Automotive & Motorsport Surface Engineering and Finishing
Automotive and motorsports are one of the most advanced fields in today’s world. A vehicle is a great demonstration of engineering practices; requiring meticulous design and machining work. Being the most competitive sector in manufacturing and technology, this field requires persistent validations for improvements as well as safety.
The meticulosity of engineering work in the automotive industry can be realised by acknowledging the fact that many small components are combined to make a final assembly and each part plays its own role in running the whole system. For instance, in a vehicle, the engine, transmission, braking, suspension and steering system all work together and thus we see a car running smoothly on the road. If we break down these bigger components, we can have a better understanding of the meticulosity of work, for example, in an engine, the opening of the valve, working of the fuel injector, movement of the piston, crankshaft, camshaft and ignition of air-fuel mixture etc, all these variables are calculated and ensured within the calculated values for the engine to function perfectly.
The functionality of different components adds different requirements to a part. In some places, we require airtight contact between two parts like the intake valves, exhaust valves, piston and cylinder walls, whereas in many other places we can accept little roughness like the housing of different components. Depending upon the utility of the part, microscopic finishing levels if not cared for, can be a cause of failure of the assembly. Therefore, it is important to take into consideration the high finishing standards.
“When the difference between winning and losing can be 1/1000th of a second, having critical components Lapped and Polished by Kemet can give you the edge”
In motorsports, different components must perform well at high torque levels at extreme speeds. The interaction of different metal surfaces in such circumstances can cause overheating, power loss and eventually a catastrophic failure, if different standards are not cared for.
Applying proper manufacturing techniques and adhering to the strict standards of the motorsports industry we can expect really good results. Even microscopic abnormalities such as excess material or contaminants can be a cause of an underachieving vehicle. Kemet gives you the confidence and trust you need in having your components finished to the absolute max, ready for racing events such as Formula 1 and Nascar. With the best machining techniques and equipment, you will definitely stand out in the racing world.
With advanced manufacturing methods and equipment, we can observe decreased friction, improved efficiency, improved maintenance and durability as well as longevity of a part/ component. For a vehicle to stand out in the racing world, it is extremely important for us to ensure the quality of the following components. For racing engines, one replaces normal parts with high-end parts.
- Engine (Camshaft, crankshaft, tappets, valves, piston, rocker arms)
- Braking system (Disc, disc pads, drums)
- Transmission component (Clutch, gears, differential, pressure plate)
- Steering system
When we perform any type of machining operations on components we are still left with some irregularities or non-uniformity, which can be referred to as peaks and valleys. The peaks and valleys are of microscopic size and thus cannot be seen or felt, but in some mechanical operations where two different components are in close contact with one another, this can be detrimental. Therefore, we require an extremely high finish for some components. If the quality is not up to the standard, it is obvious that the component will fail. Thus, a high degree of flatness and surface finish is carried out with the help of a process known as lapping.
Precision Finishing Automotive Parts
With extreme precise measurements, an engine is brought to life and to ensure it is living we must take into consideration the precision requirement of different components. Even the microscopic roughness can cause a component to fail.
Many components in a vehicle require a high degree of finish. One of the integral parts of a vehicle is the transmission system. The flywheel has a clutch plate and pressure plate mounted on it which serves as a mode of power transfer. The finish between these surfaces ensures a smooth transfer of power from the engine to the transmission, thus requiring a lapping process. Similarly, the brake disc is to have a good finished surface.
The lapping process plays a great role in smaller components of an engine, the seat ring and wedge of the valve are lapped so that it sits perfectly and there is no leakage. The camshaft, which operates the intake exhaust valves is lubricated throughout the engine operation and also requires a high surface finish. Pistons and piston pins which are an integral part of an engine also require a high degree of finish. If any roughness is present, the engine will not run smoothly and there would be hesitation in the conversion of power from linear to rotational. Similarly, components like spray nozzles, injectors, hydraulic pumps and impellers all require a high-degree finishing process like lapping for a smooth workflow.
