ASTM D5947 Standard Test Methods for Physical Dimensions of Solid Plastics Specimens

 Get Certified ASTM D5947 Testing for Accurate Plastic Specimen Measurements

Test data show manufacturers and laboratories that their specimen dimensions come from a defined procedure and a calibrated instrument. The standard requires that the micrometer, its calibration, and its use follow the stated requirements, so a laboratory that does this produces measurements that customers and auditors can trace. Accurate dimensions then carry through to every property calculated from them. Laboratories maintain measurement records and calibration certificates to support quality assurance and demonstrate measurement reliability. These records also help customers verify testing procedures and compare results across different laboratories. Consistent dimensional measurements support dependable material evaluations and informed decisions about plastic product quality. 

The scope of the test method includes

• Measured quantity: Physical dimensions of solid plastic specimens, such as thickness and width
• Purpose: Dimensions that feed directly into property calculations
• Test methods: Methods A, B, C, D, and H, each with its own micrometer or gage
• Solid plastics: Test Methods A, B, C, or D
• Other elastomers: Test Method H, for materials with a Type A durometer hardness of 30 to 80
• Instrument care: Requirements for cleaning, zero setting, and calibration
• Reporting: Material identity, method used, number of measurements, and the mean and range for each specimen
• Units: SI values are standard
• Limits: The methods do not replace practical thickness checks made with commercial portable tools

What are the uses of ASTM D5947 Testing?

ASTM D5947 helps manufacturers, laboratories, and researchers obtain accurate specimen dimensions for plastics testing. Engineers and analysts can then use these measurements to calculate mechanical and physical properties that depend on specimen geometry. This standard-

• Determines the physical dimensions of solid plastic specimens used in property testing.
• Provides standardized measurement procedures for specimen thickness, width, and related dimensions.
• Supports accurate calculation of tensile strength, flexural modulus, and other material properties.
• Facilitates consistent dimensional measurement and reporting among laboratories.
• Helps manufacturers verify that molded or machined specimens meet specification requirements.
• Supports quality control programs for plastic materials and finished products.
• Enables researchers to compare test results using standardized specimen measurements.
• Provides traceable dimensional data through calibrated measurement instruments and defined procedures.

What materials can be tested under ASTM D5947?

The method applies to solid plastic specimens made from sheet, plate, or molded shapes that the laboratory cuts or molds to the dimensions a property test requires. Test Methods A, B, C, and D cover plastic specimens. Test Method H covers other elastomeric materials with a Type A durometer hardness between 30 and 80. Soft materials compress under the presser foot, so method choice matters more for them.

Why is ASTM D5947 important?

Tensile strength, flexural modulus, and similar properties come from a force divided by a dimension. A small error in thickness or width carries straight into the final value. The standard also notes that different methods can give different readings on the same plastic, because each method applies its own pressure for its own time. Reporting the method used keeps results comparable. The test methods fall under ASTM Committee D20 on Plastics.

ASTM D5947 Testing Process and Data Collection

Technicians begin testing by conditioning the specimen and cleaning the instrument contact surfaces. They check the zero setting and place the specimen between the anvil and the presser foot at the first measurement position. They bring the foot onto the specimen as required by the chosen method, read the dimension, and correct it using the calibration curve. They then move to the next position and repeat the steps. Unless the material specification says otherwise, they record at least three measurements on each specimen and take the arithmetic mean as the specimen dimension. They recheck the zero setting after each specimen, because contamination carried from the specimen can shift it.

Common Challenges and Troubleshooting

Dirt on the anvil, presser foot, or specimen is the most common source of error and shows up as a shifting zero reading. Technicians keep specimens and instruments covered until measurement, clean the contact surfaces as the manufacturer advises, and recheck the zero after each specimen. Different methods can give different readings on the same plastic, so a laboratory must use the method the material specification names and report it. Soft materials compress under the presser foot, so Test Method H or a slow, gentle approach suits them better. An uncalibrated or worn instrument gives false readings, so the laboratory calibrates it on schedule.

• Technicians report the mean of at least three corrected measurements in SI units, typically millimeters (mm), to determine specimen dimensions.
• Analysts record the range of measured values to evaluate dimensional uniformity and variation among measurements.
• Technicians identify the test method used and document the measurement conditions, recognizing that results from different methods may not agree exactly.
• Engineers interpret the dimensional results for subsequent calculations, noting that ASTM D5947 does not provide a precision statement because methods, loads, and materials vary widely.
• The manufacturer or purchaser considers potential measurement errors in soft elastomers, as compression under the presser foot can increase errors, particularly for thinner specimens.

Link to ASTM D5947 Standard