Machining Operations: Custom Machined Parts Manufacturing

A fundamental component of the manufacturing sector is CNC machining operations. A variety of machining operations are used to transform raw materials into components and final goods.

What kinds of machining operations and procedures are therefore employed to create various products and parts? Continue reading to have a better understanding of the many types of machining operations processes and the pertinent information.

What is Machining?

Machining represents a subtractive method in manufacturing, employing cutting tools, discs, abrasive wheels, and similar instruments to eliminate surplus material from a workpiece. It serves the purpose of shaping the final product by selectively removing unwanted materials. Commonly, stock mills such as flats and bars, as well as welded or cast components, undergo machining operations.

Machined products encompass a diverse range, including automotive components, drill bits, plaques, nuts and bolts, flanges, and various tools utilized across industries.

Now, let’s explore the various types of machining operations processes.

Types of Machining Operations

Machining operations can be broadly categorized into two main types: conventional and non-conventional. Each of these main types encompasses various sub-types aimed at achieving specific final product outcomes. Let’s delve into a more detailed exploration of these machining operations.

Conventional Machining Process

Referred to as traditional machining in manufacturing, these machining operations involve the direct contact use of cutting tools to eliminate excess materials from a workpiece. Within conventional machining, different sub-types exist, including:

Turning

In the turning process, the cutting tool remains stationary while the workpiece rotates. This lathe operation effectively removes excess material, with the cutting tool moving along two axes to create precise cuts in terms of width and depth. Turning is well-suited for machining both the interior and exterior parts of a material, known respectively as facing and boring.

Milling

Milling is a machining process utilizing rotating cutters to remove material from a workpiece. There are two primary types of milling operations: face milling and slab milling. Face milling is employed for smoothing or flattening workpiece surfaces, while slab milling is ideal for machining wide flat surfaces. This intricate machining type often requires specialized cutters, and companies, such as ours, offer CNC milling services with high precision (tolerance up to 0.02mm) using 3-axis and 5-axis machines.

Drilling

Drilling involves the use of drill bits, multi-point cutting tools, to create cylindrical holes in solid materials. The drill bits used in this process typically feature two spiral channels, known as flutes, which facilitate the removal of chips from the hole as the drill bit advances. This operation is crucial for part assembly, and drilled holes may be further processed for threading, reaming, or boring to meet specific dimensional tolerances.

Grinding

Grinding stands as a machining process designed to enhance the surface finish and precision of a machined part. This method ensures the production of components with consistent shapes, finishes, and dimensions. Additionally, it serves as a preliminary step for subsequent finishing operations like honing, lapping, and superfinishing.

Two primary types of grinders exist: Surface grinders, which remove small amounts of material from flat surfaces, and Cylindrical grinders, which shape materials in cylindrical forms.

Sawing

Sawing is employed to cut extruded shapes, bars, and various materials into shorter lengths using cut-off machines. Engineers utilize different cut-off machines for sawing, such as power hack saws, circular saws, and abrasive wheel saws.

The speed of the saw band in sawing depends on the material. For example, softer materials like aluminum alloys necessitate a cutting speed of 1000 fpm or more, while high-temperature alloys may require a slower cutting speed of 30 fpm.

Broaching

Broaching involves the use of a broach to create square holes, spline holes, keyways, and other shapes. A broach is a tool with multiple teeth arranged sequentially, akin to a file. However, it differs from a file in having uneven teeth. There are two types of broaching: pull broaching and push broaching. Vertical press-type machines are suitable for push broaching, while both vertical and horizontal press-type machines work for pull broaching.

During the broaching process, the broach makes a series of cuts with increasing depth as it is pulled or pushed past a surface or through a guide hole. The cutting speed of a broach is contingent on material strength, ranging from high speeds of 50 fpm for softer metals to lower speeds of 5 fpm for stronger metals.

Planing

Planing is effective for machining large flat surfaces, especially those designated for subsequent scraping as a finishing method. To economize on machining costs, manufacturers often group small parts together for simultaneous planning.

