Neometrix / Materials & Geotechnical Test / Compression Testing Machine / NMX-CTM-74

NMX-CTM-74 · ENGINEERED-TO-ORDER CLASS — SPECIFY · FRAME · CONTROL · BUILD · TEST · PROVE

Compression Testing Machine. A stiff frame makes a safe failure.

Name: Compression Testing Machine
Brand: Neometrix
SKU: NMX-CTM-74

A compression testing machine crushes concrete cubes, blocks and rock cores to find how much load they carry. The frame of the machine is loaded along with the specimen, and it stores energy as a spring does.

When the specimen fails, the frame gives that energy back. So the machine has to keep the load square on the specimen, be stiff enough to fail it gently, and contain what flies off.

Discuss a compression machine Capability note (PDF)

A single compression testing machine on a plain white studio background: a rigid four-column frame with a grey painted steel base block, four thick polished steel columns and a heavy grey crosshead, a polished ram carrying a lower platen, an upper platen hanging on a bright spherical seat, a pale grey concrete cube between the platens, and a clear safety guard standing open on its hinge, and no people

Fig · 01 — A compression testing machine: a four-column frame, a ram below and a spherical seat above, a concrete cube between the platens and a safety guard standing open — illustrative render.

The load

square on the specimena spherical seat lines the platen up

The frame

stiffer than the specimenless stored energy at failure

The rate

held by a servo loopfixed by the test, not the operator

The guard

fragments containedan interlock stops the loading

Status

engineered to orderno compression machine claimed

ISO 9001ISO 14001EN 12390-4 reference standard

Overview

Why the whole job is the frame.

Because the frame stores the energy that the specimen releases, and a stiff frame keeps that energy small.

Two test specimens on a plain white studio background: a pale grey concrete cube with slightly rough cast sides standing beside an upright cylindrical core of speckled grey granite with flat sawn ends, and no people

Fig · 02 — A concrete cube and a rock core: brittle specimens that store energy as they are loaded and fail suddenly — illustrative render.

A stiff frame makes a safe failure.

What the machine is for

It crushes brittle specimens, such as concrete cubes and cylinders, blocks and rock cores, between two platens and records the load up to failure. It suits a stiff frame for concrete and blocks, and a servo-controlled frame for rock and for tests that follow the specimen past its peak.

Why a stiff frame makes a safe failure

As the load rises, the frame stretches a little, like a spring, and stores energy. When the specimen fails, the frame springs back and gives that energy to the specimen. A stiff frame stores less, so the failure is smaller.

A soft frame stores more, and a strong specimen can fail violently.

Why the frame also decides what the test can see

A specimen weakens after its peak. A frame that is stiff enough follows it down, and a servo loop that watches the specimen can hold it there. A soft frame cannot, and the record stops at the peak.

Why the load must be square

A platen that meets the specimen at a slant loads one edge first. A spherical seat lets the upper platen line up with the face of the specimen as it first touches, and then holds still until failure.

Why the rate of loading is controlled

A brittle material tests stronger when it is loaded fast and weaker when it is loaded slowly. The test method fixes the rate, and the machine has to hold it from the start of the test to the failure.

Why the guard is part of the machine

A brittle specimen can throw fragments when it fails. A guard of steel and shatter-resistant glass round the platens contains them, and an interlock stops the loading while the guard is open.

The method

Specify, frame, control, build, test, and prove.

Six steps in a fixed order. Sizing the frame for stiffness and not only for the maximum load, and trying the guard interlock before any specimen, are the two a quick order skips.

1 · Specify

The specimens, their materials and sizes, the maximum load and the tests are stated by the customer.

2 · Frame

The frame is sized for stiffness as well as strength, so that it stores little energy at the load of the strongest specimen.

3 · Control

A servo valve and a controller hold the rate of loading, and for rock they follow the deformation of the specimen itself.

4 · Build

The frame, the ram, the platens, the seat, the guard and the power pack are built as one installation.

