Cold Forging for the Metal Parts You Need

Are you a manufacturing professional responsible for planning, acquiring, or specifying the components of your assemblies? If that’s the case, you’re undoubtedly familiar with the cost-timing-quality triangle. To keep your business alive, you must balance all three legs: low-cost, high-quality, and delivery. It only gets worse if you don’t. You’ll fall behind in the race.

“Someone is going to make your product obsolete. Make sure it’s you.” —Edwin Land.

Cold forging may provide you with the competitive advantage you need.

What is cold forging?

Cold forging is a metal working technique to process bar stock and squeeze it into an open die. This method occurs at ambient temperature or below the metal’s recrystallization temperature to form the metal into the desired shape. 

Cold forging is an efficient and economically effective method of forming metal to manufacture large volumes of parts at low costs. The forging method is different depending on the temperature: cold or hot. It’s accomplished by machines with hammers, or by a press for shaping, pressing, and rolling steels.

This technique is comparatively less costly than hot forging as the end products require very little finishing work. Although cold forging is called cold, it happens at or close to room temperature. 

The size of the machines to accomplish cold forging varies with the material hardness and the weight of the final component to be processed.

Cold forging has a material savings of up to 70% of production costs since there is very little waste and scrap.

How does cold forging work?

The low cost of forging results from reduced labor costs and the removal of secondary  operations. Parts can be quickly and efficiently manufactured with speeds as high as 1000 pieces an hour, decreasing cost. 

Cold forging can produce near-perfect surface finishes with increased dimensional stability. Each operation enhances the strength and durability of the workpiece, making for durable components.

Forging can refer to the process of forming metal in solid form. Much forging is carried out via the upsetting process. Hammers or rams are horizontally pressed into ends to widen or change the shape of the workpiece. 

The parts usually go through station after station until they reach the final shape. Bolts of higher strength are traditionally cold-headed by utilizing this method. An automotive engine valve is formed through a forced forging process. In drop forging, parts are forged in dies to form finished pieces, with a large hammer attached to the machine.

Pictured above: A cold forged drive shaft.

Hot and cold forging – what’s the difference?

Forging is a typical manufacturing procedure where compressive forces can form metal parts. Forging is possible in different conditions, such as hot or cold forging. Forging uses hammers or presses that squeeze and deform materials into rigid pieces. 

The most significant difference between hot and cold forging is the temperature. Unlike cold forging, which starts at ambient temperature, the hot forging process occurs when metal gets heated above its crystallization temperature. The high temperature of hot forging helps prevent work hardening. At such temperatures, metals are plastic – albeit technically solid.

Cold forging is a vital process for shaping and strengthening metal.

In contrast, hot forging produces material with excellent yield strength, lower hardness, higher ductility, and higher strength of materials. 

You can decide between the two types based on economics, your mechanical properties requirements, and the machinery size needed to make a part of specific size and volume.

Note: Forging is entirely different from casting, where the molten material is poured into molds.

Cold forming and forging – are they the same?

Metalworking processes include forming and forging. They both involve the modification of metal to produce different sizes and/or forms. From iron and steel to aluminum, bronze, and more, a variety of metals and alloys are available. Even though they utilize various techniques to alter metal—forming and forging aren’t the same.

What is forming?

Deforming a metal workpiece using mechanical deformation is known as forming. By definition, the word “forming” refers to any metallurgical process that involves deforming a metal workpiece by mechanical means. The term “forming,” according to its exact meaning, refers to any metalworking operation in which a metal workpiece is deformed by physical means. Because no material is added or removed from the workpiece during forming, it does not alter its weight—only its form.

Metalworking has two types of forming: compressive and tensile. Compressive loading is used to bend metal parts via the use of compressive strain, whereas tensile stress is used to deform metal components. Rolling and extrusion are examples of compressive forming because they employ compressing force. Stretching and sinking, on the other hand, are examples of tensile forming since they subject metal products to tension stress.

