A Guide to Open Die Forging

Also known as smith forging, open die forging takes its name from the fact that the dies—the surfaces
that make contact with the metal being forged—do not enclose the piece. Instead, the metal flows
freely except in the limited areas where the dies are placed. Open die forging is an important technique
for many manufacturing applications. Here is what you should know.

Capabilities of Open Die Forging

Open die forging allows both rough and finishing shaping work to be done on metal of sizes ranging
from very small to incredibly large. In fact, some open die forges can handle pieces that are 80 feet
long and weigh a whopping 136 metric tons.

Open die forging is difficult, though not impossible, to use for pieces with a great deal of fine detail.
Therefore, except for art pieces and other specialty operations, open die forging is typically used to
create discs, blocks, hugs, shafts, cylinders, flats, plates, sleeves, and other relatively simple shapes.
It is often used to rough-shape ingots in preparation for further forging of a different type.

Common Metals

Steel and similar alloys are the most common metals used in open die forging. However, the process
also works well with a variety of other metals, including alloys of copper, nickel, and titanium.

Open Die Forging Process Operations

While closed die forging can be automated, open die forging is entirely under the control of the
metalworker. The forge operator must continuously orient and position the metal being worked as a
hammer strikes and deforms it to create the desired shape. The dies resemble tools rather than molds
and since the metal flows freely except where it is in contact with the dies, the metalworker must
carefully manage the forging process.

There are three common open die forging processes that are typically performed first, regardless of the
type of metal or what the finished product will be. Taken together, they prepare the metal for further
forging:

Cogging: Cogging is used to reduce a raw bar of metal to the desired thickness. It uses an open die
drop forge to successively deform the bar along its length.

Edging: Generally performed after cogging, edging uses a concave open die to form the metal into the
desired width.

Fullering: Fullering uses a convex open die to thin out sections of the metal as needed.

Benefits of Open Die Forging

Open die forging has a number of benefits over other types of forging. It refines the metal grain,
improving strength and reducing porosity. It improves wear resistance and fatigue resistance. The
improved microstructure reduces the chance of voids.

No single forging process is right for all applications. It is always important to speak with an expert who
can help you decide which process has the most benefits and the fewest drawbacks for your particular
project.

Ready to Start?

Atlas Bronze is a leading U.S. distributor of bronze, copper, brass, iron, and more. Contact us today at 1-800-478-0887 to place an order or learn about our custom products.

The Differences Between Brass and Bronze

Brass and bronze are often marketed interchangeably, but they are far from the same material. Both
play a valuable role in modern manufacturing, but one is often more suitable for a particular application
than the other. To know which is best for your project, it is essential that you understand the differences
between the two. Here are the basic differences between brass and bronze.

History

Bronze is far older than brass, dating to the Sumerian people around 3500 BC. A far stronger and more
durable material than stone and copper, the discovery of bronze gave mankind the hallmarks of the
Bronze Age, including more detailed metal sculptures, new decorative tiles, and a wide range of new
tools, weapons, and armor.

Brass was discovered in approximately 500 BC. Its natural golden color and tarnish resistance made
brass useful for the production of coins and other items where a lustrous appearance was desired.
However, it was difficult in those days to create brass, so it was not until medieval times that brass
became a commonly used material for church monuments and wire. By the 17th century, brass was the
alloy of choice for instruments that required accuracy, such as clocks, navigational aids, and precision
scientific instruments.

Composition and Properties

Bronze is a metal alloy based on copper and tin. Other elements such as aluminum, silicon, phosphorus,
and manganese may also be added. It is brittle and hard, but resists corrosion and metal fatigue better
than steel. Bronze is a good conductor of both electricity and heat. Its color is reddish-brown.

Brass is a metal alloy based on copper and zinc. Iron, silicon, aluminum, and manganese may be added
to improve corrosion resistance. Brass is more malleable than either zinc or copper, and it has a relatively
low melting point of 900 C. Brass is not as hard as steel. It has the appearance of muted, dull gold.

Uses

Bronze is particularly useful in marine applications due to its corrosion resistance. It is frequently used
to create cast sculptures, and it is generally considered one of the best materials for creating bells and
cymbals. Industrial uses for bronze include bearings, springs, electrical connectors, and a variety of clips.

Brass is commonly used for decorative pieces, and it imparts excellent acoustic properties to a variety of
musical instruments. It is also common in applications that require low friction, such as valves, gears,
doorknobs, ammunition, and locks. It is not prone to sparking, so it is often used for zippers as well as
fittings and tools that will be used around explosive gases. Brass is also a popular choice for boat
hardware.

Both brass and bronze are in common use today. However, they are not the same material, and their
properties differ significantly. Make sure you choose the metal that is truly the best option for your project.