5 · Test

The load measurement is checked against a reference, the seat is checked for alignment, and the guard interlock is tried, before any specimen is crushed.

6 · Prove

A record is kept for every test, with its load, its rate and its time to failure, and handed over with the machine.

Which frame for which specimen

Frame	What it suits	What to watch
A stiff frame, manual or semi-automatic	routine strength tests of concrete cubes, cylinders and blocks	it reports the peak load, and the rate depends on how steadily the load is applied
A stiff frame with servo-controlled loading	high-strength concrete, and any test where the rate has to follow the method exactly	it costs more, but it holds the rate and fails the specimen more gently
A servo-controlled frame with deformation feedback	rock cores, and tests that follow the specimen past its peak	it needs a stiff frame, a fast servo valve and a transducer that reads the specimen and not the frame

The step people underrate is the stiffness of the frame. A machine chosen for its maximum load alone can be strong enough to crush the specimen and too soft to fail it safely.

Work content

What the machine contains, element by element.

Read it as a checklist: a machine missing a row will report a strength on paper and not fail the specimen safely.

A single pair of compression platens on a plain white studio background: a bright hardened polished steel lower platen disc on a short grey base, a pale grey concrete cube centred on it, and an upper platen disc carried by a bright steel spherical seat with a short stem, and no people

Fig · 03 — Compression platens with a spherical seat: a hardened lower platen, a concrete cube, and an upper platen carried by a seat that lines it up — illustrative render.

Element	What it does	What matters
Frame and columns	carry the reaction	stiff as well as strong, with four columns and a heavy crosshead, so that the frame stores little energy at the maximum load
Hydraulic ram and power pack	apply the load	a smooth ram with low friction, and a power pack that holds the pressure without surges
Servo valve and controller	hold the rate	keeps the rate of loading steady from first touch to failure, and follows the deformation of the specimen for rock
Force transducer	measures the load	checked against a reference force, and read by the same controller that holds the rate
Platens and spherical seat	carry the load into the specimen	hardened, flat and parallel platens, and an upper seat that lines up on first contact and then holds
Deformation transducers	read the specimen	for rock and modulus tests, mounted on the specimen and not on the frame
Safety guard and interlock	contain fragments	a guard of steel and shatter-resistant glass round the platens, and an interlock that stops the loading when it is open
Test console and record	run the test	the rate, the load and the time to failure, kept for every specimen
Procedure	fixes the sequence	specify, frame, control, build, test and prove, the same for every machine
Testing & documentation	prove the machine first	load measurement checked against a reference, seat alignment checked and the guard tried before any specimen, and a record the customer can inspect

The elements that decide whether the machine is safe are the frame stiffness and the guard, because a brittle specimen in a soft frame can fail suddenly enough to throw fragments past a poor guard.

