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ISO 527-2
Tensile Test Conditions for Moulding and Extrusion Plastics

Dumb-bell tensile test specimens of the kind used for ISO 527-2

Written by Chris Thomas, Universal Grip Company · Reviewed by Frank Bertini · Updated October 24, 2026

ISO 527-2 defines the specimens and test conditions for tensile testing of moulding and extrusion plastics: the injection-moulded multipurpose dumbbell A1 (called Type 1A until 2025), the machined A2 (Type 1B), the reduced-scale 1BA and 1BB and the small 5A and 5B dumbbells for thin mouldings and limited material. It is used together with ISO 527-1, which supplies the definitions, speeds, extensometer classes and calculations. Between them they produce the tensile modulus, yield stress, tensile strength and strain at break on nearly every thermoplastic and thermoset datasheet published outside North America, and the A1 specimen is also the donor bar for ISO 178 flexural and ISO 179 impact specimens.

This guide gives the complete dimension tables with tolerances for all six specimens, which no equipment-maker page publishes; the 2025 renaming and what did and did not change; the speed for each specimen with the strain-rate arithmetic behind it; the 0.05 to 0.25 % modulus, preload, measurement and conditioning rules as they apply to moulded specimens; a worked example; the common errors with their magnitudes; a numeric comparison with ASTM D638; and the grips, extensometers, cutting equipment and machines Universal Grip supplies. The plastics testing page gives the lab overview and the ISO standards hub lists the other ISO methods we equip.

In this guide: Scope: Which Materials and Which Specimens · ISO 527-2:2025: the Renaming and What Did Not Change · A1 (Type 1A) and A2 (Type 1B): Dimensions with Tolerances · Small Specimens: 1BA, 1BB, 5A and 5B · Test Speeds by Specimen · Measurement, Preload, Conditioning and Specimen Count · Step-by-Step Procedure for A1 Specimens · Formulas and a Worked Example · Common Errors and Their Magnitudes · ISO 527-2 vs ASTM D638: the Numbers · Equipment for ISO 527-2: Grips, Machines, Extensometers, Dies · FAQ

Scope: Which Materials and Which Specimens

ISO 527-2 covers rigid and semi-rigid thermoplastic moulding, extrusion and casting materials, filled or reinforced with anything other than textile fibres, rigid and semi-rigid thermosets, and thermotropic liquid-crystal polymers, in specimens that are either moulded directly to size (ISO 294-1 for thermoplastics, ISO 10724-1 for thermosets) or machined from sheet and plate (ISO 2818). It does not cover films and sheets under 1 mm thick, which go to ISO 527-3; rigid cellular plastics (ISO 1926); sandwich structures with cellular cores; or textile-fibre composites, which go to ISO 527-4 and ISO 527-5. Rubbers and elastomers use ISO 37.

Six specimen types are defined. A1 and A2 are the full-size dumbbells and give the reference data; 1BA and 1BB are A2 scaled down by 1:2 and 1:5 (except in thickness) for small parts and limited material; 5A and 5B are small dumbbells with large shoulder radii, derived from the rubber dies of ISO 37 Type 2 and Type 4, for flexible plastics and thin mouldings. The standard is explicit that results from the small specimens are not comparable with A1/A2 results on the same material, because the stress concentration at the shoulders, the surface-to-volume ratio and the strain rate all differ.

ISO 527-2:2025: the Renaming and What Did Not Change

The current edition is ISO 527-2:2025, published in June 2025, replacing ISO 527-2:2012. Its main change is nomenclature: the specimen designations were aligned to ISO 20753, the plastics specimen standard that replaced ISO 3167. Type 1A became A1 and Type 1B became A2; the reduced-scale specimens follow the ISO 20753 'Axy' convention in which the second digit is the scale, so 1BA corresponds to a 1:2 scale A2 and 1BB to a 1:5 scale A2. The Figure 1 and Table 1 dimensions moved to a new subclause and the references were aligned to ISO 527-1:2019. The dimensions, tolerances, gauge lengths and speeds did not change, so an A1 specimen is a Type 1A specimen and a mould that makes one makes the other. Most equipment pages, datasheets and material specifications still say 1A and 1B; this guide uses both names.

The 2012 edition made the technical changes that still matter: the preferred gauge length of the multipurpose specimen rose from 50 to 75 mm (50 mm remains acceptable for quality control and where specified), tensile strength became the first local maximum of the curve, and nominal strain Method B was introduced for materials that yield. The ISO 527-1 guide covers those definitions in full.

