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Game changing: developing automatic indentation measurement

Brinell Hardness Tester 1962

Foundrax MD Alex Austin on the ‘slow revolution’ in Brinell testing that the company pioneered

Foundrax has been in the hardness testing business since the 1948 (the booklet in the picture is from our company archive) when the Brinell test was regarded in certain quarters as somewhat ‘rough-and-ready’; a tool for the machinist, certainly, but perhaps not for the professional engineer. The main reason for this was the difficulty of measuring the diameter of indentations accurately with a microscope and ambient light. Where, exactly, does the profile of the indentation created by the sphere end and the ‘pile up’ of metal that’s been forced to the rim of the indentation begin? And, if you can see that on the hardest metals, it doesn’t necessarily mean you’ll be able to see it on soft ones. Sometimes you think you can see it but what you’re actually seeing isn’t the edge of the indentation at all. As anyone familiar with this subject knows, the metals behave differently, they look different and light appears to reflect off their surfaces differently, so the angle at which light falls onto the materials’ surfaces can change the apparent position of the edge of an indentation. Operator-dependent measurement is thus fraught with difficulties and, to complicate matters further, the workshop technician then has to take the diameter figure and read the hardness rating from a conversion table.

Things started to improve about 40 years ago when Foundrax began a collaboration with Birmingham University. We developed a microscope, partnered by a dedicated computer, which could judge the edge points accurately and consistently and read the diameter in hundreds of positions within a split second.

In 1982 we launched the first automatic Brinell hardness tester onto the market – the ‘BRINscan’ – and it self-checked and adjusted too. It came with an integral computer and a screen that displayed the calculated hardness value boldly, to make life as easy as possible for operators in steelworks conditions.

Looking back, I’m surprised how long it took to get market traction – technicians like their tried-and-tested methods, certainly, but this was a game changer. In fact, in 1990 Gill Wood, the National Physical Laboratory’s expert on hardness testing, told us that we had single-handedly transformed the perception of the test from problematic to highly reliable. Nonetheless, in 2000 the machines were still not common and I think we have a major oil and gas customer to thank for spreading the word: Back in 2002 its quality manager saw the improvement our equipment offered and proactively demonstrated it to companies in his supply chain.

In the late 1990s we launched a portable device – the BRINtronic – which utilised the same technology but in a ruggedised case with a hand-held scope. This device, along with our heavy-duty machines, remains in a state of continuous development and we’re trialling a new model now.

An important consequence of this improvement in measurement accuracy was that manufacturing industry was able to tighten its acceptance criteria and reduce measurement uncertainty which, in turn, drove improved measurement practice and the replacement of equipment and, ultimately, brought us to where we are today with the Brinell test acknowledged as an exceptionally reliable way of getting good-quality hardness results in harsh industrial shop-floor environments.

More on Hardness Testing

Further information for the non-specialist

The ‘hardness’ of a material is a physical property. It’s a term that’s used frequently to describe a material’s ability to resist being deformed.

Hardness testing is crucial in much of manufacturing industry (it doesn’t require any specialist knowledge to grasp the significance of proper hardness for an application; imagine car wheels that became oval because they were too soft, or springs that snapped because they were too brittle!). The various hardness testing systems in use provide reliable information through straightforward methods involving measuring how much a material is deformed by being subjected to a specific load: In Brinell tests an indentation is made in the material and its width is measured; in Rockwell tests it’s a depth measurement. The tests are designed to meet internationally agreed standards and are carried out using sophisticated machines.

Brinell Hardness Testing Machines

Foundrax develops and manufactures Brinell hardness testing machines which enable measurements to be taken in almost every conceivable industrial condition.  They have a direct pedigree stretching back over 60 years and an industrial heritage that can be traced to the 19th Century. An understanding of the rigours of steelworks conditions has informed the development of the entire Foundrax range.

When it comes to controlling the quality and consistency of material testing, the Brinell hardness testing process offers the assurance professional engineers seek.  Foundrax is an acknowledged leader in this field and, through the development of accurate machines that automated both indentation and measurement, the company was instrumental in making the Brinell test the default option in much of heavy industry.

Benefits of Hardness Testing Machines

There are, then, two great benefits of using Foundrax’s Brinell hardness testing machines.  Not only do they provide the technical information engineers seek but by automating the indenting and measuring processes they also save users a great deal of time. Given that some industrial processes require each and every component to be checked (for example every link, in every tank track in service with the British Army has been tested on a Foundrax machine, a total of well over 25 million test cycles), the cumulative time – and cost – saving can be huge.

Additionally, the Brinell test can be carried out on a wide range of metals and does not require the ‘laboratory level’ cleanliness demanded by some other systems.

At Foundrax, these machines are manufactured, serviced and calibrated to internationally recognised standards.  They are purpose-built to test the hardness of metals (ie they are not modified versions of machines for other disciplines) and are UKAS certified. They are straightforward to maintain and priced for a range of budgets.

If your budget is stopping you from getting the equipment that you need, the Foundrax Finance Scheme might be the solution as it allows payments to be spread out over an agreed timeframe.