Ready to Start?

Atlas Bronze is a leading U.S. distributor of bronze, copper, brass, iron, and more. Contact us today at 1-800-478-0887 to place an order or learn about our custom products.

A Guide to Closed Die Forging

Closed die forging, also known as impression die forging, uses two or more dies that contain a precut
profile of the desired product. Heated metal, such as steel, bronze, titanium, or aluminum, is poured
into the bottom die. As the dies come together, pressure and impact forces form the metal to fit the
shape.

Capabilities of Closed Die Forging

A major advantage of closed die forging is its preciseness. Parts weighing anywhere from several
ounces to 60,000 pounds can be produced in a virtually limitless variety of 3-D shapes. Closed die
forging is equally effective for simple spheres and blocks, for extremely intricate components with high
vertical projections and thin webs, and for parts that include detailed design elements such as bent or
curved flanges and protrusions.

Metals and Alloys

Virtually all metals and alloys that are used in engineering can be used in closed die forging. Some
materials that are particularly sensitive to temperature or strain rate, such as refractory alloys and
nickel-based super-alloys, may require special equipment for closed die forging.

Closed Die Forging Process Operations

The simplest version of closed die forging brings two dies together to cause plastic deformation in the
heated metal until its sides touch the side walls of the dies. A small amount of the metal then starts to
flow outside the die, forming flash. The rapidly cooling flash adds deformation resistance, building up
pressure inside the dies to boost material flow into all areas of the dies.

Closed Die Upsetting

Closed die forging can be performed on horizontal forging machines known as upsetters. In this case,
“grip dies” consist of one stationary die and one moving die that contain the desired impression and
can be closed to hold the material in position for forging. A ram-operated “heading tool” acts as a
hammer or press, forcing metal into all sections of the grip dies.

Closed die forging can produce products with tighter tolerances and higher precision than other
methods such as open die forging. The finished products also have better strength and tightness, as
well as an improved surface finish. Like anything else, though, closed die forging is not always the
right choice. It can be expensive for small runs due to the need to create customized profiles for each
piece. In addition, fatigue resistance is not as high for closed die forged items as for open die forged
items.

At Atlas Bronze, we carefully select the forging or casting process that is right for each item. Using the
best process lets us ultimately produce the best results.

Ready to Start?

Atlas Bronze is a leading U.S. distributor of bronze, copper, brass, iron, and more. Contact us today at
1-800-478-0887 to place an order or learn about our custom products.

Understanding Hot Extrusion

Extrusion creates objects by pushing raw materials through a die to create complex cross-sections in
finished products, such as bars, tubes, or strips, and to improve the strength of metal construction or
manufacturing materials. The finished materials could be hollow or solid. It is one of the most common
methods of metal processing, though it can also be used with other types of raw materials.

How Hot Extrusion Works

Hot extrusion happens when the process takes place at a higher temperature than the metal or alloy’s
recrystallization temperature. This makes the process of pushing the material through a die easier.
How hot the metals must be depends on the specific metal. However, temperatures typically range
from 650°F for magnesium to 2,400°F for some types of steel. The exact temperature varies based on
many factors, including the final application.

Benefits of Hot Extrusion

Hot extrusion creates products with homogeneous properties that are of very high quality. This improves
the appearance and functionality of the finished product, as well as increasing the strength of the metals
(in most cases). The process of hot extrusion can save energy compared to cold extrusion processes,
where more force must be exerted onto the materials. It can also reduce material waste, which can
mean material savings, especially from large projects.

While hot extrusion may not be economically advantageous for small or very large batches, it might be
the most cost-effective option for medium to large volume projects. However, this largely depends on the
materials being rolled. Some types of steel produced in quantities over 50,000 pounds are more cost
effective using a hot extrusion process.

Disadvantages of Hot Extrusion

Hot extrusion is a more expensive process than other methods because of the upfront cost of the
required machinery as well as the cost of maintaining it. Some manufacturers may not offer hot extrusion
as a result. You may be required to pay more for parts created using hot extrusion rather than other
processes.

Additionally, the pressure range required for the process requires the use of lubrication. The heating
process could weaken the materials. Cold extrusion, as opposed to hot extrusion, may provide a better
surface finish. Under high heat, some metals can become oxidized, which could change the appearance
of the metal and increase friction, again requiring the use of lubrication. Which process is best will
depend on the raw materials and the final intended use of the products.

Ready to Get Started?

Atlas Bronze sells a range of engineered products for every industry, including made to order plates,
castings, and forgings. Check out our online store at www.atlasbronze.com to see what existing
products we sell or contact us for a quote on your custom project. Our expertise and experience can
help to ensure that you have access to the highest quality metal products for your project.