Forgings Processes

INTRODUCTION

In the forging process, metal is shaped by pressing, pounding, or squeezing under very high pressure to form parts called forgings. Almost any metal can be forged, including carbon, alloy and stainless steel, aluminum, titanium, brass, copper, and others. The metal is usually preheated prior to the forging services process, but not melted, as in the casting process.

FORGING PROCESSES

The types of forging services selected are determined by the shape, size and material of the metal to be forged and the end product. There are several different types of forging processes.

1. COLD FORGING

In cold forging, the metal being processed is not directly heated. Instead, it is molded under extreme pressure. This process makes products that are precisely sized to final shape. It is often used to create small components like fasteners. While the forces required to mold the metals are extreme, the overall energy needed to forge items using this process is rather small, as no heating is required. Items prepared through this process are generally strong, as heating has not weakened the strength and consistency of the metal.

2. IMPRESSION DIE FORGING

It is the most commonly used of the forging services. In impression die forging, a metal workpiece is placed between two dies. As the dies are brought closer together, the workpiece undergoes plastic deformation until its enlarged sides touch the die sidewalls. During the process, flash is formed, as some of the molten metal from the workpiece flows outside the die impression. As the flash cools, it imparts deformation resistance to the workpiece, strengthening the final product. This builds pressure inside the bulk of the workpiece, aiding material flow into unfilled impressions.

3. OPEN DIE FORGING

In open die forging, the dies do not completely cover the workpiece. Instead, there are open spaces that allow various aspects of the workpiece to move from direct hot die contact, and to cooler open areas. During open die forging services the metal workpieces are heated to above their recrystallization temperatures, and the working process begins. Throughout the process, the workpiece is moved so that all aspects of the workpiece may be forged. As the workpiece is moved and repositioned, aspects that are in the open area cool to below the metals recrystallization point, which must then be reheated as forging continues.

4.RING ROLLING

Involves heating a metal perform to forging temperature. The preform is then placed into an internal rolling machine. As pressure is applied by the walls of the rolling machine, the preform begins to take on a cylindrical, or ring, shape. As the inner and outer dimensions are expanded within these forging services, the cross-sectional area is reduced.

WHY FORGINGS ?

It is important to note that the forging process is entirely different from the casting (or foundry) process, as metal used to make forged parts is never melted and poured (as in the casting process).
The forging process can create parts that are stronger than those manufactured by any other metalworking process. This is why forgings are almost always used where reliability and human safety are absolutely critical.
Forgings are stronger. In making a forging, the metal is worked twice under tremendous pressures. First during rod extrusion, drawing or rolling and then during forging. The double working under pressure compacts the metal and produces a very dense and refined grain or fiber structure. The tensile strength of the parts is thereby increased, and resistance to impact and abrasion is enhanced.
Forging refines defects from cast ingots or continuous cast bar. Pre-working forge stock produces a grain flow oriented in directions requiring maximum strength. Dendritic structures, alloy segregation`s and like imperfections are refined in forging. Hot-working also imarts high strength, ductility and resistance properties.
The dense non-porous forged metal permits the designer to specify thinner sections without the risk of leaks due to flaws and voids. Often the thinner forged parts result in lighter weight and lower piece cost compared to other manufacturing processes.
A forging produced in a steel die with close tolerances offers several advantages. Overall part dimensions are held closer than in sand casting. Dimensions show minimum variation from part to part and permit automatic chucking and handling in subsequent operations. The precise designs on the die surface can produce sharp impressions on the forging surface, which is normally not the case with other forming processes.
Cost effective. Mass production of forged parts lends itself to maximum savings. And they are manufactured without the added costs for tighter process controls and inspection that are required for casting.
Forgings offer better response to heat treatment. Castings require close control of melting and cooling processes because alloy segregation may occur. This results in non-uniform heat treatment response that can affect straightness of finished parts. Forgings respond more predictably to heat treatment and offer better dimensional stability.
Forgings` flexible, cost-effective production adapts to demand. Some castings, such as special performance castings, require expensive materials and process controls, and longer lead times. Open-die and ring rolling are examples of forging processes that adapt to various production run lengths and enable shortened lead times.

