Overview
ISO 9138:2015 defines the standardized methodology and apparatus for sampling and splitting abrasive grains. This international standard ensures that samples taken from lots of abrasive grains are representative and suitable for comparative testing of uniformly produced abrasive grains. The procedures are essential to maintain accuracy and consistency in quality control for industries relying on abrasives.
This standard applies to various packaging forms such as big-bags, drums, and paper bags and specifies appropriate sampling devices called sampling thieves and splitters tailored to grain size and packaging. The document also addresses challenges such as segregation during transportation, ensuring that collected samples reflect the true distribution of abrasive grains.
Key Topics
-
Sampling Equipment
ISO 9138:2015 specifies four types of sampling thieves constructed from seamless steel tubing:
- Type 1: With holes, used primarily for big-bags and drums.
- Type 2: With a single slot, for small bags.
- Type 3: With multiple slots, recommended for small bags.
- Type 4: Motor-driven, for compacted powders ensuring representative sampling.
-
Sample Splitters
Riffle-type samplers (Jones samplers) are employed to divide bulk samples into equal portions. Slot widths and splitter size depend on the grain size and sample mass to maintain accuracy.
-
Sampling Procedure
- Sampling thieves must be inserted at a 60° angle with slots or holes facing downward to ensure complete filling.
- For big-bags/drums, at least two samples are extracted at different points for reliability.
- Paper bags require horizontal orientation sampling with types 2 or 3 thieves.
- Motor-driven thieves facilitate uniform sampling from compacted powders.
-
Sample Preparation
After initial sampling, splitting the sample to obtain a test portion is done either mechanically with a splitter or manually by quartering. The final test sample should be about 25% larger than the quantity needed for testing to compensate for handling losses.
-
Segregation Handling
Special attention is given to mitigating segregation effects in transported materials. Additional homogenization or increased sampling frequency may be necessary to obtain truly representative samples.
Applications
The ISO 9138:2015 standard is crucial for industries involved in manufacturing, testing, and quality assurance of abrasive grains, including:
-
Abrasive Manufacturing
Ensures uniformity and quality consistency in abrasive grain lots used in grinding wheels, coated abrasives, and bonded abrasives.
-
Quality Control Laboratories
Provides a reproducible method for sample collection and preparation to accurately assess grain size distribution and quality parameters.
-
Materials Testing Facilities
Facilitates comparative testing for product certification and compliance with international abrasive standards.
-
Logistics and Storage Management
Helps identify potential sample segregation in storage and transport, enabling better control and quality assurances.
Related Standards
ISO 9138:2015 complements and references several other standards related to abrasive grain sizing and analysis:
- ISO 6344 (Parts 1-3): Coated abrasives grain size distribution tests.
- ISO 8486 (Parts 1 and 2): Grain size distribution designation for bonded abrasives.
- ISO 9136 (Parts 1 and 2): Bulk density determination for abrasive grains.
- ISO 9284: Test-sieving machines for abrasive grains.
- ISO 9285 and ISO 9286: Chemical analysis for abrasive grains such as aluminum oxide and silicon carbide.
These referenced standards assist in grain size analysis and chemical characterization, providing a holistic framework for abrasive grain quality evaluation.
Adherence to ISO 9138:2015 ensures consistent sampling and preparation of abrasive grain samples, facilitating reliable quality assessments and maintaining high standards in abrasive product manufacturing and testing. For professionals in the abrasives industry, understanding and implementing the sampling and splitting procedures defined in this standard is vital for accurate material characterization and competitive product performance.
