Almost every product we use daily, from smartphones to cars, can trace its origins back to manufacturing processes. These processes not only determine the quality and production efficiency of products but also directly impact cost control and market competitiveness for businesses. In this article, we will define manufacturing processes, delving into their categories and various methods. Let’s get started now to explore their broad implications!
What Is Manufacturing Process?
Before discussing what a manufacturing process entails, let’s take a moment to look at the big picture of manufacturing. Manufacturing is the process of converting raw materials or components into finished goods through the use of tools, machinery, and labor.
The history of manufacturing originates from prehistoric times, when humans first used simple tools for cutting, crushing, and shaping materials. Over time, as civilizations advanced, so did the complexity and sophistication of manufacturing techniques. The Industrial Revolution marked a significant turning point, introducing steam power, mechanization, and mass production methods that revolutionized the way goods were made. Today, manufacturing processes have become highly automated and integrated with advanced technologies such as robotics, Computer Numerical Control (CNC) machining, and 3D printing.
The manufacturing process refers to the specific methods and sequence of operations within the broader activity of manufacturing to produce a specific product. It includes multiple stages such as design, material selection, processing, quality control, and final assembly. Each stage is vital in shaping the overall performance and life cycle of the finished products.
Five Categories of Manufacturing Processes
According to the production mode and the type of finished goods produced, manufacturing processes can be categorized into several types, each with its own characteristics and applications. Generally, there are five categories of manufacturing processes.
Job Shop Manufacturing
Job shop manufacturing is a highly flexible production paradigm designed for low-volume, high-variety requirements. It specializes in unique, customized products that often require specialized tools and setup time. Driven by customer orders, job shops can swiftly adapt to diverse production demands. However, this flexibility challenges forecasting workflow patterns, as production involves multiple, intricate, and non-linear operations. Despite these complexities, job shop manufacturing is ideal for industries producing heavy equipment, machinery, or specialized goods in small batches or prototypes.
Discrete Manufacturing
Discrete manufacturing involves the production of distinct, countable products which are often assembled from a variety of individual parts or components. This type of manufacturing focuses on the assembly of these individual parts into finished products. Each product, such as a car, computer, or appliance, is unique and can be tracked throughout the production process. Discrete manufacturing involves varied operations and often accommodates a high degree of customization. It is commonly used in industries like automotive, electronics, and furniture.
Repetitive Manufacturing
Repetitive manufacturing is characterized by the repeated production of the same or very similar products over a prolonged period. This approach emphasizes high-volume, identical production of standardized products at a rapid pace. Dedicated production lines and automated assembly machines streamline the process, reducing the need for manual labor. Quality control is paramount to ensure consistency and minimize defects, with materials flowing continuously through a series of automated steps. This method is highly efficient for producing automotive parts, circuit boards and processors, as well as large-scale production of uniform food and beverage items like bottled drinks and canned foods.
Batch Process Manufacturing
Batch process manufacturing is a production method in which products are produced in groups or batches rather than in a continuous stream. Similar to discrete and job-shop manufacturing, batch process manufacturing adjusts its production schedule based on customer orders or market demand. Each batch goes through the entire production process before starting the next one, allowing for a high degree of customization and flexibility between batches. For example, in the pharmaceutical industry, different batches of medications are produced with specific formulations and dosages. After each batch, the equipment is cleaned and prepared for the next batch, which might be a different medication or variation of the previous one.
Continuous Process Manufacturing
Like repetitive manufacturing, this type of process manufacturing also enhances production efficiency and standardization. In continuous manufacturing, raw materials flow continuously into a production system, with finished products exiting at the other end. This unceasing production is typically used for liquids, gases, or other flowable substances, such as chemicals, petroleum products, and food and beverages. In contrast, repetitive manufacturing is suitable for producing highly standardized products, where there may be pauses between production cycles or batches.
What Are The Different Manufacturing Methods?
Within each category, there are various methods and techniques used to achieve the desired results. In the following passage, we will discuss 7 main types of manufacturing methods and their subtypes.