FORGING METALS (Copper, Brass & Bronze Forgings)

Copper, Brass & Bronze forgings are quality parts, comparing favorably in material integrity, dimensional tolerance and surface finish with products made using other major metalworking processes. As a result of hot working, forged materials have superior density and freedom from flaws. Forming under heat and pressure in precise closed dies produces dimensional accuracy, always repeatable, part to part and lot to lot. Excellent surface finish with a clean lustrous appearance is readily available with copper and brass forgings.

Forgings of Copper, Brass and Bronze alloys offer a number of outstanding advantages over parts produced by other manufacturing processes. These advantages result from the inherent properties of copper and copper alloys plus additional improvements in mechanical and physical properties imparted by the forging process. We can offer fully machined forgings, plating, polishing, powder coating, painting, assembly work, design assistance, and much more. Copper, Brass and Bronze forgings offer the designer unique combinations of properties that other metals cannot match. Alloys can be selected to utilize the following unique characteristics :

ALUMINIUM FORGINGS

The forging process and aluminum alloys ensure the best of great strength, light weight and attractive appearance. Aluminum Forgings are generally used in applications where the high integrity of the part is of utmost importance. They are used primarily for structural components such as the intake (front end) of Gas turbine engines where light weight is crucial. In automotive applications, forged components are commonly found at points of shock and stress. Forged automobile components include connecting rods, crankshafts, wheel spindles, axle beams, pistons, gears, and steering arms. Forgings are also used in helicopters, piston-engine planes, commercial jets, and supersonic military aircraft. Many aircraft are “designed around” forgings and contain more than 450 structural forgings as well as hundreds of forged engine parts. “Forged” is the mark of quality in hand tools and hardware. Pliers, hammers, sledgers, wrenches, garden implements, and surgical tools are almost always produced through forging.

The aluminum components manufactured range in weight from a few ounces to a few hundred pounds, and are forged into a wide variety of shapes and sizes with or without cores.

Heat Treating prepare forged aluminum products for secondary machining and assembly. We offer other services such as finish machining, anodizing, painting, powder coating, polishing assembly work, design assistance, etc. A variety of cleaning processes including chemical, vibratory and shot-blast.

STAINLESS AND ALLOY STEEL FORGINGS

Stainless and Alloy Steel forgings are manufactured for use in various environments including offshore and land installations, chemical, petro-chemical, food processing, medical tool & equipment industry, power generation, marine and general engineering. Stainless Steels are used in the low -pressure turbine (hot) section of gas turbines. Alloy Steels are used for various gas turbines components where high strength and wear characteristics are required.

“Forged” is the mark of quality in hand tools and hardware. Pliers, hammers, sledgers, wrenches, garden implements, and surgical tools are almost always produced through forging. There are many other applications for these alloys. Please call us for technical assistance with your requirements.

FINISHES AND SECOND PROCESSES

Hard-Coat Anodize on Aluminum

Many products benefit from Hard-Coat Anodizing including Automotive, Military, Aerospace, Telecommunications, Medical and Industrial. Hard Anodized aluminum is non-conductive to electricity; consequently areas requiring conductivity will need selective masking. Anodize becomes integrated to the part and is qualified for use in salt/corrosive atmospheres. Hard Anodized aluminum products exhibits wear resistance over 10 times that of regular anodize. Requirements for close tolerances are met and process variables are maintained. Hard-Coat Anodized Colors can be clear, black, blue, red and green.
Hard-Coat Anodizing enhances many of the desirable properties of aluminum and offers:

Properties & Advantages

Hard-coat Anodizing provides for several desirable qualities such as:
Hard-coat Anodize coatings may be dyed a variety of colors. However due to its naturally darker appearance, dyeing does not produce the vibrant colors that a Type II sulfuric anodize will. Additionally the required sealing process after dyeing does slightly reduce hardness.

