Ceramic Tiles-Methods of Test, Sampling and Basis of Acceptance, Part 1: Determination of Dimensions and Surface Quality
2006 Edition

Overview of Scope for Ceramic Tile Testing

• Coverage: This section defines the scope related to testing, sampling, and acceptance of ceramic tiles, focusing on dimensional and surface quality parameters required for performance and installation reliability.

• Rounding Rules: Values obtained from measurements or calculations need to be rounded according to IS 2:1960, maintaining consistent significant figures throughout reporting.

• Referenced Codes: The standard integrates related Indian Standards for complementary design and quality control aspects.

For detailed formulas or tables, specify the element or parameter of interest.

Measurement Guidelines for Tile Dimensions

Core Instructions:

• Ignore protrusions like spacer lugs or glaze imperfections concealed by joints.
• Tiles smaller than 400 mm² are exempted from dimensional and flatness testing.

Measurement Protocol:

• Square tiles: Average size calculated from four side measurements.
• Rectangular tiles: Average per side from two measurements per pair.
• Sample averaging involves 40 individual measurements.
• Length and width averages computed from 20 measurements each.

Rectangularity Assessment:

• For rectangular tiles, expressed as a percentage relative to length and width.
• For square tiles, expressed as a percentage of tile size.

Rectangularity Formula:

[ \text{Rectangularity %} = \frac{|L - W|}{\text{Reference Dimension}} \times 100 ]

• Reference dimension is tile length or width for rectangular tiles; tile size for square tiles.

flowchart LR
    Tile[Tile] --> Type{Tile Shape}
    Type --> Square[Square: Measure 4 sides]
    Type --> Rectangular[Rectangular: Measure 2 sides per pair]
    Square --> AvgSquare[Calculate average of 4 sides per tile]
    Rectangular --> AvgRect[Calculate average of 2 sides per pair]
    AvgSquare --> SampleAvgSquare[Average of 40 tiles]
    AvgRect --> SampleAvgRect[Average of 20 measurements per dimension]
    SampleAvgSquare --> RectCalc[Compute rectangularity %]
    SampleAvgRect --> RectCalc

This method standardizes measuring tile dimensions.

Guidelines for Sampling and Test Specimen Preparation

• Quantity: Ten entire tiles per tile type are required for testing to ensure statistical reliability.

• Sampling Method: Random selection from the batch to represent the overall quality.

• Specimen Condition: Tiles should be free of any visible defects unless defect testing is intended.

• Uniformity: The sample size remains consistent across various test clauses.

No formulas are necessary; the standard mandates a minimum of 10 whole tiles per type.

flowchart LR
    Batch[Tile Batch] --> Sampling[Random Sampling]
    Sampling --> Selection[Select 10 Whole Tiles]
    Selection --> Testing[Conduct Tests]
    Testing --> Evaluation[Analyze Results]

This ensures representativeness and validity in quality assessments.

Methodology for Measuring Edge Straightness

Definitions:

• Straightness refers to how much the center line of a tile edge deviates from a perfectly straight line.
• Applies only to edges that are intended to be straight.
• Ignore accessory features such as spacer lugs and glaze protuberances.

Equipment:

• A dial gauge mounted on a straightedge or steel square is used to detect deviations.

Measurement Steps:

1. Place the tile on a level surface.
2. Align the straightedge along the tile side.
3. Move the dial gauge along the edge to record deviations.
4. The greatest deviation from zero indicates the straightness error.

Typical Limits:

flowchart LR
    Side[Tile Side] --> StraightEdge[Straightedge Placement]
    StraightEdge --> DialGauge[Dial Gauge Movement]
    DialGauge --> Deviation[Record Maximum Deviation]

Ensure dial gauge calibration and cleanliness of tile surface for accurate results.

Procedure for Rectangularity Measurement

Explanation:

• Rectangularity measures how far a tile’s corner deviates from a perfect 90-degree angle.
• Measurement involves placing the tile corner against a calibrated angle plate.

Calculation Formula:

[ \text{Rectangularity (%)} = \frac{8}{L} \times 100 ]

Where:

• (L) is the length of the adjacent sides (in mm)
• (8) is the measured deviation at 5 mm from the corner (in mm)

Result Expression:

• For rectangular tiles, deviation is given as a percentage of length and width.
• For square tiles, as a percentage of tile size.