Non-Conventional Machining Processes

This category of precision machining does not necessitate direct contact with the workpiece for material removal. In essence, the machinery involved operates without making direct contact with the cutting material. Various types of non-conventional machining operations processes exist, including:

Electrical Discharge Machining (EDM)

The Electrical Discharge Machining (EDM) process, also referred to as spark machining, die sinking, wire erosion, or wire burning, achieves material removal through erosion. Notably, this process does not entail direct contact between the workpiece and the tool, making it well-suited for machining materials that are susceptible to distortion.

Moreover, EDM excels in cutting extremely hard and challenging exotic materials with exceptionally close tolerance requirements. While the material removal rate in EDM is relatively slow, the resulting products or parts often require minimal or no additional polishing.

Chemical Machining

Chemical machining involves immersing a workpiece into a tank containing a chemical solution (etchant). The etchant utilized is typically a blend of potent chemical acids that react with the metal. Submerging the metal into the etchant leads to the uniform dissolution of metal from the workpiece.

For successful chemical machining, specific components are essential:

• Tank: Constructed from robust metal coated with chemicals resistant to the etchant needed for the process.
• Heating Coil: Maintains a consistent temperature within the tank and can adjust the tank’s temperature based on the material’s requirements.
• Stirrer: Facilitates the mixing of the etchant, ensuring uniform heat and concentration throughout the tank’s volume.
• Workpiece: Small workpieces are held using a hanger, while larger ones are secured with fixtures coated in polymers and rubber.

This method is particularly effective for machining hard, brittle, and challenging-to-machine materials. Additionally, the tooling costs are low, and the produced parts or products are free from burrs. Furthermore, using chemical machining saves time due to its high material removal rate.

Electrochemical Machining (ECM)

Electrochemical Machining (ECM), also recognized as reverse electroplating, distinguishes itself by removing materials instead of adding them, in contrast to electroplating. Similar to electrical discharge machining, ECM entails passing a high current between electrodes and a conductive liquid. However, ECM stands out for its absence of spark production, tool wear, and the avoidance of thermal or mechanical stresses. Achieving a mirror surface finish and a high material removal rate is possible with ECM.

Despite the significant initial setup cost, ECM proves advantageous for mass production. Its versatility makes it suitable for machining extremely hard metals and alloys, as well as unconventional shapes, small sizes, and deep holes.

Abrasive Jet Machining

In this non-conventional machining process, a workpiece is impacted by a high-speed stream of abrasive particles. The pressurized abrasive particles, propelled by gas or air, cause small portions of the material to dislodge upon repeated impact. Consequently, the jet carries away these loosened fragments, revealing a fresh surface to the abrasive particles’ impact.

The flexibility of abrasive jet machining sets it apart from other processes, allowing for application in areas typically inaccessible to conventional machining. The hose used in this process facilitates the transportation of abrasive material to any part of the workpiece.

Furthermore, abrasive jet machining generates minimal heat, minimizing distortion in products and parts. It is well-suited for tasks such as removing parting lines from injection-molded components and engraving permanent marks on materials. Additionally, the process excels in cutting metal foils, machining robust alloys, and deburring plastics.

Essential components for the success of this machining process include:

• Gas Supply: Utilizing either compressed air or gas.
• Filter: Evaluating fuel supply purity and eliminating foreign bodies.
• Pressure Gauge: Determining and controlling the required pressure level.
• Regulator: Managing the flow of compressed air or gas through pipes.
• Mixing Chamber: The site where compressed air and abrasive particles combine.
• Nozzle: Composed of durable material, with a diameter typically ranging from 0.18mm to 0.8mm.

Ultrasonic Machining

Ultrasonic machining is a process that eliminates material from a part’s surface through low amplitude and high-frequency vibrations. This procedure takes place in the presence of fine abrasive particles mixed with water, forming a slurry. The particles exhibit varying grain sizes, typically ranging from 100 to 1000.