Full specification — expand

System	A stiff four-column frame with a heavy crosshead; a hydraulic ram and power pack; a servo valve and controller that hold the rate of loading; a force transducer checked against a reference; hardened flat and parallel platens with a spherical seat for the upper platen; deformation transducers for rock and modulus tests; a safety guard of steel and shatter-resistant glass with an interlock; a test console with a record for every specimen; a written test plan; and testing and documentation before handover
The One Idea	A stiff frame makes a safe failure.
Why A Stiff Frame Makes A Safe Failure	As the load rises the frame stretches a little, like a spring, and stores energy, and when the specimen fails the frame springs back and gives that energy to the specimen, so a stiff frame stores less and the failure is smaller, while a soft frame stores more and a strong specimen can fail violently
Why The Frame Also Decides What The Test Can See	A specimen weakens after its peak, and a frame that is stiff enough follows it down while a servo loop that watches the specimen can hold it there, whereas a soft frame cannot and the record stops at the peak
Why The Load Must Be Square	A platen that meets a specimen at a slant loads one edge first, so a spherical seat lets the upper platen line up with the face of the specimen as it first touches and then holds still until failure
Why The Rate Of Loading Is Controlled	A brittle material tests stronger when it is loaded fast and weaker when it is loaded slowly, so the test method fixes the rate and the machine has to hold it from the start of the test to the failure
Why The Guard Is Part Of The Machine	A brittle specimen can throw fragments when it fails, so a guard of steel and shatter-resistant glass round the platens contains them and an interlock stops the loading while the guard is open
Standards	EN 12390-4 is the public standard for the performance of compression testing machines for concrete, ASTM C39 covers the compressive strength of cylindrical concrete specimens and ASTM D7012 covers the compressive strength and elastic moduli of intact rock core specimens. This page prints none of their loads, rates, tolerances or times, and no edition year: those come from the method the customer names and from the specimen. Approval of a machine, or of a test result, rests with the customer and the authority they name; none is claimed here
Configurations	A stiff-frame machine for routine specimens, a servo-controlled compression machine and a rock testing frame
Scope Boundary	This page is the compression testing machine. It is not a hydraulic press, which forms parts (see hydraulic press machine), not a servo-hydraulic fatigue test system, which loads metal specimens cyclically (see servo-hydraulic fatigue and structural test system) and not a triaxial test system, which tests soil with water in it (see triaxial test system). A flexural frame, a tensile testing machine and a rebound hammer are different equipment again. No certification is claimed here
Status	Neometrix engineers compression testing machines to order, and no delivered compression testing machine is claimed.

Configurations

One method, three ways to build the machine.

The method, the stiff frame and the guard are shared. What changes is how the rate of loading is held and whether the machine follows the specimen after its peak.

Stiff-frame machine

Frame, ram and platens

A four-column frame, a ram, platens with a spherical seat and a guard, with the rate set by the operator or a simple controller, for routine cubes, cylinders and blocks.

Servo-controlled compression machine

Servo valve and controller

The same stiff frame with a servo valve and a controller that holds the rate of loading from first touch to failure, for high-strength concrete and strict methods.

Rock testing frame

Deformation feedback

A stiff frame with a fast servo valve and deformation transducers on the specimen, so that the loading follows the specimen, for rock cores and tests past the peak.

And the part that is not equipment at all, yet decides all three: the test plan. It fixes the rate of loading, how the load measurement is checked, when the guard is tried, and what is recorded. It is written from the specimens, not from the ram.

Where it is used

Wherever strength is read from a break, and the break has to be safe.

The common thread is a brittle specimen crushed to failure, and a result that other people will build on.

Concrete and block laboratories

Where cubes, cylinders and blocks are crushed to check that the strength is what was specified.

Construction quality control

Where samples from site come to the laboratory, and the record has to be the same for every one.

Rock mechanics laboratories

Where rock cores are tested for strength and stiffness, and sometimes for what happens after the peak.

Research and teaching laboratories

Where the behaviour of a brittle material as it fails is studied and shown.

Watch

See it in motion.

A short walkthrough video of the compression testing machine.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does a compression testing machine actually do?

It crushes a brittle specimen, such as a concrete cube, a block or a rock core, between two platens and records the load up to failure. The ram applies the load, a servo valve holds the rate, a force transducer measures the load and a guard contains the fragments. For rock it can also follow the deformation of the specimen. It does not prepare or cap the specimen, it does not test in tension or bending, and it does not replace the judgement of the person who reads the result.

Q · 02 Why does a stiff frame make a safe failure?

Because a loaded frame behaves as a spring. As the load rises it stretches a little and stores energy. When the specimen fails, the frame springs back and releases that energy into the specimen. A stiff frame has stored less, so the failure is smaller and easier to contain. A soft frame has stored more, and a strong specimen then fails with a bang. That is why a machine chosen for its maximum load alone can be the wrong machine for a strong specimen.

Q · 03 Why does the frame also decide what the test can see?

Because a brittle specimen does not lose its strength all at once. After the peak it weakens along a falling curve. If the frame is stiff enough, and a servo loop watches the specimen, the machine can hold the specimen on that curve and record it. If the frame is soft, it releases its stored energy at the peak and the specimen fails in an instant, so the record ends at the peak. For a very brittle rock, a servo loop that watches the deformation of the specimen itself helps further.

