Metallurgical Equipment Lab Equipment Manufacturer, Supplier and Exporter in India

Metallurgical Equipment: Mounting and Polishing

Section, mount, grind, polish, etch

Five steps, each removing the damage left by the one before it. Skip or rush any of them and the artefact survives into the micrograph.

1. Section: cut without changing what you came to look at

Cutting generates heat, and heat changes microstructure in the material next to the cut - which is precisely the material you are about to examine. On a heat-treated or hardened steel a dry cut can temper a visible band at the edge of the sample, and a student will then report that band as a feature of the component.

So: an abrasive cut-off wheel with flood coolant, the wheel grade matched to the hardness of the material, and moderate feed. A dry hacksaw or an angle grinder is not a sectioning method for metallography. Note that the cut-off machine is not in this listing - tell us if you need one quoted with the preparation equipment, because the chain starts there.

2. Mount: and the reason is edge retention

A mounting press encapsulates the sample in resin under heat and pressure, giving a flat cylinder that is easy to hold, easy to grind square, and - the real reason - supported right up to the sample edge.

Edge support matters because the edge is very often the part being examined: a case-hardened layer, a coating, a weld toe, a corroded surface. If the resin is softer than the sample, grinding and polishing wear the resin faster, the sample edge is left standing proud, and the edge rounds over - which both loses the feature and puts it out of focus in the microscope. So ask about the resin, not just the press: a resin chosen for edge retention, often a filled type, is what makes an edge examination possible.

Two further points:

• Semi-automatic against automatic press. The difference is throughput and repeatability: an automatic press runs the heat-and-pressure cycle to a programme, so every mount is the same and an operator is not standing over it. For a teaching laboratory preparing a few samples a week, semi-automatic is usually right; for a quality laboratory preparing dozens, the automatic press pays for itself in consistency as much as in time.
• Hot mounting is not for everything. Heat-sensitive materials, some polymers, fragile or porous samples and anything where the thermal cycle would alter the structure must be cold mounted in a castable resin at room temperature, which needs moulds and a vacuum pot rather than a press. If your samples include any of those, say so - a press is the wrong answer for them.

3. Grind: the trick that makes it teachable

Grinding runs through a sequence of papers of decreasing coarseness, each stage removing the scratches left by the previous one. The question students always ask is how long each stage takes, and there is a precise and satisfying answer:

Rotate the sample ninety degrees between stages. The new scratches then run across the old ones, and the stage is finished when all the scratches run the same way - the previous stage's marks have gone. It is visible, it is unambiguous, and it turns "grind until it looks right" into a criterion a student can apply. Teach it in the first session; it is the single most useful practical tip in metallography.

Specify: the paper sizes and grades the machine takes, whether water feed is provided, and whether the papers are available locally - grinding paper is a consumable and a laboratory that runs out grinds with worn paper, which polishes badly and takes longer.

4. Polish: cleanliness is most of it

Polishing moves from a diamond stage to a fine final stage, on the appropriate cloth with the appropriate lubricant. Three things decide the result:

• Cleanliness between stages, which is not a housekeeping matter but the method itself. One coarse particle carried over on a finger, a cloth or the sample makes a single deep scratch across a finished surface - and a long straight scratch in a micrograph is routinely reported by students as a crack. Wash the sample and hands between every stage, keep a dedicated cloth per stage, and never put a coarse and a fine cloth on adjacent wheels if you can avoid it.
• Light, even pressure and adequate time. Pressing harder does not polish faster; it smears soft phases, pulls out inclusions and rounds edges.
• The right final stage for the material. Soft metals smear, and some alloys need a chemical or electrolytic final polish rather than a mechanical one. Tell us the materials and we will advise rather than quoting a generic sequence.

On the machines in this listing: a hand polisher teaches the feel and is where students should start; a double-disc machine lets two stages run side by side, which is the practical arrangement for a class; a semi-automatic polishing machine holds several samples at set pressure and time, which is what makes results repeatable between groups; and the spectro polishers are for preparing the flat, clean surface a spark emission spectrometer needs, which is surface preparation for chemical analysis rather than for microscopy - a different job with a different finish requirement, and worth not confusing with metallography.

