Machining: What to know about metal machining

If your business involves metal manufacturing, you have to keep abreast of the latest in the industry.

Metal machining has evolved from traditional manual-operated metal cutting to micromachining using laser technology. Machining refers to a manufacturing process that encompasses a vast range of techniques and technologies.

For novice business owners or aspiring metal part suppliers, learning the basic metal machining process is a must. The machining process involves material removal from a workpiece. Power machine tools are used to shape metal into the desired design to create metal parts or components in various applications. Also, machining can be performed on any existing part, like forging or investment casting.

In this post, you’ll learn more about the metal machining process for your reference when choosing the best manufacturing techniques for your products, as well as in meeting your clients’ needs and preferences.

What is metal machining?

Metal machining is a form of a manufacturing process that is used in creating metal parts, tools, or machinery. It involves different processes to achieve the final product’s desired design, in terms of shape, hole diameter, size, texture, and finishing, and this blog post explains what quality metal machining service is all about.

Types of machining process

Metal machining includes non-conventional and conventional processes. Non-conventional machining processes involve using either a thermal or chemical means of removing material. On the other hand, conventional machining processes are often frequently used for metals, which involves three categories. These include single point cutting machining, multi-point cutting, and abrasive machining.

Each machining process uses a specific type of cutting tool and technique in a workpiece. The machining of a metal part would require different operations performed in a planned sequence, so the desired design and features are achieved.

Here are the different metal material removal processes:

1. Mechanical machining

Single-point cutting

This uses a single sharp-edged cutting tool to remove metal material from the workpiece. Turning is a commonly used single-point cutting process in which the workpiece is rotated, and the cutting tool is fed into it to cut away material.

Turning operations, like boring, grooving, cut-off (parting), facing, and thread cutting create a wide array of features. These features include slots, tapers, flat surfaces, threads, and complex contours. Planning and shaping are also single-point cutting processes that don’t require rotating the workpiece.

Multi-point cutting

Multi-point cutting uses multiple sharp-teeth cutting tools moving against the workpiece in removing material. Milling and drilling are the most common multi-point cutting processes, wherein the cylindrical cutting tool has a sharp tooth that rotates at very high speeds. During milling, the rotating tool is used in the workpiece, creating different features through different rotating depths and paths.

The different milling operations include chamfer milling, face milling, and end milling, which are done on a milling machine. The features of milling processes include pockets, slots, flat surfaces, complex contours, and chamfers. Also, milling machines can perform drilling and other types of hole-making operations as well. Broaching and sawing are types of milling, which will be discussed further below.

2. Abrasive machining

Abrasive machining is a mechanical process that uses an abrasive tool to remove metal materials from a workpiece. While this process can be used to shape and form features of a workpiece, it is primarily used to improve a part’s surface finish.

Grinding is a common abrasive machining process in which the abrasive grains of the cutting tool are bonded into a wheel rotating against the workpiece. You can perform grinding on a surface grinding machine or a cylindrical grinding machine. The other types of abrasive machining include honing, ultrasonic machining, abrasive jet machining, and lapping.

3. Chemical machining

The process of chemical machining uses chemicals to remove material such as electrochemical machining or ECM. It is a way of removing metal using an electrochemical process for mass production. Also, it is used for dealing with electrically conductive materials that are extremely hard or those that are difficult to machine utilizing conventional methods.

4. Thermal machining

Thermal machining includes torch cutting, electrical discharge machining or EDM, and high-energy beam machining. EDM refers to a non-traditional machining method, which removes a workpiece with the use of thermal energy. It’s like laser cutting, except EDM doesn’t require mechanical force during the removal process. 

What is CNC metal machining?

CNC stands for Computer Numerical Control. In manufacturing, CNC machining means using a computer to convert the product design (produced by CAD software) into graph coordinates or numbers, controlling cutter movements. In short, CNC machining involves pre-programmed computer software that dictates the movement of manufacturing tools and pieces of machinery such as grinders, lathes, mills, and routers.

CNC machining runs pre-programmed designs in repetitive and predictable cycles. Because human operators are kept to a minimum level, this machining process is now widely used in the manufacturing sector.

How does CNC machining work?

CNC machining involves open or closed-loop machining systems that determine position control. Open-loop machining systems involve signaling runs in one direction between the motor and the controller. On the other hand, a closed-loop system involves using a controller that is capable of receiving feedback to correct errors or irregularities in position and velocity.

The movement in CNC machining includes X and Y axes directions. The tool is positioned and guided in steppers or servo motors, following the exact movements determined by the programmed code. For processes requiring minimal force and speed, it can be run through open-loop control. Closed-loop control is necessary for more detailed requirements to ensure the accuracy, speed, and consistency required for metalwork and other industrial applications.

CNC machines and applications

The most common manufacturing processes using CNC machines include drilling, hole punching, bending, gluing, laser cutting, grinding, flame and plasma cutting, picking and placing, routing, and ultrasonic welding. Lathes, mills, water jet cutters, and electric discharge machining often operate using CNC.

