Falling Impact Test Procedure
Falling Impact Test Program
1. Introduction
This work instruction sheet (WIS) describes the purpose, the execution of the process and the requirements for the test. For reproducible test conditions and hereupon following test results, as well as for the safety of the employees and the equipment, the herein-mentioned regulations must be observed. This WIS is prepared according to ISO 3127-1994 and GB/T 14152-1993.
If customers have specifically requirements, it will carry out the customer designated test parameters and the test report not according to ISO 3127-1994 and GB/T 14152-2001
2. Purpose
The falling impact test is used to observe the brittleness or toughness of a plastic sample under specific test conditions (material, temperature, impact energy, shape of hammer and notch).
3. Fundamental
Test pieces are subjected to blows from a falling striker, of specified mass and shape, dropped from a known height onto specified positions around the circumference of test piece. The true impact rate (TIR) of the batch, or production run from an extruder, is estimated. The maximum value acceptable for the TIR is taken to be 10 %.
4. Test Preparation
Sampling:
Pipe:
Test piece of Length (200±10) mm shall be cut from pipe selected at random from the batch, or the production run from an extruder. The cut ends shall be square to the axis of the pipe, clean and free from damage.
Diameter x thickness: d63 (DN50) mm x 7.1 mm
Number of test piece: 9 or more
Mass of falling Striker: 0.8kg
Height of falling: 1m
Figure1 -- Noses of the strikers (see table 1)
Rigid test support, consisting of a 120o V-block at least 200 mm long, positioned so that the vertical projection of the point of impact of the falling striker is within 2.5 mm of axis of the V-block.
Release mechanism, such that the striker can fall from a variable height, which can be adjusted to any height up to at least 2m, as measured from the top surface of the test piece, with accuracy of ±10 mm.
5. Test preparation
Test piece: Test piece of length (200±10) mm shall be cut from pipe selected at random from the batch, or the production run from an extruder. The cut ends shall be square to the axis of the pipe, clean and free from damage. For pipes with outside diameters greater than 40 mm, a straight line shall be drawn along the length of each test piece at a random position. Further lines shall be drawn at equal distance around the pipe so that each test piece has the number of lines given in table 3. For pipes with outside diameters less than or equal to 40 mm, only one blow per test piece shall be made.
5. Condition
The test piece shall be conditioned in liquid bath or in air at the temperature of 0℃±1℃for at least the period given in table 4. In case of dispute over the results, liquid bath shall be used. Test piece with wall thickness up to 8.6mm shall be tested within 10s of their removal from air conditioning or within 20s of their removal from liquid conditioning, as applicable. Test piece with wall thickness greater than 8.6mm shall be tested within 20s of their removal from air conditioning or within 30s of their removal from liquid conditioning, as applicable. If this interval is exceeded, the test piece shall be returned immediately to the conditioning unit for recondition for a minimum period of 5min.
6. Test Procedure
The mass of the falling striker and the drop height appropriate to the pipe size shall be as specified in the appropriate product standard. (See table 5).
< 20 m m
No t e: Fo r p r act ical r easo n s, t h is t est is n o t r elevan t t o p ip es w it h d
n
o
For pipes of outside diameter 40 mm or less, subject the test piece to a single blow.
For pipes of outside diameter greater than 40 mm, subject the test piece to a blow by allowing the striker to fall on one of the marked lines. If the test piece passes the test, rotate it in the V-block to the next marked line and again subject it to a blow from the falling striker.
Continue this procedure until the test piece fails the test or until all marked lines have received one blow.
If required, carry out the test on subsequent test pieces, subjecting each one to a single blow.
Figure 2 __ Number of test pieces for 10% TIR (at 90 % confidence level)
Table 6—Number of bellows and failures
Sampling to confirm value of TIR on isolated batches
If the number of failures from a sample falls into region A of figure 2 (for a TIR of less than or equal to 10%), then reasonable confirmation is obtained that the batch has a TIR less than or equal to the specified level.
If the number of failures falls into region C,the batch can be judged to have a TIR greater than 10%.
If the number of failures falls into region F urther test piece should be taken so that a decision can be reached, this decision is made by considering the cumulative result of all the test piece which were impact
After test procedure
In order to protect the equipment, after each test finished, the striker should take away from the frame. This is very important; otherwise, it could damage the whole apparatus.
7. Relate document
ISO 3127-1994 thermoplastics-Determination of resistance to external blow-Roud-the-clock method
GB/T 14152-2001热塑性塑料管材耐性外冲击性能_试验方法_时针旋转法