5. Etch: the step with the real hazards

A polished sample is a mirror and shows almost nothing. Etching attacks the surface preferentially - grain boundaries, different phases, different orientations - and that is what makes the structure visible. It is also the one step in this sequence with chemical hazards that deserve respect:

• The etchant is specific to the material, and using the wrong one gives either no result or a destroyed surface. Ask for the etchant appropriate to your materials and obtain its safety data sheet before you obtain the etchant.
• Several standard etchants are acid-alcohol mixtures. Mix only what you need, use it, and dispose of it - do not store mixed etchant in a sealed bottle, because some mixtures generate pressure and some become unstable on standing.
• Picric acid, used in some classic steel etchants, is explosive when dry and is a restricted material in many countries. Do not order it casually, do not let a bottle dry out, and check your national rules before planning a method that requires it. We will flag it rather than quoting it silently.
• Work in a fume cupboard, with gloves and eye protection, and have a water wash and an acid spill provision to hand. The etching step is where a metallography laboratory needs extraction - see the fume cupboard discussion on our laboratory furniture page.
• Etch time is part of the method. Under-etched shows nothing; over-etched is unrecoverable and the sample goes back to the polishing stage. Time it rather than judging it, at least until the laboratory has experience of the material.

The Brinell tester, and where the error actually comes from

A Brinell test presses a ball into the surface under a specified load and the hardness is calculated from the diameter of the impression. That last point is the one that matters for a teaching laboratory: the test is a measurement of an indentation, not a reading from a dial, so a measuring microscope or a graduated loupe is part of the apparatus, and operator variation in measuring the indent is the dominant error in practice. Two students measuring the same impression will get different hardness numbers until they have been taught where the edge of the impression is.

Why Brinell rather than something finer: the indentation is large, which averages over a volume of material and makes it the right method for coarse-grained, heterogeneous or cast materials where a small indent might land entirely within one phase. Its cost is that it damages the surface visibly and needs a thick enough specimen to support the load.

For the portable tester in this listing, and for the comparison between bench and portable instruments - which measure a different physical quantity and convert it - see metal testing machines, where that distinction is set out in full.

What is not in this listing, and must be budgeted

• The inverted metallurgical microscope. Without it there is no result. Specify the magnification range, whether a camera port is needed, and whether image capture and measurement software are required.
• The abrasive cut-off machine with coolant, which is where the chain starts.
• Consumables, which dominate the running cost: grinding papers, diamond suspension or paste, polishing cloths, mounting resin, lubricants and etchants. Ask for the list and the prices with the quotation and work out the cost per sample - it is often more informative than the capital figure.
• A fume cupboard and chemical storage for the etchants.
• Standard hardness test blocks, if hardness results are to be reported to anyone - they are how the tester is verified, and they are a consumable with a finite usable surface.

What to tell us when you enquire

• The materials - steels, non-ferrous, castings, coatings, polymers - because they decide the resin, the polishing sequence and the etchants.
• Whether edges or coatings are examined, which makes edge retention a requirement rather than a preference.
• Whether any samples are heat-sensitive or fragile, which means cold mounting rather than a press.
• Samples per week, and whether results must be repeatable between operators - this decides semi-automatic against automatic.
• Whether a microscope, cut-off machine, fume cupboard and hardness test blocks are needed with the order.
• Whether spectro sample preparation is required as well as metallography - they are different finishes.
• Supply voltage and frequency, water supply, and destination country.

Related ranges: metal testing machines for hardness, tensile and torsion testing, geography lab models which includes the ore, metal and alloy specimen sets that introduce this subject, industrial training kits and advanced physics experiments including four-probe resistivity. The full educational kit and educational lab equipment categories list the rest.

Frequently asked questions

Our micrographs are full of scratches. Is the polisher faulty?