Q · 04 Why does the load have to be square, and what do the platens do?

Because a platen that meets a specimen at a slant loads one edge first, and the specimen then fails early and unevenly. The upper platen sits on a spherical seat that lets it line up with the face of the specimen on first contact, and it then holds still until failure. The platens are hardened, flat and parallel so that they do not take a mark from the specimen or spread the load unevenly. A worn platen gives a result that is harder to trust.

Q · 05 Is this the same as the hydraulic press, the servo-hydraulic fatigue system or the triaxial system?

No, and the differences are worth stating precisely. The hydraulic press machine page covers a press that forms parts. The servo-hydraulic fatigue and structural test system page covers loading metal specimens cyclically. The triaxial test system page covers testing soil with water in it. This page is the compression testing machine. A flexural frame, a tensile testing machine and a rebound hammer are different equipment again. It does not replace any of them, and it does not claim what they claim a second time.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix engineers compression testing machines to order, and no delivered compression testing machine is claimed. What stands behind the offer is adjacent: Neometrix engineers a hydraulic press machine (see the hydraulic press machine page), a servo-hydraulic fatigue and structural test system (see the servo-hydraulic fatigue and structural test system page) and a triaxial test system (see the triaxial test system page). The rams, power packs, servo valves, force transducers and controllers are catalogue items, bought in, not invented. What Neometrix engineers is the machine around them: the stiff frame, the platens and seat, the guard and interlock, the control and the record, the procedure and the test plan. So the honest position is that the machine is engineered to order, the neighbouring disciplines are in the building, and the first machine of this exact kind will be built around the customer's own specimens rather than taken off a shelf.

Q · 07 Which standard applies, and what can the machine not do?

EN 12390-4 is the public standard for the performance of compression testing machines for concrete, ASTM C39 covers the compressive strength of cylindrical concrete specimens and ASTM D7012 covers the compressive strength and elastic moduli of intact rock core specimens. This page prints none of their loads, rates, tolerances or times, and no edition year: those come from the method the customer names and from the specimen. The machine crushes specimens and keeps a record. It does not certify concrete or rock: this page claims no certification or accreditation. No load, rate, stiffness or quantity figure is printed here, and approval for use rests with the customer and the authority they name; none is claimed here.

Q · 08 What do you need from us to quote?

Six things, and most of them describe your specimens rather than the machine. First, the specimens: the material, the shape and size, and the strongest you expect to test. Second, the maximum load the machine must reach. Third, the tests: routine strength, stiffness, or behaviour past the peak. Fourth, the rate of loading that your method requires. Fifth, the throughput: how many specimens are crushed in a day. Sixth, the record: what you want kept for each test. From that we come back with a machine concept, a written test plan you can check, and a budgetary price.

The neighbouring hydraulic and test pages, and how they differ from this one.

Three neighbours: one forms parts, one loads metal cyclically, one tests soil with water in it.

↗ Forming parts

Hydraulic Press Machine

C-frame, H-frame and four-column presses that form parts - a press for making, where this page crushes a specimen and measures the load.

↗ Loading metal

Servo-Hydraulic Fatigue & Structural Test System

A stiff frame and a servo-hydraulic actuator that load metal and structure again and again - cyclic loading, where this page loads a brittle specimen to its failure.

↗ Soil with water

Triaxial Test System

A soil specimen squeezed from all sides with its pore water measured - a wet soil, where this page crushes a dry brittle specimen between platens.

Browse all Neometrix product lines.

Get a quotation

Tell us the specimens, the load,
and how they should fail.

The projects desk replies within two working days with a machine concept, a written test plan you can check, and a budgetary quotation. Write to [email protected] or use the form.

Enquire — compression machine Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — COMPRESSION TESTING MACHINE SPECIFY · FRAME · CONTROL · BUILD · TEST · PROVE — A STIFF FRAME MAKES A SAFE FAILURE ENGINEERED IN NOIDA · INDIA