Solution

With the rapid advancement of science and technology, various new materials are emerging continuously, especially polymer materials have seen rapid development in recent years. Plastic, as its branch, has significantly improved its various properties, and in some fields, there is a trend of replacing wood and metal materials. To ensure the safe and reliable use of plastic materials and their products, it is very necessary to conduct performance tests on them. Among these, mechanical performance tests are one of the most important tests.
The following introduces several types of testing machines for reference:
1. Conventional electronic universal material testing machine
This type of testing machine is the mainstream product of universal material testing machines at present. It uses servo motors as the power source, and leads and nuts as the actuating elements to achieve the speed control of the moving crossbeam. It is easy to operate and has low requirements for the tester. The test travel can be customized as needed. Although the control mode is relatively simple, with only one control mode of speed, its control accuracy and range are very high and wide. For example, when conducting friction coefficient tests, the full-load value is only 5N. It has great flexibility in configuration and can be equipped with different tonnage sensors, fixtures, and accessories as needed to achieve multi-functionality of one machine, completing functions such as tension, compression, bending, shearing, peel, tear, friction coefficient, torsion, etc. Looking at the relevant standards for plastic mechanical performance testing, the control mode requirements for testing machines are almost all speed control. Therefore, from the control mode, speed range, test travel, and tonnage of the testing machine, this type of machine is the preferred choice for plastic mechanical performance testing.
2. Three-closed-loop Electronic Universal Material Testing Machine
This type of testing machine has the characteristics of a conventional electronic universal testing machine, such as a wide speed range, large testing stroke, and flexible configuration. It also has the advantages of the electro-hydraulic servo testing machine in force, displacement, and deformation control. Therefore, it is a type of testing machine with good performance. However, when performing force control and deformation control, the stability of the machine is closely related to the rigidity of the mainframe, the rigidity of the sample, and the stability of the machine is affected by these factors. Generally, the tonnage of plastic testing machines is relatively small, so the rigidity of the mainframe is low, and the rigidity of the sample itself is not too large. Therefore, this type of testing machine rarely has models below 10KN, while models below 10KN are the most commonly used for plastic materials. As mentioned earlier, the stability of this type of machine is related to the sample. If the sample is single and the test method is also relatively simple, it can still be selected. Otherwise, the control parameters (i.e., the conventional P, I, D parameters) of the testing machine need to be adjusted at any time. This is almost unimaginable for non-automatic control professionals. Therefore, from an overall perspective, except for specific requirements for control methods, it is not easy to choose to conduct tests on plastic materials.
3. Simple Electric Pulling
Since the tensile strength of plastics is a very important indicator for plastic mechanical performance testing, in the past, when the types of plastics were not many and their application was not very widespread, the mechanical performance testing items for plastics were relatively simple, and the corresponding standards were not very complete. During this period, a very simple structure, very single purpose, and very lacking in performance indicators, but very low-cost single-purpose tensile testing machine powered by an electric motor was widely used. As the name suggests, it can only be used for a single tensile test, and the data it can handle is very limited, and the control and measurement accuracy is relatively low. Although it is still used in some occasions now, due to its relatively simple function, it has gradually been eliminated from the market.
4. Electro-hydraulic servo universal material testing machine
This type of testing machine is currently one of the more advanced ones. Due to its adoption of electro-hydraulic servo control technology, it can achieve closed-loop control of force, displacement, and deformation, and has excellent control performance. Currently, it is widely used in metal, building materials, and other occasions that require constant stress, constant strain, and creep tests. However, due to the limitation of the oil source flow rate, its testing speed is relatively low. To increase the system stiffness and ensure the stable operation of closed-loop control, the stroke of this type of testing machine is relatively small, and the operation is complex. The expansion configuration is rather difficult. Models below 10KN are rare, so it is not suitable for testing materials such as plastics and rubber.
5. Manual hydraulic universal material testing machine
This type of testing machine is the "ancestor" of the testing machine family. It has a long history, is simple to use, has a low price, and a large tonnage. As the name suggests, manual hydraulic indicates that it is an open-loop control, with poor performance, and the operation completely relies on the operator's operational level. In addition, due to its mechanical structure and hydraulic loading principle, its loading speed is small, and the testing stroke is also small. Currently, the smallest model of this type of testing machine is 50KN. Therefore, its small load measurement accuracy is very low, and the expansion configuration ability is very poor. Generally, it is only used in structural component tests or simple material performance tests, such as the detachment of connection components and the tensile strength of steel bars.