Reporting Requirements:

• Include tile description and straightness data.
• Report maximum rectangularity deviation relative to work size.

flowchart LR
    PlaceCorner[Place tile corner on calibrating plate] --> MeasureDeviation[Measure deviation 5 mm from corner]
    MeasureDeviation --> MeasureSide[Measure adjacent side length]
    MeasureSide --> Calculate[Compute deviation % = (8/L)*100]
    Calculate --> ExpressResult[Express as % of length/width or size]

This ensures accurate rectangularity evaluation for quality assurance.

Key Points on Surface Flatness Measurement

Definitions:

• Surface flatness is assessed by measuring curvature and warpage.
• Measurements are conducted at three distinct points on the tile surface.
• When the top surface features relief, measurements are taken on the reverse side.

Measurement Details:

Calculation:

[ \text{Flatness (%)} = \frac{\text{Maximum deviation (mm)}}{\text{Reference length (mm)}} \times 100 ]

graph TD
  TileSurface[Tile Surface]
  TileSurface --> CentreCurvature[Centre Curvature Measurement]
  TileSurface --> EdgeCurvature[Edge Curvature Measurement]
  TileSurface --> WarpageMeasurement[Warpage Measurement]

Use precision tools such as straightedges, feeler gauges, or laser flatness meters to ensure valid measurements.

Guidelines for Test Reporting and Result Presentation

Contents of the Test Report:

• Detailed tile description including type, size, and shape.
• Recorded length and width measurements per tile.
• Average dimensions across specimens.
• Thickness and rectangularity data.
• Deviations expressed as percentages relative to nominal or work sizes.
• Surface flatness data including curvature and warpage percentages.
• Number and area of tiles tested and percentage free of defects.

Important Formulas:

Expression:

• Report averages and deviations as percentages.
• Surface flatness expressed relative to tile dimensions.
• Defect percentages for quality monitoring.

flowchart TD
    Specimens[Test Specimens] --> Measure[Conduct Measurements]
    Measure --> Report[Prepare Test Report]
    Report --> Analyze[Analyze Deviations & Acceptability]

This format ensures clarity and completeness.

Key Terminology in Ceramic Tile Measurement

• Curvature: The maximum height difference of the tile surface relative to a flat plane, measured along length or width.
• Warpage: The distortion causing bending or twisting measured as the maximum height difference diagonally.
• Surface Flatness Measurement: Quantified as the greatest gap between tile surface and a straightedge or reference plane.

Measurement Specifications:

• Utilize a straightedge matching tile size.
• Measure gaps at multiple points to find maximum deviation.
• Flatness limits are dependent on tile dimensions.

Typical Flatness Limits:

flowchart LR
    Surface[Tile Surface] --> MeasureCurvature[Measure Curvature]
    Surface --> MeasureWarpage[Measure Warpage]
    MeasureCurvature --> MaxDiffLength[Max height difference along length/width]
    MeasureWarpage --> MaxDiffDiagonal[Max height difference diagonally]
    MaxDiffLength --> CompareLimits[Compare against flatness limits]
    MaxDiffDiagonal --> CompareLimits

This terminology supports consistent quality assurance in tile production.

Apparatus and Calibration Essentials

• Select equipment appropriate in size and function for the tests.

• Place the calibration plate firmly on three precisely positioned studs.

• Calibration Plate Details:

  • Made from metal or glass.
  • Minimum thickness of 10 mm.
  • Must be perfectly flat for accurate calibration.

• Use vernier calipers or equivalent tools for precise linear measurements.

• Calibration Steps:

  • Insert the calibration plate.
  • Adjust the dial gauge to a known reference reading with the plate in position.

flowchart TD
    SelectEquip[Select Proper Apparatus] --> PlacePlate[Position Calibration Plate on 3 Studs]
    PlacePlate --> MeasureThickness[Verify Plate Thickness ≥ 10 mm]
    MeasureThickness --> InsertPlate[Insert Plate into Device]
    InsertPlate --> AdjustGauge[Calibrate Dial Gauge to Reference]

This procedure guarantees precise and reliable measurements.

Acceptance Guidelines per the Standard

Acceptance is based on conformity with test results and specified tolerances.

Essential Components of Test Reports:

• Tile descriptions.
• Quantity and area of tiles tested.
• All dimensional measurements including length and width.
• Average sizes for each tile type.
• Percentage deviations from nominal and average dimensions.
• Percentage of defect-free tiles.

Dimensional Deviation Formulas:

Where L = side length, D = diagonal, and C, Ac, As, Aw are measured deviations.

Rounding:

• Follow IS 2:1960 for rounding to appropriate significant figures.

This ensures tiles meet required standards before acceptance.