Moreover, ultrasonic machining employs smaller grain sizes (higher grain numbers) and generates less heat, resulting in smooth surface finishes. This type of machining is well-suited for materials with high hardness or a brittle nature. Additionally, its vibratory motion facilitates the creation of hole-cut shapes.

Electron Beam Machining (EBM)

In Electron Beam Machining (EBM), electrons are focused and concentrated on a small spot on a metal material. This method is particularly effective for machining very hard or brittle materials that are challenging to process using conventional techniques.

EBM incurs lower tooling and setup costs, and it operates without geometric restrictions, allowing for the machining of very small holes with exceptional accuracy. Consequently, EBM is an excellent choice for micro-finishing.

Laser Beam Machining (LBM)

Laser Beam Machining (LBM) employs a laser beam and heat energy to remove material from a workpiece. This process is well-suited for both drilling and cutting applications, enabling the machining of very small holes and the cutting of complex geometries in hard materials.

LBM excels in partial cutting or engraving, steel metal trimming, resistor trimming, and blanking. With a rapid cutting rate and the capability to cut shallow angles, LBM simplifies the automation of complex cutting patterns. Moreover, as a non-contact process, LBM eliminates tool wear or breakage during machining.

Differences Between Conventional and Non-Conventional Machining

Several distinctions exist between conventional and non-conventional machining. Here are the key differences between these two types:

Surface Finish

Non-conventional machining yields parts with superior surface finishes compared to conventional machining. This is attributed to the high accuracy and precision inherent in non-conventional machining processes. In contrast, conventional machining tends to produce products that are less precise and accurate.

Material Used

Non-conventional machining is capable of cutting any material, irrespective of its hardness. This makes it well-suited for machining very hard and brittle materials. On the other hand, conventional machining is limited by the requirement that the raw material should not be harder than the cutting tool. Consequently, conventional machining is more suitable for softer materials like brass, mild steel, and aluminum 6061.

Machining Speed

Conventional machining is generally a slower process when compared to non-conventional machining. Non-conventional processes, such as ECM, can be completed in seconds, while conventional processes like milling and turning take longer. The slower speed in conventional machining is primarily due to the friction generated by the contact between the tool and the workpiece.

Accuracy

Non-conventional machining processes result in the production of more accurate parts. In contrast, conventional machining, which produces chips during the process, often leads to deflection in the cutting tool when these chips accumulate, thereby reducing the overall accuracy of the machining.

Physical Tool Requirement

Conventional machining operations necessitates a physical cutting tool, as cutting involves direct contact. However, this contact also contributes to a reduction in tool life. In contrast, non-conventional machining does not heavily rely on a cutting tool, minimizing the significance of a physical tool in the process.

Start Your Custom Machined Parts Projects

You may have discovered the advantages of each type of machining operations by now and have developed a thorough understanding of them. Do you need intricately shaped custom-machined parts as soon as possible? Then, we’ll be your perfect production partner.

We provide machining services across and we work on both traditional and non-traditional machining operations projects. Our several sets of 3, 4, and 5-axis CNC machines, along with our team of skilled machinists, ensure prompt delivery and high-quality goods. We would always deliver, regardless of the machining operations processes required for your goods.

We provide free DFM analysis and feedback and instant CNC online quotes. Additionally, we’re always available to answer your questions and make modifications to your designs with our 24/7 engineering support. So contact us today about your processing needs.

FAQs

What constitutes a basic machining elements set?
The workpiece, the tool, and the chip are the three fundamental components of machining operations. The rationale is that every cutting activity requires relative motion between the tool and the workpiece, and chip production is a byproduct of this motion.

What is the 5-axis machining?
It is a part of a CNC milling machine used in manufacturing. Moreover, this part permits the machine to move along five distinct axes or directions. As a result, it is easier to produce intricate forms and deeper portions. Additionally, compared to other machines, 5-axis machining cuts down on the amount of time needed for milling.