Aluminum Profile Extrusion
Shandong University
Contents
Chapter1 Process of Extrusion of Aluminum ...........................................................................................................1
Process Overview........................................................................................................................................1
Billet .........................................................................................................................................................2
Dies and Tooling .........................................................................................................................................2
Direct Extrusion Operation .........................................................................................................................5
Aging...........................................................................................................................................................6
Packaging ....................................................................................................................................................7
Chapter 2 Metallurgical Principles............................................................................................................................8
Introduction .................................................................................................................................................8
Structure ......................................................................................................................................................8
Lattice Structure Single Phase .........................................................................................................9
Multiphase Structure—Equilibrium Diagrams ..............................................................................14
Diffusion, Precipitation, Non-equilibrium .....................................................................................18
Melting and Casting Processes.......................................................................................................21
Development of the Continuous Cast Structure........................................................................................22
Peripheral Shell and Peripheral Segregation..................................................................................23
Cast Log Surface ............................................................................................................................24
Cast Grain and Cell Structure, Intermetallic Phases ......................................................................26
Chapter3 Machinery and Equipment for Direct and Indirect Hot Extrusion ..........................................................31
Machinery for Direct Extrusion ................................................................................................................31
Extrusion Press Design Principles .................................................................................................33
Main Subassemblies of the Direct Extrusion Press........................................................................40
Auxiliary Equipment for Direct Extrusion.....................................................................................51
Hydraulic Drive and Control Systems for Direct Extrusion ..........................................................54
Electrical Drive, Control, and Regulation for Direct Extrusion.....................................................59
Typical Operating Sequence for Direct Extrusion .........................................................................59
Chapter 4 Extrusion Tooling................................................................................................................................59
Requirements of Tooling and Tooling Material........................................................................................59
Requirements of the Extrusion Tooling .........................................................................................59
Requirements of the Tooling Materials..........................................................................................59
Design of Tool Sets for Direct and Indirect Extrusion .............................................................................59
Design of the Tool Set for Direct Extrusion ..................................................................................59
Design of the Tool Set for Indirect Extrusion................................................................................59
Sealing of the Shape-Producing Tooling with the Container.........................................................59
Chapter5 Extrusion of Semifinished Products in Aluminum Alloys ......................................................................59
General ......................................................................................................................................................59
Extrusion Behavior of Aluminum Alloys .................................................................................................59
Flow Stress .....................................................................................................................................59
Flow Process ..........................................................................................................................................59
Thermal Balance and Extrusion Speed ..........................................................................................59
Section Surface and Surface Defects .............................................................................................59
Procedures to Control the Thermal Balance ..................................................................................59
Joining by Extrusion ......................................................................................................................59
Chapter 6 Billet Heating Systems ...........................................................................................................................59
Induction Furnaces ....................................................................................................................................59
General ...........................................................................................................................................59
Gas-Fired Billet Preheat Furnace ...................................................................................................59
Temperature Measurement and Control.........................................................................................59
Economics ......................................................................................................................................59
Extrusion Billet Transport Mechanisms.........................................................................................59
Age-Hardening Ovens for Aluminum Alloys ........................................................................................59
Heat Transfer by Convection .........................................................................................................59
Design of the Chamber Furnace.....................................................................................................59
Heating ...........................................................................................................................................59
Transport Mechanisms ...................................................................................................................59
Chapter7 Aluminum Extrusion Glossary .............................................................................................................59
Chapter1 Process of Extrusion of Aluminum
Process Overview
The aluminum extrusion process really begins with the design process, for it is the design of the
product--based on its intended use--that determines any of the ultimate production parameters.
Questions regarding machinability, finishing, and environment of use will lead to the choice of
alloy to be extruded. The function of the profile will determine the design of its form and, hence,
the design of the die that shapes it.
Once the design questions have been answered, the actual extrusion process begins with billet,
the aluminum material from which profiles are extruded. The billet must be softened by heat prior
to extrusion. The heated billet is placed into the extrusion press, a powerful hydraulic device
wherein a ram pushes a dummy block that forces the softened metal through a precision opening,
known as a die, to produce the desired shape.
