PlasticsWhat do the standards on a plastic data sheet mean? ISO 527, ISO 179, UL 94 and more
A plastic data sheet is full of acronyms: DIN EN ISO 527, ISO 179, UL 94, IEC 60243. Each one identifies the standard used to measure a property, and without understanding them it is easy to compare values that are not comparable. In this guide we explain what each test measures, how it is done and what reference values our engineering plastics have.
Why does the standard matter alongside the value?
Two materials can report "70 MPa strength" and still not be comparable if one was tested per ISO 527 at one speed and the other per ASTM D638 at another, or if hardness is given in Shore D on one data sheet and in Rockwell R on another. The standard fixes the specimen shape, the load, the speed, the temperature and the reading time. That is why in our data sheets each property comes with its test method, and why you should always compare values from the same standard.
The families of standards you will see on a data sheet
- ISO and DIN EN ISO: international standards adopted in Europe (DIN is the German institute); they are the most common in data sheets for semi-finished engineering plastics.
- ASTM: North American standards; they appear in materials such as polycarbonate, PE 300 or Ceramic UHMW.
- IEC: international electrical standards; they measure dielectric strength, dielectric constant and insulation resistance.
- UL 94: flammability rating from UL Solutions, the global reference in fire safety.
What each test measures
| Property | Standard | What does it measure and how? | Reference values for our materials |
|---|---|---|---|
| Density | DIN EN ISO 1183 / ASTM D792 | Mass per unit volume (g/cm³). Defines the weight of the part and lets you calculate how much material is needed. | Polypropylene 0.91 · Nylon 1.15 · Teflon 2.13 to 2.21 |
| Water absorption | DIN EN ISO 62 / ASTM D570 | Percentage of water absorbed by a specimen when submerged. The more it absorbs, the more its dimensions and properties change with humidity. | Polyethylene 0.01% · Acetal 0.2% · Nylon 2.5% |
| Yield strength, elongation and modulus | DIN EN ISO 527 / ASTM D638 | Tensile test: stretches a specimen at constant speed and records the stress at which it begins to deform permanently (yield), how much it elongates before breaking, and its stiffness (modulus of elasticity). | PEEK 110 MPa and 4,000 MPa · PET 85 MPa and 3,000 MPa · UHMW 19 MPa and 750 MPa |
| Flexural strength | ISO 178 / ASTM D790 | Stress a bar can withstand when supported at two points and loaded at the center. Useful for plates and shapes that work in bending. | G10/FR4 350 MPa · Polycarbonate 100 MPa · PETG 79 MPa |
| Charpy and Izod impact | DIN EN ISO 179 / ASTM D256 | Energy absorbed by the specimen when broken with a pendulum (kJ/m² or J/m), with or without a notch. Indicates toughness against impact. | UHMW PE 1000 115 kJ/m² · Acetal 6 kJ/m² · PETG and Teflon: does not break |
| Hardness | DIN EN ISO 868 / ISO 2039 / ASTM D785 | Resistance to penetration (Shore D, ball in N/mm² or Rockwell). See our plastics hardness guide. | Bakelite 90 Shore D · Nylon 83 Shore D · Teflon 50 to 55 Shore D |
| Deflection temperature (HDT) | DIN EN ISO 75 / ASTM D648 | Temperature at which a loaded bar (1.80 MPa in method A) reaches a defined deflection while being heated. It marks how far the part keeps its stiffness under load. | Polycarbonate 130 °C · Acetal 110 °C · PET 80 °C |
| Vicat softening | ISO 306 / ASTM D1525 | Temperature at which a 1 mm² needle penetrates 1 mm into the material under 10 N or 50 N. It indicates when the plastic starts to go from solid to molten. | PE 300 125 °C · PE 500 and PE 1000 80 °C · PETG 83 °C |
| Melting temperature | ISO 11357 (DSC) | Temperature at which the crystalline phase melts, measured by differential scanning calorimetry. It applies only to semi-crystalline thermoplastics. | PEEK 343 °C · PET 255 °C · Nylon 216 °C · Polyethylene 135 °C |
