Which mass finishing media is best to use in a finishing process?

Not sure where to start when it comes to choosing the right mass finishing media for your finishing process? That’s where we can help, join us as we explore the essential factors to consider when selecting the best media for your specific needs in our video and blog below…

What are the main types of media?

One of the key factors in any mass finishing process is to select the correct media, according to your parts. Firstly, it’s important to understand the different types of media that are available. There are 3 main types of mass finishing media, ceramic, plastic and agro. 

Ceramic – Generally speaking, ceramic media is used on harder materials such as steel, inconel and titanium 

Plastic – Generally used on softer materials such as brass, copper and aluminium 

Agro (such as maize or walnut shell) – Generally used as drying media’s, although in some circumstances they can be used to polish components 

Why does the size and shape of the media matter?

Once we have decided on which material to use for the process, the next thing we need to look at is the size and shape of the mass finishing media. Whilst it can be daunting to see how many sizes and shapes are available, there are a few questions we can ask to help narrow this down. The first thing to consider is which process are we looking to carry out, for instance, are we looking to deburr, clean or polish the parts? 

Deburr 

More often than not, when we’re looking to deburr the components, we want to choose a mass finishing media that has some sharp points or a triangular shape. This will allow the media to have a greater impact on the parts, and to access some areas which the entire piece of media cannot get to. 

Polish

If we are looking to polish, we will look for a media shape which is smoother, such as a cyclical shape. This will mean the media rolls over the part as opposed to impacting onto it, it should also mean there is less damage or pits coming from the media. 

After we have established the shape of the mass finishing media, we will then establish which size of media is required. Usually, a smaller media, regardless of grade, will give a better, more polished finish than a larger media. Likewise, a larger media will deburr better and quicker than a smaller media as there is more weight. 

Understanding the part geometry

The main thing is to consider the part geometry. When running the parts in a bowl machine, where we have automated separation, we want to make sure there is a big enough difference between the size of the mass finishing media and the size of part, so we can get an effective separation once the process is finished. Normally this will involve choosing a media smaller than the part, so the parts can pass over the screen, and the media can return to the bowl via the holes in the screen. Occasionally this will be done the opposite way round, where the parts will fall back into the machine and the media is evacuated. 

Of course, when choosing a smaller media, we need to make sure that any blind holes or slots in the part will not become blocked with the media. Over time as the media wears on, this may start to happen, and this is when the media should be changed for fresh media. Sometimes, it may not be possible to prevent media lodging from happening, and therefore, certain slots or holes may need to be plugged or massed off to prevent media from becoming stuck. 

Choosing the grade of media

Finally, we will decide on the grade of media which is mainly looking at the amount of abrasive that we want to use in the process. 

Polishing 

When polishing, we want to look at something with very little abrasive, where the media effectively acts as a carrier for the liquid compound in the process.

Deburring 

When looking at a deburring operation, the requirement for the customer becomes more important, choosing a more abrasive mass finishing media will mean that the deburring time will reduce, however it will also mean that the media will wear quicker and the finish on the parts may appear to be more dull. Getting the right balance between the speed of operation, and the volume of media being used, will ultimately come down to what is most important to the customer. 

If you’d like advice on which media to use during the finishing process, please request a brochure or get in touch with us and we’d be more than happy to help you.