Material Selection

1 M11 MAE – ADVANCED MANUFACTURING PROCESS AND MATERIALS

COVENTRY UNIVERISTY

Faculty of Engineering and Computing

Mechanical and Automotive Engineering Department

COURSEWORK

M11 MAE- ADVANCED MANUFACTURING PROCESS AND MATERIALS

ANOOP VELLITHIRUTHYNHALIL AYYAPPAN 5349292


AUTOMOTIVE BRAKE DISC AND CALLIPER

SUBMITTED BY: ANOOP VELLITHIRUTHYNHALIL AYYAPPAN / ID No. 5349292

MODULE LEADER: PHILIP SWANSON

Table of Contents

List of Figures........................................................4List of Tables.........................................................4Introduction...........................................................5Section 1..............................................................61.1 Functions of the components as a part of the system..............61.1.1 Brake Disc....................................................61.1.2 .............................................................Caliper

61.2 In-service conditions and loading modes of the components........7



1.2.1 Brake Disc....................................................81.2.2 Caliper.......................................................8

Section 2..............................................................92.1 Material Selection of Components using CES Software..............92.1.1 Brake Disc....................................................92.1.2 .............................................................Caliper

112.2 Relevant Surface conditions of the components...................122.2.1 Disc Brake...................................................132.2.2 Caliper......................................................13

Section 3.............................................................133.1 Influence of material on manufacturing route for Disc and Caliper.

133.2 Manufacturing route of the components...........................153.2.1 Disc Brake...................................................153.2.2 Caliper......................................................15

3.3 Micro structural changes of the components during manufacturing process.............................................................15

Section 4.............................................................174.1 Advanced material Selection using CES Software..................174.1.1 Disc Brake...................................................174.1.2 .............................................................Caliper

194.2 Advantages and disadvantages of the advanced materials..........204.2.1 Disc Brake...................................................204.2.2 Caliper......................................................20

Section 5.............................................................215.1 Manufacturing of Advanced material..............................215.1.1 Disc Brake...................................................21



5.1.2 .............................................................Caliper26

Conclusion............................................................28References............................................................29Appendix – 1..........................................................31Table of Comparison of GCI to Advanced Materials....................31

Appendix-2............................................................32Vehicle Data........................................................32



List of FiguresFigure 1 : Caliper Disc brake assembly.................................5Figure 2 : Brake System Layout.........................................5Figure 3 : Cross Section view of Fixed Caliper Disc Brake Assembly.....7Figure 4 - Cross Section view of Sliding Caliper Disc Brake............7Figure 5 : Graph of Specific Compressive Strength Vs Thermal Expansion Coefficient...........................................................10Figure 6 : Graph of Density Vs Price..................................10Figure 7 : Graph of Specific Fatigue Strength Vs Specific Fracture Toughness.............................................................11Figure 8 : Graph of Price Vs Density..................................12Figure 9 : Available Manufacturing Routes for Grey Cast Iron..........14Figure 10 : Graph of Relative Cost Index per Unit of Gray Cast Iron Process...............................................................14Figure 11 : Cast Iron Disc Manufacturing..............................15Figure 12 : Grey Cast Iron Graphite Flakes in Ferrite matrix..........16Figure 13 : Three Dimensional shape of Graphite in GCI - 50 microns. . .16Figure 14 : Graph Specific Compressive Strength vs Thermal expansion coefficient...........................................................18Figure 15 : Graph Fatigue Strength vs Compressive Strength............18Figure 16 : Graph specific Fatigue Strength Vs Specific Fracture Toughness.............................................................19Figure 17 : Ceramic Disc Brake........................................21Figure 18 : Pouring of Carbon fiber into the Moulds...................22Figure 19 : Aluminum Core Insertion...................................22Figure 20 : Filling and leveling of Ceramic in the Die................22Figure 21 : Pressing of Ceramic material in the Die...................23Figure 22 : Mould entering large press for Treatment..................23Figure 23 : formation of Plastic into Carbon..........................24Figure 24: Crucible for Disc heating with Silicon.....................24Figure 25 : Pouring of Silicon Powder.................................25Figure 26 : Machining of Discs........................................25Figure 27 : A finished Composite Disc Brake..........................26Figure 28 : schematic of High Pressure Die Casting....................26



Figure 29 : Caliper with Grey Cast Iron and Aluminum Matrix Composite with Nextel Ceramic fiber.............................................27

