Which flap disc should I use?

Welcome to our blog post about flap discs. Whether you are a seasoned veteran using flap discs or a newbie we hope you find some new and useful information to help you on your next project.

Why use a flap disc?

Flap discs were invented in the 1970’s and Eisenblätter in Germany were one of the first in the world to produce the zirconium flap disc. At the time most engineering and fabrication companies would use grinding discs to grind down welds and stock removal.

Flap discs have revolutionised the workflow for many businesses. This is because flap discs not only remove stock as good if not better, but they can also be made into finer grits for blending and deburring and are much easier to use.

Flap discs also last much longer compared to grinding discs. When a flap disc is starting to wear on the side it will expose new grain to cut with. Grinding discs on the other hand are discarded when only a small amount of abrasive has been used thus making flap discs much more cost effective in the long term.

Flap disc backing types

There are three main types of backing on the market, fibreglass, plastic and metal. Each has unique advantages and disadvantages.

Fibreglass is the most common backing material and is also the cheapest. The advantage of fibreglass is that it is cheap to produce. There are however numerous cons, this backing cannot be easily trimmed and even when trimmed it releases harmful fibre glass into the air. Also due to its rigidity it does not conform to the workpiece, making it run hotter and discolouring the workpiece. The rigidity also reduces the contact patch of the flap disc meaning it grinds slower. In some regions disposal of these backing plates is not straightforward due to environmental factors. Fibre glass is brittle and is more likely to crack than an ABS plastic for example.

Metal backing plates are another low-cost option. The advantage of this backing plate is its durability. This again comes with some obvious cons. The backing plate can deform when dropped which could be dangerous to use again or could provide inconsistent results. Also, a metal backing plate cannot be trimmed.

ABS Plastic is becoming a more popular backing. This option has many advantages, it is durable, lightweight and flexible, this ensures that there is a greater contact patch allowing faster and cooler grinding. Also, it can be easily trimmed to make use of the entire disc. The cons with this type of backing are that it is more expensive to produce, but usually this cost is offset by the improved lifespan and efficiency of the disc.

There is also a unique natural fibre compound backing that is made from hemp. This backing has many of the advantages of ABS Plastic, it is durable, flexible and lightweight however it is also ECO friendly by being Co2 neutral and hemp being a renewable resource. These discs can also be easily trimmed and provide a greater contact patch. This backing is unique to Eisenblätter and is only imported and distributed by 111 Abrasives Australia here in Australia.

Types of abrasive

There are 3 main types of grit for flap discs:

Aluminium Oxide: This is generally the cheapest and is best used on softer metals such as aluminium. The con with this type of abrasive is that it does not self-sharpen, it will become a finer grit over time as it dulls over time it also generally does not last as long as the other types of abrasive.

Zirconium: Generally blue in colour this abrasive is great for hard metals such as stainless steel because it remains sharp for a long period of time*. Zirconium can self-sharpen so it is renowned for its consistency in cutting and leaves a much nicer finish for subsequent work*

Ceramic: This red coloured abrasive is ideal for heavy stock removal on mild steel as it’s self-sharpening grains maintain a consistent strong cut.

*Dependant on the quality of the abrasive used.

Flap Disc Grits

Flap discs usually are made in 4 different grits. 40, 60, 80 & 120 these grits cover the vast majority of possible applications for flap discs. The coarser grits, grit 40 & 60 are used for stock removal applications while grit 80 and 120 are used for deburring and blending.