A1 (Type 1A) and A2 (Type 1B): Dimensions with Tolerances

A1 is the injection-moulded multipurpose specimen (ISO 20753 Type A1, the old ISO 3167 Type A); A2 is the same outline machined from sheet or from a moulded plate, with a much larger shoulder radius so that machining does not leave a stress raiser. Dimensions in millimetres from Table 1 of the standard:

  • A1 (1A), moulded: overall length l3 = 170 (tabs may be lengthened, for example to 200, for materials that need more grip length); narrow parallel section l1 = 80 ± 2; shoulder radius r = 24 ± 1; distance between the broad parallel sections l2 = 109.3 ± 3.2; width at the ends b2 = 20.0 ± 0.2; width of the narrow section b1 = 10.0 ± 0.2; preferred thickness h = 4.0 ± 0.2; gauge length L0 = 75.0 ± 0.5 preferred, 50.0 ± 0.5 acceptable for QC or when specified; initial distance between grips L = 115 ± 1.

  • A2 (1B), machined: overall length l3 ≥ 150; l1 = 60.0 ± 0.5; r = 60 ± 0.5; l2 = 108 ± 1.6; b2 = 20.0 ± 0.2; b1 = 10.0 ± 0.2; h = 4.0 ± 0.2; L0 = 50.0 ± 0.5; L = 115 ± 1.

The distance l2 is not an independent dimension: it follows from the radius and the two widths as l2 = l1 + √[4r(b2 − b1) − (b2 − b1)²]. For A1 that is 80 + √(4 × 24 × 10 − 100) = 80 + √860 = 80 + 29.3 = 109.3 mm, which is why the table carries that odd-looking value. With 170 mm overall and 115 mm between the grips, each A1 tab has 27.5 mm inside the jaws; a jaw face longer than that reaches onto the shoulder radius and causes shoulder breaks. The nominal cross-section is 10 × 4 = 40 mm², but the standard requires every specimen to be measured, because moulded parts run 0.05 to 0.15 mm over or under on thickness and that is 1.3 to 3.8 % in every stress value.

Moulding and machining. A1 specimens are moulded to ISO 294-1 (thermoplastics) or ISO 10724-1 (thermosets) in the ISO 294 two-cavity mould, with the melt and mould temperatures from the material's ISO data standard (ISO 1873-2, ISO 1874-2 and so on), and the moulding conditions are part of the report because orientation and crystallinity change the result. A2 specimens are machined to ISO 2818 with a fine finish on the edges; a rough milled edge on a brittle material such as PMMA or a glass-filled grade starts the crack and lowers strength by 10 % or more.

Small Specimens: 1BA, 1BB, 5A and 5B

The reduced-scale specimens are for parts too small to yield an A1, for machining from thin mouldings, and for screening work where material is scarce. Dimensions in millimetres from Annex A:

  • 1BA (A2 at 1:2): l3 ≥ 75; l1 = 30.0 ± 0.5; r ≥ 30; l2 = 58 ± 2; b2 = 10.0 ± 0.5; b1 = 5.0 ± 0.5; h ≥ 2; L0 = 25.0 ± 0.5; L = l2 + 2/0 (58 to 60).

  • 1BB (A2 at 1:5): l3 ≥ 30; l1 = 12.0 ± 0.5; r ≥ 12; l2 = 23 ± 2; b2 = 4.0 ± 0.2; b1 = 2.0 ± 0.2; h ≥ 2; L0 = 10.0 ± 0.2; L = l2 + 1/0 (23 to 24).

  • 5A: l3 ≥ 75; width at ends b2 = 12.5 ± 1; l1 = 25 ± 1; b1 = 4 ± 0.1; small radius r1 = 8 ± 0.5; large radius r2 = 12.5 ± 1; L = 50 ± 2; L0 = 20 ± 0.5; h = 2 ± 0.2. Corresponds to the ISO 37 Type 2 rubber dumbbell.

  • 5B: l3 ≥ 35; b2 = 6 ± 0.5; l1 = 12 ± 0.5; b1 = 2 ± 0.1; r1 = r2 = 3 ± 0.1; L = 20 ± 2; L0 = 10 ± 0.2; h = 1 ± 0.1. Corresponds to ISO 37 Type 4 and DIN 53504 S3.

