and anti-slip design)
• Deformation measurement systems (laser displacement sensors or high-precision encoders)
• Environmental preconditioning chambers (for temperature and humidity adjustment)

Differences Between Stacking Test and Other Packaging Tests

Stacking Test focuses on evaluating packaging performance under long-term static pressure, while other tests focus on packaging performance under dynamic impact, vibration, etc., together forming a complete packaging performance evaluation system.

Importance & Necessity of Stacking Test

Stacking Test is crucial for lithium battery manufacturers as it directly determines whether products can be exported by air transport. Airlines will refuse to accept lithium battery packages that fail the Stacking Test.

In addition, this test helps enterprises:

• Evaluate the rationality of packaging design: Ensure packaging does not deform or damage under stacking pressure
• Safeguard battery transport safety: Prevent safety hazards such as battery short circuits and leakage caused by packaging damage
• Meet international regulatory requirements: Comply with international transport standards like IATA DGR
• Reduce supply chain risks: Avoid transportation delays and economic losses caused by packaging issues

Our Advantages in Stacking Test Services

As a professional testing and certification institution, we provide comprehensive and efficient Stacking Test services for customers:

1. Professional Qualification Guarantee

• The laboratory holds CMA (202019014977) and CNAS L13753 accreditation
• Test reports have international credibility and are recognized by major global transport agencies and airlines

2. Technical Team Strength

• An experienced technical team familiar with international transport regulations such as IATA DGR
• One-stop services from packaging design consulting to testing and certification

3. Advanced Equipment Support

• Equipped with high-precision stacking test equipment to ensure accurate and reliable test results
• Complete environmental simulation capabilities for testing under different temperature and humidity conditions

4. Efficient Service Process

We offer a standardized Stacking Test service process:

1. Consultation & Requirement Confirmation: Understand customer products and transport needs in detail
2. Solution Formulation: Develop a test plan based on product characteristics and transport mode
3. Sample Preparation: Guide customers to prepare test samples meeting requirements
4. Test Execution: Conduct precise tests in a standard environment
5. Report Issuance: Provide detailed test reports and professional improvement suggestions
6. Follow-up Support: Assist customers in responding to audits by airlines and regulatory authorities

5. Rich Project Experience

We have provided Stacking Test services for numerous enterprises in lithium batteries, energy storage power supplies, consumer electronics, etc., covering various packaging types and product categories. With extensive project experience, we can provide customers with accurate technical guidance and problem-solving solutions.

Frequently Asked Questions (FAQs)

Q: What products require a Stacking Test?A: Mainly lithium battery products to be transported by air, as well as other product packages requiring multi-layer stacking for warehousing and transportation.

Q: How many samples are needed for the Stacking Test?A: Usually 3 complete packaged samples (containing contents or simulants) are required.

Q: How long does the Stacking Test take?A: The standard stacking test cycle is 24 hours; including sample preparation and report issuance, it can usually be completed in 3-5 working days.

Q: What if the test fails?A: We will provide a detailed failure analysis report and improvement suggestions, assisting customers in optimizing packaging design before re-testing.

Stacking Test, as an important testing method to ensure the safety of product packaging during transportation, plays an irreplaceable role in the transport of dangerous goods such as lithium batteries. With the continuous tightening of international transport safety requirements, passing the Stacking Test has become a necessary step for lithium battery enterprises to export their products.

Choosing a professional testing institution for Stacking Test not only ensures the accuracy and compliance of the test but also helps enterprises optimize packaging design, reduce transportation costs, and enhance market competitiveness.

If you have Stacking Test needs or related questions, please feel free to contact Guangdong Energy Storage Testing Technology Co., Ltd.! Our professional team will provide you with detailed technical consulting and personalized test solutions to escort the safe transportation of your products.