List of Tables

Table 1: Comparison of Grey Cast Iron Vs Carbon Fiber ................31Table 2 : Comparison of Properties of GCI and Al/Si Composite.........31

IntroductionAutomotive caliper disc brake is a form of brake used for deceleratingor stopping the automobile or to maintain a constant velocity or to parkthe vehicle on a gradient. The figure 1 is a typical caliper disc brakeand the major components are caliper assembly, Rotor assembly and brakepads. As per figure 2 below ,to stop the vehicle, the brake pads made offrictional material which is attached to the piston of the caliperassembly is squeezed on both sides of the rotor disc by a mechanical,hydraulic or pneumatic force. The friction between the brake pads androtor disc attached to the wheel stops the vehicle and during theprocess the kinetic energy of the vehicle is converted into heat (Abhang& Bhaskar, 2014).



Figure 1 : Caliper Disc brake assembly (Erjavec, 2004).

Figure 2 : Brake System Layout (Abhang & Bhaskar, 2014)

Section 1

1.1 Functions of the components as a part of the system

1.1.1 Brake Disc



The Disc has machined braking surfaces on each side which provides the frictional surface to stop the vehicle wheel mounted to the rotor hub bywheel lug nuts and studs. The wheel bearings in the hub allow the wheel to freely rotate and keeping it concentric to the axle. There are two type of disc brakes- Solid and Vented as the name describes Solid Disc is with material throughout the disc and is heavy but vented discs are having vents made in order to quick heat transfer and to reduce the weight of the disc for providing more fuel efficiency for the vehicle.(Erjavec, 2004).

1.1.2 Caliper

The caliper is the housing that holds the piston and the brake pads .it is connected to the fluid power pack system and when brake is applied, the fluid force is converted to mechanical force making the pads on the piston/caliper squeeze the rotor. The caliper is attached to the stationary part of vehicle such as axle casing or stub axle. The caliperis cast in two parts and assembled with pistons. The friction pads are held in position by retaining pins, spring plates etc. For fluid flow, passages are drilled in the caliper housing and are connected to one another for bleeding (Abhang & Bhaskar, 2014).

There are two kinds of calipers:-

Fixed Calipers ( Figure 3) Floating/Sliding Calipers (Figure 4)

Fixed caliper brakes are disc brakes that use a caliper which is fixed in a position and does not slide or move. The calipers have piston with friction pads on both sides of the disc. The number of pistons may be 2 or 4 according to the vehicle. But in floating/sliding caliper, the outside half of the caliper on which one brake shoe is fixed will move inline opposite to the piston of the other caliper applying a uniform braking from each side on the disc. Normally, floating calipers are withsingle piston (Erjavec, 2004).



Figure 3 : Cross Section view of Fixed Caliper Disc Brake Assembly(Childs, 2004)

Figure 4 - Cross Section view of Sliding Caliper Disc Brake (Puhn,1985).

1.2 In-service conditions and loading modes of the components

“The work a disc brake has to do and the heat it has to dissipate duringbraking are directly proportional to the weight of the vehicle and speedwhen the brake is operated” (Brembo, 2014).



According to Brake Handbook by Puhn(1985), the brake performance limits are:-

Force limit – The magnitude of braking for to be applied on the disc for a smooth operation.

Deflection limit – The allowable deflection of the brake components.

Wear limit - the wear limit of the brake disc and shoes allowed forsafe operation.

Temperature limit – force, deflection & wear depends on the allowable temperature.

Tyre Traction limit - The uniform wear of brakes determines the life of tyres as well.

Data taken from edu-point (Oder, 2009) along with the result for analysing the loading modes of Disc and Calliper.The complete vehicle data is shown in Appendix-2.

1.2.1 Brake DiscThe braking and stopping a heavy vehicle creates huge heat flux into thedisc instantaneously and the high temperature creates high stress in thedisc material. This phenomenon is called as heat shock (Oder, 2009).

From Oder (2009), Normal Force on the Disc – 9125.5 N & Brake disc temperatures – 350°C. The stresses due to Centrifugal loads are 185 MPa and the Maximum thermal Stress is 170 MPa.The temperature above is considered for the particular vehicle model with a certain mass and velocity. But in general, the heat dissipated can range 300 - 800°C (Belhocine & Bouchetara, 2011). The common disc damages or fading and reasons are as follows (Anon., 2014):-

Warping – This is caused by excessive heat making the disc materialsoft and allows reshaping and is caused due to undersized disc and excessive braking, keeping the overheated disc in contact with padscreating uneven cooling or due to asymmetric assembly of pads.