5A and 5B are die-cut from sheet with a sharp cutting die on a die press in one stroke, exactly as rubber dumbbells are; 1BA and 1BB are usually milled. A 5B specimen has a 2 mm² cross-section, so a 50 MPa material breaks at 100 N and the 0.05 to 0.25 % modulus window spans 20 µm of extension on the 10 mm gauge, which is at the limit of what a contact extensometer can resolve and is why strain gauges or a high-magnification video extensometer are used on the smallest types. The standard also permits the ISO 20753 Type C small tensile specimen cut from plates and the CW specimen for comparative work; neither is comparable with A1 data.

Test Speeds by Specimen

ISO 527-2 takes its speeds from Table 1 of ISO 527-1 (0.125 to 500 mm/min) and sets the modulus speed so that the strain rate is about 1 % per minute. Because the speed is a crosshead speed and the small specimens have a shorter length between the grips, the modulus speed scales with the specimen:

  • A1 and A2 (L = 115 mm): modulus at 1 mm/min (0.87 %/min); yield and strength at 5 mm/min for rigid and brittle materials, 50 mm/min for ductile materials; strain at break at 50 mm/min; tolerance ± 20 % at 1 and 5 mm/min, ± 10 % at 50 mm/min.

  • 1BA (L ≈ 60 mm) and 5A (L = 50 mm): modulus at 0.5 mm/min (0.83 and 1.0 %/min); strength at 2 or 5 mm/min for rigid materials and 20 or 50 mm/min for ductile ones, matching the A1 strain rate.

  • 1BB (L ≈ 24 mm) and 5B (L = 20 mm): modulus at 0.25 mm/min (1.0 and 1.25 %/min); strength at 1 or 2 mm/min, 10 or 20 mm/min for ductile materials.

The rule is strain rate (%/min) = speed (mm/min) ÷ L (mm) × 100, and the material standard (ISO 1873-2 for polypropylene, ISO 1874-2 for polyamides, ISO 7391-2 for polycarbonate and so on) names the speeds for the properties it lists. A two-speed test, 1 mm/min through 0.25 % strain and then the property speed on the same specimen, is permitted and is how most automated labs run A1 specimens. Running everything at 5 mm/min saves time but gives a modulus a few percent high and is not a value to ISO 527-2.

Measurement, Preload, Conditioning and Specimen Count

  • Dimensions: width and thickness measured per ISO 16012 with a 0.02 mm resolution micrometer (finer on 5B) at the centre and within 5 mm of each end of the gauge length; the cross-section used in the calculation is from the measured values of that specimen. Moulded A1 specimens vary from cavity to cavity and shot to shot; measure every one.

  • Number of specimens: at least five per direction and property, more where a 95 % confidence interval per ISO 2602 needs it; specimens that break in the shoulders, slip, or break within about 10 mm of a jaw are discarded and replaced.

  • Conditioning: per the material standard, otherwise ISO 291 at 23 ± 2 °C and 50 ± 10 % RH, in practice at least 16 hours, tested in the same atmosphere. Polyamides are tested either dry as moulded (sealed from the mould) or conditioned to equilibrium moisture by ISO 1110 (70 °C, 62 % RH, typically 3 to 7 days for 4 mm), and the state is reported because PA66 drops from roughly 3,000 to 1,300 MPa in modulus and from about 80 to 55 MPa in yield stress between the two states.

  • Preload: no substantial prestress; for the modulus the specimen must stay below the 0.05 % strain that starts the window, in practice no more than about 1 % of the expected strength: about 14 N on A1 polypropylene, 25 N on A1 polycarbonate, 75 N on A1 PA66-GF30.

  • Machine and extensometer: force class 1 to ISO 7500-1; ISO 9513 class 1 extensometer for modulus (1.5 µm absolute on a 75 mm gauge, 1 µm on 50 mm, 0.5 µm on the 25 mm gauge of 1BA and 5A); self-tightening grips aligned with the load axis.

Step-by-Step Procedure for A1 Specimens

  • 1. Mould at least five A1 specimens per property and direction under the ISO 294-1 conditions in the material standard; record melt and mould temperature, injection speed and hold pressure.

  • 2. Condition to ISO 291 (or the material standard) and keep the specimens in the test atmosphere.

  • 3. Measure b1 and h at three points in the gauge length; compute A for each specimen; mark the 75 mm gauge or fit extensometer targets.

  • 4. Set the grips 115 mm apart, insert the specimen square with the shoulders clear of the jaws, apply slight tension, tighten, and attach the class 1 extensometer at 75 mm.

  • 5. Preload to the limit above and zero the strain.

