Hardness Test Blocks, Indenters and Accessories

Our Brinell blocks are certified to ASTM E10 and ISO 6506. Our Vickers and Knoop blocks are certified to ASTM E384 and ISO 6507. The standard follows the method the block is used for, so a lab running both Brinell and microindentation testing keeps a separate set of blocks for each.

Brinell blocks are offered for test loads from 62.5 kg up to 3000 kg, and Telebrineller test bars belong to the same family. During calibration, the force of our tester is held with a proving ring and a load cell, and the impressions are read with a stage micrometer. Both the force instruments and the micrometer are traceable to NIST.

All of our blocks are calibrated and accredited to ISO Guide 25, and the certification work is performed in an ISO 17025 compliant facility. That gives your verification records a documented chain back to national standards.

ASTM E18 is the industry standard for Rockwell hardness testing of metallic materials. This specification includes both theory and standard practice statements. For those companies Nadcap accredited in heat treat where the AC7102/5 for hardness and conductivity testing is included, an additional layer of requirements comes into play. ASTM E18 lists three types of verification testing: direct verification, indirect verification, and daily verification.

ISO 6508 specifies the method for Rockwell regular and Rockwell superficial hardness tests for metallic materials and is applicable to stationary and portable hardness testing machines. For specific materials or products, other specific International Standards apply (for instance, ISO 3738‑1 and ISO 4498).

• Standard Rockwell Hardness Test Blocks - ASTM E-18 and ISO 6508
• Superficial Rockwell Hardness Test Blocks - ASTM E-18 and ISO 6508
• Brinell Hardness Test Blocks — ASTM E-10 and ISO 6506
• Vickers and Knoop Hardness Test Blocks - ASTM E-384 and ISO 6507

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Standard Rockwell Hardness Test Blocks - ASTM E-18 and ISO 6508 use the following materials:

• Steel
• Brass
• Carbide

Superficial Rockwell Hardness Test Blocks - ASTM E-18 and ISO 6508 use such materials:

• Steel
• Brass

In tungsten carbide hardness testing Rockwell hardness of HRA is often used. HRA, named Rockwell Hardness A scale, which as the initial pressure uses 98.07N (equal to 10kgf), use a diamond pressure head with 120°cone apex angle or steel ball with 1.59, 3.18mm in diameter and then pressurized to 588.4N (equal to 60kgf).

These brass alloys are single-phase alloy, which metallurgically we call "Alpha” phase, which has a face-centred cubic structure. The solubility of zinc in copper is 32.5% at the solidus temperature of 900˚C and 30% at room temperature. The brasses used in cartridge cases are entirely alpha phase and are ideally suited to cold working having superior ductility to the copper-zinc alloys.

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According according to the latest ASTM E18 (v. 2022) specifications. The tolerance on the HRB test blocks are as follows:

If HRB is less than 88 the acceptable tolerance is +/- 2.5.

If HRB is greater than 88 the tolerance is +/-1.0.

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A grid matters most at the lower end of the Rockwell range and on the ball scales. Soft blocks take larger indentations, and ASTM E18 requires each impression to be spaced from its neighbours and from the edge of the block. With larger indents, freehand placement quickly wastes surface or breaks the spacing rule.

A grid gives every indentation its own cell, so the operator places each test without measuring distances and anyone reviewing the block can see which positions are already used. Every standard Rockwell block we offer is supplied with a grid.

On harder blocks the indentations are small, and an experienced operator can space them on an ungridded surface. Even then, a grid helps when several operators share the same block across shifts, because nobody repeats a position by mistake.

One indentation per cell. The grid is laid out so that each impression keeps the distance ISO 6508 and ASTM E18 require from its neighbours and from the block edge, so the usable count equals the number of cells on the block.

Once every cell has been used, the block is retired. A test block is a consumable with a finite number of valid indentations, and squeezing extra impressions between cells would break the spacing rule and make those readings invalid for verification.

To get the most from a block, keep set-up and trial indents on a separate piece of material and use the certified block only for the checks your procedure requires. A gridded version is also listed in our consumables catalogue for superficial Rockwell and Brinell blocks.

Based on ASTM Standards, distance between 2 indents is a minimum of 2 times the indentation's diagonal (dK), and 2 ½ times the indentation's width (dW).

The distance between an indentation's center and a test piece edge is at least 1 dK or 2 ½ times the indentation's dW.

Based on ISO Standards, distance between 2 indents is at least 2 times the indentation's dK, and 3 ½ times the indentation's dW.

The distance between an indentation's center and a test piece edge is at least 1 dK or 3 ½ the indentation's dW.

