The Heat That Proves Your Plastic Holds Its Shape Under Temperature
Heat Deflection Temperature Testing for medical device housings and moulded polymer components at our Oragadam laboratory — HDT and Vicat softening point evaluation referenced to ASTM D648 and ISO 75.
Call 90876 86986 WhatsApp UsA housing that holds its shape at room temperature can still soften, warp, or sag the moment it sits in a hot vehicle, a sterilization cycle, or a warm storage room.
Heat Deflection Temperature Testing answers the question a room-temperature mechanical test never can: at exactly what temperature a loaded plastic specimen begins to deform, which is the number that decides whether a device housing keeps its dimensional integrity through a real-world thermal excursion. Our Heat Deflection Temperature Testing for plastics programme at the Oragadam laboratory immerses a loaded specimen in a heated bath and raises the temperature at a controlled rate until a defined deflection is reached, referenced to ASTM D648 and ISO 75 — the two governing standards for deflection temperature of plastics under flexural load used across device housings, structural components, and rigid moulded parts.
HDT at 0.45 MPa applies a lighter flexural stress and is the more forgiving of the two standard test loads, appropriate for lightly loaded housing walls and non-structural components. HDT at 1.8 MPa applies a substantially higher stress, and is the more demanding figure that matters for anything expected to carry real mechanical load while hot — a structural rib, a snap-fit clip, or a component that sits under spring tension inside a warm enclosure. The gap between these two numbers on a single material is often significant, and a design team that specs against the wrong one can end up with a part that passes on paper and still sags in the field.
ASTM D648 testing defines the specimen dimensions, bath medium, and heating rate used across the US medical device and plastics industry, while ISO 75 testing sets the equivalent internationally recognized method, and running both on the same specimen batch lets a single test report satisfy FDA submissions and CE-marked device files together. Vicat softening point runs alongside HDT on the same instrument, measuring the temperature at which a flat needle penetrates the specimen to a set depth under a lighter, unflexed load — a complementary figure some material specifications call for in place of, or alongside, HDT. Manufacturers rely on Kiyo R&D Lab for plastic testing services because a single missed heat deflection reading doesn’t surface as a data-sheet footnote — it surfaces as a warped housing, a sagging bracket, or a device that fails the very first time it’s actually left in a hot environment. Running the full Heat Deflection Temperature Testing panel under one accredited scope at Oragadam, with reports formatted for direct regulatory submission, is what turns a raw heated-bath reading into evidence your quality team can actually stand behind.
Four Readings Every Heat Deflection Temperature Testing for Plastics Panel Reports
Part of our wider plastic testing services, referenced to ASTM D648 and ISO 75
HDT at 0.45 MPa
Deflection temperature under low flexural stress, for lightly loaded parts
ASTM D648 / ISO 75
HDT at 1.8 MPa
Deflection temperature under high flexural stress, for load-bearing parts
ASTM D648 / ISO 75
Vicat Softening Point
Temperature at which a flat needle penetrates the specimen a set depth
ASTM D1525 / ISO 306
Deflection Onset Temperature
Exact temperature at which measurable specimen deflection begins
ASTM D648 / ISO 75
How Our Heated-Bath Testing Process Works
Four steps, from sample intake to a validated report
Specimen Preparation
Bar specimens cut and conditioned to ASTM D648 / ISO 75 geometry.
Load Application
Specimen immersed in the bath and loaded at the specified flexural stress.
Controlled Heating
Bath temperature raised at a controlled rate until the defined deflection is reached.
Certified Report
Delivered digitally, ready for your validation file.
Standards Behind This Test
| PROPERTY | SCOPE | STANDARD |
|---|---|---|
| HDT at 0.45 MPa & 1.8 MPa | US-standard heated-bath deflection method | ASTM D648 testing |
| HDT at 0.45 MPa & 1.8 MPa | Internationally recognized equivalent method | ISO 75 testing |
Kiyo R&D Lab – Oragadam
Our heat deflection testing suite — part of our full range of plastic testing services — is based at No.13, Srinivasa Perumal Street, Panapakkam, Serapanacheri, Greater Chennai, Tamil Nadu 601301.
Frequently Asked Questions
What does Heat Deflection Temperature Testing for plastics actually measure? +
It captures HDT at 0.45 MPa, HDT at 1.8 MPa, Vicat softening point, and deflection onset temperature, referenced to ASTM D648 and ISO 75.
Which HDT load should I spec for my design, 0.45 MPa or 1.8 MPa? +
The lighter 0.45 MPa figure suits lightly loaded housing walls, while the 1.8 MPa figure is the more demanding number for structural ribs, snap-fits, and anything under real mechanical load while hot; our team confirms which applies once your design is known.
Why does this test include Vicat softening point as well? +
Some material specifications call for Vicat softening point in place of or alongside HDT, and since both run on the same heated-bath instrument, capturing both figures from one visit costs nothing extra and covers either reference format your file needs.
Why request both ASTM D648 testing and ISO 75 testing on the same batch? +
Running both methods on the same specimen batch lets a single test campaign satisfy an FDA submission that references ASTM D648 and a CE-marked device file that references ISO 75, without duplicating the whole study for two different markets.
How do I get a quote for this testing? +
Call us at 90876 86986, message us on WhatsApp, or fill in the enquiry form below with your material and testing needs.
Book Your Heat Deflection Test Today
Talk to our Oragadam team about your housing or structural polymer component — one of our core plastic testing services, run on the same specimen batch as your tensile, flexural, or impact programme.
Call 90876 86986 WhatsApp UsRequest This Test
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