  • 6. Modulus: 1 mm/min through 0.25 % strain, recording at 20 to 50 Hz.

  • 7. Property run: switch to 5 mm/min (rigid) or 50 mm/min (ductile) to yield and break; for ductile materials remove the clip-on at its safe limit and continue with nominal strain by Method B from the grip separation.

  • 8. Inspect the break location and discard shoulder, jaw and slip failures.

  • 9. Calculate Et, σy, σm, σb, εy, εb or εtb per specimen and the mean, standard deviation, CoV and 95 % confidence interval.

  • 10. Report per ISO 527-1 Clause 12 plus the specimen type (A1/1A, A2/1B, 1BA, 1BB, 5A, 5B), moulding or machining details, gauge length used, both speeds and the nominal-strain method.

Formulas and a Worked Example

  • Stress: σ = F ÷ (b1 × h) in MPa with F in N and dimensions in mm.

  • Strain: ε = ΔL0 ÷ L0 from the extensometer; nominal strain εt = ΔL ÷ L (Method A) or εy + ΔL* ÷ L (Method B) from the grip separation.

  • Modulus: Et = (σ2 − σ1) ÷ (ε2 − ε1) at ε1 = 0.0005 and ε2 = 0.0025, or the regression slope over that interval.

  • Tensile strength σm = stress at the first local maximum; yield stress σy = first stress at which strain increases without a stress increase; stress at break σb; strain at yield εy and strain at break εb from the extensometer or εtb nominal.

Worked example (A1 PA66 with 30 % glass fibre, dry as moulded). Measured b1 = 10.04 mm and h = 3.98 mm, so A = 39.96 mm², rounded to 40.0 mm². Gauge length 75.0 mm, grips 115 mm apart. At 1 mm/min the force at 0.05 % strain is 190 N and at 0.25 % strain it is 1,010 N: σ1 = 190 ÷ 40.0 = 4.75 MPa, σ2 = 1,010 ÷ 40.0 = 25.25 MPa, and Et = (25.25 − 4.75) ÷ 0.002 = 20.5 ÷ 0.002 = 10,250 MPa, reported as 10,250 MPa (10.3 GPa). The crosshead switches to 5 mm/min; the force rises without a yield plateau to a maximum of 7,560 N at an extensometer strain of 3.2 % and the specimen breaks there. σm = σb = 7,560 ÷ 40.0 = 189 MPa and εb = 3.2 %; there is no yield stress to report because the curve has no point where strain increases without stress increasing. Five specimens give 10,250, 10,180, 10,310, 10,090 and 10,220 MPa, mean 10,210 MPa, standard deviation 83 MPa, CoV 0.8 %; strengths 189, 186, 191, 184 and 188 MPa, mean 188 MPa, CoV 1.5 %. The same compound conditioned to equilibrium moisture would give roughly 7,000 MPa and 130 MPa, which is why the moisture state is in the report.

Capacity check from the example: 7,560 N on a 40 mm² section means a 10 kN frame is at 76 % of capacity, comfortable for the specimen but leaving no margin for grips rated at 10 kN; a 25 kN frame with a 10 kN load cell, or a 10 kN frame with 10 kN pneumatic grips, is the sensible configuration for glass-filled grades.

Common Errors and Their Magnitudes

  • Nominal 10 × 4 mm assumed. Moulded A1 thickness commonly runs 3.9 to 4.1 mm; 0.1 mm is 2.5 % in every stress value and in the modulus.

  • Gauge length 50 mm reported as 75 mm or mixed. Strain at break on 50 mm reads higher than on 75 mm for the same ductile material; state which was used.

  • Modulus from crosshead travel reads 20 to 40 % low on glass-filled grades because grip and frame compliance is added to the specimen strain.

  • Modulus at 5 mm/min instead of 1 mm/min reads a few percent high and is not an ISO 527-2 value.

  • Global maximum reported as σm on a strain-hardening material such as polycarbonate or PET; σm is the first local maximum, which equals σy for a yielding polymer.

  • Jaw reaches the shoulder. A 40 mm jaw face on a 27.5 mm tab sits on the radius and causes shoulder breaks; use jaws no longer than the tab or set the grip distance correctly at 115 mm.

  • Small-specimen results compared with A1. 1BA, 1BB, 5A and 5B values are not comparable with A1/A2 and should not be entered on a datasheet as if they were.

  • Polyamide moisture state not controlled or not reported: a factor of about two in modulus between dry and conditioned.