Based on JIS Standards, the distance between an indentation and a test piece edge is a minimum of 3 times the short dW. The distance from one indentation to an adjacent indentation is at least 2 ½ times the short dW, or a minimum of the long dK. If 2 indentations have different sizes, the spacing minimum is based on the short dW of the bigger indentation.

Based on ASTM Standards, measuring the distance between 2 indents or the edge of a test piece and an indent involves at least 2 ½ times the indentation's diagonal (dV).

Based on JIS and ISO standards, the distance between 2 indent centers is a minimum of 3x the indent's diagonal for copper, copper alloys, and steel, and a minimum of 6 times for lighter metals, tin, lead, as well as their alloys.

The distance from an indent's center and the test piece edge must be a minimum of 2 ½ times the dV for copper, steel, and copper allows, and a minimum of 3x for light metals, tin, lead, as well as their alloys.

Spacing on a test block follows the same rules as spacing on a part. For Rockwell, ASTM E18 and ISO 6508 require each impression to be kept a set distance from its neighbours and from the edge of the block, and for Brinell, ASTM E10 and ISO 6506 do the same. The distances are expressed relative to the size of the indentation, so larger impressions need more room.

On our standard Rockwell blocks the grid settles the question: every standard Rockwell block is supplied with one, and each indentation has its own cell. Brinell blocks and Telebrineller test bars carry their indentations along the face, and because Brinell impressions are large, a Brinell block offers fewer valid positions than a Rockwell block.

An impression placed too close to another or to the edge is not valid for verification, so plan the positions before the first test and take the exact distances from the edition of the standard your quality system cites.

Check the tester on a certified test block every day it is in use, and again whenever you change the indenter, the anvil or the test force. ASTM standards specify exactly that, and it catches a worn indenter or a shifted load before it affects production readings.

For Rockwell work, ISO 6508-2 covers direct and indirect verification of the machine and its indenters, and ISO 6508-3 covers calibration of the reference blocks used for indirect and daily verification. The ISO 6508 series has counterparts in ISO 6506 for Brinell and ISO 6507 for Vickers, each with its own reference block part.

Use a block certified for the scale and force you actually test on, and keep a dated record of every check. ISO/IEC 17025 asks for intermediate checks between calibrations where drift is a risk, so a log of daily block readings is also the evidence an assessor will want to see.

We supply blocks for the full Rockwell line. Standard Rockwell blocks cover the A, B, C, D, E, F, G, H, K, L, M, P, R, S and V scales, and superficial blocks cover the N, T, W, X and Y scales at 15, 30 and 45 kg. Aluminum blocks are also available in the B, E, F, G, H and K scales, with more limited ranges.

Brinell blocks are certified at test forces of 62.5, 187.5, 250, 500, 750, 1000, 1500 and 3000 kg, and Telebrineller test bars complete the Brinell range.

For microindentation we carry Vickers micro blocks for 1 g to 1,000 g, heavy load Vickers blocks for 1 kg to 50 kg and Knoop blocks for 1 g to 1,000 g, all available across hardness ranges. Certified indenters for Rockwell, Brinell, Vickers and Knoop testing are carried alongside the blocks, so a block and its matching indenter can ship on one order.

Our test blocks are certified in accordance with ASTM E18 for Rockwell, ASTM E10 for Brinell and ASTM E384 for Vickers and Knoop, and each family is listed against its ISO counterpart: ISO 6508, ISO 6506 and ISO 6507.

All blocks are calibrated and accredited to ISO Guide 25, and the calibration work is performed in an ISO 17025 compliant facility. ISO/IEC 17025 is the standard that testing and calibration laboratories are assessed against, covering competence, impartiality and traceability of measurements to national standards.

When an assessor reviews your hardness scope, the questions are about certified reference materials and records that can be followed back to national measurement standards. Our ISO/IEC 17025 page explains what accreditation asks of equipment and reference blocks, which helps when you prepare a verification procedure.

Compliance starts with the material. Each block is made in the material that suits its scale: steel for HRC, HRD and the N scales, brass for most ball scales, and carbide for the carbide range of HRA. Aluminum blocks are offered in the B, E, F, G, H and K scales, with more limited hardness ranges.

The surface comes next. Our micro hardness blocks are mirror-polished and mounted, which gives the best possible test surface at low forces, and the heavy load Vickers block is mirror-polished with the same surface area as our Rockwell blocks.

Each block is then calibrated and certified to its method, ASTM E18, E10 or E384, with the work performed in an ISO 17025 compliant facility. For Brinell blocks, the calibrating force is held with a proving ring and a load cell, and the impressions are read with a stage micrometer, all traceable to NIST. The certified value goes on the block's calibration certificate.

