Semi
metallic brake pads are among the most widely used brake pads in the
world. They are the preferred types of brake pads in almost every
commercial vehicle these days. Read on to know more about these
robust brake pads.
A
car is a magnificent piece of engineering. The amount of research
that goes into the design and manufacture of every minute aspect of a
vehicle is mind-boggling. Sadly, not may appreciate the intricacies
of this engineering and only have a regard for the final product and
their functionality. Take brake pads for example. The primary
requirement for an efficient baking system is a firm, yet smooth
braking capabilities over a wide temperature range and varied road
conditions. Today, auto markets are flooded with a variety of
consumer grade brake pads - from organic brake pads and semi metallic
brake pads to ceramic brake pads that feature their own set of pros
and cons. The choice in material dictates the friction of the pads,
which in turn is responsible for the stopping power of the brake
pads.
What
is a brake pad?
A
disc brake pad comprises of friction materials mounted on a sturdy
steel backing plate. Each wheel has two brake pads contained in the
brake caliper on either side of the rotor, with the friction sides
facing the rotor. When the brakes are applied, the caliper squeezes
the brake pads so that they contact the rotating rotor, thus slowing
down and eventually stopping the vehicle. Over time, these brake pads
tend to wear out with use and need to be replaced at regular
intervals, as recommended by the manufacturer, to ensure that they
maintain a credible degree of stopping power. The disc wear rate
varies with the type of material used and the number of miles driven.
A
brief history of brake pads
Asbestos
was the preferred material of brake pads manufacture during the
1950’s and 60’s when disk brakes began to gain popularity.
Asbestos has excellent durability and heat resistance
characteristics, which has made it the preferred material of choice.
However, as its detrimental environmental and health implications
came to light in the 70’s, it was phased out and replaced by safer,
more durable materials that were made of organic and metallic
compounds.
The
organic brake pads are primarily made of glass, rubber and associated
“soft” compounds that are fused together with heat resistant
resins. These types of braking pads are lighter in weight and are
quieter in operation. However, owing to their soft structure, these
pads tend to wear out quite fast. Hence, they are suitable for
smaller vehicles that do not require frequent hard stops.
Metallic
pads, like the name suggests, are made of metals such as iron,
copper, steel etc. along with a graphite lubricant. The materials
used for the manufacture of this product give it a unique structure
and thus makes it one of the most robust types of brake pads today.
These types of pads are known to easily dissipate heat from the
rotors during braking. This increases the overall life of the entire
braking system and requires less frequent rotor replacements. The
metallic brake pads are considered to be much better than their
organic counterparts in terms of overall performance. Another popular
type of brake pads in the markets today are the ceramic pads, which
are made of stacked ceramic fibers, bonding materials, and filler
materials with trace amounts of metal for added stability.
What
are semi metallic brake pads?
Semimetallic brake pads are an amalgamation of both metallic and organic
brake pads. They are made of strands of steel, which comprises of up
to 35- 60% metal by weight. These metallic stands, which are made of
steel, iron, copper, etc., are combined with friction modifiers and a
graphite lubricant (and infused in an organic resin) that makes them
highly durable. The metallic composition has a high thermal threshold
and hence these brake pads have a wider operating temperature range,
which results in low compressibility and provides firm braking.
Apart
from the efficiency of operation, another factor that is responsible
for the popularity of semi metallic brake pads is their cost factor.
The compositional materials and manufacturing methods of semi
metallic brake pads are not cost intensive, and hence are available
at a cheaper price. Since they don’t wear as much as other types of
brake pads, they don’t have to be replaced frequently. These pads
are extremely versatile and can be used for small cars and large
trucks/ SUVs as well. Despite all advantages, these brake pads do
come with their own set of problems. The most persistent of them are
the noise and the brake dust generated during braking. This material
is also quite abrasive, and tends to wear brake rotors faster than
organic brake pads.
Comparing
with the closest rival- Ceramic brake pads
The
tussle between the semi metallic brake pads and the ceramic type has
always yielded in ambiguous results. Your choice in either one will
always be a compromise- either in terms of longevity or performance.
Although the ceramic pads offer cleaner, quieter stops, you will be
sacrificing braking performance. While the semi metallic ones offer
excellent stopping power, they do result in loud screeches and dust
from the eroding pads.
Ceramics
are harder than their semi metallic counterparts. This hardness does
increase their life, but as they have a lower cold bite, the ceramic
brake pads tend to be practically less effective in colder weathers.
Ceramics are not very good heat sinks and cannot effectively absorb
the heat from the rotors during braking, and contribute to the
increase of temperature within the entire braking system. Ceramics
also have a lower coefficient of friction and were never designed for
high performance action. Semi metallic brake pads, however, offer an
excellent stopping power despite the noise and dust. They operate
better on a wide range of temperatures due to their higher thermal
threshold. They offer a consistent stoppage throughout their wide
band of operating range.
Pad
selection
Selecting
the right braking pad can be quite difficult. The right kinds of pads
are not always the most expensive ones. You need to consider various
factors such as the weight of the vehicle, acceleration, and the
ambient temperature of the place you drive in as well. When in doubt,
replace your existing brake pads with factory specified types. This
will ensure optimal performance for your vehicle. If you do choose to
upgrade your existing pads, then you need to consider the
implications and take professional help in choosing and installing
the right kinds of brake pads. In most cases, it is recommended that
you use high quality, semi metallic brake pads which offer excellent
stopping power and fade resistance.