  • Machined A2 edges left rough, lowering strength on brittle and filled materials by 10 % or more.

  • Preload above the 0.05 % point, which deletes the start of the modulus window and biases Et upward.

ISO 527-2 vs ASTM D638: the Numbers

The two standards produce similar but not interchangeable results, and both say so. Where they differ:

  • Preferred specimen: A1 170 × 20/10 × 4.0 mm, narrow section 80 mm, radius 24 mm, gauge 75 mm (50 for QC), grips 115 mm apart; D638 Type I 165 × 19/13 × 3.2 mm, narrow section 57 mm, radius 76 mm, gauge 50 mm, grips 115 mm apart.

  • Sub-size specimens: ISO 1BA (25 mm gauge), 1BB (10 mm), 5A (20 mm), 5B (10 mm); ASTM Type IV (25 mm gauge, 6 mm wide) and Type V (7.62 mm gauge, 3.18 mm wide).

  • Speeds: ISO modulus at 1 mm/min and properties at 5 or 50 mm/min, from the 0.125 to 500 mm/min list with ± 20/10 % tolerance; ASTM 5, 50 or 500 mm/min ± 25 % chosen by type and rigidity.

  • Modulus: ISO chord or regression from 0.05 to 0.25 % with no toe compensation; ASTM tangent to the initial linear portion with toe compensation; the difference is commonly 5 to 15 % on semi-crystalline polymers.

  • Strength: ISO first local maximum; ASTM maximum stress.

  • Extensometer: ISO 9513 class 1; ASTM E83 class B-2.

  • Specimens: both at least five; ASTM ten for anisotropic materials.

  • Conditioning: ISO 291 23 ± 2 °C / 50 ± 10 % RH; ASTM D618 23 ± 2 °C / 50 ± 10 % RH for at least 40 hours.

  • Thickness resolution: 0.02 mm (ISO 16012) versus 0.025 mm (0.001 in).

The 4 mm versus 3.2 mm thickness and the 75 versus 50 mm gauge are the reasons ISO strain-at-break values are generally lower than ASTM values on the same ductile material, and the modulus definition is the reason the stiffness numbers differ. Labs that supply both markets mould both specimens; the D638 guide covers the ASTM side.

Equipment for ISO 527-2: Grips, Machines, Extensometers, Dies

Grips and jaw faces

  • A1 and A2 up to about 10 kN: pneumatic grips with 25 mm wide jaws, serrated faces for filled and reinforced grades, smooth or rubber-coated faces for soft, brittle or notch-sensitive materials; constant air pressure keeps the clamp as the tab thins, and foot-pedal or sequential closing inserts the specimen square. Jaw face length 25 mm or less so it stays on the 27.5 mm tab.

  • A1 glass-filled grades above 10 kN (PA66-GF, PBT-GF, PPS-GF, long-fibre PP): mechanical wedge grips with serrated faces; self-tightening by geometry and unaffected by air supply.

  • 1BA and 5A: pneumatic or vise grips with 10 to 15 mm jaw faces; 1BB and 5B: small vise or pneumatic grips with 5 to 10 mm faces and reduced clamping force so that a 1 mm thick section is not crushed. Our D638 Type I–V article covers the same jaw-face logic for the ASTM sizes.

  • Every grip is supplied with the adapter for your frame; see tensile grips and the grip selection guide.

Machine capacity

Multiply the measured cross-section (40 mm² for A1/A2, 10 mm² for 1BA, 4 mm² for 1BB, 8 mm² for 5A, 2 mm² for 5B) by the expected tensile strength. A1 polypropylene at 35 MPa needs 1.4 kN, polycarbonate at 65 MPa 2.6 kN, PA66-GF30 at 190 MPa 7.6 kN, PPS-GF40 at about 200 MPa 8 kN and long-fibre PP at 120 MPa 4.8 kN; a 5B specimen of the same materials needs 70 to 400 N and wants a 1 kN load cell for resolution. The 5 kN benchtop UTM handles unfilled thermoplastics, the 10 kN and 25 kN benchtop machines cover reinforced grades with margin for 10 kN grips, and the 50 kN and 100 kN frames are for labs that also run ISO 527-4 and -5 composites. A Mark-10 tensile tester with a 5 kN cell and pneumatic grips is a cost-effective station for A1 polyolefins and all of the 5A/5B work; the UTM buyer's guide goes into frame selection.

Extensometers

Specimen preparation and environment

ISO 527-2 FAQ

What is ISO 527-2?

