How to choose a single-column electronic universal testing machine based on the maximum test force

This article introduces how to select a single-column electronic universal testing machine based on the maximum test force. First, determine the strength range according to the material type and standards, such as plastics, metals, etc. Then, calculate the maximum force using tensile strength and specimen area, and multiply it by a safety factor of 1.3 to 1.5. When selecting a model, ensure that the daily test force falls between 20% and 80% of the machine's range to maintain accuracy. Additionally, consider the frame stiffness and test space. If the force value exceeds 30 kN, it is recommended to switch to a dual-column model. Finally, a four-step selection process is summarized.

Selection basis and analysis

The single-column electronic universal testing machine is mainly used for testing the mechanical properties of materials, such as metals, plastics, rubber, composite materials, etc. Reasonable selection of the maximum test force is the key to ensuring that the test accuracy matches the equipment safely. Different materials, specimen shapes and standard requirements determine the required force range.

Determine the type of material to be tested

First, the strength level of the material to be tested is determined. For example:
The tensile strength of plastics or films is typically between a few hundred newamps (N) and thousands of newlons (kN);
The tensile strength of non-ferrous metals such as aluminum or copper can reach thousands of N;
Structural materials such as steel or alloy steel may require tens of kiloN or more.
Each material can refer to the specimen size and loading rate specified in the corresponding national or industry standard.

Reference standards and specimen specifications

The following table shows common standards and corresponding specimen sizes, as well as recommended test force ranges (in kN).

Material types and standards	Specimen cross-section and recommended test force range
Plastics (GB/T 1040)	Thickness 4 mm, width 10 mm, force range 0.5–5 kN
Aluminum alloy (GB/T 228.1)	Diameter 10 mm, force range 10–30 kN
Steel Wire (GB/T 228.1)	6 mm diameter and force range 15–40 kN
Rubber (GB/T 528)	Dumbbell type with a force range of 0.1–1 kN

The above table is a general example only and should be checked against the new standard.

Calculate the maximum test force

The maximum test force is usually obtained by multiplying the tensile strength of the material by the cross-sectional area of the specimen:
$F_{\max} = σ_{b} \times A_{0}$
Among them:
$F_{\max}$ is the maximum tensile force (N);
$σ_{b}$ It is the tensile strength of the material (MPa);
$A_{0}$ is the original cross-sectional area (mm²).
For example, if the tensile strength of a steel is 500 MPa and the diameter of the specimen is 10mm (area 78.54 mm²), the theoretical maximum force is about 39.27 kN. On this basis, it is recommended to take a safety factor of 1.3–1.5, that is, the maximum force of the single-column testing machine is 50 kN. If testing materials with small force values at the same time, it should be confirmed whether the selected load sensor range covers this range.

The relationship between equipment range and accuracy

Electronic universal testing machine sensors typically guarantee specified accuracy (e.g., Class 1 or Class 0.5) in the range of 1% – 100% full scale. If the test force is below 10% of the full scale for a long time, the accuracy will be reduced. Therefore, when selecting the maximum test force, most of the test force should be within 20%–80% of the equipment range. For example, if the main test plastics are mainly concentrated below 2 kN, you can choose a 5 kN or 10 kN single-column machine instead of blindly choosing 50 kN.

Structural stiffness and space requirements

Single-column testing machine in $F_{\max}$ When it is larger, the stiffness of the fuselage needs to be matched with the alignment performance. When the test force exceeds 10 kN, it is necessary to check whether the deformation of the frame affects the stroke or the use of the extensometer. At the same time, the test space (upper and lower chuck spacing) should be able to meet the maximum specimen length and deformation requirements.

Applicable scenario trade-offs

The single-column structure has a small footprint and is suitable for light to moderate force testing (1 kN to 50 kN typical). If the continuous test force exceeds 30 kN, it is recommended to evaluate the twin-column model or add a robust base. In addition, when used frequently or need to be kept for a long time, the servo motor drive model should be selected to ensure the stability of the force value.

Summary of the selection process

Step 1: Count the materials and standards to be tested, find out the tensile strength and cross-sectional area of the specimen;
Step 2: Calculate the maximum force of each material and take the maximum value;
Step 3: Determine the sensor range according to the daily test force range;
Step 4: Check the stiffness, space and accuracy indicators of the equipment to confirm that the selection is reasonable.

References

1. National standard GB/T 228.1—2010 Tensile test method for metallic materials.
2. National standard GB/T 1040-2006 Tensile property determination of plastics.
3. Relevant content of the technical literature "Selection and Application Guide for Electronic Universal Testing Machine".