How to Grind Aluminum With Flap Disc

December 31, 2021

How to Grind Aluminum With Flap Disc

Aluminum is a fine metal and has many useful applications. However, there are some major challenges along with usefulness, especially when you don't have an effective tool to grind aluminum.

According to experts, you need the right flap disc for aluminum grinding when it comes to surface grinding.

Can You Use Flap Discs for Aluminum?

YES, The best grinding tool to grind aluminum is a flap disc because flap discs grind aluminum metal surfaces at very low temperatures as compared to other abrasive discs. In a solid grinding wheel, the abrasive cloths do not absorb the heat, while in a flap disc there is space between each flap that allows extra ventilation to keep the surface cool.

Why Flap Discs are Best for Aluminum Grinding?

Polishing, surface finishing, deburring, metal cutting, grinding, all can be done with flap discs. Flap disc metalworking applications are similar to wire wheels

Wire wheels are power brushes, with an arbor hole that allows brushes to be used with grinding machines or CNC machines.

Wire wheels are a heat-resistant tool. While flap discs are less sensitive to heat and provide much cooler while grinding aluminum. Other abrasive discs can cause damage by excessive grinding, therefore advanced aluminum flap discs are designed to avoid such problems. 

Before you select a right flap disc make sure to be aware of the following things:

  • Always prefer a contaminant-free abrasive that won't involve after-rust caused by metals such as iron, sulfur, chlorine, and carbon steel.
  • Secondly, select a flap disc with a calcium stearate (also known as a no-load coating). When the disc is rotated, a calcium stearate coating liquefies, creating a protective coating for the aluminum surface and cooling the disc to avoid loading.
  • Flap discs must have aluminum oxide grains with a protective calcium stearate coating to efficiently grind aluminum at lower temperatures.

What are Flap Discs?

Flap discs are a type of abrasive wheel that has overlapping sanding strips called "flaps." Each flap is covered with abrasive grains that wear away with use to extend the lifespan of the disc. Flap discs are specially designed to fit with power tools like a die grinder or an angle grinder.

Popular uses of the flap disc include grinding, deburring, removing stock, blending, and finishing. In terms of aluminum, the flap discs are the perfect abrasive disc for aluminum polishing preparation. There are much more benefits of using flap disc for aluminum grinding, such as:

Flap Disc Benefits

  • Economical/Low-Cost
  • Long-Lasting
  • Multi-Purpose
  • Gentler on Soft Metals, like Aluminum
  • Less vibration than Grinding Wheels
  • A Consistent Rate of Removal
  • Lightweight Nature

Concerns Regarding Aluminum Grinding

Aluminum is a soft and light metal, there are two main reasons for its wide uses. y It is an extremely flexible metal that can be easily processed and designed than other metals. Aluminum can also be transported at minimum cost, because of its lightweight qualities.

With all these advantages of aluminum, there are certain disadvantages too and what are they let's explore them. 

Heat Tolerance/Low Melting Point

Aluminum is a very sensitive metal and can easily melt with the rising of little temperature by a sanding disc. Its melting point ranges from 865-1240 °F. Very low compare to stainless steel's 2750 ° F and iron 2800 ° F. So, Aggressively grinding of aluminum metal leads to the melting of the material.

Loading/Chip Adhesion

At extreme temperatures, grinding aluminum allows aluminum bits to get lodged between the abrasive grains and lodge them into your grinding disc.  This leads to a rise in temperatures that can damage the aluminum and risk an explosion of the grinding disc if the temperature gets too high.

Oxidation/Aluminum Oxide

Although Aluminum doesn't rust like iron or steel when it is exposed to oxygen, aluminum oxidizes rapidly. Aluminum oxide forms a white layer on the material surface. This is why, to prepare for aluminum welding, you should always grind the surface.

Read: Guide to Aluminum (Fabrication, Grinding, and Finishing)

Tips for Grinding Aluminum with Flap Discs

Tips for Grinding Aluminum with Flap Discs

Here are three important tips for aluminum grinding:

Apply the Accurate Pressure

Although flap discs for aluminum are designed to generate less heat and prevent loading, inappropriate usage can somehow invalidate these benefits. By applying light and accurate pressure when grinding aluminum, you can minimize loading and heat buildup.

Choosing the Right Flap Disc Types

Flap discs come in two different types, T27 and T29.

  1. T27 flap discs are flat and are intended at an angle of 0-15 ° for grinding. For flat sanding and for smoothing and blending surfaces, they are more suitable.
  2. T29 flap discs are conically shaped with a 15 ° angle from the middle of the disc towards the edge. These are supposed to be used as an angle to the surface between 15-25 °. For vigorous grinding and for surface contouring and forming, they are stronger.

Avoid Contamination

It is recommended to use a new flap disc for grinding every time, in order to prevent contaminating aluminum surfaces. For example, if you use old and used flap discs for another project, such as grinding cast iron, it can contaminate the aluminum with pieces of iron.




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