Square Pattern - The entire block is grid patterned. The problem with this design is that soft blocks create bigger indents, and don't always satisfy ASTM E18-17e1 for the distance between the edge and another indent. You can use any other square to solve the issue.

Circle Pattern - The design solves the distance problem between indents, thereby meeting the standard. There are complaints of excessive space wastage. This, however, is the ASTM E18-17e1 rule.

Our Knoop blocks are micro blocks for test forces from 1 gram to 1,000 grams, the range where Knoop testing is normally used. Each block is mirror-polished, mounted and shipped in a case that protects the polished surface, because at these forces a scratch or film on the surface changes the diagonal you read.

The Knoop indenter is a pyramidal diamond like the Vickers indenter, but elongated rather than symmetrical, and hardness is calculated from the long diagonal. The shallow, narrow impression suits thin layers and brittle materials.

Blocks are available for all hardness ranges, and the hardness value and mount are confirmed at quotation to suit the stage of your micro Vickers and Knoop hardness tester. A certified Knoop diamond penetrator is also available from us.

We supply two kinds of Vickers block. Micro Vickers blocks cover test forces from 1 gram to 1,000 grams, and heavy load Vickers blocks cover 1 kg to 50 kg (2.2 to 110 lbs). Both are available across all hardness ranges.

The heavy load block is mirror-polished and has the same surface area as our standard Rockwell block, so one heavy load block carries the same number of test opportunities as a Rockwell block. Micro blocks are mirror-polished and mounted, which gives the best possible test surface at low forces.

Because the standards set a minimum distance between indentations, the usable surface decides how many checks a block will give you. Tell us the forces in your procedure and we will match the blocks to your macro Vickers hardness tester or micro hardness system.

The grid in our range belongs to the standard Rockwell blocks: every standard Rockwell block is supplied with a grid, so each indentation has its own cell. Brinell blocks are listed by test force and carry their indentations along the face.

Layout still matters on a Brinell block, because ASTM E10 and ISO 6506 set minimum distances between impressions and from the edge, and Brinell impressions are large. If your procedure calls for a circle or grid layout on a Brinell block, state it when you order, and the layout and price are confirmed at quotation.

Telebrineller test bars are a separate format, used with comparison testing on portable systems such as the NG-Telebrineller Brinell hardness testing system. They are certified like our blocks and are available across hardness ranges.

The Master Calibration Kits we produce give customers the ultimate Quality Control tool. Every kit contains test blocks or a single block, as well as the penetrator unit used for calibrating them. Matching the blocks to a particular penetrator establishes a set relationships, which can then be disregarded as probable variables in hardness test systems. If a problem crops up, an available master kit lets you accurately and promptly determine if the source is your hardness tester.

All the blocks that come with our kits have been calibrated using a tester, the accuracy of which has been verified with NIST traceable depth and load measuring devices. The kits come with a polished wood case, as well as certificates that cover all applicable standards.

Start with the specification. The drawing, purchase order or your own procedure usually names the scale, for example HRC, and that is the scale the part is tested and reported on.

When nothing is named, the choice follows the material and the part. Each Rockwell scale pairs a penetrator with a load, and the heavier, harder combinations need a thicker, harder part. A thin part or a case-hardened surface may need a superficial scale or a Vickers test instead, and the standards ask you to confirm that the surface finish and thickness suit the indentation method before testing.

Take care with conversions. ASTM E140 provides conversion tables for use when a specification requires a conversion between scales, but a converted value is not a direct measurement, so test on the specified scale wherever you can. For thin sections and small features, our Vickers and Knoop hardness testers are the usual route.

A test block verifies the tester, not the part. Its job is to show that the tester reads correctly at the scale and force you use, here HV 0.5, so a certified block at 370 HV still proves the tester at that force, even though your part sits nearer 300 HV.

Verifying close to the hardness you test is still good practice, because a tester can read correctly in one part of its range and drift in another. Block values come from the material and its heat treatment, so the certified value of a delivered block can sit some way from a nominal target. What counts for verification is the certified value on the certificate.

If your procedure needs a value inside a narrow window, give us the target and the acceptable range on the order, and we will confirm the closest certified value available before the block ships. For a special part, it also helps to tell us the material and the feature you test, so we can suggest a block and indenter that suit it.

A block's life is counted in indentations, not years. It is a consumable with a finite number of valid positions: ASTM E18 requires impressions to be spaced from each other and from the edge, so once the usable surface is filled, the block is retired.

How fast that happens depends on use. A lab that verifies every day the tester runs, and again at every change of indenter, anvil or force, fills a block far sooner than a lab that runs the tester on a few days a month. Large impressions use surface faster, so soft blocks at high forces and Brinell blocks run out sooner than hard blocks at low forces.