1. Subtractive Manufacturing
Subtractive manufacturing is a versatile process in which material is removed from a solid block to create a desired shape. It's adaptable for a wide range of materials, including metals, plastics, ceramics, and composites. Modern subtractive manufacturing processes are automated by CNC technology, ensuring high-speed, precise tooling for intricate details and smooth surfaces. Job shop manufacturing and discrete manufacturing businesses widely use subtractive processes for custom parts and component production.
Below are the common subtractive manufacturing processes:
Turning: Using a lathe, the workpiece rotates while a cutting tool removes material to create cylindrical parts.
Milling: A rotating multi-point cutting tool moves across the workpiece to remove material, often to create complex shapes or contours.
Drilling: A rotating drill bit is used to make a hole of circular cross-section into the solid material.
Boring: Using a boring tool, an existing hole is enlarged and refined to achieve a precise diameter and improved alignment.
Reaming: Typically performed after drilling or boring, a reamer with multiple cutting edges is used to slightly enlarge and smooth the existing hole, achieving a final precise diameter and high-quality surface finish.
Grinding: An abrasive wheel removes small amounts of material to achieve high-precision surfaces and fine finishes.
Laser Cutting: Using a high-powered laser beam to cut through materials. It is precise and can cut complex shapes with a fine surface finish.
Electrical Discharge Machining (EDM): A non-traditional machining process that uses electrical sparks to erode material from the workpiece, useful for hard or electrically conductive materials.
Water Jet Cutting: Using a high-pressure jet of water, sometimes mixed with abrasive particles, to cut through materials without generating heat.
2. Joining
Joining is the process of permanently or semi-permanently connecting two or more pieces of material to create an assembly. This technique is widely used in manufacturing complex products that is often impractical to produce directly. By producing multiple simpler components and then joining them, production costs for complex parts can be reduced. Additionally, joining processes allow for the replacement of faulty components without discarding the entire product. Some examples of joining processes are:
Welding: A process that fuses materials by applying heat, pressure, or both, together with the addition of a filler material to form a strong joint upon cooling.
Brazing: A joining method where a filler metal with a melting point higher than that of soldering but lower than the base materials is melted and flowed into the joint by capillary action.
Soldering: Similar to brazing, but performed at lower temperatures. A filler metal (solder) is melted and drawn into the joint between closely fitted parts.
Adhesive Bonding: A process where an adhesive material is applied between the surfaces to be joined, creating a bond upon curing.
Mechanical Assembly: Connecting components using fasteners such as bolts, nuts, rivets, or screws.
Interference Fit (Press Fit): A method where parts are joined by forcefully pressing them together, creating a tight fit due to the interference between the parts.
Others: Such as clinching and crimping, which are specialized joining techniques.
3. Forming
Forming is a manufacturing process in which the shape of a material, typically metal, is changed using mechanical forces without adding or removing material. This process is based on the plastic deformation of the material, resulting in minimal material waste . The different types of manufacturing processes under forming are:
Forging : A metalworking process where metal is shaped by applying compressive forces. The metal is typically heated to a high temperature to make it more malleable before being hammered, pressed, or rolled into the desired shape. Forging produces strong and durable parts due to the refinement of the grain structure and the elimination of internal voids.
Stamping: Involving sandwiching a flat sheet of metal(either in coil or blank form) between a punch and a die, then applying force via a press to deform the metal into the die's cavity shape. Stamping can be performed in a single stroke or through a series of operations known as progressive stamping. It is widely used in various industries, particularly for high-volume production of components where precision and consistency are critical.
Bending: Involving deforming a material, typically metal, along a straight axis to create an angular shape or a curve. The process does not remove material but rather changes its geometry by applying force, causing the material to plastically deform and hold the new shape. This can be done using tools and machines like press brakes, roll benders, or hand brakes. In press brakes, for example, the workpiece is clamped between two dies, and a ram applies pressure to the top die, bending the material to the desired angle.
