Charpy Impact Tester for Plastics

What is the Charpy Impact Tester for Plastics?

A Charpy impact tester strikes a horizontally supported notched or unnotched specimen in the middle and reports the energy absorbed. It is widely used for sheet, plate and weld evaluation and for comparing toughness in European specifications.

Overview

The specimen rests horizontally on two supports with a defined span, and the pendulum strikes the face opposite the notch at a defined velocity, usually about 2.9 m/s under ISO 179-1. Notched, unnotched and instrumented variants are available, and results are expressed as energy per unit of cross-sectional area for unnotched specimens or per unit of width for notched ones. Because the specimen is not clamped, support friction and specimen straightness matter more than in the Izod geometry, and the span must be verified against the standard. Larger pendulum frames accommodate high-energy hammers suitable for reinforced or very tough compounds, and low-temperature conditioning baths allow the ductile-to-brittle transition to be mapped across a range of temperatures.

How does it work?

Impact tests apply a defined energy in a very short time, so the material responds in a brittle or semi-brittle manner that differs from slow tensile behaviour. Pendulum instruments release a weighted hammer from a fixed angle; the hammer strikes a supported or cantilevered specimen and the energy absorbed is calculated from the difference between release and follow-through angles, or measured directly by an encoder. Instrumented hammers add a strain-gauge striker that records force against time, so crack initiation and propagation energies can be separated. Drop weight and dart methods use a falling mass: a dart striking a clamped film gives the energy for 50% failure, while a tup striking a pipe section assesses resistance to external damage. Specimen geometry, notch radius, support span and conditioning temperature all control the result.

What are the key features?

• Horizontal two-point specimen support
• Notched and unnotched specimen options
• Hammers from 0.5 J to 50 J
• Instrumented striker option for force curves
• Adjustable span verified against the standard
• Low-temperature conditioning bath option

What are the technical specifications?

A typical charpy impact tester for plastics configuration offers hammer energies of 0.5 / 1 / 2 / 4 / 7.5 / 15 / 50 J options, impact velocity of About 2.9 m/s (ISO 179-1), support span of 62 mm standard, adjustable, specimen size of 80 × 10 × 4 mm typical, notch types of Type A 0.25 mm, B 1 mm, C 0.1 mm and energy resolution of 0.01 J. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Charpy Impact Tester for Plastics is used in sheet, plate and profile toughness testing, weld line and butt weld evaluation, comparison of reinforced compounds and ductile-to-brittle transition mapping. Across the wider Impact Analysis class, laboratories also deploy it for impact strength qualification of moulding grades, notch sensitivity comparison between formulations and low-temperature toughness testing.

Which standards and certifications apply?

Relevant standards and methods include ISO 179-1, ISO 180, ISO 6603-2, ISO 8256, ASTM D256, ASTM D6110, ASTM D1709, ASTM D2444 and IEC 61010-1. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Cut specimens with the notch in the specified orientation, because anisotropy from moulding flow changes the result substantially; use a motorised notch cutter and verify the notch radius with a profile gauge. Condition specimens at 23 °C and 50% relative humidity, or in a bath at the test temperature when low-temperature toughness is measured, and transfer them to the machine quickly. Verify the pendulum by releasing it without a specimen, confirm that friction losses stay within the standard limit, and check the blade and supports for wear or damage. Report the specimen type, notch geometry, hammer energy and observed failure mode together with the numerical result.

How do I select the right Charpy Impact Tester for Plastics?

Choose Charpy configuration when your specification follows ISO 179 or when specimens are plates, sheets or welded joints. Confirm the span, hammer set and notch types required, and select the instrumented striker if the failure mechanism must be recorded. A low-temperature bath is worth specifying if the material is used outdoors or in cold service.

How does it compare with other Impact Analysis variants?

Select the method named in your material or product specification, because results are not interchangeable between geometries. Izod suits rigid moulding materials and is common in resin specifications, while Charpy is preferred for plate, sheet and weld evaluation and is more widely used in Europe. Instrumented hammers are chosen when the failure mode itself must be studied rather than only the absorbed energy. Falling dart testing applies to films and thin sheets where a pendulum cannot hold the specimen, and falling weight testing applies to pipes, fittings and thick sections. For any of these, specify the energy range, specimen conditioning options, notch-cutting equipment and whether low-temperature conditioning is required.