Chapter 1: Importance of brake caliper housing in automotive braking system

Importance of brake caliper housing in automotive braking system-chapter 1

Suppose you had to choose a part of your vehicle you wanted to be efficient or one part of your car you always kept shipshape. You would probably say your car's braking system. There is no doubt that a correctly operating vehicle contains numerous critical components. However, consumers always inspect their braking systems during the inspection. You can prevent road accidents if your vehicle's braking systems function properly.

When considering the manufacturing phase, the braking system is one of the vehicle's most critical and significant aspects. From early mechanical braking systems to hydraulic braking systems and now servo and electromagnetic braking systems, the automotive industry has witnessed a variety of braking systems. 

The HYDRAULIC BRAKING SYSTEM is the most effective and dependable of the abovementioned methods, making it the most extensively used and important braking system for modern vehicles. Mechanical braking was accomplished using springs, linkage, and other mechanical components. The hydraulic pressure of the liquid is employed to perform the desired braking in the hydraulic braking system. In contrast, magnetism is utilized to carry out the desired braking in electromagnetic braking systems.

The brake plates in the BRAKING CALIPER are the most important aspect of this braking system. The hydraulic braking principle applies hydraulic pressure to the braking plates. Glycol ethers or diethylene glycol force the brake pads to stop the moving wheel by creating pressure within. The caliper is in charge of delivering pressure to the brake plates.

This process generates heat and friction at the braking point, the brake caliper, and breaking plates. As a result, the manufacture of the same braking caliper must be extremely exact and capable of providing the calipers with the ability to endure the heat and friction generated while braking.

In this article, we will look at the complete manufacturing process of braking calipers. We will share the knowledge in different chapters to make the article easier to grasp. 

In this chapter, we have focused on the machinery used and its desired capabilities. We have covered the entire manufacturing process of brake calipers. We will divide the article into chapters to make it easier to comprehend the process. 

Before we go into the production process, let us first define BRAKE CALIPER and where it is utilized in braking systems.

Brake Caliper

A caliper is a component of the disc brake system in most cars' front brakes. The brake caliper assembly is a stationary or non-rotating component of the braking system that may be mounted on the spindle or splash shield for support. The caliper assembly comprises the caliper housing, pistons, seals, dust boots, brake pads, and the bleed port screw.

The caliper contains one or more pistons that are hydraulically activated by the system's hydraulic oil pressure. When the driver presses the brake pedal, brake fluid runs into the caliper cylinder. Fluid pressure forces the piston to move outward to apply the brake pads.

The piston seals in the caliper cylinder keep the piston and cylinder from leaking. When the brakes are removed, the piston seals help pull the piston back into the cylinder. When the brakes are released, the elastic action of the seal acts as a spring to retract the piston and maintain a clearance of roughly 0.125 mm. The piston boot keeps road dirt and water away from the caliper piston and cylinder wall. The boot and seal are designed to fit into grooves in the caliper cylinder and piston.

The bleeder screw removes air from the hydraulic system. When loosened, it is threaded into the top or side of the caliper housing, and system pressure is utilized to drive fluid and air out of the bleeder screw.

Disc brake pads

Disc brake pads are steel shoes that are riveted or glued to the liner. Asbestos or semi-metallic friction material is used to make brake pad liners. Many new automobiles, particularly front-wheel drive, have semi-metallic linings that can operate at greater temperatures without losing frictional qualities. Anti-rattling clips are widely used to prevent vibrating and rattling brake pads. The clips clamp into the brake pads, creating a tight fit in the caliper.

Calliper housing is composed of aluminum or forged steel; steel is a less expensive material in comparison to aluminum. 

Machine configuration considered for this process:

The machine utilized to demonstrate this procedure was set up as shown below.

The horizontal machining center with twin spindle and twin pallet machines:

Machine Configuration: Twin spindle, Twin Pallet Machine HMC

1. X-Axis travel 320mm, servo axis with rapid travel 60 m/min, with brake motor option.
2. Y-Axis travel 800mm, servo axis with rapid travel 70 m/min, with brake motor option.
3. Z Axis travel 400mm, servo axis with rapid travel 60 m/min, with brake motor option.
4. The Center distance between two spindles is 320 mm.
5. W Axis servo drive, with 48 tools capacity.
6. A1 Axis is hydraulic with an encoder for pallet positioning of rotary pallets.
7. A2 Axis is servo with torque motor, 4th axis rotary axis.
8. A3 Axis is servo with a torque motor, 4th axis rotary axis.
9. Spindle 1 & 2 HSK A80 with 20 KW power and 126 nm torque,8000 rpm, with through coolant and high-pressure options for 18 bar.
10. Hydraulic counterbalancing.

