With the progress of society and the enhancement of national strength, all kinds of new materials emerge in endlessly, the performance of the original materials has been further improved, and the application area is also expanding. Therefore, higher requirements are put forward for the inspection of materials. As we all know, before the 1980s, the use of material testing machine was limited to a few fields such as metal, but now, the use of material testing machine is no longer limited to metal and other fields, and it has been extended to all industries. The material testing machine has developed from the manual hydraulic testing machine in the past to the era of coexistence of multiple control modes, different performance characteristics and blooming flowers. In this dazzling range of testing machines, how to choose a testing machine suitable for their own characteristics is the concern of most users. At present, most material tests are static performance tests. Therefore, the following is a simple comparative analysis of the performance characteristics of common universal testing machines in the market, and puts forward a selection principle for your reference (technical reference of Baoda instrument company).

1、 Types of common universal material testing machines

At present, the universal material testing machine commonly used in the market mainly has two series and four types:

1. Hydraulic series: manual hydraulic universal material testing machine

Electro hydraulic servo hydraulic universal material testing machine

2. Electronic universal series: conventional electronic universal material testing machine

High performance electronic universal material testing machine

They have different performance, advantages and disadvantages, and have different user groups.

2、 Performance characteristics

1. Hydraulic series

1) Manual hydraulic universal material testing machine

The manual hydraulic universal material testing machine mainly uses a simple high-pressure oil source as the power source, a manual adjusting valve as the control element, and carries out manual loading. Therefore, it belongs to an open-loop control system. Due to the limitation of oil source flow and host structure, its oil cylinder piston stroke is small, the common is about 300mm, and its test speed is generally small. Affected by price factors, Pressure sensor is generally used as force measuring sensor (pressure sensor is basically used for large tonnage). Therefore, the accuracy is low and the measuring range is small. Generally, the accuracy is level 1 or 2, and the measuring range is generally 4% - 100% F.S. due to the influence of oil cylinder friction, the tonnage is generally difficult to be very small, and the minimum in China is 5T. However, due to its unique characteristics of low price and large tonnage, there are still a lot of problems in finished product inspection and single material index test use.

2) Electro hydraulic servo universal material testing machine

It mainly uses the precision high-pressure oil source as the power source, and uses the servo valve or proportional valve as the control element for closed-loop automatic control. Therefore, the control performance is high. Generally, three control modes of load, strain and displacement can be realized. Like the manual hydraulic universal material testing machine, its testing speed is low due to the restriction of oil source flow. Due to the use of closed-loop automatic control, the system stiffness has become the key to the normal operation of the whole system. As we all know, the stiffness of liquid is relatively low. In order to reduce the impact of liquid on the stiffness of the whole machine as much as possible, the stroke of general electro-hydraulic servo testing machine is small. Similarly, affected by the stiffness of the whole machine, the tonnage of electro-hydraulic servo testing machine can not be very small, basically more than one ton. However, because it has a variety of control modes, it has the characteristics of flexible use and high performance.

2. Electronic universal series

1) Conventional electronic universal material testing machine

The conventional electronic universal mainly uses the servo motor as the power source and the lead screw and nut as the executive parts to realize the speed control of the moving beam of the testing machine. Its test speed range can be adjusted. Taking rgm-200 as an example, its test speed can reach 0.001mm/min-1000mm/min, the speed ratio can reach 1 million times, and the test stroke can be determined as required, up to a few meters. This can not be achieved by hydraulic testing machines. With the development of electronic technology and the improvement of the performance of servo motor, the performance of electronic universal has made a qualitative leap from the early DC servo motor to the current more AC servo motor, from the early power component selection of thyristor for phase-shifting trigger control to today's use of a variety of power modules to realize pulse width modulation control, The situation of high failure rate and poor performance of electronic universal in people's mind no longer exists. Because the conventional electronic universal adopts speed control, the requirement for system stiffness is not high, which creates favorable conditions for the realization of small tonnage testing machine. From the current international and domestic situation, the testing machines below one ton are basically conventional electronic universal testing machines. It is the most widely used and cost-effective.

2) High performance electronic universal testing machine

Like the conventional electronic universal testing machine, the high-performance electronic universal testing machine also uses the servo motor as the power source and the lead screw and nut as the executive parts. What is different from the conventional electronic universal testing machine is that its control mode can be load control, strain control or displacement control. In addition to the characteristics of wide speed and large stroke of conventional electronic universal testing machine, it also has all the advantages of electro-hydraulic servo testing machine. Therefore, it is the universal material testing machine with the best performance at present.