Finish standards for Engine and vehicle-driven components are given below in the table. The following values can be considered as a standard for different components but it must be remembered that the values for different companies would vary to some extent.
| Component | Acceptable Roughness (Micro inches) | Manufacturing process |
|---|---|---|
| Cylinder bore | 16-20 | Honing |
| Tappet bore | 60-75 | Reaming |
| Main bearing bore | 60-80 | Boring |
| Head surface | 40-50 | Milling |
| Piston skirt | 45-55 | Lapping |
| Piston bore | 30-38 | Lapping |
| Piston pin | 9-12 | Lapping |
| Crankshaft Main Journal Bearing | 4-6 | Lapping |
| Crankshaft Connecting Rod Journal Bearing | 4-6 | Lapping |
| Camshaft Journal Bearing | 4-6 | Lapping |
| Camshaft | 15-20 | Lapping |
| Rocker Arm | 14-20 | Lapping |
| Intake valve stem | 34-38 | Lapping |
| Intake valve seat | 25-40 | Lapping |
| Exhaust valve stem | 18-20 | Lapping |
| Exhaust valve seat | 34-45 | Lapping |
| Tappet Face | 4-5 | Lapping |
| Hydraulic lifter | 22-25 | Lapping |
These standards get stricter for performance cars, the below table is related to the standards of automatic transmission, clutch and braking systems. If any of the moving parts fail earlier than the estimated time then the problem lies mostly with the surface inspection. Depending upon the requirement of different engines the standards vary. A recent example has shown that in diesel engine piston pins with 6 and 5 micro inches failed rapidly but a fine finish to 4 micro inches would work well whereas, in petrol engines, the required standard is 9 micro inches.
| Automobile Driven Components | Acceptable Roughness (Micro inches) | Manufacturing Process |
|---|---|---|
| Front Pump Journal Shaft | 18-22 | Lapping |
| Front Pump Shaft Thrust surface | 11-14 | Lapping |
| Reverse Gear Drum – Braking surface | 150-170 | Turning |
| Intermediate Shaft Journal no1 | 6-7 | Lapping |
| Intermediate Shaft Journal no2 | 50-60 | Lapping |
| Central main shaft journal | 23-27 | Lapping |
| Central Main Shaft Thrust Surface | 20-30 | Lapping |
| Output Shaft Journal no1 | 14-16 | Lapping |
| Output Shaft Journal no2 | 10-15 | Lapping |
| Output Shaft Journal no3 | 27-32 | Lapping |
| Front Drum – Braking Surface | 90-110 | Turning |
| Clutch Plate | 16-24 | Turning |
| Main shaft Journal No1 | 20-25 | Lapping |
| Main Shaft Journal No2 | 25-30 | Lapping |
| Low Range Reaction Member – Thrust surface 1 | 35-40 | Lapping |
| Low Range Reaction Member – Thrust surface 2 | 65-75 | Lapping |
| Front Drum – Braking surface | 90-110 | Turning |
| Brake Drum – Front | 65-75 | Turning |
| Rear | 75-85 | Turning |
| Clutch Pressure plate | 40-50 | Turning/Lapping |
| Kingpin | 6-8 | Grind |
| Universal Spider Race | 14-16 | Grind |
Deburring Automotive Components
The process of removing a burr is known as deburring. Small ridges or protrusions left in metal after different mechanical operations (like turning, milling, welding, grinding and casting) are called burrs. These burrs affect the quality of the component and can disturb its functionality. It is important to treat these burrs to ensure longevity and proper functionality of the part/assembly. To enhance the life of a machined part, we remove the burrs through different techniques involving the following:
- Manual deburring - In this process, experienced workers remove the burrs with the help of hand tools. It is obvious that it is a dilatory process, as well as the quality of deburred part cannot match automated quality
- Machine deburring - In machine deburring, different types of machines are used to remove burrs which includes grinding and CNC machines. It is an expensive process but renders a good quality machined part
- Thermal deburring - In this process, the imperfection is removed by melting it as it is subjected to high temperature and pressure
- Electrochemical deburring - The burr is removed with the help of electrochemical energy and this process is useful for working with challenging metals
The Automotive industry performs different mechanical processes on components involving casting, forging and milling. All these processes leave behind some rough surfaces which are known as burrs. The precision that is required in a transmission system has zero allowance for rough surfaces or burrs. If there are any burrs, they will break off from the main part during operation and remain suspended in the transmission system, eventually damaging the system.
