LANDSKRONA, Sweden – Haldex posted the following on its European website detailing the benefits of spending a bit more to get higher-quality friction products which has fueled the company’s customers.
“Why customers may wish to pay more, rather than less, for friction materials”
In normal times, it’s natural that customers will want to restrict their spending on business expenses. All the more reason that now, when rising costs of fuel, gas, electricity and food products are causing worry for both private individuals and businesses across Europe, some commercial vehicle operators may be tempted to cut corners wherever they can.
Haldex offers a range of products to suit all kinds of customers. They can search for parts in the product catalogue and Trailer Application Guide via www.haldex.com.
In particular, Haldex supplies friction material (brake pads and brake shoes), calipers and assemblies for new axles made by original equipment manufacturers, as well as replacement supplies to them, and to the independent aftermarket via a network of distributors.
Among other products, customers can find Haldex-branded friction material suitable for use in Haldex brakes. There is no secret that these friction materials are likely to be on the more expensive end of replacements. That is particularly true compared to off-brand ‘will fit’ materials. The question might arise, why should they pay more, particularly at the moment?
What these customers may not know is that years before the materials reach the market, they have been evaluated by a stringent Haldex testing initiative involving both off- and on-road trials. Far exceeding the minimum UNECE R90 legal requirements, these trials aim to ensure that the material will meet customers’ requirements in performance, durability and reliability for every wheel end configuration in almost every possible operation.
The road to a new friction material is a long one. Having pre-screened products and having vetted the supplier for high quality, testing begins on a static dynamometer test rig with the legislative requirements. Materials which fail at the first hurdle need not go any further. Those that pass are then put into a brake disc cracking test. Vehicle homologation and testing manager Jonas Benson says: “Some friction materials can be aggressive to discs” – and if the disc breaks, there’s an expensive repair for the customer, so any material that damages discs is rejected.
Those materials that make it through this test are then assessed in ISO standard tests for global specifications of performance and wear. After that comes Alpine descent testing. “If you are driving the wrong way down the Alps, your discs can heat up to 900°C, depending on the size of the discs,” he adds.
After passing the disc cracking test, brakes are sent out for field trials. Haldex chooses different driving scenarios to gauge their impact on the material; it attempts to insert the material as great a range of applications as possible, from very severe off-road duty to long-haul on-road work, aiming to find, and test, the worst-case scenario.
Haldex application engineering and technical support manager Fredrik Rennstam adds: “The part that takes the longest to catch is environmental impact. One year is way too short; most friction material has no problem withstanding one year in the field; it can take two years before we start to see signs of this, so we decided that the minimum time for field tests is two years, and it needs to include two winter periods, which is when environmental conditions have the greatest impact.”
Test criteria include mechanical integrity – ‘We can’t have sections of friction material crumbling, or having cracks,’ says Benson. The thickness of the pads is measured, and compared to distances travelled, to estimate the wear rate. Not that one such figure has much meaning in isolation. “Based on specific conditions for that vehicle, we evaluate the wear rate and collect some information from several different operating conditions and then paint a picture about how they are working in general,” says Benson. The team also scrutinise copies of the results from trial vehicles’ statutory tests on a roller brake tester, which measures brake performance, and at the same time conducts interviews with drivers.
Once approved, the friction material specification is locked. Observes Rennstam: “There are at least 30 different ingredients in a brake pad. A minimum of 30. And if you change any, in their relationship or their properties, you change also their performance.” When Haldex supplies OEM axle suppliers with friction materials for new products, those contracts will require particular material references; only some will do. Brake pads for original equipment are always branded Haldex.
Of course, the company is not alone in carrying out testing. Friction material specifications are included in a brake’s type approval. Legally speaking, to meet the R13 requirements, suppliers must carry out annual conformity of production testing to make sure their material remains in specification. This is done by the axle manufacturer and covers Haldex callipers and pads. In addition, adds Benson: “Our friction material suppliers also have their own audit plans. And if they change a raw material, even if it’s the same, we have a discussion. Where the raw material is mined could even have an impact. We don’t change anything in the recipe: it’s a tricky cake to bake.”
As rigorous as the testing regime is, it cannot cover every possible operational circumstance, as the company found a few years ago when a friction material that had been released into the market was discovered to have, in certain rare, extreme-use cases, too low a mechanical integrity. As a result, Haldex responded to the issue, invested in a new round of testing and ended up approving a different material which it subsequently released it to the market, and has been generally successful.
Despite the expense of the testing programme, Haldex continues to keep an eye on market trends. Adds Benson: “Of course, we are looking at new materials. In future, commercial vehicles might have much more regenerative braking; we could have a material optimised for that scenario.” And in another example, last year, reacting to environmental requirements in the USA, it launched a copper-free class N friction material for use there.
In summary, many commercial vehicle operators will be able to find less-expensive friction materials in the independent aftermarket than Haldex-branded brake pads. However, they should not discount the extra work that has been done to evaluate these premium products, in terms of the material validation and extensive trials undertaken. With that R&D, Haldex offers customers an assurance that Haldex-branded friction material will be safe, reliable, long-lasting and offer good performance throughout the product lifespan.
It is up to the customer to decide whether going without such assurances and buying a cheaper alternative is worth the price.
