Commercial manufacturing processes

Introduction to Commercial Manufacturing Processes

In your school workshop, you might make one or two products by hand. However, in the "real world," companies need to make thousands or even millions of items quickly, accurately, and at a low cost. This is where commercial manufacturing processes come in.

In this chapter, we will look at the specific high-speed processes used for different materials. Understanding these helps you design products that can actually be built in a factory! Don't worry if some of the machine names sound new—we will break them down step-by-step.

1. Commercial Processes for Papers and Boards

When we talk about paper and card on a commercial scale, we are usually looking at two things: how to print on them and how to cut them into shapes for packaging.

Offset Lithography (Printing)

This is the most common commercial printing process. It is used for books, magazines, and folding carton-based packaging. It works on the simple rule that oil and water do not mix.

• How it works: The image is put onto a flat plate. The parts that should have ink are coated in grease (oil-based), and the rest is kept wet with water.
• The "Offset" part: The ink isn't pressed directly onto the paper. Instead, it is "offset" onto a rubber blanket cylinder, which then rolls the ink onto the paper.
• Color: It uses four main colors known as CMYK (Cyan, Magenta, Yellow, and Key/Black) to create full-color images.

Die Cutting (Shaping)

Imagine a giant, super-strong cookie cutter. That is a die. This process is used to cut, crease, or perforate paper and board in one quick motion.

• The Die: A "die" is made of sharp steel blades (for cutting) and blunt blades (for creasing).
• The Process: The die is pressed into the sheet of card. In a split second, it cuts out the "net" (the flat shape) of a box and adds the fold lines.

Quick Review: Offset lithography is for printing; die cutting is for shaping and creasing.

2. Commercial Processes for Timbers

While a carpenter might use a hand chisel, commercial factories use high-speed machines to ensure every piece of wood is identical.

Commercial Routing

A router uses a high-speed spinning bit to cut shapes, grooves, or decorative edges into timber. In factories, these are often CNC Routers (Computer Numerical Control), meaning a computer guides the tool.

• Usage: Creating the slots for "flat-pack" furniture or decorative patterns on cabinet doors.
• Advantage: It is extremely fast and can follow complex 2D or 3D paths perfectly every time.

Commercial Turning

This involves using a lathe. Unlike a router where the tool moves, in turning, the wood spins and the cutting tool is held against it.

• Usage: Anything cylindrical, such as table legs, baseball bats, or wooden bowls.
• The Process: A long piece of timber is rotated at high speed while a sharp tool removes waste to create a symmetrical, rounded shape.

Key Takeaway: If it's a flat groove or a complex 2D shape, it's routing. If it's round or cylindrical, it's turning.

3. Commercial Processes for Metals

Metal requires a lot of force or heat to shape. Commercial processes are designed to handle these tough materials efficiently.

Milling

Milling is similar to routing but for metal. A spinning cutting tool moves across a piece of metal to remove material.

• The Process: The metal (workpiece) is clamped tightly to a table. The milling cutter spins and moves along \(X\), \(Y\), and \(Z\) axes to shave off metal layers.
• Usage: Creating flat surfaces, slots, or gears.

Casting

Casting is used for complex shapes that would be too difficult or wasteful to cut out of a solid block. It involves melting the metal until it is liquid.

• The Process: Molten metal is poured into a mold. Once the metal cools and hardens (solidifies), the mold is opened to reveal the part.
• Commercial Example: Die Casting uses reusable steel molds to mass-produce items like engine parts or metal toy cars.

Did you know? Casting is one of the oldest manufacturing techniques, but modern die casting can produce thousands of parts per hour!

4. Commercial Processes for Polymers (Plastics)

Polymers are incredibly versatile because they can be easily melted and formed into almost any shape.

Injection Moulding

This is the "king" of plastic manufacturing. If you look at a plastic product and see a tiny circular mark (an injection point), it was probably made this way.

• Step 1: Plastic granules are fed into a hopper.
• Step 2: An Archimedes screw turns, pushing the granules through a heated tube (barrel) where they melt.
• Step 3: A hydraulic ram "injects" the molten plastic into a cold metal mold at high pressure.
• Step 4: The plastic cools instantly, the mold opens, and the part is ejected.
• Usage: Lego bricks, phone cases, and plastic chairs.

Extrusion

While injection moulding makes individual parts, extrusion makes continuous lengths of a shape. Think of it like squeezing toothpaste out of a tube.

• The Process: Just like injection moulding, plastic is melted by a screw. However, instead of filling a mold, it is forced through a die (a shaped hole).
• The Result: As it comes out, it forms a long, continuous strip in the shape of the die.
• Usage: Pipes, drinking straws, window frames, and curtain rails.

Common Mistake: Don't confuse these two! Injection moulding is for "closed" shapes (like a bucket). Extrusion is for "long" shapes (like a pipe).

Summary Table: Which Process for Which Material?

Quick Review Quiz

1. Which process uses an oil-and-water principle to print?
Answer: Offset Lithography.

2. If you need to make 10,000 meters of plastic water pipe, which process would you use?
Answer: Extrusion (because it is a continuous shape).

3. What is the difference between Turning and Routing for timber?
Answer: In Turning, the wood spins; in Routing, the tool spins.

4. Why is Die Casting used for metals?
Answer: To mass-produce complex shapes quickly using a reusable mold.

Note: For more information on the quantity of items produced by these methods, see the chapter on Scales of Production.