Scarring – caused due to damaged pads and is the uneven assimilation of material on the disc surfaces which softens the disc due to irregularity in cooling and affecting the friction



coefficient between the pads and disc. During the replacement of worn brake pads, the discs are machined off a thin layer in order to remove the scars on the discs.

Cracking- “The brake disc is a heat sink”. During operation, the disc undergoes various cycles of mechanical and thermal stresses. The uneven distribution of the masses due to wears will create imbalance in the operation and the cumulative effects will lead to cracking or permanent damage of the discs.

The following properties are expected with a brake disc for smooth operation (Li & Youg-chen, 2014).

Wear Resistance Compressive Strength Rigidity with Low weight High thermal capacity ,Low thermal expansion , Fast Cooling &

Thermal Stability Abrasive Resistance Capacity to bear high mechanical and thermal stresses

1.2.2 CaliperThe forces of the working fluid are acting on the calipers and the surface forces between the pads and the disc also acts on the caliper. During braking the pressure is 1.14 MPa apart from the force 233N and surface pressure of 0.03 MPa (Oder, 2009).

Floating callipers malfunctions due to sticking which occur due to accumulated dirt and corrosion. This makes the brake pad to rub on the disc even when the brake is disengaged. This affects mileage and cause excessive wear on both disc and calliper. The Calliper must possess highstiffness, wear resistance, Rust prevention (Anon., 2014).

Section 2

2.1 Material Selection of Components using CES SoftwareThe Material selection is performed in CES Edupack 2013 – Level 2. As per Maleque( 2010), the following parameters can be considered for



selection of material for disc brake and caliper along with cost per property.

Compressive Strength Friction coefficient Wear resistance Thermal conductivity Specific gravity

2.1.1 Brake DiscFor the Material selection, graphs are plotted in CES using following material Indices (Maleque, 2010).

σc/ρ Vs α . Price Vs ρ

Where σc – Compressive Strength (Pa) ρ - Density (kg/m3) α – Thermal Expansion Coefficient (strain/°C) Price – GBP/kg

Limits considered for plotting the graph are:-

Working Temperature is 350°C (Oder, 2009). Good Thermal Conductor (Li & Youg-chen, 2014).



Figure 5 : Graph of Specific Compressive Strength Vs Thermal ExpansionCoefficient (CES 2013)



Figure 6 : Graph of Density Vs Price (CES 2013)

Comparing Graphs in Figure 5 and Figure 6, Grey Cast Iron is selected asthe Material for Brake Disc which fulfills the Mechanical Property requirement and with low price which will be desirable for the mass production of Grey Cast Iron Brake Disc.

2.1.2 CaliperAccording to Oder( 2009), the calliper is subjected to the reaction forces of the applied braking force so it should potray high stiffness with fratigue strength and toughness against Fracture during frequent operation. Thus the following Indices are considered.

{K1c /ρ} and {σe/ρ} Price Vs ρ

Where K1c – Fracture Toughness at 107 cycles (Pa m 0.5 ) σe – Fatigue Strength (Pa)



ρ - Density (kg/m3) Price – GBP/kg

The following Limits are considered for plotting the graph.

Working Temperature is 350°C(Oder, 2009). Good Thermal Conductor (Oder, 2009). Cast ability (Oder, 2009).

Figure 7 : Graph of Specific Fatigue Strength Vs Specific FractureToughness (CES 2013)



Figure 8 : Graph of Price Vs Density (CES 2013)

Comparing Graphs in Figure 7 and Figure 8, Grey Cast Iron is selected asthe Material for Caliper which fulfills the Mechanical Property requirement and with low price which is desirable for the mass production of Caliper by Casting.

Iron in metallic form comprise more than 2% of dissolved carbon (steel comprise less than 2%) but Grey cast Iron contain less than 4.5%.Taking its cost, simplicity to manufacture and thermal stability, gray cast iron is the ideal material for automotive brake discs and calipers. The parts are manufactured in the foundry with stringent chemistry and cooling cycles to control the shape, form of the precipitation of the excess carbon and material distribution. This seizes distortion in machining, damps vibration, provide good wear characteristics and resistcracking in frequent operations (Maleque, 2010).



