Information on the most widely used ASTM standards within the materials testing industry
Model: HVT302 / HVT304 / HVT306
Heat Distortion Temperature Tester/ VST softening temperature apparatus/ Heat Deformation Vicat Softening Point Tester, specially designed for testing the heat deformation temperature and Vicat softening point temperature of non-metallic materials such as plastics, rubber, and nylon. With advantages in technology, performance, and service, it has become the preferred equipment for quality inspection agencies, universities, and enterprise self-inspection.
Floor type motorized lifting and lowering of the test station, eliminating the need for manual adjustment and reducing operational effort; after the test is completed, the system can automatically stop heating, preventing equipment overload or sample damage due to human oversight, while also saving waiting time.
General introduction
Heat Distortion Temperature Tester/ VST softening temperature apparatus/ Heat Deformation Vicat Softening Point Tester, specially designed for testing the heat deformation temperature and Vicat softening point temperature of non-metallic materials such as plastics, rubber, and nylon. With advantages in technology, performance, and service, it has become the preferred equipment for quality inspection agencies, universities, and enterprise self-inspection.
Floor type motorized lifting and lowering of the test station, eliminating the need for manual adjustment and reducing operational effort; after the test is completed, the system can automatically stop heating, preventing equipment overload or sample damage due to human oversight, while also saving waiting time.

Main Features
1, Can execute both HDT and Vicat tests on the one machine, only change loading nose for HDT test, and needle for VICAT test.
2, Conforms to ISO 75, ISO 306, ISO 2507 and ASTM D648, ASTM D1525, ASTM D5944, ASTM D5945. GB/T 8802, GB/T 1633, GB/T 1634
3, Three working stations, with all necessary press nose, needle and weights.
4, Use the Digital micrometer to replace the old dial indicator and displacement sensor, more accuracy;
5, Floor frame type;
6, Three kinds display and operation mode for selection; digital economical, 5.7” touching screen and computer controlled.
7, Motorized lifting sample racket type;
8, Micro-Printer function to print test report;
9, With CE certificate.
ISO 75 Plastics -- Determination of temperature of deflection under load
ISO 306 Plastics -- Thermoplastic materials -- Determination of Vicat softening temperature (VST)
ISO 2507 Thermoplastics pipes and fittings -- Vicat softening temperature
ASTM D648 Standard Test Method for Deflection Temperature of Plastics Under Flexural Load in the Edgewise Position
ASTM D1525 Standard Test Method for Vicat Softening Temperature of Plastics.
HDT Heat deflection temperature test:
The bars are placed under the deflection measuring device. A load of 0.45 MPa or 1.80 MPa is placed on each specimen. The specimens are then lowered into a silicone oil bath where the temperature is raised at 2° C per minute until they deflect 0.25 mm for ASTM, 0.32 mm for ISO flatwise, and 0.34 mm for ISO edgewise.
VST VICAT softening point test:
A test specimen is placed in the testing apparatus so that the penetrating needle rests on its surface at least 1 mm from the edge. A load of 10N or 50N is applied to the specimen. The specimen is then lowered into an oil bath at 23 degrees C. The bath is raised at a rate of 50° or 120° C per hour until the needle penetrates 1 mm.
Main technical specification
| Model | HVT302/ HVT304/ HVT306 |
| Structure | Floor |
| Sample racket lifting | Motorized |
| Control & Display | LCD/ Touching screen/ Computer |
| Printer | Micro printer/ A4 paper printer |
| Temperature range | Ambient temperature to 300℃ |
| Heating speed | 120±10℃/h, (12℃±1℃/6min ) 50±5℃/h, (5℃±0.5℃/6min) |
| Temperature resolution | 0.01℃ |
| Deformation resolution | 0.001mm |
| Temperature accuracy | ±0.5℃ |
| Deformation measuring | 0~2mm |
| Load range | 0.73N~49.03N |
| Test stations | 3 sets |
| Vicat Loading capacity | GA=10N±0.2N, GB=50N±1N |
| HDT test | Method A: USE FIBRE STRESS 1.80Mpa Method B: USE FIBRE STRESS 0.45Mpa Method C: USE FIBRE STRESS 8.00Mpa |
| Specimen rack span | 60mm ~ 120mm continuous adjusting |
| Power | 4Kw |
| Electrical supply | 220V, 50HZ/110V, 60HZ |
| Heating medium | methyl silicon oil or transformer oil |
Main Accessories
| Item | Quantity |
| Frame | 1 set |
| Electrical control cabinet | 1 set |
| Sample supporter racket | 3 pcs |
| Weight (2000g,500g,100g,50g) | 3 pcs for each |
| Weight (1000g, 200g) | 6 pcs for each |
| Weight (40g, in one box) | 3 set |
| Vicat needle indenter | 3 pcs |
| HDT pressing head | 3 pcs |
| Displacement sensor | 3 pcs |
| Platinum resistor | 1 pc |
| Electric wire | 1 set |
| Connection wire | 1 set |
| Accessories containing case | 1 pc |
| Computer (for HVT305, 306) | 1 set |
| Professional software (English version) (for HVT305, 306) | 1 set |
| Documents (Manual, packing list, certificate) | |
Standard
ISO 75 Plastics -- Determination of temperature of deflection under load.
ISO 75 outlines the universal standardized test procedure for measuring plastics’ temperature of deflection under load, also referred to as heat deflection temperature (HDT) under three-point flexural loading. This testing protocol applies to a broad range of polymer materials, including thermoplastics, rigid hard rubber, and thermosetting plastic laminates.
ASTM D648 is the globally recognized testing standard for measuring deflection temperature under flexural load (DTUL, also widely known as HDT) of rigid and semi-rigid plastic materials. This standard defines the critical heat deflection temperature as the heating temperature that triggers a specified 0.25 mm midspan deformation, when plastic test specimens bear fixed flexural stress under a steady, controlled heating rate.
DTUL/HDT values measured per ASTM D648 directly evaluate how rigid plastics retain mechanical load-bearing capacity under high-temperature working conditions, a core index for plastic material quality verification. The standard covers molded and extruded rigid thermoplastics, thermosetting plastics, filled and unfilled polymer composites with base thickness no less than 3 mm. Thin plastic sheets ranging 1–3 mm thick can be laminated into multi-layer composite test samples to satisfy the minimum specimen thickness testing requirements for ASTM D648 HDT testing machines.
ISO 306 used to determine the Vicat Softening Temperature (VST) of thermoplastic materials. The VST is defined as the temperature at which a thermoplastic material starts to soften rapidly under a specified load and heating rate.
ASTM D1525: Standard Test Method for Vicat Softening Temperature of Plastics
ASTM D1525 test method covers determination of the temperature at which a specified needle penetration occurs when specimens are subjected to specified controlled test conditions. It's equivalent to standard ISO306.
Test Procedure:
A test specimen is placed in the testing apparatus so that the penetrating needle rests on its surface at least 1 mm from the edge. A load of 10N or 50N is applied to the specimen. The specimen is then lowered into an oil bath at 23 degrees C. The bath is raised at a rate of 50° or 120° C per hour until the needle penetrates 1 mm.
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