The machine has a direct tool change, which occurs when the X, Y, and Z axes are moved simultaneously, resulting in a tool change time of 3 to 5 seconds.

In addition, the chip-to-chip time will be 5 seconds.

The pallets A2 and A3 are rotating axes with servo torque motors, and the rotary drums each have a working envelope of 500 diameters. The A2 axis serves as a servo fourth axis, as does the A3 axis. According to the process sequence, the part can be oriented to the required angular position, which is possible in the fourth axis rotation.

Fixture concept:

The machine has two servo fourth-axis pallets, one for caliper housing LH and RH and the other for caliper bracket LH and RH. The second caliper setup for the bleed port is planned for another setup on the same pallet and fixture plate. Both configurations are intended for two-component loading.

Component Datum: Caliper Housing

Component Location: Cone

Orientation: V block at half bore end

Resting: Flat pad

Clamping: Against resting

It was the entire machinery configuration during the whole production process.

The cutting parameters are used to determine the process sequence and operational details.

Pallet One is outfitted with a caliper housing fixture arrangement. Two calipers are loaded, and the fixture is ready for cutting after a dry run.

Tooling for Calliper machining:

1. T1: Drilling pin hole for dia. 18.5, through;

In other circumstances, lug face milling is not required, and the pinholes are drilled straight into the case face. Because of the case face and the possibility of drifting the tool, the beginning settings are maintained low.

The cutting speed is 145 m/min, feed per rev is 0.1mm, the feed rate is 250 mm/min, 2500 rpm, the tool travel is 5 mm, and the pure cutting time is 1.2 sec.

The parameters are increased after 5 mm and changed to

• The cutting speed is 145 m/min, feed per rev is 0.3 mm,
• the feed rate is 750 mm/min, 2500 rpm,
• the tool travel is 20 mm, and
• pure cutting time is 1.6 sec.

02.  T2: Milling of clearance pad bottom face and half bore vertical face; the cutter disc diameter is 200mm. Z/8;
The cutter mills the open cut's vertical face first, then touches the bottom face. Because we must mill the entire bottom face, we must shift to the Z axis to accommodate the clearance width.

The cutting speed is 302 m/min, feed per rev is 1.45 mm, the feed rate is 700 mm/min, 480 rpm, tool travel is 46 mm, and pure cutting time is 3.94 sec. Now the cutter is moving in radius for milling the bottom face first travel is 22.5 mm and then 6 mm.

The cutting speed is 302 m/min, feed per rev is 1.25 mm, the feed rate is 600 mm/min, 480 rpm, the tool travel is 22.5 mm, and the pure cutting time is 2.25 sec. When the tool touches the bottom, the feed is reduced to 0.625, feed rate 300 mm/min, for the travel 6mm. The cutting time for this cut is 2.05 sec.

03. T3: Milling of control cut on half bore vertical face and rough bore of the main bearing bore. The cutter diameter for the control cut is 41/53.6mm. Z/1/4;

The cutter first mills the open cut's vertical land and then touches the bottom radius.

The cutting speed for vertical travel is 129 m/min, feed per rev is 0.45mm, the feed rate is 450 mm/min, 1000 rpm, the tool travel is 15 mm, and the pure cutting time is 2.00 sec. 

The cutter is now moving in Z to mill the whole width face, with tool travel of 6 mm.

The cutting speed is 129 m/min, feed per rev is 0.25mm, the feed rate is 250 mm/min, 1000 rpm, the tool travel is 6 mm, and the pure cutting time is 1.44 sec. 

After radius milling, the tool moves in the Z direction to rough the bearing bore.

The cutting speed for roughing is 168 m/min, feed per rev is 0.9mm, the feed rate is 900 mm/min, 1000 rpm, tool travel is 27 mm, and the pure cutting time is 1.80 sec.

Now the cutter is moving further in Z for milling the balance step, and the tool travel is 16 mm. The cutting speed is 168 m/min, feed per rev is 0.12mm, the feed rate is 500 mm/min, 1000 rpm, and the pure cutting time is 1.92 sec.

04. T4: Facing and entry bore of W Line Face of the main bearing bore;

The cutter diameter is 72mm. Z/2, The cutter will travel in Z for 12 mm.

The cutting speed for initial travel of 7 mm is 226 m/min, feed per rev is 0.25mm, the feed rate is 250 mm/min, 1000 rpm, tool travel is 7 mm, and the pure cutting time is 1.68 sec.

Now the cutter is moving in Z for further travel of 5 mm, and the cutting speed is 226 m/min and, feed per rev is 0.12mm, the feed rate is 120 mm/min, 1000 rpm, the tool travel is 5 mm, and the pure cutting time is 2.50 sec.

