Solve grinding burn problems

Grinding burn is a serious and widespread problem in manufacturing technology, and many manufacturing companies, machine tool manufacturers, service providers and researchers are working on a solution. The fact that grinding burn usually does not occur solely due to a specific trigger, such as an incorrectly set process parameter on the machine tool, is particularly problematic. Rather, grinding burn occurs due to complex interactions between a wide range of influencing variables during grinding, which is why solving the “grinding burn problem” is generally by no means a trivial task.

Grinding burn: inconspicuous but problematic

During grinding, excessive heat is applied to the component, causing the edge zone of the workpiece to be thermally overstressed. It “burns”! This results in local overheating of the edge zone structure to austenitizing temperature with subsequent quenching hardening. The component's state of tension also changes, resulting in local tensile stresses that can cause microcracks.

The consequences of grinding burn can be visually recognizable and show a dark coloration (thermally induced carbon enrichment of the surface zone) of the affected areas of the workpiece. In many cases, however, grinding burn is difficult to detect with the naked eye.

Regardless of whether or not it can be seen, a component that has grinding burn will no longer be able to reliably fulfill the tasks for which it was designed over its planned service life. Its ability to meet requirements, for example in terms of fatigue strength or hardness, is significantly reduced, which can lead to premature component failure.

Burn detection – the first step in solving the problem of grinding burns

To avoid that sanding burn problems remain undetected and the defective components are delivered to the customer, many manufacturing companies use grinding burn testingprocedures in quality assurance. These procedures are divided into “non-destructive” and “destructive” procedures.

The detailed difference between “non-destructive” and “destructive” methods, as well as known methods, are explained in more detail in the magazine article “Methods of grinding burn testing”. These include Barkhausen noise, nital etching or microhardness testing.

Additional quality control ensures that defective components are not delivered, but this does not eliminate the cause of the grinding burn problem. Components with grinding burns must also be sorted out. Re-manufacturing usually incurs very high costs and also costs a lot of additional labor time.

The core competences of Grindaix for the prevention of grinding burns

Use our know-how!

To solve the grinding burn problem permanently and thus keep the scrap rate low and component quality high, a holistic optimization of a process susceptible to grinding burn is necessary. To do this, the cooling of the grinding process and the addition of the grinding wheel should be optimized. Once the cause has been eliminated, all that needs to be done in the future is to ensure that the correct process parameters are adhered to.

The solution to many grinding burn problems

Grinding burn can be effectively and sustainably avoided with two approaches: “improving cooling” and “optimizing grinding wheel cleaning”.

[Translate to Englisch:] Nadeldüse - Kühlen

Improvement of cooling

A sufficientsupply of cooling lubricant is the be-all and end-all when it comes to avoiding grinding burn. To achieve this, the jet speed and the cooling lubricant pressure at the nozzle must be adequately aligned with the cooling lubricant quantity. To ensure effective cooling, the jet velocity at the grinding point should be approx. 30-50% of the grinding wheel peripheral speed.

A Grindaix needle nozzle will achieve the above-mentioned characteristics and effectively prevent grinding burn in up to 80% of all applications.

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Optimizing grinding wheel cleaning

The grinding wheel cleaning may seem confusing at first when it comes to solving the problem of “grinding burn”, but coolant must also be transported to the contact zone and chips removed. This is achieved by ensuring that the pore space between the abrasive grains of the grinding wheel is always sufficiently large and free of impurities. The coolant fills the free pore space of the grinding wheel and thus reaches the contact zone directly.

Grindaix offers a suitable Grindaix cleaning needle nozzle (pdf) for pre-rinsing the pore spaces of the grinding disks!

Excess material chips are reliably removed from the pore spaces and coolant can be transported to the grinding zone to significantly reduce the risk of grinding burn.

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[Translate to Englisch:] KSS-Düse zum reinigen

Simultaneous cooling and cleaning of the machining zone is reliably achieved with the special Grindaix dual nozzles!

Foreign particles are flushed out of the machining zone by the dual nozzles at high pressure, the free pores are filled with coolant and sufficient coolant reaches the intended zone.

Overview of measures to prevent grinding burns

Various measures can be taken to prevent grinding burn in the future. Which measures the manufacturing company takes first depends entirely on the company itself. However, it should be noted that each of these measures has a different effect on the process and is therefore associated with different costs:

Measures

Cooling

grinding wheel cleaning

monitoring process parameters

Costs

€€

€

Effect

Thermal relief, grinding burn reduction

Better cutting ability & wheel life

Reproducible, simple error analysis

Keep an eye on all process parameters – the coolant products from Grindaix help

The solution to the grinding burn problem can be effectively avoided with the help of an adequate cooling lubricant supply and optimal cleaning. However, these and other process parameters must be kept in mind in order to protect components from grinding burn during production in the future. Wear of the grinding wheel, machining residues in the machining area or blockage of cooling lubricant pipes can lead to changes in the machining process. This can be achieved easily and reliably with the Grindaix coolant products for monitoring your process!

Coolant Display

The Grindaix Coolant display can be used to monitor the coolant-related control variables “pressure”, “volume flow” and “outlet speed” individually for each nozzle. With the help of the corresponding nozzle characteristic curve and a pressure measuring point close to the nozzle, all relevant nozzle data can be measured, calculated and displayed in real time.

Find out more about real-time control

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Customization of process parameters

The thermal component load can be reduced by changing the process parameters. This can be done while maintaining the existing cooling and is therefore a measure that can be implemented at very short notice to reduce grinding burns. To reduce the thermal load, the cutting performance must be reduced. This is done by reducing the infeed. A major disadvantage of this approach, however, is the simultaneous reduction in economic efficiency, since the cycle time increases due to the lower cutting performance.

Your questions – our answers

Why is simple quality assurance not enough to prevent grinding burn?

A simple quality assurance is already the first step in the right direction! With the help of a quality assurance according to the “microhardness testing” method, for example, grinding burn is detected and the affected workpiece can be sorted out. However, this process destroys the component and even if a flawless component is detected, it can no longer be used. In addition, quality assurance is time-consuming and alone cannot sustainably prevent grinding burn. To do that, it must be actively involved in the process and, if necessary, make changes. This is precisely where Grindaix nozzles come in! The cooling nozzles help to provide more effective and targeted cooling of the process without wasting coolant. The cleaning nozzles clean impurities from the grinding wheel and fill the pore spaces with coolant so that it can reach the contact zone directly.

What factors need to be considered to avoid grinding burn?

On the one hand, the correct cooling lubricant supply and, consequently, adequate cooling are crucial. To achieve this, both the pore spaces of the grinding wheel, for cooling lubricant transport, and the cooling lubricant jet, for precise supply to the machining zone, must be aligned. Furthermore, the “cutting performance” factor is important and must be taken into account when avoiding thermal stress and grinding burn.

What are the methods for checking for grinding burns?

The most common methods for checking for grinding burns include nital etching, Barkhausen noise, surface crack testing, scanning electron microscope imaging and microhardness testing. These are divided into “destructive” and “non-destructive” methods. The scanning electron microscope image and the microhardness test are among the “destructive” methods. You can find more detailed information about the individual methods on our “grinding burn test” magazine page!

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