Specifications

There are hundreds of governmental, industrial and commercial anodizing specifications in use. Each with their own method of calling out coatings, seals, dyes, etc. Any anodizer should recognize the Type III designation to indicate a Hardcoat Anodize, Class 1 to specify natural color or no dye, and Class 2 to indicate a dye.

Materials

Hardcoat anodizing works very well with 2000(2014), 3000, 5000, 6000 and 7000 series aluminum alloys and 214, 355 and 356 series die casting material.

Regular or Conventional Anodize

Conventional Anodizing increases strength, wear and corrosion resistance, while adding a beautiful finishes to aluminum’s comparative low cost, lightweight and malleability.
Regular Anodizing has outstanding abrasion and corrosion resistance. It lends its self readily to clear and the colors of red, blue, green, gold, OD-green and black. The colors will be light to dark depending on required thickness. Regular anodizing provides an excellent base for primers, bonding agents and organic coatings.. Given that anodized parts are electrically nonconductive, masking can be offered using stop-off lacquers, plus assorted tapes and plugs for areas designated as “anodize-free” or “conductive” by the customer.

Black Oxide

Black Oxide is used to provide a protective, corrosion resistant coating over metal. It has a uniform black finish that does not alter the dimensions of the part after processing. The coating does not chip or peel and acts as an absorbent to hold oils or wax. Black Oxide coatings are used on firearms, spark plugs, furniture brackets, mower blades and other products where a uniform black surface is desired. This coating is economical and offers a variety of valuable

Properties & Advantages

Hard-coat Anodizing provides for several desirable qualities such as:

Hard-coat Anodize coatings may be dyed a variety of colors. However due to its naturally darker appearance, dyeing does not produce the vibrant colors that a Type II sulfuric anodize will. Additionally the required sealing process after dyeing does slightly reduce hardness.

Specifications

There are hundreds of governmental, industrial and commercial anodizing specifications in use. Each with their own method of calling out coatings, seals, dyes, etc. Any anodizer should recognize the Type III designation to indicate a Hardcoat Anodize, Class 1 to specify natural color or no dye, and Class 2 to indicate a dye.

Materials

Hardcoat anodizing works very well with 2000(2014), 3000, 5000, 6000 and 7000 series aluminum alloys and 214, 355 and 356 series die casting material.

Regular or Conventional Anodize

Conventional Anodizing increases strength, wear and corrosion resistance, while adding a beautiful finishes to aluminum’s comparative low cost, lightweight and malleability.
Regular Anodizing has outstanding abrasion and corrosion resistance. It lends its self readily to clear and the colors of red, blue, green, gold, OD-green and black. The colors will be light to dark depending on required thickness. Regular anodizing provides an excellent base for primers, bonding agents and organic coatings.. Given that anodized parts are electrically nonconductive, masking can be offered using stop-off lacquers, plus assorted tapes and plugs for areas designated as “anodize-free” or “conductive” by the customer.

Black Oxide

Black Oxide is used to provide a protective, corrosion resistant coating over metal. It has a uniform black finish that does not alter the dimensions of the part after processing. The coating does not chip or peel and acts as an absorbent to hold oils or wax. Black Oxide coatings are used on firearms, spark plugs, furniture brackets, mower blades and other products where a uniform black surface is desired. This coating is economical and offers a variety of valuable
properties to extend the service life and improve the performance characteristics of the part. Black Oxide is usually on copper alloys and on steel.

Chem-Film or Chromate Conversion

Silver Plating

Industrial Silver plating provides an economical coating typically used for aerospace, telecommunication and electrical products. It bestows a surface that can be soldered and exhibits low electrical resistance. The tarnish resistance is equal to that of a good water dip lacquer coating. Silver processe can produce a matte to bright finish on aluminum, brass, copper and steel.

