Abrasives are
an extremely important material that are used in grinding, deburring,
and finishing of the product. The ideal selection of abrasives is highly imperative
to attain a healthier appearance of the product.
In spite of abrasives being a critically important material for
any machine workshop, they are usually overlooked. It is important that a
welding or metal fabrication operator should select the right abrasive, as it
can reduce the cost and give better outcome. Inappropriate weld knowledge, prolonged
deburring operations, surface finishes that fail to meet drawing
specifications—are the consequences of using the inappropriate abrasive.
However, as thousands of options are available in the market for
choosing the best pad, belt, cloth or wheel for this highly important metal removal
process, selecting an abrasive can be as extremely challenging. Also, as deburring
and polishing are usually the last part of the whole process for various
workpieces, using an incorrect abrasive can be a highly expensive mistake.
Here are 5 tips that can help you choose the
best abrasive.
1. Work material that needs to be grounded
Abrasive should be chosen based on the type of
material to be grounded. The most usually used abrasive is made up of aluminum
oxide (Al203) or silicon carbide (SiC). Silicon carbide is ideally suitable for
fragile and rigid materials such as hard steels, tungsten carbides, stones, and
other porcelain materials.
Aluminum oxide is an ideal choice, if the object
produced is built with hard materials and has better tensile strength like tough
bronze, alloy steel, mild steel, annealed malleable iron, etc.
Hence, one should choose an abrasive as per
the material of the workpiece.
2. Degree of stock removal
Quick removal of metal is essential to finish
the workpiece in less time duration. The degree of stock removal completely
depends on grade, grain size, and structure of abrasives.
GRADES: Rigid materials possess enhanced resistance to
the wheel at the time of grinding. Such materials are tough for the wheel to
grind, and thus weaken the wheel and results in inefficient grinding. In case
of metals having greater strength, it is ideal to use an abrasive of which
particles break easily, thus allowing the wheel to shape the workpiece
efficiently.
In case of softer materials, an abrasive
having high-quality bond is suggested.
GRAIN SIZE: It is detected by the mesh number that is maintained
even after passing through a vibrating strainer. Usually, in case of softer
materials, an abrasive having coarse grain size is ideal; and in case of harder
materials, fine grain is suggested.
STRUCTURE: It is the cavity between the abrasive and
workpiece. For harder materials, an abrasive having dense structure is necessary.
And in case of softer materials, an abrasive having open structure is optional
as the degree of metal removal is high and the size of the chip is also large.
3. Area of contact between wheel & workpiece
If the area of contact is big, the whole
grinding pressure is circulated across a huge area. The pressure per unit automatically
reduces. Therefore, a softer wheel is required in cases where the curvature of
contact is more. Moreover, a harder wheel is an ideal choice in case of
external grinding.
4. Grinding machine’s condition
The abrasives used should be in a good
condition; there must be no scratches or cuts on it. For a long-lasting
grinding machine, purchase abrasives as per the machine. If the machine is heavyweight
and tough, it is ideal to use a soft grade abrasive. On the other hand, in case
of lightweight machines, it is ideal to use a hard grade abrasive.
5. Work Speed and Wheel Speed
In the process of grinding, 70% of the issues take
place owing to the incorrect selection of work speed as well as wheel speed. If
the surface of the workpiece is burnt, the speed of the wheel can get reduced. The
speed of the wheel is dependent on the type of process such as internal
grinding, external grinding or parting off operation. Work speed depends on the
type of finish required for that particular workpiece. For greater work speed,
a harder wheel is required.
Other aspects that are needed to be deliberated
while choosing an ideal abrasive are revolutions per minute, the period it
takes to finish the job, cost, user-friendliness, and others.
The Bottom Line
After going through all these tips for
choosing an abrasive, one can easily figure out the ideal abrasive for any
workpiece. So, if you are a welding or metal fabrication operator planning to purchase an abrasive you should take care of all these
factors, and choose the best that suits your needs.
Comments
Post a Comment