If you need to know more about hardness testing machines, please call Foundrax on 01458274888 today!

Hardness Testing – Some Information for Non-Specialists

The term ‘hardness’ is used to describe a material’s ability to resist deformation. The values generated from the test are extremely useful, not only when it comes to making comparisons between materials but also when assessing fitness-for-purpose of a given material

What is Brinell Hardness Testing?

The Brinell hardness test tends to be used in harsh industrial shop-floor environments such as foundries, forges and steelworks and is employed to determine the hardness of metals in order to assess their suitability for particular applications. Brinell hardness testing is especially useful for materials that have coarse grain structure or rough, hand-prepared test surfaces.
In the Brinell test a tungsten carbide ball indenter is forced into the surface of the metal in a tightly controlled manner. The force is generated in a time period of between two and eight seconds, and is then maintained for a minimum of ten seconds (this may be increased when used with softer materials such as aluminium). This “dwell time” ensures that the indentation is what engineers call as ‘plastic’ (ie permanent) as possible, so that its dimensions do not change after the end of the indenting process. The diameter of the indentation is then measured in a minimum of two axes, normally with a purpose-built microscope. Foundrax’s automated machines measure the indentation across hundreds of diameters and then calculate the hardness for the operator. Without the benefit of automatic measurement, it is a question of doing a calculation with the hardness formula or, more commonly, reading the hardness off conversion tables.

Why is Hardness Testing important?

Whether it be for aerospace, automotive, oil and gas or rail (among others), our hardness testing machines are an essential investment for many companies because of the safety-critical nature of their products. The worst railway crash in Germany’s history was caused by a wheel being too brittle, and since that crash, in 1998, the manufacturer of the wheel has purchased several of our highest specification machines.
As an example, if you consider the pulleys that a lift cable goes around, overly hard ones would wear out the cable and under-hard ones would be worn out by the cable. In either case, you’d prefer not to be in the lift at the point it becomes obvious that the materials are incorrect. Or consider a more ‘heavy duty’ example: every tank track link in use by the British Army since approximately 1982 has been tested by a Foundrax machine, testament to the accuracy, high quality and reliability of our products.

How to choose a Hardness Testing Machine?

Our hardness testing machines are suitable for a multitude of applications. All are manufactured to meet the appropriate ISO and ASTM standards. Detailed information is here: foundrax.co.uk/hardness-testing-machines/
There are several factors to consider, including the rate of testing you wish to achieve, burden on the operators, degree of automation, and size of components – not to mention health and safety. It is not unknown for people to test longer items by holding one end in the testing machine and the other on a crane – without considering that not only may the results be incorrect as a result of movement under load, but if the machine should be pulled over by the component, the operator could easily be seriously injured.

Special machines

At Foundrax, we understand that certain circumstances require a unique solution, which is why we design and manufacture special-purpose hardness testing machines following detailed consultation with the customer.

If you need to know more about why hardness testing is so important, don’t hesitate to get in touch with the Foundrax experts on 01458274888 today.

The problem of testing large, unwieldy items accurately

Sometimes, if you’re testing something that’s heavy and awkward to manoeuvre, it’s easier to take the tester to the component rather than the component to the tester. Sometimes, if you’re testing a part “in situ”, there is no possibility of taking the component to a testing machine at all. Having worked in the hardness-testing field for around 60 years we’ve accumulated extensive knowledge about the struggles of in-situ testing and have a range of solutions.

Many of our customers have found that their problems have been solved by our <a href="http://Model 134 Portable Brinell hardness tester or our MHMA transportable Brinell hardness tester. The model 134 is fully hand-portable, whilst the MHMA is able to test items over 900mm in height. Both therefore overcome the problem of transporting awkward, heavy materials to a static tester.

Convenience

Portable machines, like the Model 134 Portable Brinell hardness tester, are lightweight when compared to other hardness testing machines and are easy to manoeuvre.
The full hand portability of the Model 134 allows it to be taken almost anywhere whilst the MHMA is a wheeled machine that replicates the test capacity of many static machines.

Versatility

Industries such as aerospace, automotive, defence, general engineering, mining and oil, can benefit from portable hardness testing and our portable Brinell tester can be used:

  • On shop floors
  • On oil rigs
  • On pipelines
  • On a construction site
  • In a yard
  • In a factory
  • in a laboratory
  • In a shed

Accuracy

Both machines allow accurate hardness testing to be carried out not just in remote locations but also on awkwardly shaped samples. The machines exceed the accuracy requirements of both ISO 6506 and ASTM E10 and the design of the test head permits its use in non-vertical orientation.
Portable Brinell hardness testing machines don’t require extensive training; the process can be learned very quickly but our team is always on hand to advise you, should you need any assistance.

Get in touch

Need to know more about portable hardness testing machines like the Foundrax Model 134? Our Foundrax experts are always on hand to help you to choose the right hardness testing machine for your applications. Feel free to contact us on +44 (0)1458 274 888 or email us at sales@foundrax.co.uk.

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