Electroless and Electro-Deposited Nickel Plating

These Nickel Plating processes deposit a uniform thickness of Nickel onto products by chemical reduction; this allows even the most complex shaped product to be plated with no edge build-up. Other advantages of Nickel Plating include superior chemical and corrosion resistance, a hard, highly protective, bright, and reflective coating that yields excellent wear. Nickel`s low friction and superb conductivity characteristics, makes it appropriate for Electronic, Tooling, and Commercial Industries. It is also used for cosmetic appearances. Masking is offered by means of stop-off lacquers, assorted tapes and plugs for selected “no-plating” product areas. Both plating methods may be applied to Aluminum, Brass, Copper and Steel metals.

Masking and Plugging

Proper masking is critical to high-quality product finishing and painting. Automotive, Military and numerous other industries require masking services. The masking or plugging of parts is sometimes necessary, where dual processes are to be performed. The use of the correct masking and plugging products can save you rework, or rejected parts. The most critical element is to use the correct masking material for the critical dimensions, and exact locations as designated on the customer`s blueprint. The fit must be exacting and mirror the form of the finished product requirements.

Phosphate Coating: Zinc, Iron or Manganese Phosphate

Phosphate coating is the treatment of castings, iron, steel or steel-based substrates with a solution, whereby the surface of the metal is converted to an integral, mildly protective layer of insoluble crystalline. Phosphating is considered the heart of pretreatment operations; it is here that the top surface of the metal is converted into a highly insoluble, corrosion-resistant coating that provides the primary bond between substrates and the next process. There are several phosphate processes:
Iron Phosphate produces coatings with course to fine crystals providing a receptive surface for the bonding of other applications and is useful where corrosion protection requirements are not of the highest levels.
Zinc Phosphate may be used as a base for Paint or for increasing wear resistance, or rust proofing, and provides inherently better corrosion resistance than iron.
Manganese Phosphate is applied chiefly to ferrous parts (Internal combustion engine parts for example) for break-in and to prevent galling and are mostly used as an oil base.

Plating

Dry Film - Solid Film Lubricant

Dry film lubricants, also known as Solid Film Lubricants, provide a lubricating film and are intended for use as dry, low friction coatings to reduce wear and inhibit troublesome corrosion. Solid Film Lubricants have a wide temperature range and high load carrying ability. Solid Films conduct electricity or may be used as insulators. Being clean lubricants they do not attract dust or dirt, and are not diluted or washed from surfaces by water or most solvents. High quality dry film lubricant fills all the voids and depressions of a surface, covering it with a solid, long lasting lubricating film capable of withstanding load and environmental extremes..

Gold Plating

Gold Plating is used for many different electronic and electrical purposes, where the part is designed to operate on complex, high-reliability electronic devices. The majority being applied to three specific types of components: semiconductors, printed/etched circuits, contacts/connectors and high-end decorative items. Industries also use Gold plating for decorative applications. Gold plating can easily be applied to brass, aluminum, copper or steel.

Tin Plating

Tin plating is extensively used in Food, Electrical and Electronic Industries. Because it is safe and nontoxic, Tin is universally utilized in the Food Processing Industry. Plus offers first-rate corrosion resistance and is pliable with low porosity. Also used for Electrical and Electronic, Tin plating has the ability to protect base metals from oxidation, thereby preserving the potential for soldering. Tin provides a bright cosmetic surface, excellent electrical conductivity and applies without difficulty to metals such as steel, copper, brass and aluminum.

Paint, Primers and Top Coats

Varied painting techniques enhance our ability to meet customers` requirements and expectations. We paint to required tolerances and blueprint specifications with the use of: low – medium and high solvents, enamels, lacquers and two-component coatings, on any metal or surface, and to all standard color requirements. Plugging and masking per blueprint, are available using stop-off lacquers, assorted tapes and plugs.