05. T5: Seal grooving operation; the cutter diameter is 52.3mm. Z/3;

The cutter will travel in interpolation to construct the seal groove, 

The cutting speed is 159 m/min, feed per rev is 0.04 mm, the feed rate is 40 mm/min, 965 rpm, tool travel is 11.3 mm for the cutter entry, and cutting time is 16.95 sec.

The tool, once enters in the bore inner dia, the cutting parameter changes to The cutting speed is 159 m/min and feed per rev is 0.08 mm, the feed rate is 80 mm/min, 965 rpm, the tool travel is 23 mm for the cutter entry, and the cutting time is 17.03 sec.

The grooving profile is completed, and now the tool will come out in the feed. The cutting speed is 159 m/min, feed per rev is 1.04 mm, the feed rate is 1000 mm/min, 965 rpm, tool travel is 11.3 mm for the cutter entry, and cutting time is 0.68 sec.

06. T6: Piston bore reaming operation, the reamer diameter is 54mm. Z/6; 

The tool will travel in feed for finishing the main bore in Z.

The cutting speed is 160 m/min, feed per rev is 0.84 mm, the feed rate is 792 mm/min, 943 rpm, the tool travel is 32 mm for the cutter entry, and the cutting time is 2.42 sec.

07. T7: Pad end milling operation, the end mill diameter is 12mm. Z/4; 

The two-pad milling is done with a 12-dia end milling cutter. The cutting speed is 90 m/min, feed per rev is 0.42 mm, the feed rate is 1004 mm/min, 2390 rpm, tool travel is 26 mm for the cutter entry, and cutting time is 1.55 sec.

08. T8: Connecting hole drilling and spot facing operation, where the drill spot face diameter is 9.05/28mm. Z/2.

The drilling and spot-facing are combined tools.

The cutting speed for drilling is 90 m/min, feed per rev is 0.2 mm, the feed rate is 634 mm/min, 3170 rpm, tool travel is 11 mm for the drilling, and cutting time is 1.00 sec.

At the end of the drilling, spot facing is done with the cutting parameters like; cutting speed 110 m/min, rpm 1250, feed/rev 0.2, feed rate 250 mm/min, and the cutting time is 1.7 sec.

09. T9: Connecting hole tapping operation, and the tap size is M10x1.

The cutting speed is 18 m/min, feed per rev is 1 mm, the feed rate is 570 mm/min, 570 rpm, tool travel is 12 mm, and cutting time is 1.26 sec.

There will be a dwell of 0.5 sec before the reverse travel of the tap;

The cutting speed is 36 m/min, feed per rev is 1 mm, the feed rate is 1140 mm/min, 1140 rpm, tool travel is 12 mm, and cutting time is 0.63 sec.

10. T10: Channel hole drilling operation, the drill diameter is 3.1mm. Z/2;

The cutting speed for drilling is 60 m/min, feed per rev is 0.12 mm, the feed rate is 740 mm/min, 6160 rpm, the tool travel is 21 mm for the drilling, and the cutting time is 1.70 sec.

11. T11: Bleed hole drilling operation, the drill diameter is 6.8 mm. Z/2.

The cutting speed for drilling is 90 m/min, feed per rev is 0.18 mm, the feed rate is 758 mm/min, 4210 rpm, tool travel is 19 mm for the drilling, and cutting time is 1.5 sec. 

12. T12: Bleed hole tapping operation, and the tap size is M8x1.25.

The cutting speed is 14 m/min, feed per rev is 1.25 mm, the feed rate is 716 mm/min, 573 rpm, tool travel is 15 mm, and cutting time is 1.22 sec.

There will be a dwell of 0.5 sec before the reverse travel of the tap;

The cutting speed is 28 m/min, feed per rev is 1.25 mm, the feed rate is 1432 mm/min, 1146 rpm, tool travel is 15 mm, and cutting time is 0.61 sec.

13. T13: Channel drilling bleed hole operation and the drill diameter is 3.5mm. Z/2.

The cutting speed for drilling is 60 m/min, feed per rev is 0.12 mm, the feed rate is 655 mm/min, 5500 rpm, tool travel is 10 mm for the drilling, and cutting time is 0.92 sec.

The caliper housing procedures are completed on the first setup. This setup has a cycle time of 146.5 seconds. The second pallet is outfitted with the clamping configuration for the caliper bracket. There are 13 tools used.

The second phase of the operations performed on the caliper will be covered in the following chapter of the article; manufacturing braking calipers.
Read Chapter 2 here.

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