Cold heading is a metalworking process where a slug or wire is inserted into a die and formed into a specific shape at room temperature through successive hammering or squeezing actions. The Federal Group USA has been manufacturing cold headed products for over 40 years.
What is Cold Heading?
Cold heading manufacturing is a multi-step cold forming process used to form metal parts at room temperature. Unlike other metal fabrication processes, hammers and dies are used at a high speed to form the metal without heating the material.
Advantages of Cold heading
Because the volume of the blank is being hammered into a die and there is no cutting required, the process has little or no scrap material or raw material waste versus other processes like screw machining. A screw machine can produce material scraps above 70 percent. Cold heading creates stronger components much more efficiently.
In addition, because no heat is required, there is less environmental impact, and workers are provided with a safer environment. The production is fast with no cooling down process required and creates pieces with closer tolerances without secondary operations like machining. Additional advantages of cold heading include:
- Less waste
- Faster production
- Stronger parts
- Reduced costs
- Cost effective
Using cold heading for your parts reduces material waste. More of the material is utilized during the cold forming process. This limits material scrap and improves cost savings.
Disadvantages of Cold Heading
Without heat, the pieces must be created with more force. While dies may be cheaper, the machinery required is bigger and more expensive. The pieces cannot be as thick as they may in machining because hammers can only force so much metal into a given space.
Harder metals can require multiple blows to fill a die and certain materials cannot be used in a cold heading machine at all. More complex pieces will require secondary operations as cold heading machines cannot perform operations like rolling, stamping, or bending.
The Cold Heading Process
Here is an overview of the manufacturing process:
- Material Selection:
- Choose the appropriate material for the cold heading process. Common materials include steel, aluminum, brass, and copper.
- Die Design:
- Design dies that represent the final shape of the cold-headed part. Dies are typically made from tool steel and must withstand high pressure and repetitive impacts.
- Die Making:
- Manufacture the dies based on the designed specifications. Precision CNC machining is crucial to ensure the accuracy of the final product.
- Billet Preparation:
- Cut metal blanks, known as billets, from a larger piece of material. The billet size is determined based on the final part specifications.
- Feeding Mechanism:
- Implement a feeding mechanism to accurately position the billet in the heading machine. This ensures proper alignment before the cold heading process begins.
- Heading Machine Setup:
- Set up the cold heading machine with the required dies and tooling. Adjust the machine settings for factors such as pressure, feed rate, and stroke length.
- Cold Heading Process:
- The machine applies pressure to the billet, forcing it into the dies. The metal is deformed and takes the shape of the dies. This is a cold forming process, meaning it occurs at room temperature without the need for additional heat.
- Trimming and Piercing:
- Afterwards, excess material (flash) may be present. Trimming and piercing operations remove this excess material, resulting in the final shape of the part.
- Quality Control:
- Inspect the cold-headed parts for dimensional accuracy and quality. Use measuring tools and visual inspection to ensure that the parts meet specifications.
- Finishing Operations:
- Additional operations such as heat treatment, thread rolling, surface coating, or secondary CNC machining may be performed depending on the specific requirements of the part.
- Tool Maintenance:
- Regularly inspect and maintain the dies and other tooling components to ensure continued accuracy and performance.
Cold Heading Techniques
There are 2 main categories of the cold heading process which are essentially 2 different techniques for forcing the material into the die. These 2 categories are cold heading upsetting and cold heading extrusion. With the upset method, the punch block forces the metal out of the die to produce a head larger than the initial blank.
Cold heading extrusion has 2 subprocesses which are forward extrusion and reverse extrusion. In addition, there are two types of forward extrusion which are open extrusion and trapped extrusion. We will outline the process of each of these below.
Cold Heading Upsetting
A large coil of metal wire is fed into and pulled through a drawing machine. The drawing machine compresses the metal wire material to the desired diameter and cuts it to the desired length. The resulting piece of cut metal is referred to as a metal blank or metal slug. The metal blank then passes into the cold heading machine.
Inside the cold heading machine, the blank is hit between a die and a punch block, pushing the material into the die to create the desired shape.
Cold Heading Extrusion
The cold heading extrusion technique includes two methods, forward extrusions and backward extrusion, also referred to as reverse extrusion. With forward extrusion, the cavity of the two dies is smaller compared to the diameter of the wire, which creates compression. With backward extrusion, the metal is forced backward through a punch to create a hole or cavity.
This type of cold heading process involves feeding a metal slug into a cold heading machine. The machine’s dies and punches shape the slug by applying compressive force at room temperature, resulting in the formation of complex metal parts, such as fasteners. The 2 types of cold heading forward extrusions are:
- Open Extrusion: The cold heading open extrusion process involves deforming a metal slug at room temperature by forcing it through a die with an open end, typically used for producing parts with a consistent cross-sectional shape, such as pins or small rods.