Rolling: A fundamental and cost-effective manufacturing process that involves passing metal stock through one or more pairs of rolls to reduce thickness, ensure uniformity, or impart desired mechanical properties. It can be conducted at room or elevated temperatures (cold rolling or hot rolling), depending on the material and desired properties of the final product. Rolling is commonly used to produce flat sheets, strips, plates, beams, and other structural components.
Extrusion: A versatile and efficient forming process where material is forced through a die to create objects with a fixed cross-sectional profile. The material, which can be metal, plastic, ceramic, or food, is typically heated and then pushed or drawn through the die, taking the shape of the die opening.
4. Casting
Casting involves pouring liquid metal into a mold cavity to create a solid object with a specific shape. Once the metal cools and solidifies, the mold is removed, revealing the cast part. Casting encompasses a wide variety of processes, and its classifications include the following:
Sand Casting: Using sand as the mold material to produce castings. It produces castings in sand molds. This is a low-cost method with flexibility in material choices but has lower dimensional accuracy and a coarser surface finish compared to other casting methods, requiring significant finishing work.
Investment Casting (Lost-Wax Casting): Using a wax pattern coated with ceramic to create precise and intricate parts. It is known for its excellent surface finish and high dimensional accuracy. However, it has size limitations on parts and is a high-cost process due to its labor-intensive nature.
Centrifugal Casting: Involving pouring molten metal into a rotating mold. The centrifugal force distributes the metal evenly around the mold cavity, resulting in high-quality, dense cylindrical parts with a fine grain structure.
Die Casting: Involving forcing molten metal under high pressure into a precision metal mold cavity, where it cools and solidifies into a casting. Known for fast production cycles, it excels in high-volume manufacturing of intricate parts. However, the initial mold cost is substantial, and it's primarily suited for low-melting-point metals like aluminum, zinc, magnesium, and copper.
Permanent Mold Casting (Gravity Die Casting): Involving pouring molten metal into a reusable metal mold under gravity, which is then cooled naturally or by using a cooling medium. While it has a slower production speed, this casting method can accommodate a wider range of metals and alloys, including some high-melting-point materials.
Continuous Casting: A process where molten metal is continuously poured into a mold, solidified, and then extracted in an ongoing flow. It is highly efficient and is commonly used to produce long metal sections such as beams, rods, and slabs.
Shell Molding: An advanced casting method using resin-coated sand to form a mold shell around a heated pattern, creating precise and complex parts. It is known for its good surface finish and high dimensional accuracy, suitable for gears, valves, and small to medium-sized castings in industries such as automotive, aerospace, and machinery manufacturing.
There are other casting methods like vacuum die casting, low-pressure casting, lost foam casting, etc. They are also employed in various industries to meet specific production requirements with their unique advantages.
5. Molding
Molding is similar to the casting process, but molding is more commonly associated with plastics, while casting mainly deals with metals. In molding, molten material is poured into a mold to solidify into the desired shape. Although creating molds is costly and time-consuming, the process is ideal for mass production of parts with precise dimensions and good surface finishes. The reusable nature of molds also reduces production costs. The common molding methods include:
Injection Molding: A highly versatile process for producing plastic parts. It involves injecting molten plastic into a closed mold cavity under high pressure. Once the plastic cools and solidifies, the mold is opened, and the part is ejected. This method offers high production rates, excellent repeatability, and the ability to produce complex shapes with fine details, making it a cost-effective solution for many industries.
Compression Molding: It involves placing a pre-measured amount of molding material into an open mold cavity. The mold is then closed, and pressure is applied to shape and cure the material. This method is suited for materials with low flow characteristics and is ideal for producing high-strength, high-density parts that are large, flat, or moderately curved.
Blow Molding: A process used to create hollow plastic parts by inflating a heated plastic tube (parison) until it fills the mold cavity. It is efficient for high-volume production of hollow plastic parts such as bottles, containers, and pipes, and is relatively low-cost.