2.2 Relevant Surface conditions of the components

As explained in Sections 1.2.1 and 1.2.2, the Disc and caliper are frequently subjected to Mechanical and Thermal stresses and is always prone to Corrosion and Abrasive wear. The surfaces of the Disc and Caliper must possess surface qualities for provide smooth service.

Some feasible Surface Treatments according to CES Edupack 2013 are electro Plating, Electrophoretic and autophoretic painting, Electroplating, Grinding & Mechanical Polishing, Metal Flame spraying, Organic Solvent based painting, Polymer powder coating, Water based painting etc.

2.2.1 Disc BrakeThe frictional surface of the Disc is to be smooth in order to maintain the constant coefficient of friction between the brake pads and disc (Erjavec, 2004).

The frictional surface to be machined to 125 Micron Surface Finish (ISO N8) and should possess a Brinell hardness of 200(Oder, 2009).

The non frictional contact areas are machined for imparting self cleaning during rotation. The surfaces are either fine machined or coated with anti-rust paint (Puhn, 1985).

2.2.2 CaliperThe piston bores in the Caliper are hardened and machined to high surface finish in order to eradicate damages in operation. The fluid power lines are drilled with extreme care and without wear. The contact surfaces are machined and the un-machined caliper body is left exposed with anti-rust coatings (Puhn, 1985).



Section 3

3.1 Influence of material on manufacturing route for Disc and Caliper.

Grey cast Iron has selected as the Material for both Brake Disc and Caliper, which are used in common. The manufacturing routes for disc andcaliper are different as the Geometry explains, the disc is made as a single piece but the caliper is made of two distinct pieces and machined(Puhn, 1985).

The available manufacturing routes are selected with the aid of CES Edupack 2013 / Process Universe: Edu level 2 –Shaping.

The following Limits are considered as per reference with “Manufacturingprocess overview Process Selection via CES” from CU Moodle (p 45).

Tree: Gray Cast Iron

Limits:

Shape: - Circular Prismatic, Non Circular Prismatic, Solid 3D , Hollow 3D (for both Disc & Caliper) Physical Attribute:- Range of Selection Thickness : 0.01 – 0.03 m ( Considering Solid & Vented) Surface Roughness:- A Process Characteristics : Primary Machining Process , Machining Process,Cutting Process Economic. Attributes (all low):- Relative tooling Cost, Relative equipment Cost, Labor Intensity.

The observed Shaping Process is as shown in figure below which is used for manufacturing of Gray Cast Iron Disc and Caliper.



Figure 9 : Available Manufacturing Routes for Grey Cast Iron (CES 2013)

The Graph is plotted against the Relative Cost per Index Unit for each processes of Grey Cast Iron.



Figure 10 : Graph of Relative Cost Index per Unit of Gray Cast IronProcess (CES 2013)

3.2 Manufacturing route of the componentsSection 3.1 above summarizes the available methods or the choice of manufacturing processes for Gray Cast Iron Brake Disc and Caliper. The commercial manufacturing process of the Disc and Caliper is done precisely with stringent methods incorporating the process methodologies. Brembo (2014) take précised steps for achieving quality Disc Brakes with its Design, Casting, Machining, and Quality Control & Testing.

3.2.1 Disc Brake

Figure 11 shows the manufacturing of Gray cast iron discs by Resin Impregnated Sand Casting for obtaining the best surface and material qualities under stringent chemical inspection. The Casting is heat ANOOP VELLITHIRUTHYNHALIL AYYAPPAN 5349292


treated for stress relieving and then machined on a CNC machining centrefor obtaining the desired shape and surface finish. Thorough inspection is performed for material disparity in machining before the final machining for fixing holes and dimples are performed on the CNC drillingmachine (EBC , n.d).

Figure 11 : Cast Iron Disc Manufacturing (EBC, n.d)

3.2.2 CaliperThe Gray Cast Iron Calipers are manufactured by Sand Casting or Investment Casting- for precision (Puhn, 1985). The Sliding/floating calipers are cast in two halves separately (Internal & External). The castings are inspected for porosity and lean walls and stress relieved .The mating surfaces, bores for piston and fluid lines are machined with High precision CNC Special purpose Machines with the aid of specialized jigs and Fixtures (Matech, n.d).