Here are the types of CNC machines:

• CNC Mills: This type of CNC machine is capable of running on the number and letter-based prompt programs developed by your manufacturing team, guiding the pieces in different distances. Basic mills have a three-axis system (including X, Y, and Z), and most newer mills accommodate additional axes.
• Lathes: Using lathe machines involves cutting of materials in a circular direction, which are carried out with high velocity and precision. CNC lathes produce complex designs that are impossible to do on manually-operated machine versions. While the control functions of mills and lathes are very similar, CNC lathes only consist of two axes (namely X and Z).
• Plasma Cutters: A plasma torch is used to cut not only metal materials, but it can be used on other surfaces, too. Plasma cutters involve producing heat and speed needed to cut metal, and plasma is generated, combining electrical arcs and compressed-air gas. You can also look at these plasma cutters to check a variety of brands, lengths, and capacities.
• Electric Discharge Machines EDM: This is also called spark machining and die sinking, molding workpieces into specific shapes using electrical sparks. The electrical current discharges happen between two electrodes, removing sections of a workpiece. The electric field becomes stronger and more intense when the electrode spaces become smaller, allowing electricity to pass between two electrodes.
• Water Jet Cutters: These CNC tools cut hard materials, like metal and granite, using high water pressure applications. Sometimes, the water is combined with sand or other strong abrasive substances. Many factory machine parts are usually shaped using water jet cutters. Water jets are usually used in mining industries and aerospace, wherein the process is powerful and used in cutting and carving.

Metal CNC machining process

The metal CNC machining process involves a series of processes to achieve desired product specifications, features, and benefits.

1. Turning

This is a form of metal CNC machining that involves removing unwanted metal materials from rotational parts. A lathe or a turning machine can be used, which is fed into a workpiece at high rotating speeds. As already discussed above, the two types of turning are single-point cutting and multi-point cutting. Tools are used depending on the product requirements.

Turning adds precision to rotational metal part features with an existing shape, so you can always refine or add some features on metal components. Custom-designed fasteners and shafts are some examples of metal parts you can fabricate using this procedure.

You can use different raw materials for turning such as nickel, magnesium, steel, brass, aluminum, nickel, zinc, and titanium. The important considerations when selecting a material includes the cost, strength, machinability, and resistance to wear. You should aim for a material that will provide the best surface finish for your metal products. Turning is efficient and it promotes longer tool life.

Here are the different specs or features you can create with turning:

• Holes
• Grooves
• Different diameter steps
• Contoured surfaces
• Tapers

2. Milling

You can create symmetric metal parts, such as slots, three-dimensional surface contours, holes, and pockets. Metal tools are usually fabricated using milling. Other examples include custom-designed brackets and fasteners.

Milling cutting tools may include carbide, high-speed steel or HSS, high-speed cobalt steel, and carbon steel. The type of cutting tool material you’ll need will depend on the cutter’s properties, such as resistance to wear, toughness, and hardness, and also the workpiece material.

3. Reaming

Reaming uses a tool called a reamer with one or more cutters. It is used to enlarge the size of a hole. The same machine is used in drilling in which reamer materials may include HSS or carbide in various sizes.

4. Grinding

Grinding involves using grindstones, grinding wheel, hand-cranked knife-sharpening, or grinders for performing an abrasive machining process. Abrasive particles cut metal wherein a bond material is mixed with temporary binders, and the metal is shaped pressing the grinding wheels. This machining process is a mechanical type of machining incorporated into CNC machining.

5. Boring

Boring is the process of enlarging existing cast or drilled holes. The types of boring include line boring (one of both ends supported by a boring bar), back boring (boring a hole on the workpiece’s back part), and lathe boring (enlarging a hole with a single-point cutting tool to create tapered or square holes).

6. Honing

It’s a form of abrasive machining process which aims to achieve a precise metal surface. The rotating abrasive tool comes in the form of a stone that is scrubbed against the workpiece in a controlled path to remove unwanted material, thus improving surface form and texture. Honing is used in surface finishing to achieve the required diameter of the metal component.

7. Broaching

Broaching is used to create odd shapes and precision machining. This machining process uses a toothed tool called a broach to remove unwanted material. Linear broaching runs broach linearly on the surfaces of a workpiece. A lathe machine is used in rotary broaching.

8. Shaping

Of course, you’d want to shape metal components according to your requirements or your clients’ needs. One way to achieve this is through metal shaping. It includes hot forging wherein a malleable metal part is hammered, pressed, and upset to attain the desired shape. It involves heating the material to achieve the desired shape 75 percent beyond its melting temperature.

9. Laser engraving

High-precision labeling or marking is performed best by laser engraving, utilizing laser technology for permanent marking, flexibility, fast cycle times, and production line integration. It’s a cost-efficient labeling process for metal parts.

Precision metal stamping can be done with laser technology through laser engraving. With metal precision stamping, labeling metal products with appropriate serial numbers, identity codes, or brand names and model numbers can be achieved with precision and uniformity. Impress your clients and investors by adopting laser technology.

Conclusion

Now you’re more knowledgeable about the different types of machining and processes involved. Depending on the workpiece or material used, as well as your desired product outcome, machining involves the use of different tools and techniques. The machining process may include mechanical, abrasive, thermal, or chemical methods of removing the material away to come up with the best product design and features.

Whether you’re a novice entrepreneur or someone who is looking forward to manufacturing and supplying metal parts for automotive, electronics, and other industries, understanding metal machining will help you with planning. While there are so many things to learn, consulting a metal machining expert can definitely help you achieve your goals.