Buy tester must understand three aspects

Life no matter what to buy will know first, testing machine, the following is in the testing machine in the view of customer before buying machine should understand aspects of summary.
1, the tensile test
Tensile test (stress-strain test) is generally the material on both ends of the specimen are sandwiched between two interval distance of clamp, two jig separation and tensile samples at a certain speed, determination of stress change on sample, until the sample destruction.
Tensile test is the one of the most widely used method of material mechanics strength, need to use the constant speed movement of the tensile testing machine. According to the different methods of determination of load, tensile testing machine can be divided into pendulum tensile testing machine and electronic tensile testing machine, is currently using more electronic tensile testing machine.
2, electronic tensile testing machine selection index
Due to the flexible packaging materials mainly polymer or its related materials, polymer materials as described above the elongation is much better than the material such as metal, fiber, wood, plate, so testing polymer tensile machine and usually materials tensile properties test tensile machine has certain difference, it is important to note, especially effective stroke of electronic tensile machine, and sample clamp two aspects.
2.1 effective stroke
In the tensile test, the sample size, although small, but the elongation common material is higher, so the tensile properties of the flexible packaging materials used in the detection of which requires a trip larger tensile machine, otherwise the use of jig operation may be more than the trip limit, causes the damage of equipment.
It is important to note in the calculation of elongation, only collect specimen between two lines on the elongation. Marking printed or manually, by painting on the sample making complete (line to add to sample don't have any effect), and what's the distance between lines? Different standards are certain differences in most of the distance, and is often in the same standard are different sample size for different materials, so the distance between the lines are different, but it is helpful to detect elongation is very large or very small material and get accurate test results. For plastic film, the distance between the lines is usually between 25 and 50 mm.
Due to the deformation of specimen in tension test elongation is not just within the lines, where there are two fixtures between sample will have different degrees of pre-tension deformation. In the standard and marking distance of the initial distance between the corresponding fixture within 80 ~ 115 mm, if can keep the same specimen between two fixture elongation and assuming is 500%, the tensile machine should be effective stroke in 480 ~ 690 mm, if is the specimen elongation is 1000%, the tensile testing machine's effective to guarantee the normal test schedule for at least 880 mm.
3, the tensile properties of the polymer
When used as a material for polymer has the necessary mechanical properties. Can say, for most of the application of polymer, the mechanical properties of physical performance is more important than others.
Polymer materials with all known variability in the widest range of mechanical properties, this is due to the high polymer composed of long chain molecules, molecular motion with obvious relaxation properties. Like high polymer material has very high elongation, elongation at break of PE was 90% ~ 950% (of which the high elongation of linear low density polyethylene (LLDPE), through the special craft, part of the material of elongation can be above 1000%, and the elongation at break of common polymer materials is between 50% ~ 100%. Usually higher requirements on the tensile properties of the material with heat shrinkable film, stretch film, etc.