Questions on grinding process ( wheel dressing, burn and chatter)

I am a PhD student working in grinding process.

Hi, colleague! If it's not a secret, at which university did you grind your dissertation?
The answers to all your questions will depend greatly on what exactly you need - to improve your understanding of the grinding process, or just to start grinding parts better/faster.

Wheel Dressing: How do you decide when and how much to dress the wheel? Are there clear signs that indicate a wheel needs dressing, and what is your method for verifying that it’s been dressed properly?

1. When.
There are many options here. If we are talking about some automated or human-independent solution:
- sound analysis
- analysis of grinding spindle body vibration
- analysis of workpiece vibration
- analysis of spindle motor torque
- analysis of X-axis motor force/torque
- exotic, video analysis of grinding wheel surface

If we are talking about a simple grinding machine without electronics, then most of the above methods work, only the "analyzer" is the grinder The worker hears:
- change in the sound of the spindle drive operation when the load increases
- change in the sound emitted by the entire system when the wheel and the workpiece come into contact
- how much the sound changes when the wheel starts cutting and when the wheel comes out into the air.
The worker sees the change in the color of the grinding wheel surface.
2. How much. This question should be divided into two main sections: the minimum amount that needs to be removed from the wheel and the required depth when dressing.
The best source here are books on grinding combined with an iterative approach.
In general, to be 100% sure that the wheel is completely dressed and there are absolutely no worn grains of abrasive and metal chips left on the surface of the wheel, there are two main ways:
- cut off a layer from the wheel of a thickness that is obviously several times greater than the maximum value of the wear layer. This is a rather expensive and stupid method, but it always works
- examine the surface of the wheel. Under a microscope, you will be able to see if there are worn grains of abrasive on the surface. And examining scrapings from the surface of the wheel will show you if there are metal particles there.

People much smarter than me have already done this before: they grinded the same metal in the same modes, each time increasing the depth of dressing - and examined the surface of the wheel. When worn grains and metal particles cease to exist on the wheel surface - great, this is the very minimum value of the worn layer for a specific combination of grinding modes, grinding wheel and part (material, hardness, material structure). A reasonable safety factor must be added to this value - and we will get the minimum thickness of the layer that must be removed from the wheel. In good books, dissertations and scientific articles you can find detailed values for very specific conditions, but more often, of course, average indicators are given. This is reasonable, there is no point in taking into account the difference of several microns. So usually you take the meaning from a book or your experience, and then adjust it after trial and error.
Now directly about dressing modes. I have always said that dressing modes are from some point of view more important than the choice of grinding wheel. By changing the dressing tool and dressing modes, you can change the cutting ability and/or roughness of the part several times! When choosing what you need: to get the maximum cutting ability of the wheel in order to remove the maximum amount of material as quickly as possible with minimal heating of the part, or to achieve the best roughness of the part, you choose the type of dressing tool, the depth of dressing, the speed of movement of the dressing tool, etc.
Dressing modes, as well as the minimum depth, will depend on the mode in which you work - is it a one-time job, or a large series when you need to minimize wheel consumption.
If you write specific details of your task, such as the material of the part, the type of grinding machine, the number of parts, the required accuracy and roughness, I think you will get specific advice including on dressing modes.

Burn and Chatter: Under what conditions do these issues typically arise? There are times when the wheel makes a rubbing noise without significant power consumption or visible burn marks, though leading to chatter, what does this tell about the wheel condition? This is also making me think there is a wheel failure criteria that decides if its going to be chatter or burn. Am I thinking in the right direction?

One of the reasons for such behavior of the wheel is an unfortunate combination of grain size, porosity and material of the part. Sometimes some pores on the wheel surface can be clogged with metal in just one pass! Similarly, the sharpness of the grains can be greatly impaired in several passes with an unsuitable wheel/part material and poor cooling.

Read the following questions and their answers in this section. They will teach you how grinding wheels are helpful in the real world.

Goto SINOTOOLS to know more.

Question 1. How can I choose the correct grinding wheel?

Answer. Choosing the right wheel is crucial to ensuring grinding effectiveness. First, we need to select the appropriate grinding plate material. Also, we must consider the processing requirements of the workpiece material. Not only this, it’s important to pay attention to the hardness and bonding type of the grinding disc. Thus, it will help you to ensure its stable performance and shape during the grinding process.

Question 2. What dressing and maintenance are necessary during the use of grinding disks?

Answer. Grinding disks wear out during use, making regular dressing and maintenance essential. Dressing involves using tools such as oilstones, diamond pens, or dressing rollers. Thus, it will help you to restore the performance and precision of this wheel. Additionally, it is necessary to clean the grinding plate surface at regular intervals. It will finally prevent damage from impurities and coolant residues. Proper storage of grinding discs to avoid moisture, heat, or impact is also necessary.

Question 3. What are common equipment failures during the grinding wheel process? How can you avoid them?

Answer. Common equipment failures include excessive spindle vibration and motor overheating. These failures may happen due to equipment aging, improper installation, or incorrect operation. To avoid these issues, inspect the equipment at regular intervals. Moreover, you also need to replace old parts. Apart from this, you must ensure the secure and proper installation of the grinding wheel. Also, you must follow standard operating procedures. During operation, control grinding parameters to avoid overloading.

Additional reading:
Difference between Standard Electric Torque Screwdrivers and ...

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Question 4. How can you prevent sudden breakage or bursting of grinding disks during grinding?

Answer. Grinding disc breakage or bursting is a serious safety issue. Also, it is often related to improper grinding disc selection or insecure installation. To prevent such incidents, ensure that the grinding disc matches the equipment. Moreover, you should follow proper installation procedures. Next, check the grinding disk's condition during operation as well. After that, stop the machine and inspect it to see if you detect any abnormalities.

Question 5. What causes substandard surface quality of workpieces after the grinding wheel?

Answer. Substandard surface quality of workpieces can result from several factors. These factors include severe grinding wheel wear. Moreover, it also includes improper grinding parameter settings or incorrect coolant usage. To address this issue, consider the grinding plate condition and grinding process. Furthermore, you should choose the coolant with care. Moreover, you should make necessary adjustments and optimizations.

Question 6. How do you deal with rapid grinding disc wear?

Answer. Rapid grinding disc wear increases production costs and affects grinding efficiency. To tackle this issue, optimize grinding parameters. Then choose more wear-resistant grinding plate materials. It also enhances the dressing and maintenance of grinding discs.

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Question 7. How can the contact area between the grinding disk and the workpiece be controlled?