- Trapped Extrusion: Cold heading trapped extrusion is a metalworking process that forms metal components by forcing a metal slug into a confined space within a die using a punch, allowing for the creation of intricate and precise shapes.
Cold heading reverse extrusion or sometimes called backward extrusions is a metalworking process where a metal slug is placed on a die, and a punch is used to force the material to flow in the opposite direction of the punch movement. This process is often used to form the heads of bolts and other fasteners, creating features like flanges or large heads.
When should you choose cold heading for your parts?
Cold forming comes with advantages and disadvantages compared to other machining processes, such as screw machining. While using a screw machine may eliminate the need for dies, cold forming requires dies to set the head shapes, which increases the lead time and initial cost. A swiss screw machine also produces more material scrap.
The cold heading process is ideal for projects that require large quantities or if you are looking to reduce the need for secondary operations of a component in your current product lineup. Some of our clients had previously been machining parts which we were able to easily transfer to the cold heading process.
Since cold forming processes don’t involve the use of heat, you should also consider cold forming or cold heading when product strength is a priority. Cold working processes result in work hardening which affects the grain flow of the metal which typically results in a strong final product.
The cold heading process is commonly used for creating custom screws, bolts, and other custom fasteners out of round metal stock.
Cold Heading & Cold Forming
Cold heading and cold forming are both manufacturing processes used to shape and create parts or components at near room temperature, but they are distinct techniques with different applications and processes. Cold heading is a type of cold forming process that is typically used to create products with a “head” like screws, bolts, and rivets.
Cold forming is the broader category used to describe an array of manufacturing processes performed without the use of heat. The basic types of cold forming processes include extrusion, forging, rolling, blanking, wire drawing, and more. As long as the manufacturing process is performed at room temperature, it can be considered cold forming.
Cold Heading Applications
Above: Cold headed wheel studs manufactured by The Federal Group.
Cold headed products include items like simple fasteners, though with cold heading technology always improving, it can be used to create highly specialized fasteners and specialty pieces. This includes cold headed fasteners used in bridges, automotive manufacturing, electronics, specialty bolts, and other components.
Some common cold headed parts include:
- Screws and Bolts: The cold heading process creates various types and sizes of screws, bolts, and studs used in construction, automotive, aerospace, and other industries.
- Nuts: Different types of nuts, including hex nuts, lock nuts, and flange nuts, are often manufactured through cold heading processes.
- Rivets: Cold heading is used to create custom rivets, essential in construction, automotive assembly, and aerospace for joining materials together.
- Pins and Fasteners: Cotter pins, dowel pins, and other fasteners are often produced using cold heading techniques for their precision and strength.
- Electrical Contacts: Small components like electrical contacts in various devices are often manufactured through cold heading due to the precision required.
- Automotive Components: Cold heading is extensively used in creating various automotive parts like gears, shafts, and transmission components.
- Metal Components for Consumer Goods: Items like furniture hardware, appliance components, and various metal parts in consumer goods are often produced via cold heading.
These products are used across industries due to the advantages of cold heading, such as cost-effectiveness, material efficiency, and the ability to create high-strength parts with minimal material waste.
Cold Heading Materials
Cold heading materials possess excellent formability characteristics and can be transformed into intricate shapes and fasteners without the need for heat. Their diverse mechanical properties make them ideal for a wide range of applications.
Softer metals typically form more easily while harder metals may require multiple blows in order to create the final product or specific shape.
The Federal Group utilizes a variety of materials for cold formed parts such as:
- Alloy steel
- Carbon steel
- Exotic metals
- Nickel alloys
- Specially blended materials
- Stainless steel
Cold Heading Machines
Our equipment ranges from your average 2 die/2 blow all the way to the most advanced 5 die/5 blow machines available. These cold heading machines can produce between 3,000 to 4,000 components per hour.
The Federal Group’s Cold Heading Capabilities
Cold heading technology has been around for about 100 years. A shortlist of our cold forming and cold heading strengths are exotic metal fasteners, gear blanks, ball studs, piston pins, sparkplug shells, valve spring retainers, engine poppet valves (intake and exhaust), transmission shafts, agricultural parts, bearings, screws, bolts, nuts, terminal studs, specialty and per print items.
Work With an Experienced Header Today
The Federal Group boasts a proven track record of high quality, cost-efficient, and timely metal cold heading components. We can handle your specific shapes, unique material requirements, or large quantities. Contact us today to receive a free quote on your next project.
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