Expert advice on using Diamond Compound

In this blog we give expert advice on working with diamond compound. Everything is covered from what questions to ask, what grades you need, and tips and tricks.
We get a lot of questions about the correct diamond compound that our customers should buy. When we get asked about diamond compound, we always ask the following questions:

“What finish are you wanting to achieve?”
“Is there a specific Ra value you need to achieve?”
“What is your start point?”
“What material are you working with?”
“How do you intend to polish it?”

The answers to these questions help us to understand which diamond compounds you should be using. But, if you don’t know the answer to these questions, then below is some advice about how to think of Diamond Compound.

Try to think about Diamond compound in the same way that you think about abrasive paper such as wet & dry.
If you had a piece of steel that you wanted to get nice and polished, we would determine how rough the steel was. Then we would decide if we are to use 60 grit or 120 grit to start with.
After we have used this coarse grade, we would then go through the grades, such as 240 grit, 400 grit, 600 grit – until we were happy that we have got the look we are after. A lot of our customers would do exactly this and take it to 2000 grit (p2000).

We could start with 90 micron paste (extremely coarse for stock removal) if we thought we needed to, and then go through all of the grades, until we were using the 1/10 micron diamond paste. This may get you an amazing mirror finish, but most of the stages would be unnecessary.
This is why we ask our customers;

You may already have a very flat piece of metal, and you can actually start at 10 micron.
To give you a better idea, a machined part usually comes off the CNC at approx. 0.6 to 0.8Ra surface finish and a mirror finish is considered to be 0.1Ra, so we actually only need to remove approx. 0.7 microns.
There is one other thing we need to mention, and this is why we always ask our customers the question:

We could advise either DCAS which is standard concentrate diamond compound used for most materials. Or we could advise DCH which is high concentrate diamond compound used for hard metals.
From experience, we would usually advise that:

• DCAS works brilliantly on all materials below the hardness of stainless steel.
• DCH is mainly used for Alloys such as D2 and Titanium etc.

Let’s look at an example:

We now know that we are at approx. 0.7Ra.

• So, to get the Ra level down rapidly to start with, we would advise 16 micron.
• This means that the diamond particles in this compound are 16 microns large. They will be stronger and hold together better for us to get the Ra level down on the customers’ cube.
• Following the use of the 16 micron, and as a guess, we might suggest we would now be at approx. 0.4 Ra, we would then turn to the 10 micron.
• Following this stage, we would use the 6 micron and then finish with the 3 micron. This would give the customer a great lovely, polished finish.
• If the customer wanted to go further to an amazing mirror finish then they could go as fine as 1/10 micron. This is totally up to the customer.

All of these ways we list, achieve the same thing. However, some will be a lot faster and will allow you to skip stages as the method is more aggressive.

Do I use the diamond paste straight on the metal?
Our advice is that you get some Moleroda Lapping Fluid and make a small mix with the diamond compound. You only want to make the compound wet (Not soaked) this helps it move better and not feel like its scratching. A mix the size of ¼ of your thumb nail will cover approx. 1” sq.

Polishing by hand with wood

A lot of customers purchase the Hard Wood and Soft wood lapping sticks. They  make a mix with their diamond compound and lapping fluid and then gently polish away with their wood sticks, going through all of the stages above.

Polishing using a rotary tool

We would suggest that this is the most popular with our customers, but it is important that you have a rotary tool where you can control and see the RPM (this is the speed it rotates). With polishing slow is better. If you were using a 10mm dia felt bob, we advise working at about 6’000 RPM for the higher coarse micron, and slowing down to approximately 2’000 rpm for 6 micron and finer.

Polishing with a reciprocating tool

We have customers that have to get into tight corners and right angles so they chose to use a reciprocating tool with mounted felt sticks or mounted wood sticks to apply the diamond compound. 

Ultrasonic Polishing

An ultrasonic polisher sends sound waves down the handpiece so that the tip is moving at 40’000 times per second at 40 microns per movement. That’s very impressive isn’t it? So, you actually don’t need to move your hand at all, the ultrasonic Polisher does it all for you. Depending on the material you are working with and how you are going to apply the diamond would depend on the power and the frequency required, but this is all calculated on the Ultrasonic if you had the ENESKAsonic.

Polishing professionals will always use a cross hatch technique.
Professionals would use the 10 micron going from left to right, and then use the 6 micron moving from top to bottom.

The reason they do this is because when you have used the 10 micron from left to right, you have created peaks. When you then go from top to bottom, you take off these peaks with the next grade, and so on… Also, never cross contaminate. If you have used a felt bob for the 10 micron, ONLY use it for the 10 micron. Use a different consumable for every grade.

For more expert advice using diamond compound

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– we would also be delighted to visit you and take a look at your application.
And take a look at our

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for videos of us hard at work finishing!