The part of ISO 527 that defines the specimens and test conditions for tensile testing of moulding and extrusion plastics: the A1 (1A) moulded and A2 (1B) machined dumbbells, the 1BA and 1BB reduced-scale specimens and the 5A and 5B small dumbbells. It is used with ISO 527-1, which supplies the speeds, classes and calculations. The current edition is ISO 527-2:2025.

What are the ISO 527-2 Type 1A (A1) specimen dimensions?

170 mm overall, 80 ± 2 mm narrow parallel section, 24 ± 1 mm shoulder radius, 20.0 ± 0.2 mm end width, 10.0 ± 0.2 mm narrow width, 4.0 ± 0.2 mm thickness, 75.0 ± 0.5 mm gauge length (50 mm for QC) and 115 ± 1 mm between grips. The nominal cross-section is 40 mm².

What is the difference between Type 1A and Type 1B?

1A (now A1) is injection moulded with an 80 mm parallel section and a 24 mm radius; 1B (now A2) is machined from sheet with a 60 mm parallel section, a 60 mm radius and a 50 mm gauge length. Both are 10 mm wide and 4 mm thick with 115 mm between grips.

What changed in ISO 527-2:2025?

The specimen names were aligned to ISO 20753: Type 1A became A1 and Type 1B became A2, with the reduced-scale types following the Axy convention. Dimensions, tolerances, gauge lengths and speeds are unchanged from the 2012 edition.

What is the test speed for ISO 527-2?

Modulus at 1 mm/min on A1/A2 (about 1 %/min strain rate with 115 mm between grips); yield and strength at 5 mm/min for rigid materials or 50 mm/min for ductile ones; strain at break at 50 mm/min. Small specimens scale down: 0.5 mm/min for 1BA and 5A, 0.25 mm/min for 1BB and 5B modulus.

What are the ISO 527-2 5A and 5B dimensions?

5A: 75 mm long, 12.5 mm end width, 4 ± 0.1 mm narrow width, 25 mm parallel section, 2 ± 0.2 mm thick, 20 mm gauge, 50 mm between grips. 5B: 35 mm long, 6 mm end width, 2 ± 0.1 mm narrow width, 12 mm parallel section, 1 ± 0.1 mm thick, 10 mm gauge, 20 mm between grips.

What are 1BA and 1BB specimens?

The 1B (A2) specimen scaled by 1:2 and 1:5 except in thickness: 1BA is 75 mm long with a 5 mm narrow width, 25 mm gauge and about 60 mm between grips; 1BB is 30 mm long with a 2 mm narrow width, 10 mm gauge and about 24 mm between grips; both at least 2 mm thick. Results are not comparable with A1/A2.

How is modulus measured in ISO 527-2?

At 1 mm/min with an ISO 9513 class 1 extensometer on the 75 or 50 mm gauge, as the chord or regression slope between 0.05 and 0.25 % strain. Crosshead displacement is not permitted; the preload must keep the specimen below 0.05 % strain.

How many specimens does ISO 527-2 require?

At least five per direction and property, more if the ISO 2602 confidence interval requires it; specimens that break in the shoulders, slip, or break near a jaw are discarded and replaced.

What conditioning does ISO 527-2 use?

The material standard's conditioning, otherwise ISO 291 at 23 ± 2 °C and 50 ± 10 % RH, in practice at least 16 hours, tested in the same atmosphere. Polyamides are tested dry as moulded or conditioned to equilibrium moisture per ISO 1110, and the state is reported.

What is the difference between ISO 527-2 and ASTM D638?

ISO uses a 4 mm thick A1 with a 75 mm gauge, 1 mm/min modulus from a 0.05–0.25 % chord with no toe compensation, and the first local maximum as strength; ASTM D638 uses a 3.2 mm Type I with a 50 mm gauge, 5/50/500 mm/min, a toe-compensated tangent modulus and the maximum stress. Results are similar but not interchangeable.

What grips and machine are used for ISO 527-2?

Self-tightening grips aligned with the load axis: pneumatic grips with serrated or rubber faces up to about 10 kN and wedge grips above that for glass-filled grades, with jaws no longer than the 27.5 mm tab. Capacity is cross-section times strength: 1.4 kN for A1 polypropylene, 7.6 kN for PA66-GF30, so 5 to 25 kN frames cover moulding compounds.

Need grips, cutting dies, extensometers or a complete tensile system for ISO 527-2 specimens? Contact Universal Grip with your specimen type, expected strength and machine connection and we will quote the right setup.

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