Tensile Weld Strength Tests
(to view PDF of flexural strength test results, click here)
Objective
To compare test strip samples of welded and non-welded virgin polyethylene in order to evaluate the weld strength of the Drader Injectiweld plastic welding system.
Method
To verify the weld strengths, ASTM test procedure D638-87 was utilized. For this test, samples are either machined from stock shapes or injection molded. The tensile testing machine pulls the sample from both ends and measures the force required to pull the specimen apart and how much the sample stretches before breaking.
The ability of a material to resist breaking under tensile stress is one of the most important and widely measured properties of plastics used in structural applications. The force per unit area required to break a material in such a manner is the ultimate tensile strength. The figure (at left) shows the test geometry.
The test was conducted at the Northern Alberta Institute of Technology, Edmonton, Canada. The test was conducted by a Certified Engineering Technologist using a Lloyds 60006 tensile testing machine.
Test Results
Virgin HDPE sheet stock - Tensile Test
|
Sample |
N/mm2 |
N |
Width (mm) |
Depth |
|
1 |
29.54 |
1151 |
12.45 |
3.13 |
|
2 |
27.66 |
1078 |
12.45 |
3.13 |
|
3 * |
18.97
|
739.3
|
12.45
|
3.13
|
| * Note: sample 3 was physically damaged prior to being tested. The sample was tested to preserve numbers only. The data was not included in the calculations.
|
|
4 |
28.60 |
1115 |
12.45 |
3.13 |
|
5 |
28.49 |
1110 |
12.45 |
3.13 |
|
6 |
28.31 |
1103 |
12.45 |
3.13 |
|
Mean |
28.52 |
|
HDPE Sheet Stock cut through and butt welded - Tensile Test
|
Sample |
N/mm2 |
N |
Width (mm) |
Depth |
|
1 |
29.37 |
1117 |
12.15 |
3.13 |
|
2 |
27.49 |
1044 |
12.13 |
3.13 |
|
3 |
28.39 |
1078 |
12.13 |
3.13 |
|
4 |
27.71 |
1053 |
12.14 |
3.13 |
|
5 |
28.12 |
1067 |
12.12 |
3.13 |
|
6 |
27.56 |
1044 |
12.10 |
3.13 |
|
Mean |
28.11 |
|
Calculations
Welded sample strength ¸
virgin sample strength = weld strength factor (28.11 ¸
28.52 = .9856)
Synopsis
The welded sample retained 98.56% of the tensile strength of the virgin sheet stock.
The 98.56% strength of the weld can also be stated as a weld factor of 0.99.
