UTM Capacity Selector — Choose the Right Universal Testing Machine
Enter your material and specimen geometry — get the required force, the recommended machine capacity and the matching CHENJI model. Metric and imperial units.
1 · Specimen
2 · Material
Standard capacities we build: 5 · 10 · 20 · 30 · 50 · 100 · 200 · 300 · 600 · 1000 · 2000 kN (larger on request). Electronic (WDW / ETM) machines are usually preferred up to 300 kN; servo-hydraulic (WAW / WEW) from 600 kN upward.
Why the wrong machine capacity hurts
Choosing a universal testing machine (UTM) is mostly a capacity problem, and getting it wrong is expensive in both directions. Fit a machine that is too large and the load cell is used near the bottom of its range, where relative accuracy is poorest and resolution is coarse; small specimens then produce noisy curves that hide yield behaviour. Fit a machine that is too small and the frame is overloaded: results are invalid, calibration drifts and the specimen may break the grips or damage the load cell. The goal is to place the expected peak force comfortably inside the machine’s rated capacity, not at either extreme.
The 20–80% range rule
The practical guideline is to size the machine so the maximum force you expect falls between about 20% and 80% of its rated capacity. Below 20% you are paying for capacity you cannot use accurately; above 80% you leave no margin for stronger-than-expected batches, strain-hardening, or a specimen that needs more force than the nominal calculation predicts. A typical tensile test on carbon steel sits nicely around one third of the rated load, giving clean curves and headroom. This selector therefore computes the required force and then recommends the smallest standard frame that still keeps that force under 80% of capacity.
Required force = area × strength × safety factor
The core calculation is simple: the peak force a tensile test will reach is the specimen cross-section area multiplied by the material’s tensile strength, with a safety factor on top. For a round bar, A = π·d²/4; for plate, A = width × thickness; for tube, A = π·(OD² − ID²)/4. Multiply A by the tensile strength Rm in consistent units and by a safety factor (1.2–1.5 is typical) to cover scatter between the drawing’s nominal strength and the real batch. The selector applies this for tensile, compression, bending and fastener tests and reports the required force in kN or kip.
Typical tensile strength of common materials
The table below lists the typical tensile strength values used as defaults. Treat them as starting points: real plate may vary by grade, heat treatment and supplier, so confirm the actual Rm from the mill certificate before finalising a purchase. If your material is not listed, choose custom and enter the strength from its specification.
| Material | Typical tensile strength Rm |
|---|---|
| Carbon steel (structural / mild) | ≈ 400 – 550 MPa |
| High-strength / alloy steel | ≈ 700 – 900 MPa |
| Spring / wire steel | ≈ 1100 – 1300 MPa |
| Pre-stressing steel / PC strand | ≈ 1700 – 1900 MPa |
| Stainless steel 304 / 316 | ≈ 500 – 550 MPa |
| Aluminium alloy (6061-T6) | ≈ 290 – 330 MPa |
| Copper / brass | ≈ 300 – 400 MPa |
| Plastics (engineering grades) | ≈ 50 – 90 MPa |
| Rubber / elastomer | ≈ 10 – 30 MPa |
Grips, fixtures and test type
Capacity is only half the story: the correct grips and fixtures make the test valid. Round bars and wire need wedge or V-groove grips sized to the diameter; plate needs flat wedge grips; rebar is tested with rebar grips, often with bending or re-bend fixtures; bolts and fasteners need proof-load fixtures that apply axial load under a controlled torque. Compression and bending tests impose their own platen and former requirements, and high-force tensile work above 600 kN needs grips rated for the full frame capacity. When you request a quotation, telling us the specimen and the standard lets us quote the machine and the fixtures together.
Electronic or servo-hydraulic?
Electronic machines (WDW, ETM) use a motor-driven crosshead and are the default for forces up to roughly 300 kN — they are fast, accurate at low loads and need no hydraulic power pack. Servo-hydraulic machines (WAW, WEW) take over from about 600 kN upward, where the force and stiffness of rebar, plate, pipe and castings demand hydraulic actuation. Some applications also need servo-hydraulic control at lower force for fatigue or high-stiffness specimens. This selector recommends a family, but the final choice depends on the standard, the specimen and the test rate — our engineers confirm it.
Related testing resources
- Applications & industries — how testing machines are used across sectors.
- Material testing standards — ISO, ASTM, DIN and GB references.
- Hydraulic universal testing machines — the 300–2000 kN class.
- Spectroscopy & analysis — verifying material composition before testing.
Machine families we manufacture
| Type | Models | Typical capacity | Typical use |
|---|---|---|---|
| Electronic UTM (WDW / ETM) | WDW-5, WDW-10, WDW-20, WDW-100, WDW-300D, ETM-05 (500 kN), ETM-300 | 5 – 500 kN | Metals, wire, fasteners, plastics, R&D labs |
| Servo-hydraulic UTM (WAW / WEW) | WAW-B series (300 / 600 / 1000 kN), WAW-1000A, WAW-2000D, WEW-300BD / 600BD / 1000BD, WEW-2000 | 300 – 2000 kN | Rebar, plate, pipe, castings, construction steel |
| Compression testers | YAW-300B, YES-2000 | 300 – 2000 kN | Concrete cubes, cement, blocks |
Frequently asked questions
How do I know what capacity my universal testing machine needs?
Required force = specimen cross-section area × material strength × safety factor. For a 10 mm round bar of 500 MPa steel: A = 78.5 mm², so F = 78.5 × 500 × 1.3 ≈ 51 kN — a 100 kN machine covers it with headroom for higher-strength batches.
Electronic or servo-hydraulic?
Electronic (WDW/ETM) machines are faster, more accurate for low forces and need no hydraulics — the usual choice up to 300 kN. Servo-hydraulic (WAW/WEW) machines are used from 600 kN upward, or for stiff specimens and high-force compression tests.
What grip or fixture will I need?
Round bars and wire: wedge or V-groove grips. Plate: flat wedge grips. Rebars: rebar grips (often with bending fixtures). Fasteners: bolt/nut proof-load fixtures. Tell us your specimen and we will quote the matching accessories.
Which standards does the machine support?
Our UMIs are designed around ISO 6892-1, ASTM E8/E8M, ISO 7500-1, ASTM E4, GB/T 228.1, ISO 898-1 and equivalent standards. Calibration certificates are provided; force accuracy class 0.5 is standard on electronic models.
Can CHENJI supply the whole testing package?
Yes — machine, grips and fixtures, extensometer, software, calibration and after-sales support, plus training. Send your specimen details or drawing and we will confirm the capacity and model within 24 hours.
Ready for a machine recommendation?
Send your specimen, standard and required capacity — we reply with a model, configuration and quotation.
Email: annie@chenjitester.com · Phone / WhatsApp: +86 158 5311 1612