A 4-pillar universal testing machine uses four columns to guide the moving crosshead, while a 6-pillar UTM adds two more columns for greater frame rigidity and guidance at high capacities. For routine testing at lower capacities a 4-pillar frame is usually sufficient; for high-capacity, heavy-specimen work a 6-pillar frame keeps alignment tighter under load. Akuracy manufactures UTM frames in both constructions across 100 kN to 2000 kN capacities.
What the pillars do
The pillars (columns) of a UTM frame guide the moving crosshead and keep the loading axis aligned with the specimen. Better guidance means less side loading on grips and specimens, which supports repeatable tensile, compression and bend results, especially as forces rise.
4-pillar vs 6-pillar UTM at a glance
| Aspect | 4-pillar UTM | 6-pillar UTM |
|---|---|---|
| Frame guidance | Four columns guide the crosshead | Six columns guide the crosshead |
| Rigidity under load | Suited to routine and mid-range capacities | Preferred for high-capacity and heavy-specimen testing |
| Typical applications | Tensile, compression, bend and shear QC testing | TMT/rebar, fasteners and large specimens at high force |
| Footprint and access | Compact, easy specimen access | Larger frame built around rigidity |
How to choose
- Match frame to capacity first. The higher the test force, the more frame rigidity matters. Share your maximum expected breaking load and we will recommend the frame and capacity.
- Consider your specimens. Heavy or awkward specimens, such as rebar and couplers, benefit from the stiffer guidance of a 6-pillar frame.
- Think about grips and fixtures. Manual or hydraulic grips and customized fixtures are available on both constructions; the frame decision does not limit your fixture options.
Frequently asked questions
Does a 6-pillar UTM give more accurate results?
Accuracy class comes from the measuring system and calibration, which can be equivalent on both frames. The 6-pillar construction is about rigidity and alignment at high loads, which supports repeatability when forces are large.
Can both frames be computerized or servo controlled?
Yes. Pillar construction is independent of the control system. Both 4-pillar and 6-pillar frames are available in digital, computerized and servo controlled configurations.
Which standards can these machines test to?
UTMs from Akuracy are configured for common tensile, compression, bend and shear test methods. Tell us the standard you work to and we will confirm the right configuration, grips and extensometry.
Want a frame recommendation for your application? Browse our material testing equipment or send your testing requirement to our engineering team.