| Flammability | UL 94 | Classifies how the material behaves when exposed to flame: HB (slow horizontal burn), V-2, V-1 and V-0 (self-extinguishing in the vertical position, with or without dripping) and 5VB / 5VA (more severe flame). | PEEK V0 · Bakelite V0 / V1 · Nylon, PET and PP HB |
| Coefficient of friction | ASTM D1894 | Ratio of the force to slide one surface over another to the normal load, static and dynamic. The lower the value, the better the sliding. | Teflon 0.06 to 0.09 · Self-lubricating nylon ≈ 0.08 · PE 300 0.31 |
| Dielectric strength | IEC 60243 / ASTM D149 | Maximum electrical voltage per millimeter of thickness that the material withstands before breaking down (kV/mm). Key for insulators. | Ceramic UHMW 90.3 kV/mm · Teflon 59 kV/mm · Bakelite 22 kV/mm |
The UL 94 classification, explained
In the horizontal (HB) test the specimen is laid flat, the flame is applied for 30 seconds, and the speed at which the fire advances is measured: up to 40 mm/min is accepted for thicknesses of 3 to 13 mm and 75 mm/min below 3 mm. In the vertical tests the specimen is hung and the flame is applied twice for 10 seconds: for V-0 each specimen must self-extinguish within 10 seconds and not drip burning material; for V-1, within 30 seconds with no burning drips; and V-2 allows 30 seconds with dripping. The 5VB and 5VA classes use a flame about five times more severe. That is why a V0 PEEK or a V0 Bakelite is chosen where there is a fire risk, while an HB nylon or polypropylene requires another protective measure.
Thickness changes the result: the same resin can be V-0 at 3 mm and V-1 at 1.5 mm. That is why UL 94 is always reported with the test thickness, and our data sheets state "3 and 6 mm" or "3/6 mm".
How to use this when choosing a material
- Compare values from the same standard; if one data sheet is in ASTM and another in ISO, ask us for the equivalent.
- For parts under load, use yield strength and modulus (ISO 527); for parts that take impacts, use impact strength (ISO 179 / ASTM D256).
- For parts exposed to heat, use the HDT if there is a load and the continuous service temperature if there is none; the melting point only tells you when the material stops being solid.
- For electrical parts, check the dielectric strength (IEC 60243) and, if there is a fire risk, the UL 94 rating.
In summary
- The standard alongside the value defines how the property was measured: specimen, load, speed and time
- ISO 527 (tensile), ISO 179 (impact), ISO 868 (hardness), ISO 75 (HDT), ISO 306 (Vicat) and ISO 11357 (melting) are the most common
- UL 94 rates flammability from HB (least demanding) to V-0 and 5VA (most demanding), always at the test thickness
- Only values measured to the same standard can be compared
Why buy your engineering plastics at NAT MAC?
We have more than 54 years of experience in the industry and ISO 9001 certified quality. We carry all ten families of engineering plastics, each with its own data sheet, and we help you choose the right material for your part, your load and your working environment.
- Material cut to the size you need
- Data sheets with verified properties for each grade
- Advice on choosing the right plastic for your load, temperature and environment
- Stock in bars, plates and bushings with delivery throughout Mexico
- Backed by ISO 9001 certified quality
Tell us what part you'll make, the conditions it operates in and the sizes you need, and we'll recommend the right material. Request your free quote.
Sources: NAT MAC Engineering Plastics data sheets and catalog; TecnoQuim (material data sheets); ISO 527-1:2019, Plastics — Determination of tensile properties; TestResources, ISO 527 tensile test of plastics; ZwickRoell, ASTM D785 and ISO 2039-1/-2, Plastics hardness test; ZwickRoell, Heat deflection temperature (ISO 75 / ASTM D648); ZwickRoell, Vicat softening temperature (ISO 306 / ASTM D1525); UL Solutions, Combustion (Fire) Tests for Plastics (UL 94).