Passivation, Shot Blast Finishing and Tumbling Finishes

The Passivation process is a method of removing metal oxides; heat-treat scale and other foreign materials from stainless steel and other metals, leaving the surface chemically clean and prepared for further processing. Passivation restores the original corrosion-resistance surface by forming a thin, transparent oxide film on the part. Parts that are to be soldered or brazed should be Passivated before, but not after, these operations. Shot Blast gives various surface finishes used extensively on Cast products. It can produce a cosmetically better looking product. There is various size shot used for different surface finishes. Care should be taken with this process as it does add stresses to certain metals, especially copper alloy. Silk-screening

Silk-screening is essentially a stencil printing method that begins with computer-generated artwork, which is comprised of a clear film. Silk-screening is performed through the use of stainless steel or cloth mesh screens, with either fine, or course mesh-counts and many ink types. The customers chosen design is applied directly to the product with paint, ink etc. Silkscreen is very versatile, and has a wide range of materials to which it can be applied. Some examples are: paper, all types of metal, glass, plastic and rubber. The size and shape of the product to be silkscreened is almost limitless.. Military, Telecommunications and Commercial Industries use silkscreening on boxes, panels and various other parts and products.

Zinc and Zincate Plating

Deeco Metals offers two types of Zinc plating: Alkaline Zinc exhibits good brightness, ductility and chromate receptivity, and has reliable and consistent coverage. Chloride Zinc deposits an outstanding brightness and plates difficult substrates such as castings. Zinc plating is used extensively on Automotive, Aerospace and Military products. It is available in Clear, Yellow or OD Green, and may be applied to steel, aluminum, copper or brass depending on the choice of zinc process.

GLOSSARY

Age Hardening – A process of increasing the hardness and strength of an alloy by precipitation of particles of a phase from a supersaturated solid solution alloy. The hardening cycle usually consists of heating or annealing at a temperature sufficiently high to maintain solid solution; rapid cooling or quenching to retain the supersaturated solid solution, and subsequent heating at a temperature lower than the solution anneal to effect the precipitation.

Billet – A slug cut from rod to be heated and forged.

Blocker – Preformed die or impression, used when part cannot be made in a single operation.

Bottom Die – The stationary half-die.

Cavity – The impression in either the upper or lower die.

Die Shift – The impression of the top die not being in alignment with the impression of the bottom die, also, the amount of misalignment.

 Draft – The taper on a vertical surface to facilitate the removal of the forging from the die or punch.- The taper on a vertical surface to facilitate the removal of the forging from the die or punch.

Fillet – A curved inside corner to increase the strength of an object at the corner and to improve appearance. Also important as it increases forging die life.

 Flash – The excess metal that flows out between the upper and lower dies which is required to accomplish a desired forging shape.

 Flash Extension – The amount of metal extending beyond the part at the flash line.

 Flash Line – The line where the flash occurs.

 Forging – The production of semi-finished forms from wrought metal blanks hot or cold in closed dies by a sudden, sharp impact. See “HAMMER FORGING” and “HOT PRESS FORGING”.

 Gutter – A slight depression surrounding the cavity in the die to relieve pressure and control flash flow.

 Hammer Forging – A forging process in which the piece is deformed by repeated blows.

 Hardness – The resistance of a metal to plastic deformation by indentation. Common methods of measurement are Rockwell, Brinell, Scleroscope and Vickers.

 Heat Check – Fine cracks in the forging dies caused by excessive heat or extended use without polishing. The pattern of these “heat checks” is reproduced on the forged part.

 Heat Treatment – A combination of heating and cooling operations, applied to a metal or alloy in the solid state to produce desired properties.

 Hot Press Forging – A method of forming parts by pressing a heated slug, cut from wrought material, in a closed-impression die.

 Lubricate – Swabbing or spraying the dies with lubricant to assist in initial flow and to facilitate ejection of the forging.

  Mismatch – Misalignment of forging at flash line caused by die or cavity positioning. (Mismatch should not exceed allowable tolerances).

 Passivation or Vibratory Finishes – Various abrasive or polishing media is used in the process such as ceramic shapes, stainless balls, tree bark, metal chips, etc., to obtain many different finishes to metal parts.

 Parting Line – The line where the dies come together and the flash is removed.

 Shrinkage – The contraction that occurs when a forging cools.

 Sink – To cut an impression in a die by EDM or CNC Milling.