A block can also be retired by a change in the rules. Verification and reference block requirements change between editions of the standards, so a block certified under an older edition may not satisfy an audit to the current one. Check the edition your quality system cites, and order replacements before the last cells are used.

The standard dimensions of the Brinell hardness test blocks are as follows:

Square Brinell Hardness Test Blocks
Length: 152.40mm (6")
Depth: 50.90mm (~2")
Thickness: 6.85mm (~0.25")

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The standard dimensions of the Rockwell C hardness test blocks are as follows:

Square Rockwell Hardness Test Blocks
Width: 50.90mm (~2")
Depth: 50.90mm (~2")
Thickness: 6.85mm (~0.25")

Request quote to get your consumables price catalogue.

Absolutely, NextGen has the full range of regular and carbide level NIST traceable hardness test block that you need. Regular Vickers test block ranges are up to 850HV and the carbide ranges are 850HV and over. Whether you need 1200HV, 1650HV or more, we have you covered. Request quote today to get the pricing for hardness test block that best meets your testing requirements.

Do you offer expedited lead times for your NIST certified test blocks?

Expedited lead times are always an option. The prices expedited lead time will depend on our production stage. We recommend you contact us to confirm the absolute best lead time and associated cost that we can offer. It is worth noting that our standard lead times are faster than most of our competitors on the market. If waiting is an option, we will do our very best to impress you.

Yes. Every NextGen hardness test block comes with a certificate of calibration, without exception, and a soft copy can be requested for your records.

The certificate is what makes the block a reference. It records the certified hardness of that block for its scale and test force, and ties the block to the method it was certified to, so your verification records show exactly which reference was used for each check.

Keep the certificate with your verification log. During an ISO/IEC 17025 assessment, auditors look for reference materials whose calibration can be followed back to national measurement standards, and for our Brinell blocks the force and measuring instruments used in calibration are traceable to NIST.

If a certificate goes missing, contact our team with the part number and your order details, and we will send a copy.

Yes, certified test blocks can be expedited for an additional fee. The cost and the time saved depend on the block type, the hardness value and the calibration you need, so we price an expedited order against your exact requirement.

Most Brinell and Rockwell blocks are already in stock, which often makes standard shipping from stock the fastest option for those scales. An expedited request is more relevant for Vickers and Knoop micro blocks, heavy load Vickers blocks or a block that needs an additional force calibration.

For a firm date and price, send us a quote request with the scale, test force, hardness range and quantity, together with the date you need the blocks on site.

Yes, we ship hardness test blocks and test bars internationally. International orders of test blocks are prepaid in full, covering both the blocks and the freight, and the terms are set out on your quotation.

Our consumables catalogue lists test blocks and certified indenters under Schedule B code 9023.0000, which helps your customs broker classify the shipment. Blocks, indenters and anvils for the same tester can travel in one consignment.

For a delivered price, contact our team with the destination country, the blocks you need and any carrier or Incoterm preference, and we will quote the shipment along with the blocks.

Lead time for a NIST traceable Vickers block depends on the hardness range, the test force named on the certificate and whether the block carries more than one force calibration. A block in a range we already hold ships faster than one requested at a specific value or with an extra calibration.

We confirm the ship date with your quotation, based on our current stock and the calibration schedule at that moment. If the date matters, put it on the request so we can plan the calibration around it.

The simplest way to take lead time off the critical path is to plan block purchases with your verification schedule. Ordering a replacement before the current block runs out of valid positions means a new block is on the shelf when you need it.

Yes. We keep most Brinell and Rockwell test blocks in stock, and we also carry Vickers and Knoop micro blocks and heavy load Vickers blocks.

Alongside the blocks, we carry certified indenters for Rockwell, Brinell, Vickers and Knoop testing and test anvils compatible with a wide majority of hardness testers. A block, its matching indenter and an anvil can therefore ship together on one order.

Availability changes with every order, so the quickest way to check is to send us the scale, the load and the hardness range you test to. We confirm availability for each item and, if a block is out, give you the best lead time we can offer.

Yes. A single Vickers block can carry more than one force calibration, and an additional calibration is listed as its own item in our consumables catalogue. This suits labs that verify a micro hardness tester at two or more test forces and want one reference block for all of them.

Each calibration uses part of the polished surface, because the calibration indentations are made on the block before it reaches you. A block with two calibrations therefore has fewer free positions for your routine checks than a single-force block, although the mirror-polished face still leaves room for regular verification.

Our Vickers blocks are certified to ASTM E384. Tell us every force you need when you order, so all calibrations are planned on the same block and recorded together.