Almost certainly contamination between stages. One coarse particle carried over on a finger, a cloth or the sample itself leaves a long deep scratch on a finished surface - which students routinely report as a crack. Wash the sample and hands between every stage, keep a dedicated cloth per stage, and check the grinding sequence: if a stage was cut short, its scratches survive. Rotating the sample ninety degrees between grinding stages makes that visible.

Why does the mounting resin matter?

Edge retention. If the resin is softer than the sample, it wears faster during grinding and polishing, the sample edge is left unsupported and rounds over - and the edge is frequently the thing being examined, whether it is a case-hardened layer, a coating or a weld toe. A rounded edge both loses the feature and puts it out of focus. Ask for a resin chosen for edge retention rather than accepting whatever is standard.

How do students know when a grinding stage is finished?

Rotate the sample ninety degrees at the start of each stage. The new scratches then cross the old ones, and the stage is complete when every scratch runs the same way - the previous stage's marks have gone. It is visible and unambiguous, it replaces guesswork, and it is the single most useful practical tip in metallography. Teach it in the first session.

What should we know about etchants before ordering?

That they are the hazardous part of the process. Etchants are material-specific; obtain the safety data sheet before the chemical; mix only what you need and do not store mixed acid-alcohol etchant in a sealed bottle; work in a fume cupboard with gloves and eye protection; and time the etch rather than judging it. Picric acid, used in some classic steel etchants, is explosive when dry and restricted in many countries - check your national rules before planning a method that needs it.

Why is the Brinell test still used when finer methods exist?

Because the indentation is large, so it averages over a volume of material rather than sampling a single grain or phase - which makes it the right method for coarse-grained, heterogeneous and cast materials where a small indent could land entirely inside one constituent. Its costs are a visibly damaged surface and a specimen thick enough to support the load. And note that the result comes from measuring the impression, so a measuring microscope is part of the apparatus.

What is missing from this listing that we will need?

The inverted metallurgical microscope above all - without it the preparation produces a shiny disc and no result. Then the abrasive cut-off machine with coolant, the consumables (papers, diamond, cloths, resin, etchants), a fume cupboard and chemical storage, and standard hardness test blocks if hardness figures are reported to anyone. Ask us to quote the chain rather than the machines, and work out the cost per sample as well as the capital cost.

Key takeaways

• A micrograph shows the sample as prepared. Scratches, smearing, rounded edges and pulled-out inclusions are artefacts that look like microstructure.
• Cut with coolant. Heat from sectioning alters the microstructure next to the cut - which is the material you came to examine.
• Specify the resin for edge retention, because the edge is usually the feature of interest.
• Rotate ninety degrees between grinding stages - the criterion that tells a student when a stage is done.
• Cleanliness between polishing stages is the method, not housekeeping. One carried-over particle ruins a finished surface.
• Etching is the hazardous step - fume cupboard, data sheets, mix only what you need, never store sealed, and treat picric acid as restricted.
• Buy the microscope with the preparation equipment. Without it there is no result.

About this page

Ray Export is a manufacturer and exporter of laboratory, scientific and educational equipment based at Plot No. 449, HSIIDC Industrial Area, Saha, Ambala, Haryana 133104, India. Enquiries: [email protected], +91-9817319615.

Written by Palak Mall, Senior Content Writer. Technically reviewed by Arvind Kumar, Lab Equipment Specialist, 12+ years in laboratory and testing instrumentation. Last updated: 17 October 2026.

Notes on this listing, published rather than hidden: the product names carry the padding phrase "For Metallurgy Lab" or "For Metallurgical Lab" - two spellings of the same suffix in the same listing - which is keyword padding rather than product information and has truncated several names; we are removing it and standardising the rest. The listing covers sample preparation and hardness testing but contains no microscope, which is the instrument the entire preparation chain exists to serve, and no sectioning machine, which is where the chain starts; both are flagged to be added or cross-linked so that a buyer is not left with an incomplete laboratory. The preparation sequence, etchant handling and hardness method described here are general metallographic practice rather than claims about a particular model. Chemical regulations differ by country - picric acid in particular is restricted in many jurisdictions - and must be confirmed locally. All specifications will be confirmed in writing on the quotation.