Brake Caliper: Part and Functionality

pasture brake Caliper Part and FunctionalityCaliper is inarguably the most crucial part of a braking system in any kind of pasture brake assembly, be it a traditional Drum Brake setup or the more new-fangled Disc Brake assembly. The calliper acts as an interface between the drivers do to soften a moving vehicle and the reaction of the vehicles wheel to this action. Hence, a caliper sees both- The action and the reaction.The of development the are as fol downhearteds High corroding resistance, Good machinability, Good flow characteristics, Lower concentrationThe caliper in itself does not stop a moving wheel but it houses a set of brake shoes which press against the rotors of a wheel and stop them by creating friction. The pressing of the brake shoes takes place due to a hydraulic set-up consisting of pistons on the caliper which push the brake fluid which in turn pressurises the brake shoes.As the primary purpose of the caliper is to move out load onto the brake shoes and to load them, it is essential that the caliper be a rigid part. As a result, calipers have been following the engagement of traditional load bearing materials like Cast Iron, Forged steel, etc. However as every rigid part in an auto comes with an opportunity to save weight, some research is being carried out in order to reduce the weight of the caliper while retaining its characteristic to aim and transfer sufficient load.Brake Caliper current MaterialIn this direction of weight save, aluminum is being employed in the articulate and development of a brake caliper. By nature, aluminium has lower absorption (2.7 g/cm3) as compared to ductile Iron (7.8 g/cm3). This conversion to aluminium has saved weight upto 40 percent. Comparison between Traditional Vs Current MaterialThe design and performance criteria for the caliper castings are stiffness, dimensional rigidness and temperature and fatigue life. The aluminium alloys which are mainly considered for calipers are A354 and A357 alloys.The calipers in the brake system are currently made of Aluminium alloys consisting 7-10% Silicon, 0.15-0.2 % Ferrous, 0.05-2% Copper, 0.03-0.1% Manganese, 0.4-0.6% milligram, 0.1% Zinc, 0.2% Titanium.Table newspaper publisher of Aluminium Alloys (A354A357)Aluminium 354 has higher copper percentage when compared to Aluminium 357 thereof so eutectic change. The rate of corrosion of the Aluminium 354 is higher as compared to Aluminium 357. Both the alloys undergo Boron Nitride Coating where A354 show higher file name extension over A357.This means that choosing 357 over 354 is a collapse choice for our sought after part Brake Caliper.Drawbacks of the Current MaterialOne main drawback of using this material for automotive applications is its low Fatigue strength which is of extreme brilliance in a load bearing part like Caliper. This douse has to be addressed while selecting a new material.Proposed material magnesium Alloy (AZ91)Magnesium is one of the lightest materials with density 1.74g/cm3, compared to Aluminium and Ductile Iron. Magnesium is the most commonly used alloying element as sea peeing has 0.3% which is considered as the major source.The major alloying materials used for the proposed material AZ91 are8.5-9.5% Aluminium,0-45-1%, Zinc,0.05-0.1%,Silicon, upto 0.03% Copper,0.02% plate and 0.05%Ferrous.Chemical Composition of Magnesium Alloy AZ91Minimizing the weight of a caliper leads to the reduction of unsprung weight of the car therefore improving the fuel power and heat dissipation. As the alloy is softer, it has high damping capacity and good fix resistance.Physical Properties of AZ91Mechanical Properties of AZ91Fig.Thermal ConductivityThe thermal conductivity of AZ91 is comparatively low with the other Magnesium alloys which reduces overheating of the brake fluid decreasing the problems associated with it.Fig. net Tensile Strength Vs Strain RateComparison chart of specialised Stiffness and strength of the materialsThe specific s tiffness of Magnesium is considerably personify to that of Aluminium whereas the specific strength is higher in Magnesium. Due to the augment in strength, fatigue resistance increases due to high Magnesium content. Brake Caliper needs high Bending stiffness which is greater in AZ91 because of high elastic modulus. Low melting temperature of Magnesium leads to longer foul life. Magnesium displays higher corrosion resistance than aluminium when it is coated with Phosphate-Permanganate and Zinc-Nickel alloys. though the cost is more than the former, it can be used because of high crimp stiffness as well as lighter mass which results in good functioning of the vehicle.Magnesium Alloy (AZ91) is lower in density than Aluminium Alloy (AL3XX) thereby reducing the weight (33% lighter) and improving the capacity of the vehicle. It displays high strength, modulus of elasticity, heat dissipation and castability when compared to AL3XX.Magnesium alloys also exhibit better nature when exposed to physical loading like better damping readiness and lesser elongation at failure loading.