The Top 10 Grinding Problems (And How to Fix Them), Part-2

The applications experts at Meister Abrasives have seen it all, from grinding machines that have been used for decades to state-of-the-art equipment installed days before, and no matter the shop or the customer, we do our best to help them achieve the best possible results with their technology. But in many cases, a seemingly challenging operation can be made easy with just a few changes in approach. In Part 2 of our series on the top 10 grinding problems, we take a look at five more obstacles manufacturers face – and the simple solutions you can use to improve surface quality and overall productivity.

6 – Rubbing and Metal Loading
When metal flakes get stuck to the grinding wheel, the metal-on-metal rubbing will scratch the part, cause deflection or even crack and scrap the part due to excessive heat. Coolant is the first line of defense, so make sure the nozzles are aimed correctly (and that coolant can fully reach I.D. surfaces for bore grinding), the filtration system is keeping everything clean, and the pressure, flow, and temperature are all correct. If it is not the coolant causing metal loading, make sure you are removing as little stock as possible, ideally by making sure the part is as close to its final dimensions as possible before putting it in the grinding machine.

7 – Chatter
Chattering, which causes zebra-like striping on otherwise high-quality surface finishes, is nearly always caused by excess vibrations – the source of the instability is usually the difficult thing to figure out. Consider varying the speed of different parts of the grinding machine to avoid harmonic resonances and ensure that all parts of the system are properly balanced without excessive runout. Likewise, a sharper wheel will usually increase cutting efficiency, but it may also increase surface roughness, so for optimal vibration damping, be sure to select wheel specs that provide the best balance for chatter-free performance.

8 – Excessive Noise
Sometimes, your grinding operation just does not sound right, and usually, a noisy grind will involve chatter-causing vibration. Even if the wheel is sufficiently sharp, uneven wheel wear and poor wheel roundness will cause peaks of material that, when hitting the workpiece at 60,000 rpm, sound like a high-pitched scream; if you have dressed the wheel back to its proper shape and the noise persists, check the wheel, quill and spindle nose for runout.

9 – Thermal Expansion and Contraction
If a part comes out of the machine hot and you are trying to grind to micron tolerances, thermal expansion can mean that in-spec parts are out-of-spec when they cool. The first step in addressing this problem is obvious – your coolant needs to be taking the heat out of the grinding process by being well-aimed, properly cooled and at the right level of pressure. If this does not help, consider checking the temperature of each part and noting when the heat begins to get out of control. If parts come off too hot immediately after dressing the wheel, it is likely you are dulling the wheel instead of sharpening it; if they grow hotter and hotter until the wheel is dressed, you will want to shorten the dressing cycle for optimal sharpness.

10 – Wheel Wear
With modern grinding technology, wear is often good – it is how fresh abrasive is brought to the surface of a wheel to keep it sharp. But excessive wear means shorter tool life and higher costs, so an effective balance needs to be struck. Faster rotational wheel speeds and shallower cuts will usually extend the life of a wheel, as will flatter feed cycles that make more moderate adjustments to the feed rate over the course of a cycle. And as with all cutting tools, effective temperature control is essential to tool life, so be sure to optimize coolant delivery.

Looking for more? Please follow THIS LINK to see Part-1 of our series, with 5 more useful solutions.

Still facing challenges that you and your team are struggling to overcome? Meister has the expertise required to diagnose and fix any grinding difficulty. Contact Meister today to talk with an application engineer to get started.

• Contacts Headquarters
• Contacts USA