What is forging?

The process of forging is a metalworking technique that uses pressurized blows to shape and manipulate the shape of a metal workpiece. All forging operations entail the use of powerful and pressured impacts to deform and modify a metal workpiece.

Which is best?

Metal parts can be altered in size and/or form using forming or forging. Forging entails delivering strong blows to metal pieces in order to shape them, whereas forming is achieved by using mechanical deformation. There is no waste in either approach, which makes them cost-effective if you’re working with expensive materials. To find out what procedure would be best for the geometry, volume, and mechanical requirements of your final component, you should consult an expert.

Which materials work best with the cold forging process?

When it comes to selecting a metal for a project, there are many options. Hard metals such as carbon steel, alloy steel, and stainless steel are examples of these. Aluminum, brass, copper, silicon, and magnesium are soft metals that can be utilized. The only requirement for any metal is that it has a Rockwell hardness of 44 HRC or lower.

Above: Blade Bolts manufactured via the cold forging process.

What industries use cold forging?

Automotive, aerospace, agricultural, off-road, ships, piping, and hand tools — to name a few.

Sizes range from a few ounces to thousands of pounds.

Automotive: For example, suspension components like idler arm spindles and motor elements such as connecting rods and gearboxes are made using cold forging. Because of their outstanding shock resistance, cold-forged parts are used at high-stress locations. Cold-forged components include things like drive trains, driveshafts, and struts or shocks.

Pipeline: Pipeline stems and valve bodies, which are often composed of copper alloy to enhance corrosion resistance, employ cold forging.

Hand Tools & Hardware: Nails, screws, rivets, and bolts are examples of fasteners. The tight tolerances and high dimensional accuracy make forging the superior option over other processes like machining. Hand tools, such as sockets, are frequently forged.

Military: Cold forging is used in the manufacture of shell casings, bullets, and other military equipment due to strict military standards. Cold forged components deliver the excellent dependability and performance that the military requires. Parts with tight tolerances and strength are ideal for military weapons.

Gears: Cold forging is used for gear production because it eliminates the need for most machining or gear shaping. An important benefit of cold-forged gears is how smoothly and quietly they intermesh (over machined gear teeth).

What production volume do I need to justify cold forging processes?

For the production of high quantities of components at a low cost, cold forging is a successful and cost-effective metal deforming technique.

Cold forging is done with machines designed to deform and shape the metal.

You’ll save money on everything from materials to time. Because of the little amount of scrap generated (compared to metal removal processes), you may save up to 70% on materials. The cost per item is significantly reduced since components are manufactured at a very rapid rate.

You’ll need to think about the part’s size (and weight), as well as the material’s stiffness, and your production volumes. An expert in the field can give you some options to help you make your decision.

FAQs

What is meant by cold forging?

Cold forging has become a popular Chip-Free Forming Process. It typically requires no other work but drilling. The most widely used definition involves making or forging a bulk material with zero heating of the workpiece.

Is cold forging good?

It has many advantages over hot forging such as tight dimensional tolerances, high-quality surface finish, and utilizing lesser cost materials.

What are the advantages of cold forging?

In cold forging, no heat is necessary. This forging method provides increased interchangeability and reproducibility. You can achieve a superior surface finish, minimal contamination issues, improved dimensional control, and greater strength as a result of enhanced grain directional qualities.

What are the disadvantages of cold forging?

Cold forging has the drawback of being unsuitable for certain materials since it may induce cracking during production, create undesirable residual stress, and forged metals are often less ductile. An expert in the field can help you choose between several alternatives.

Ready to warm up to cold forging?

Whether you’re exploring options for a new product or you have an existing one that you’d like to put into production, The Federal Group USA will give you the data and the tools you need to make an informed sourcing decision for your next product—optimized for your manufacturing operation.

We’ve also provided high-quality contract manufacturing services to a wide variety of industries for more than 41 years. Contact us today to learn more.