3.3 Micro structural changes of the components during manufacturing process.

Grey cast iron (GCI) comprises more Carbon or Silicon than white cast irons, and requires a less cooling rate. It’s called ‘grey’ cast iron due to the appearance of a fractured surface and not because of their colour. GCI are quite ductile and possess unreflective fracture surfaces (University of Cambridge, 2013).



Figure 12 : Grey Cast Iron Graphite Flakes in Ferrite matrix (CU Moodle,2014)

Gray cast iron has randomly oriented graphite flakes, which creates brittleness and poor ductility in the material. It is extensively used for manufacturing engine blocks, brake disks, brake drums and housings. It has excellent machine ability and wears resistance characteristics along with damping capability (CES 2013).

Graphite particles are elongated and randomly oriented as in GCI, and are shorter and thicker, and have rounded edges. This graphite flakes inGCI starts crack propagation and growth making it relatively weak and brittle. Figure 12 & 13 represents Microscopic view of GCI (Dawson & Hollinger, 2001).

Figure 13 : Three Dimensional shape of Graphite in GCI - 50 microns(Dawson & Hollinger, 2001)



GCI contains carbon in free form and graphite flakes which cause discontinuity in ferrite causing the easy forming of chips while machining.

Section 4

4.1 Advanced material Selection using CES SoftwareThe Advanced Material selection using CES Edupack 2013- Level 3 is performed by taking the Mechanical & Thermal properties of Grey Cast Iron as the Minimum desirable qualities.

Summarizing major properties of Grey cast Iron (CES 2013)

Density : 7.05e3 – 7.25e3 kg/m^3 Yield Strength: 1.4e8 – 4.2e8 Pa Compressive Strength : 5e8 – 1.1e9 Pa Hardness : 8.83e8 – 3.04e9 Pa Fatigue Strength at 10^7 cycles : 4e7 – 1.7e8 Pa Fracture toughness: 1e7 – 2.4e7 Pa m^0.5 Maximum Service Temperature : 350-450°C Thermal Conductor Thermal Expansion Coefficient : 1.1e5 – 1.25e5 Strain/°C Thermal Conductivity : 40-72 W/m °C Specific Heat Capacity : 430-495 J/kg °C

4.1.1 Disc BrakeThe desirable property of an alternative material for disc brake is (Maleque, 2010)

Light weight High thermal Capacity and low thermal expansion. Mechanical strength against stress and wears.

For plotting the graph in CES 2013, the following Limits were taken

Maximum density – 7.05e3 kg/m^3 ( Minimum of GCI for being light weight)

Minimum service Temperature - 450°C ( Maximum of GCI)



Minimum Compressive Strength – 1.1e9 (Maximum of GCI)

The following Material Indices are considered.

σc/ρ Vs α ( Specific Compressive Strength vs Thermal Expansion Coefficient)

σc Vs σe ( Compressive Strength Vs Fatigue Strength) .

The Tree was selected for Fibers and Composites for advanced materials.

Figure 14 : Graph Specific Compressive Strength vs Thermal expansioncoefficient ( CES ,2013)



Figure 15 : Graph Fatigue Strength vs Compressive Strength (CES 2013)

Comparing the Graphs in Figures 14 and 15, the advanced material for Brake Disc is observed to be Carbon Fibers or Ceramics.

Studying Table 1 in Appendix-1, it concluded that Carbon Fiber Disc brakes are the best alternative material for the replacement of Gray Cast Iron brakes Discs.

4.1.2 CaliperThe current material of manufacture of Caliper is also Grey Cast Iron and the properties are summarized in Section 4.2.1.

. Thus the following Indices are considered.

{K1c /ρ} and {σe/ρ}

Where K1c – Fracture Toughness at 107 cycles (Pa m 0.5 ) σe – Fatigue Strength (Pa) ρ - Density (kg/m3)



The Tree is limited to Ceramics, Composites and alloys along with limitstaken as in section 4.2.1.

Figure 16 : Graph specific Fatigue Strength Vs Specific FractureToughness (CES 2013)

The selection resulted in Titanium alloys, Aluminum Composites, Silicon composites etc. The material as per selection from CES Level-2 indicatedAluminum/Silicon Carbide Composite. The material is selected for Brake Caliper as it has the property of Cast ability.

