Crafting Cookware: Pots And Pans

Pots and pans are made from a variety of materials, including copper, cast iron, stainless steel, carbon steel, aluminium, and ceramics. The process of making them varies depending on the material and the desired shape of the final product. For example, copper pots can be made by spinning a blank disc of metal on a lathe, forming in a press, or rolling sheets of copper. Cast iron, on the other hand, is typically poured into a mould.

Metalworking and casting

Metalworking:

Metal forming is a process of shaping metal into desired shapes and sizes using various techniques. For pots and pans, this typically involves the following steps:

• Raw Material Preparation: High-quality raw materials, usually aluminium or stainless steel, are selected and inspected for defects. These materials are then cut into sheets or blanks of the desired size and shape for the pans.
• Forming and Shaping: The metal blanks are heated to a specific temperature to make them malleable and formable. Techniques such as stamping, spinning, or pressing are used to shape the blanks into the desired pan form, including creating the rounded base, side walls, and handle attachment points.
• Trimming and Finishing: Once the basic shape is formed, excess material is removed, rough edges are smoothed out, and a uniform appearance is achieved. This may involve using cutting tools, sanding machines, and polishing tools. The surface may also be sandblasted to create a slightly rough texture that enhances the adhesion of the coating.
• Handle Attachment: After the coating process, the handle is attached using secure methods such as riveting, welding, or heat-resistant adhesives. The handle should be ergonomically designed for comfort and heat resistance.

Casting:

The casting process involves melting the metal and pouring it into a cast to form the desired shape. Here's an overview of the casting process for pots and pans:

• Melting: The metal, typically aluminium or cast iron, is melted down using a melting furnace.
• Pouring: The molten metal is then poured into casts or moulds to form the desired shape of the pot or pan.
• Cooling: The casts are cooled, and additional heat processing in an industrial furnace may be required to achieve the necessary hardness.
• Annealing: In the case of aluminium cookware, the casts are then annealed in a heat-treating furnace to improve the material's strength and durability.

Additional Steps:

After metalworking and casting, there are often additional steps in the manufacturing process of pots and pans:

• Non-stick Coating: Many pots and pans feature a non-stick coating that is applied in a separate step. This coating is then cured in an industrial oven or furnace to bond it to the surface of the cookware.
• Quality Control and Inspection: Once the manufacturing process is complete, the pots and pans undergo quality control measures and inspections to ensure they meet the desired standards and specifications.
• Packaging and Shipping: After passing quality control checks, the cookware is cleaned, packaged, and prepared for shipping, ensuring protection during transportation and storage.

Spinning on a lathe

The oldest spinning systems consisted of a lathe with a spinning roller that, using leverage, was manually pressed against the workpiece to shape it, usually against a mandrel (though simple shapes could be formed without one). Skilled craftspeople have spun metal like this since antiquity and have perfected the technique through the ages.

CNC spinning machines reduce the need for skilled labour. A disk blank or preform is clamped against a chuck by the machine tailstock and rotated by the drive motor. The roller, on a two-axis compound slide, is programmed to make a series of sweeping motions to form the metal progressively onto the mandrel, behind the chuck.

Metal spinning has several iterations that suit different applications, and among them all, multipass spinning remains the most common. Performed either manually or on a CNC spinning lathe, a roller sweeps across the spinning disk multiple times, shaping the metal against the mandrel.

Another common iteration, shear forming, finishes a part in just one pass, with the shear-forming roller pressing against the metal in a unique fashion. In multipass spinning, the unformed flange section of the disk bends forward and backward during the process, depending on the type and direction of the spinning stroke. In shear forming, the roller keeps that spinning flange perfectly vertical during the process. A very skilled operator can perform shear forming on a manual machine, keeping just the right pressure to ensure that the flange is perfectly vertical throughout the operation. Most shops, however, use a CNC machine for the process.

Pressing

To press a pan, manufacturers simply place a blank of copper on a form, press a button, and watch as a mechanical arm forces the copper down over it. The process is so simple that it can be left to a machine, and there's no real quality difference between spun and pressed copper cookware. However, some manufacturers still prefer to spin their pans, taking pride in using this more demanding technique.

Rolling

To begin the rolling process, a blank disc of metal is placed on a lathe next to the chuck, which determines the size and shape of the pot. As the lathe spins, rollers apply pressure to the metal, gradually bending it over the form. The speed and pressure of the rollers must be carefully controlled to ensure an even finish. This technique requires training and skill, as uneven pressure can result in a lopsided pot with lumpy sides.

In addition to rolling, other methods used to shape pots and pans include spinning on a lathe and forming in a press.

Handle attachment

Once the copper vessel is formed, it's time to attach the handle. In most cases, the handle is mounted with copper rivets, which are placed through drilled holes in the handle and pot, heated until softened, and then hammered into place. With each hammer blow, the metal hardens a little more. By the time the rivet is nice and tight, the metal is also hard enough to keep the handle in place.

Handle materials vary. Brass has fallen in and out of fashion, though cast iron is among the most common and traditional. Cast iron is a sensible choice since it doesn't conduct heat as well as copper, slowing down how quickly the handle becomes too hot to touch.

The handle is usually attached with a small area to the pot with a big air gap to slow down how fast the heat gets from the pan to the handle. The handle is narrow near the pan and widens as it extends further to where you'd grip it. Stovetop use shouldn't heat the handle; that being said, it will obviously be hot coming out of an oven. The best handles are also hollow to allow for more rapid heat dissipation.

The design of the handle is important. Longer handles slow down how quickly heat travels from the pan to the handle. Longer handles are also useful for pots and pans that are intended to have a liquid boiling in them, as boiling water limits the temperature to 100°C so they do not get too hot. A frying pan, on the other hand, has a much longer handle because you usually fry with fat, and the typical boiling temperature of cooking oil is around 200°C. This means the metal gets a lot warmer, and you need a longer handle to stop it from heating up too much.

Frequently asked questions