In the automotive industry, the parts of automobiles with complex features like angle cuts, off-centre holes, and cavities are fabricated using Custom CNC machining.

It is capable of creating parts that cannot be created with standard CNC machining. It helps the engineers to modify and innovate the design according to the specifications of the vehicles. Moreover, custom-milled parts of the vehicle having complex features can be made by CNC custom milling with high accuracy and quality.

1. Benefits of Custom Machining in the Automotive Industry

CNC Custom Machining In Automotive Industry

Some people are still using classic and vintage cars, which require restoration of parts like the exhaust system, interior components of the engine, engine parts, gearboxes, brakes, hydraulics components, bushings, suspension components, engine components bodies, etc.

The manufacturer does not manufacture these components, so custom machining is required to make these necessary parts with specialized features. Engineers do reverse engineering to make these parts, and by creating 3D models of these obsolete parts, customized parts are made.

The following are some benefits of custom machining in automotive industries:

a. Accuracy and Precision:

In the automobile industry, custom parts must be made with precise and highly accurate specifications. CNC Custom machining can produce highly accurate details of required specifications by meeting high-quality standards.

b. Time-Saving:

One of the critical factors in manufacturing is the time required to complete the project. Custom CNC machining offers the advantage of time-saving, which may be wasted in locating the ready-made parts that you need and that are not available in the market.

Instead of wasting time in market surveys, the required specific features can be manufactured through custom CNC machining, and the project can be completed well in time.

c. Repeatability:

In the case of mass production of the parts, the CNC custom machining can reproduce the parts precisely with the exact specifications and standards.

d. Automation:

Automation is another benefit of CNC machining. In CNC machining, different operations are controlled numerically by computers which minimize the requirement of manual operations. With the elimination of labour-intensive machining, robotics arms perform other machining processes.

Production Speed: CNC offers a high production rate compared to conventional machining. In CNC custom machining, there is less labour involvement, and the manufacturing process is controlled by a computer so that the parts can be produced at higher rates than the conventional manufacturing process.

2. Some Design Guidelines for Custom CNC Machining

To produce high-quality parts and products at lower cost, the following are some guidelines for custom CNC machining:

a. Cavities:

The depth of the recesses or pockets should be less than four times the width of the cavity (i.e. d < 4xL). If the depth-to-width ratio is smaller, the limited cutting length of the end tools may cause tool deflection or vibration during the fabrication of the cavities. However, if holes with larger depth-to-width ratios are required, then special cutting tools are required for manufacturing. The manufacturing cost is also increased due to the requirement of specialized tools in CNC custom machining.

b. Wall Thickness:

Some Design Guidelines for Custom CNC Machining

The parts must be produced with high accuracy and tight tolerances using CNC machining. In the case of thin walls, the accuracy and desired tolerances may be suffered due to the vibration in thin walls.

To avoid this, as a rule, the metal walls should have at least 0.8mm thickness, while parts made of plastics should have a minimum thickness of 1.5mm. If thinner parts are mandatory, they can be made, but the manufacturing costs will be increased.

c. Holes:

It is desired to have spots of standard diameters in the design to avoid requiring specialized drilling tools. It will minimize the deflection of the tool. It is recommended that the hole depth should be less than four times the end mill’s nominal diameter.

d. Tolerances:

Tolerances in parts manufacturing is the allowable variation in the parameters of the products without affecting the proper working of the parts.

Tolerances are specified with physical dimensions by using ± symbol (plus or minus) and adding a value, e.g. ±0.01mm. For example, a designer has decided to make a circular part with a diameter of 50 ± 0.5mm. This means that 1mm extra is allowed during the manufacturing without affecting the part’s functionality.

If the manufacturer has made the part with 50.5mm or 49.5mm, it will still function properly. The CNC machines can manufacture parts with tight tolerances up to 0.04mm. The manufacturing cost is increased in case of tighter tolerances.

3. The Challenges Faced by CNC Custom Machining in the Automotive Industry

There are a lot of benefits of CNC custom machining over the traditional machining processes, but there are also some challenges that are faced by CNC custom machining. The following are some drawbacks of custom CNC machining:

a. Lead Time:

Lead term is one of the main problems in manufacturing processes. It is essential to meet the deadlines of manufacturing projects. Due to the complexity of the machining processes, it may take months to complete even a single part with desired specifications. It can be the main hurdle for the manufacturers who are bound to complete the project in a specified time.

b. Cost:

Cost is another problem in CNC custom machining. Although the initial investment is high in traditional machining, the long-term costs are lower. However, in the case of custom CNC machining, some tools or fixtures may be required to produce desired complex parts. In these cases, the additional cost is included in the total cost.

c. Quality:

Another challenge faced in CNC custom machining is the quality of the required products. High-quality machinery and expert operators are required to manufacture the parts with the highest standards. In the case of small business or production orders, it may not be favorable and the quality of the product is compromised.


The custom parts of automobiles are made to beautify the vehicle and promote the car’s individuality, enhance the vehicle’s performance, or replace parts. In automotive industries, CNC custom machining is an ideal option to produce parts with complex features that are not readily available in the market.

Due to the requirement of high accuracy of critical components of automobiles, The Engine Block components like pistons, cylinders, rings, engine block, and manifolds are made by custom CNC machining process.

The Challenges Faced by CNC Custom Machining in the Automotive Industry

In the case of headlights of the vehicle, it is desired to have custom headlights that enhance the vehicle’s overall look as well as efficiently diffuse and transmit lights for better vision. The custom headlights of the different vehicles can also be made by CNC custom machining.

To make these custom parts some essential guidelines are vital to consider while making customized complex parts (including cavities, wall thickness holes, and specified tolerances) using CNC custom manufacturing.