Analyzing Table 2 in Appendix-1, it obvious that Aluminum Silicate Composites or in general Aluminum Metal Matrix Composites(AMMC) are the best alternative material for the replacement of Gray Cast Iron Calipers(Kedari, 2014).



4.2 Advantages and disadvantages of the advanced materials.

4.2.1 Disc BrakeAdvantages of Carbon Fiber Disc Brake:-

Less Density for the Brakes (CES 2013). The weight is reduced from 50-60% by using Carbon Fiber Disc Brakes

(Brembo, 2014). High Yield strength, Compressive Strength, Fatigue Strength &

Fracture Toughness imparting durability compared to the GCI Discs (CES 2013).

Superior hardness imparting high resistance to wear and tear and Surface Finish.

Superior Service temperature, Heat Capacity and low thermal expansion coefficient giving high performance during frequent braking.

Disadvantages of Carbon Fiber Disc Brakes:-

High cost of Manufacture compared to GCI (CES 2013). Not Suitable for Mass Production- requiring specialized Machines. Long Manufacturing Lead Time (Brembo, n.d.). Lack of Lubricant leading to Distorted performance (GCI has solid

lubricant-graphite) (Maleque, 2010).

4.2.2 CaliperAdvantages of Aluminum Metal Matrix Composites:-

Less density hence less weight compared to GCI Calipers that increases the fuel efficiency (Maleque, 2010).

High Yield strength, Compressive Strength, Fatigue Strength & Fracture Toughness imparting durability compared to the GCI Calipers (CES 2013).

Superior hardness, Surface Finish and anti-oxidizing. Cast ability and Machinability featuring any desirable design. No moisture absorption (Kedari, 2014).

Disadvantages of Aluminum Silicate Composites:-



High cost of Manufacture (CES 2013). Inconceivable for Mass Production with long lead time. Less developed Technology (Kedari, 2014).

Section 5

5.1 Manufacturing of Advanced material The perfect design of the

5.1.1 Disc Brake (Brembo, n.d.)Figure 17 is a typical Ceramic Disc brake manufactured by Brembo. Compared to the Cast iron disc brakes in common cars, in high performance cars, ceramic disc brakes are installed because the high power on wheels demands being light weight as cast iron being heavy and which wear out quickly due to high frictional heat generation when such powerful engine brakes.

Ceramic is heat resistant up to 1000°C thus making it 60times durable than the standard cast iron discs. Ceramic composites require the ceramic materials-carbon fiber is combines with silicon for strength. During manufacturing, the strong Carbon fiber interweaving of filaments is mixed with the heat moldable resin and chopped pieces of raw carbon fibers.



Figure 17 : Ceramic Disc Brake (Brembo, n.d.)

Automated machines pour the carbon fiber into the aluminum molds inthe shape of the disc rings. The first filling station fills the mold cavity in halfway (Figure 18).

Workers then fit a slotted belt around the mold and inserts aluminum cores into the slots (Figure 19).These cores will form a ventilation channel into the disc ring to keep the disc from overheating.

Figure 18 : Pouring of Carbon fiber into the Moulds (Brembo, n.d.)

Figure 19 : Aluminum Core Insertion (Brembo, n.d.)

Now the mold moves to the next filling station where the remainder of the cavity is filled by carbon fiber. A roller levels the top



(Figure 20). The workers closes the mold and small press pushes down the cover to lightly compact the contents (Figure 21).

Figure 20 : Filling and leveling of Ceramic in the Die (Brembo, n.d.)

Figure 21 : Pressing of Ceramic material in the Die (Brembo, n.d.)

The mold enters a large press which applies 2000kg of pressure while heating to 200°C .This compacts carbon fiber and transforms the resin powder into plastic(Figure 22).



Figure 22 : Mould entering large press for Treatment (Brembo, n.d.)

Once the mold is cooled down enough to be handled, workers submergeit in cold water for 5-8 minutes making the disc ring to be pulled out of the cores.

A computer guided laser then examines the mold to make sure that every last core has been removed. When everything is clear, they open the top and bottom sections of the mold and extract the disc rings.

Computer guided machines then smooth out the rough areas and drill tiny ventilations holes.

Then disc ring is put into an oven for 2 days and by gradually heating to 1000°C causing chemical changes transforming the plasticinto carbon (Figure 23).