 Slug – The blank, cut from wrought material, from which a forging is made, see “BILLET”.

 Tensile Strength – The value obtained by dividing the maximum load observed during tensile straining by the specimen cross-sectional area before straining. Also called “Ultimate Strength”.

 Tolerance – The amount by which any characteristic such as dimensional, chemical, physical or mechanical properties, may vary from that specified.

Tumbling – Rolling in a revolving container to remove sharp edges and improve finish.
Web – The thin section of metal remaining at bottom of a cavity or depression in a forging. The web may be removed by piercing or machining.

 Yield Strength – As commonly applied to copper and copper-base alloys, yield strength is the stress which will produce a .5 percent extension under load. It is known as “Yield Strength (.5 percent extension).

But you`ll rarely see forgings, as they are normally component parts contained inside assembled items such a airplanes, automobiles, tractors, ships, oil drilling equipment, engines, missiles and all kinds of capital equipment – to name a few

How to buy forgings?

1. Identify the product end use then decide the requirements in terms the strength, toughness, dimensional accuracy and overall integrity of a forging.The buyer should have a clear understanding of what their component specifically requires and ensure their needs can be met by individual forgers.

2. Identify the forging process required to make the product.This is a straightforward decision based on part size, configuration and quantity required.

3.Designing the product : One should clearly express how the desired forging will be used, the operating environment and critical mechanical properties. The forger needs to clearly understand the service stresses like load-bearing, power transmitting, impact, hydraulic pressure, operating temperatures, corrosive condition and the stress locations. This will help the engineer design and pass on suggestions to improve the overall product while reducing manufacturing costs.

4.Main design points:
a.Material Selection : Consider the tensile, hardness, impact and other mechanical properties are realistically based on the service requirements of the component being forged. select the best material for optimum performance, forgeability, heat treatability, machineability and cost.
B. Part Configuration : The forging engineer will look at its tooling and processing requirements and see where they can reduce draft angles or sharper radii without affecting part function. Often a simpler die can be used or the parting line can be adjusted to allow the use of a flat top die which will produce a more affordable part.
c.Dimensional Tolerances A wise buyer will see if the forger could help evaluate the trade-offs between reduced machining and increasing die and processing costs.
d.Machining : For open die forging, nearly all forgings will require some machining. Determining where and how much machining stock “envelope” should be specified and the complex decision is best made together with the forger.

e. Applying Guidelines – There is a system that was developed that act as dimensional tolerance guidelines that set limits on size, length, width and thickness, die match and straightness. Guidelines for impression die applications can be found in the Forging Industry Association’s Tolerances for Impression Die Forging, Hammer, Press and Upsetter.

f. Surface Finishing .

g.Inspection & Testing – The only tests that are needed will be ones that establish the mechanical properties and quality required for reliable performance. This will help keep costs low while also ensuring the part performs as needed because any additional tests will increase the cost. Non-destructive testing like ultrasonic and magnetic particle inspects have become increasingly important for critical service applications like generator or turbine rotor shafts. These tests are expensive and time-consuming so they should only be used when absolutely necessary. Statistical process/quality control techniques are being used in many forge shops and these capabilities could reduce the need for costly testing on individual

h. Delivery.

.

Some points to consider when choosing a forger.

-Does the forger have experience in applications similar to the one being considered?

-Is design assistance offered?

-Does the forger have the equipment required to produce your part?

-Is the forger able to provide related services like heat treating, machining and testing?

-Is the forger accustomed to producing the volume required?

-Does the company specialize in long runs, short runs or quick delivery?

-Is the forger capable of producing nonstandard alloys, specs & sizes?

Answering these questions is key to finding the qualified forger to meet your needs.

QUALITY CERTIFICATIONS / ENVIRONMENT / ENERGY certifications  required for supplying forgings.

ISO 50001

Lloyds Register

ISO 9001

IATF 16949

ISO 14001

EN 9100

AD 2000

NADCAP Heat Treating

NADCAP Non Destructive Testing

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