Another example includes the engine blocks; which are normally made through casting. The process of casting always gives rise to rough surfaces such as burrs. These burrs must be treated to maintain the aesthetic as well as the practicality of the part. Similarly, other examples include axle shafts, differentials, valves, transmission housing, engine parts etc. Component examples below, using xebec deburring brushes:
Transmission case
Processing conditions
Tool: XEBEC Brush Surface (A11-CB40M)
Processing detail: Deburring of the matching surface after face milling process
Spindle Speed (min -1): 2,160
Table Feed (mm/min): 7,000
Depth of cut (mm): 0.5
Before and After Deburring Transmission case
Injector Body (Nozzle)
Processing conditions
Tool: XEBEC Brush Surface (A11-CB15M), XEBEC Floating Holder (FH-ST-12)
Processing detail: Deburring the edge face after drilling process
Spindle Speed (min -1): 2,000
Depth of cut (mm): 4
Before and After Deburring Injector Body
Cylinder Head
Processing conditions
Tool: XEBEC Brush Surface (A11-CB100M)
Processing detail: Deburring of the matching surface after face milling process
Spindle Speed (min -1): 1,350
Table Feed (mm/min): 2,000
Depth of cut (mm): 0.5
Before and After Deburring Cylinder Head
Reduction Gear
Processing conditions
Tool: XEBEC Brush Crosshole (CH-A12-3L)
Processing detail: Crosshole deburring after drilling process
Spindle Speed (min -1): 10,800
Table Feed (mm/min): 300
Non-Destructive Testing Automotive Parts
We also need to ensure the quality of a component, because after assembling a vehicle it is difficult to point out the defect. Therefore, we need to check different components before assembling as to ensure standard quality. For that purpose, we perform a different type of testing on the equipment. Here we will discuss Non-Destructive Testing techniques (NDTs), where there is no damage caused to the test specimen. With time and advancements in science, we use the following Non-Destructive tests for the Automotive Industry which doesn’t damage the workpiece.
- Penetration Testing (PT)
- Eddy Current Testing (ECT)
- Magnetic Particle Inspection (MPI)
- Ultrasonic Testing (UT)
- Laser Holographic Inspection
Penetration testing can be used to find surface defects in any non-porous workpiece. In the automotive industry, one can find small cracks in rims, suspension and steering components using this technique. The process starts with ultrasonic cleaning, after that, the component is sprayed with a coloured penetrating liquid, as a result of the capillary action, this liquid will penetrate into holes and cracks (if there are any). The component can then be inspected for defects.
Cleanliness standards in Automotive Industry
The quality of a vehicle is dependent on the quality of its parts and it is important for automotive industries to adhere to strict standards of excellence for different components. The industries must take different parameters like fitting tolerances and cleanliness into consideration because these play a key role in the longevity as well as durability of the component.
With the precise calculations done in manufacturing an automobile, the presence of any foreign particle will impede the system from functioning smoothly and will have an adverse effect on the assembly. Foreign particles and residues as a result of different machining processes can weaken their structural strength and eventually the life of the component. Thus, after performing different machining operations it becomes extremely important for us to clean the component as to ensure that there is no unwanted contamination in the assembled part. Different components like crankshaft, camshaft, cylinder walls, pistons, injectors, valves, hydraulic system etc require a very high finish and cleaning standards.
Two standards ISO 16232 and VDA 19 were introduced in the 2000s and intended to assist the automotive industry in ensuring the cleanliness of different parts in the engine, transmission, suspension, steering system and many other components. The cleaning of components is performed with the help of a cleaning fluid and ultrasonic cleaning method.