Figure 23 : formation of Plastic into Carbon (Brembo, n.d.)

Next, in a high heat resistant crucible the disc is placed on five mounts inside the crucible. Then in the middle a funnel into which they pour a ceramic material-fine silicon powder. They load the crucible into the oven for 24 hours gradually heating to 1700°C, melting the silicon. Then it applies low level suction drying thenow liquid silicon into the disc ring. This makes an exceptionally hard material called silicon carbide (figure 24 & 25).

Figure 24: Crucible for Disc heating with Silicon (Brembo, n.d.)

Figure 25 : Pouring of Silicon Powder (Brembo, n.d.)



After a computer guided drill bores mounting holes, the disc ring goes to a chamber where it receives a coat of protective paint. Thepaint shields the carbon in the disc from oxygen which is critical because oxygen burns carbon at high heat. This anti-oxidation treatment significantly increases the life of brake discs. The paint is cured in a oven leaving behind a white residue. A robot sands it off then polishes the entire disc ring surface.

Figure 26 : Machining of Discs (Brembo, n.d.)

Every single brake disc undergoes a meticulous inspection. A sophisticated machine takes thousands of high definition photographs of the surface which the computer then analyses in micron level detail.

To complete the brake disc, they fix the bell, a circular componentin the middle of which connects the brake discs to the vehicle. Theball is either made of Aluminum or stainless steel or bolted in themounting ring of the disc ring.



Figure 27 : A finished Composite Disc Brake (Brembo, n.d.)

5.1.2 CaliperThe Aluminum Metal Matrix Composite (AMMC) Calipers are manufactured by High Pressure Die Casting process (CES 2013). Figure 28 is a schematic of High Pressure Die Casting.

Figure 28 : schematic of High Pressure Die Casting (CES 2013)



With high pressure, the molten metal is injected into the die (die machined with precision and are water cooled) through spruces and runners. The high pressure is maintained until the casting is completelycooled down and ejected thereafter. The casting is machined for precision using special machines and tools. Figure 29 shows the same Caliper manufactured with GCI and AMMC.

Figure 29 : Caliper with Grey Cast Iron (left) and Aluminum MatrixComposite with Nextel Ceramic fiber (right) (Kainer, 2006)



ConclusionThe disc brake and Caliper material is selected for both conventional and advanced material with the aid of CES Edupack 2013. The manufacturing process of the conventional cast iron discs and calipers are studied and the purpose of the advanced material was postulated by observing the limitations of grey cast iron. The advanced material is selected by considering the mechanical and thermal properties of grey cast iron and keeping the requirements as minimum for advanced material.



The Advanced Material for Brake Disc is selected as Carbon fiber and Caliper as Aluminum Metal Matrix Composite.



References

Abhang, S. R., & Bhaskar, D. P. (2014, Febraury 4). Design and Analysis of Disc Brake. 1-3. Pune, India. Retrieved July 14, 2014, from IJETT: http://www.ijettjournal.org/volume-8/number-4/IJETT-V8P231.pdf

Anon. (2014). Retrieved July 15, 2014, from scribd: http://www.scribd.com/doc/6934150/Disc-brake#download

Beeley, P. (2001). Foundry Technology. London: Butterworth - Heinmann.

Belhocine, A., & Bouchetara, M. (2011). Study of the Thermal Behaviour of Dry Contacts in the Brake Discs. MECHANIKA (pp. 271-278). Algeria: University of Sciences and Technology of Oran.

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Brembo. (n.d.). Youtube. Retrieved July 16, 2014

Childs, P. (2004). Mechanical Design. Oxford: Elsevier Butterworth-Heinmann.

Dawson, S., & Hollinger, I. (2001). The eggect of Metallurgical Variables on the Machinability of Compact Graphite Iron. Swedon: Society of Automotive Engineers.

EBC . (n.d). EBC Brakes Corporate Video . Retrieved August 10, 2014, from youtube: http://www.youtube.com/watch?v=e0GbTN0wVYU

Erjavec, J. (2004). Automotive Brakes. NY,USA: Thomson Delmar Learning,Inc.

Kainer, K. U. (2006). Metal Matrix Composites. Germany: Wiley-VCH.