Rotational Molding: A process used to create hollow plastic products of various sizes and shapes. It involves filling a heated mold with plastic resin and slowly rotating it around two perpendicular axes. The resin melts and coats the interior of the mold, forming a hollow part. This method has low tooling costs and the ability to produce large, complex parts with smooth interior surfaces, thick walls, and minimal assembly requirements. It is particularly suitable for low-volume production runs and custom designs.
Thermoforming (Hot-Air Forming or Vacuum Forming): A plastic forming process that utilizes heat and pressure to shape a plastic sheet into a desired three-dimensional form. This method offers low tooling costs, quick production cycles, and flexibility in design and material choices. It is commonly used for packaging, disposable cups, trays, lids, and other lightweight plastic products.
6. Additive Manufacturing
Additive Manufacturing (AM), commonly known as 3D printing, is a process that builds objects by adding material layer by layer, based on digital models. AM works with materials that are moldable by heat, including metals and certain plastics, allowing for a high degree of customization, complex geometries, and reduced material waste. The common types of additive manufacturing processes are as below:
Selective Laser Sintering (SLS): Using a laser to fuse powdered material into solid parts, ideal for producing functional prototypes and complex end-use parts. SLS is commonly used in aerospace and automotive industries, utilizing materials like nylon and other thermoplastics.
Digital Light Processing (DLP): Using a digital light projector to cure resin layers in a single flash, speeding up the printing process while maintaining high detail and precision. DLP is ideal for applications requiring fine details and smooth surfaces, such as dental models, jewelry, and detailed miniatures.
Selective Laser Melting (SLM): An advanced additive manufacturing process using a high-powered laser to fully melt and fuse metallic powder particles, creating dense and strong metal components. SLM is widely used in aerospace, automotive, and medical industries for high-performance parts made from materials like titanium, aluminum, and stainless steel.
7. Surface Treatment Processes
Surface treatment processes involve various techniques applied to the surface of a material to enhance its properties, such as appearance, corrosion resistance, wear resistance, and adhesion. These treatments can be mechanical, chemical, or electrochemical. Common types of surface treatment include bead blasting, polishing, powder coating, electroplating, and anodizing.
Three Types of Manufacturing Strategies
Based on customer demand and production processes, there are three manufacturing strategies commonly used in manufacturing and supply chain management:
Make to Stock (MTS)
In the Make to Stock (MTS) approach, a manufacturer produces goods in anticipation of future demand based on past sales data, market trends, and forecasts. The products are manufactured, assembled, and stocked in warehouses before any specific customer orders are received.
This method allows for quick fulfillment of customer orders, as the products are already available and ready for shipment. It minimizes lead times and enhances customer satisfaction by providing immediate availability. However, it also carries the risk of excess inventory if demand predictions are inaccurate.
Make to Order (MTO)
The Make to Order (MTO) strategy involves initiating the production process only after a customer places an order. Manufacturers maintain a flexible production system capable of adjusting to varying orders, often with shorter production runs.
While MTO reduces inventory costs and the risk of obsolescence, it typically results in longer lead times as production starts from scratch for each order. This method is ideal for products with low demand volumes or high levels of customization.
Make to Assemble (MTA)
Make to Assemble (MTA), also known as Assemble to Order (ATO), is a hybrid approach that combines elements of both MTS and MTO. In this model, manufacturers pre-produce and stock components or sub-assemblies that can be quickly assembled into final products upon receipt of customer orders.
This strategy allows for customization to a certain extent while maintaining shorter lead times compared to full MTO. MTA reduces the need for extensive customization during the production process, making it more efficient and cost-effective. It also ensures that only the necessary components are manufactured, minimizing waste and overstocking. MTA is particularly suitable for products with a mix of standard and customizable features.
Conclusion
Regarding the types of manufacturing processes, it is evident that there exists a diverse range of methodologies customized for specific industries, products, and production goals. The discussion on manufacturing methods has highlighted key aspects that can help you achieve efficiency, cost-effectiveness, and quality in your products. At Chiggo, we pride ourselves on our expertise in CNC machining and sheet metal fabrication. Additionally, we offer 3D printing and injection molding services, providing comprehensive solutions tailored to your needs. Contact us if you have any questions!
