Test machine terminology

Testing Machine

It is a device for strength test. Generally, it is called strength testing machine, tensile testing machine, universal testing machine

Load sensor [Load Cell]
It is a part to measure the test force.
Depending on the maximum test force (loading capacity) that can be tested, load sensors are also divided into 50N and 5kN types.

Cross Head [Cross Head]
It is a part that moves up and down to stretch and compress the test piece during the test.
As shown in the figure, the load cell and the jig for holding the test piece are mounted on the crosshead to perform the test.

Crossbeam [Yoke]
Refers to the top metal sheet of the testing machine.
There are also components for mounting load sensors and clamping test pieces on the beam,
When moving the crosshead down to perform a tensile test. (This is called the next tensile test.)

Servo Motor [Servo Motor]
The movement of the crosshead is achieved by turning the motor. The servo motor is a high-performance motor that can control the rotation speed.

Ball Screw [Ball Screw]
Directly connected to the motor, the screw also rotates as the motor rotates.
The screw and the crosshead are also directly connected, and the crosshead moves up and down as the screw rotates.

Limit switch, emergency stop switch [Limit SW, Emergency SW]
It is a safety device to prevent accidents.
The function of the limit switch is to automatically stop the movement of the crosshead when the crosshead moves to a position beyond normal.
The function of the emergency stop switch is that the operator manually stops the testing machine when an abnormal situation occurs during the test.

Accuracy [Accuracy]
It is an indicator that indicates how well the tested force, displacement, etc. are compared with the actual value.
It is a numerical value showing the performance of the testing machine.
For example, "1% of the indicated value" means that the difference between the measured value and the actual value is within ± 1%.
The accuracy of the test force must be guaranteed by the periodic verification of the measurement unit approved by the national authority.

Calibration (Calibration) [Calibration]
In order to meet the specified accuracy requirements of test force and displacement, adjust the testing machine.
Adjusting with a weight (counterweight) whose weight is known in advance is called "F calibration"
Making electrical adjustments is called "E calibration".

Resolution [Resolution]
It is an index to measure the fineness of data such as test force and displacement.
"Resolution: 0.001mm" refers to the unit of mm, which can display its digits up to 3 digits after the decimal point, and the fourth digit after the decimal point cannot indicate a number.
For example: "123.456mmm" etc.

Testing Machine Rigidity [Frame Rigidity]
The index indicating the strength of the testing machine itself.
When a large test force is applied, if the test machine itself cannot be bent, the test will not produce the correct result.
The degree to which the testing machine itself will be bent and deformed is expressed by a numerical value, for example, "42kN / mm".
This means that how much load will bend 1mm, the greater the value of kN, the higher the rigidity (not easy to be bent), indicating that it is a good test machine.

Capacity, Full Scale [Capacity, Full Scale]
The capacity generally refers to the capacity of the testing machine and the load sensor capacity, which indicate the maximum endurance of the testing machine.
Full scale also means the same, but it is generally used to indicate the full scale of the extensometer,
The maximum value of various values ​​other than the test force such as the full scale of the graph.

Range [Range]
The range is expressed by × 2, × 5, etc.
The value obtained by dividing the load cell capacity by the range value becomes the maximum range electrically inside the testing machine, so that more detailed data can be tested.
This maximum range is called "full scale".
For example, the full range of the × 2 range of a 100kN load sensor is 100 ÷ 2 = 50kN.

Test Speed ​​[Test Speed]
Refers to the speed at which the crosshead moves during the test.
Test speed: "constant speed (mm / min)" moving a specified distance within one minute,
Increase the "constant stress (N / min)" of the specified test force within one minute.
The most typical data processing has the following points.
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Return [Return]
After the test, the crosshead returns to the preset position at high speed.
Continuous testing of a large number of test pieces can improve work efficiency.

Hold [Hold]
Refers to the case where the test piece is not removed on the test machine during the test, and the crosshead temporarily stops moving.
There are only cases where the crosshead stops moving and when a certain test force is continued to move the crosshead slightly ("test force retention").

Sampling Interval
It indicates the time interval taken during the test to determine the test force and displacement value.
"10msec" means 100 data measurements in 1 minute.

Intermediate point [LASE, EASL]
Test force, displacement, etc. during the midpoint test.
In particular, when performing a rubber test, the strain at a certain stress is called "constant elongation".

Test conditions [Method]
In order to carry out the test, set the condition parameters such as test speed and measuring range.
The test conditions are set by the software of the operation panel or computer.

[Lot, Batch]
Sometimes several test pieces are made into a set of tests for strength testing. At this time, the number of test pieces is expressed by "pieces" and "batch".
There are many ways to use such terms.
For example: a group of tests has several test pieces called "several pieces", and several groups of tests are called "several batches".

Statistics Processing [Statistics]
Several test pieces are continuously tested as a batch of tests, and statistical processing is carried out when investigating the overall strength tendency of a batch of test pieces.
There are "average value", "standard deviation", etc., based on the test results of each test piece, and calculate the value of statistical processing.

Fixture [Jig]
Refers to the parts used for strength testing that are sandwiched and compressed by the test piece and installed on the testing machine.
Depending on the type of test piece to be tested (plastic, metal, etc.) and the type of test method (tensile, compression), the jig needs to be replaced for testing.
Governance has the following.

Stretching fixture [Grip]
The jig used to clamp the test piece during the tensile test.
After clamping the test piece, tighten the screw by hand, and fix the test piece by the pressure (pneumatic, hydraulic) of air, oil, etc.
As shown in the photo, there are many types of universal fixtures to special fixtures dedicated to wire test pieces.

Compression Plate [Compression Plate]
During the compression test, press the test plate.

Indenter, fulcrum table [Punch, Support Block]
The jig used in the bending test.
Place the test piece on the fulcrum table and press the test piece from above with the indenter.

Extensometer [Extensometer]
It is a device for measuring deformation. . The testing machine itself can measure the amount of crosshead movement.
However, when the measurement requires higher accuracy, an extensometer should be installed on the testing machine or test piece.
According to the different measurement methods, it can be divided into "strain gauge extensometer", "video extensometer" and so on.

Strain gauge extensometer [Strain Gauge]
A small thin plate called a strain gauge deforms and sends an electrical signal.
The extension meter manufactured using this structure can measure very small deformations with high accuracy.
The company called this extensometer the SG extensometer.

Differential sensor type extension meter [Linear Variable Differential]
The electrical signal is output by moving the position of the iron core in the coil.
Extensometers with this construction function can measure small displacements.
The company called it ST extensometer and DTF extensometer.

Amplifier [Amplifier]
The position of the iron core in the coil is a device for measuring the deformation measured by the extensometer with a testing machine and converting it into a large voltage.
The extensometer is connected to the amplifier and the amplifier is connected to the testing machine to measure the deformation.

Thermostatic Chamber [Thermostatic Chamber]
It is a device used to test the strength of the test piece in an environment other than temperature and humidity.
As shown in the photo, put the jig and test piece into the thermostat to test.
The temperature in the tank is different according to the product, but it can be changed up and down within the temperature range of -180 ℃ ～ + 320 ℃.

JIS
Abbreviation for Japanese Industrial Standard.
Test methods for various materials are also described in terms of strength tests.

ISO
Abbreviation for International Organization for Standard.
It is an international standardization organization in the non-motor field.
Like JIS, it also describes the test methods and other content.

ASTM
The abbreviated name of American Society for Testing and Material.
Equivalent to the Japanese JIS test method and material standard specifications.
It is an authoritative specification all over the world, which is revised every year.

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