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Li, S., & Youg-chen, L. (2014, July 15). The Disc Brake Design and Perfomance Analysis. Huai'an, China. Retrieved July 15, 2014, from IEEE:http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5768733



Maleque, M., Dyuti, S., & Rahman, M. (2010). Material Selection Method in Design of Automotive Brake Disc. Proceedings of the World Congress on Engineering (pp. 2322-2326). London: WCE 2010.

Matech. (n.d). Double Bore Brake Caliper Line in Mexico made by Matech Industrial Co., Ltd.Retrieved Aug 11, 2014, from youtube: http://www.youtube.com/watch?v=Hh9hunj14ic

Oder, G., Reibenschuh, M., Lerher, T., Sraml, M., Sanec, B., & Potrc, I.(2009, January). Retrieved July 14, 2014, from edu-point: http://edu-point.eu/digitaledition/adveng/AE0301/AE0301_095_102.pdf

Pehle, M. (n.d.). Wear and Damage Charecteristics on Friction Brakes. Retrieved July15, 2014, from BPW: http://www.bpw.co.uk/downloads/technical/V-SB%203902801e_Disc%20Brake%20Wear%20and%20Damage.pdf

Puhn, F. (1985). Brake Handbook. USA: HP Books.

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Appendix – 1

Table of Comparison of GCI to Advanced Materials

Comparing the Properties of Grey Cast Iron with Carbon Fiber (values taken from CES 2013).

Properties Grey Cast Iron Carbon Fiber Remarks of Advanced MatlDensity 7.05e3 - 7.25e3

kg/m^31.8e3 – 1.85e3 kg/m^3

Light weight

Young’s Modulus

8e10 – 1.38e11 Pa 3.7e11 – 3.9e11 Pa Less elastic deformation

Yield Strength

1.4e8 – 4.2e8 Pa 1.9e9 – 2.11e9 Pa High yield Strength

Compressive Str

5e8 – 1.1e9 Pa 2.7e9 – 5.2e9 Pa High Compressive Strength

Hardness 8.83e8 – 3.04e9 Pa 6.47e9 – 7.94e9 Pa High Wear ResistanceFatigue Strength

4e7 – 1.7e8 Pa 1.87e9 – 4.42e9 Pa High Durability



Fracture tough

1e7 – 2.4e7 Pa 1e6 – 2e6 Pam^0.5 Satisfactory in service

Max. ser Temp

350-450°C 530-580°C Excellent

Ther. Ex. Coeff

1.1e-5 - 1.25e-5Strain/°C

2e-7 - 4e-7 Strain/°C

Low Thermal Expansion

Table 1: Comparison of Grey Cast Iron Vs Carbon Fiber (CES 2013)

Comparing the Properties of GCI with Al/Si Composite (CES 2013).

Properties Grey Cast Iron Al/Si Composite Remarks of Advanced MatlDensity 7.05e3 - 7.25e3

kg/m^32.66e3 – 2.9e3 kg/m^3

Light weight

Young’s Modulus

8e10 – 1.38e11 Pa 8.1e10 – 1e11 Pa Satisfactory

Yield Strength

1.4e8 – 4.2e8 Pa 2.8e8 – 2.11e8 Pa High yield Strength

Compressive Str

5e8 – 1.1e9 Pa 2.7e8 – 3.25e9 Pa High Compressive Strength

Hardness 8.83e8 – 3.04e9 Pa 6.86e8 – 1.39e9 Pa High Wear ResistanceFatigue Strength

4e7 – 1.7e8 Pa 5e7 – 1.1e8 Pa Acceptable

Fracture tough

1e7 – 2.4e7 Pa 1.5e7 – 2.5e7 Pam^0.5

Excellent

Max. ser Temp

350-450°C 525-627°C Excellent

Ther. Ex. Coeff

1.1e-5 - 1.25e-5Strain/°C

1.5e-5 - 2.3e-5 Strain/°C

Low Thermal Expansion

Table 2 : Comparison of Properties of GCI and Al/Si Composite



Appendix-2

Vehicle Data

Data Considered for the calculation of Parameters taken for Brake Disc and Caliper Loading (Oder, 2009).

Mass of the vehicle - 70 000 kgInitial velocity – 70 m/sConstant Velocity – 250 m/sDeceleration – 1.4 m/s2

Braking time –50 sEffective radius of the braking disc –0247mRadius of the wheel –0.460mFriction coefficient disc/pad – 0.4Surface area of pad – 20000m2


Documents

Material Selection