Plastic Impact Machines
MPM Pendulum 8000 Plastic Test Machines
The MPM 8000 is a variable energy capacity (2.7 J to 67 J) table top model for Izod, Charpy, and dynamic tensile testing. Figures 1 and 2 show the machine configured for Izod and Charpy, respectively. This machine has been designed so that weights can be attached to the machine to increase or decrease the test capacity above the 2.7 J (2 ft-lb) baseline value (see Figure 1 with weights and Figure 2 with baseline essential weight only). The machine uses high precision optical encoder technology to measure the absorbed energy to within about one encoder count 0.007 J (0.005 ft-lbs).
Series 8000 Test Machine Description
The test machine measures the energy absorbed in fracturing a test specimen using an optical encoder with 20,000 divisions per revolution. This is one of the finest division encoders ever used in plastic impact testing. The energy absorbed by the test piece is automatically acquired by the ImpactTM v6.1 software. In addition, the velocity of the striker is recorded from release up to the impact event. The software provides a printed test record which includes key information such as the test specimen ID, the date of the test, name of operator, test temperature, impact velocity, measured energy, etc.. The software also has a statistical calculation capability for average and standard deviation calculations of key parameters. A data acquisition computer is used to record the encoder energy and the optional instrumented striker voltage-time signal. For data acquisition without a computer, an on-machine data acquisition system can be provided.
Izod Clamping Fixture
MPM offers either a manual Izod clamp (hand tightening knob) or a pneumatic clamp for rapid specimen fixturing. Figure 3 shows both the pneumatic clamp and the hand tightening knob. The pneumatic clamp is removable, and can be replaced by the optional hand tightening knob. The pneumatic clamp has the advantage that the clamping force is adjustable and repeatable from test-to-test. The pneumatic clamp automatically positions the specimen and applies the user controlled clamping force.
The machine can be easily converted for Charpy impact testing by removing the Izod clamp and installing the Charpy anvils. To place a specimen on the Charpy fixture, MPM provides a Charpy Specimen Centering tool (Figure 4). This tool fits between the supports and has a protrusion for precise notch centering.
Figure 2 shows the pendulum with the essential weights attached to provide a nominal 1 pound pseudo mass. More weight can be added to increase the pseudo-mass in order to increase the energy capacity of the test machine. MPM can provide any weights desired to achieve energies capacities up to 67 J.
Continuous Impact Velocity Adjustment
The test machine design incorporates a continuous hammer release height adjustment. Adjusting the hammer release height enables testing at velocities from 0 to 11.3 ft/s (0 to 3.5 m/s). In order to adjust the release height, the user must loosen the two latches holding the pendulum to the angle disc. Using the markings on the angle disc (Figure 5), the user can select any latch angle from 0 degrees to the maximum angle (180 degrees).
MPM strongly recommends that the test machine base plate be securely bolted to a massive base that will prevent any movement of the machine during impact. Movement of the base during a test can result in incorrect data. If it is desired to install a concrete base, MPM offers a full service installation or the option of a machine base installation kit. In addition, MPM offers a massive steel table which can be securely bolted to the floor.