Fig. This is a simple diagram of a typical horizontal hydraulic extrusion press; the direction
of extrusion here is from left to right.
That is a simplified description of the process known as direct extrusion, which is the most
common method in use today. Indirect extrusion is a similar process, but with some important
differences. In the direct extrusion process, the die is stationary and the ram forces the alloy
through the opening in the die. In the indirect process, the die is contained within the hollow ram,
which moves into the stationary billet from one end, forcing the metal to flow into the ram,
acquiring the shape of the die as it does so.
The extrusion process has been likened to squeezing toothpaste out of a tube. When pressure is
applied at the closed end, the paste is forced to flow through the open end, accepting the round
shape of the opening as it emerges. If the opening is flattened, the paste will emerge as a flat
ribbon. Complex shapes can be produced by complex openings.
注释：
Main cylinder [′silində] 主液压缸
Hydraulic pressure [haɒ′drɒ:lɒk] 液压
Press column [′kɒləm] 柱式压机
Container 挤压筒
Dummy block [′dɒmi:] 挤压垫
Ram 挤压杆
Billet 坯料
Front platen 挤压机前牌坊，前挤压盘
Runout table 输出辊道
Ribbon [ɒribən] 带状物
Squeeze [skwi:z] 榨取, 挤出
Billet
Billet is the starting stock for the extrusion operation. Extrusion billet may be a solid or hollow
form, commonly cylindrical, and is the length charged into the extrusion press container. It is
usually a cast product but may be a wrought product or powder compact. Often it is cut from a
longer length of alloyed aluminum, known as a log.
Alloys are metals composed of more than one metallic element. Aluminum extrusion alloys
contain small amounts (usually less than five percent) of elements such as copper, manganese,
silicon, magnesium, or zinc. These alloying elements enhance the natural properties of aluminum
and influence the extrusion process.
Billet length varies according to a number of factors, including the desired length of the finished
profile, the extrusion ratio, the length of the run-out, and the requirements of the extrusion press.
Standard lengths may run from about 26 inches (660 mm) up to 72 inches (1,830 mm). The
Fig. These photos show a new length of extrudate, just emerging from the press (left)
and the production of a profile in progress (right).
outside diameter may range from 3 inches (76 mm) to 33 inches (838 mm); 6-inch (155 mm) to
9-inch (228 mm) diameters are the most common.
注释：
Copper [′kɒpə，′kɒpə(r)] 铜
Manganese [′mæŋɒəni:z] 锰
Silicon [′silikən] 硅
Magnesium [mæg′ni:zi:əm, -ɒəm] 镁
Zinc [ziŋk] 锌
Wrought [rɒ:t] 制造的; 形成的; 精炼的, 锻成的
Metallic [miɒtælik] 金属的
Dies and Tooling
Dies can be made to form a virtually limitless array of shapes and sizes. Several factors
influence the actual cost and lead-time of a specific die; the best combination of product
performance, quality and cost is achieved when the product designer, the die maker, the extruder,
and the purchaser recognize each other’s requirements and work together.
A typical extrusion operation will make use of a die assembly, including the die itself, which,
together with a backer, is enclosed within a die ring, placed in front of a bolster, with a sub-bolster
behind, all held together as a unit by a tool carrier. The backer, bolster, and sub-bolster provide the
necessary support for the die during the extrusion process.
. 3 This diagram shows the components that typically make up a die slide, the tooling
assembly, for a solid die.
注释：
Platen 挤压机前牌坊，挤压盘
Bolster [′bəɒlstə] 前垫
Backer 模垫
Die 模具
Die ring 模套
Stem 挤压杆
Dummy block 挤压垫
Liner 挤压筒内衬
Container 挤压筒
Die slide 模架
Pressure ring 压力垫圈
Horse shoe 马蹄形止口
The extrusion die, itself, is a steel disk (normally H13) with an opening, the size and shape of
the intended cross-section of the final extruded product, cut through it.
Dies are broadly grouped as solid (or flat) dies, which produce solid shapes, and hollow dies,
which produce hollow or semi-hollow shapes. Combinations of solid, semi-hollow, and/or hollow
shapes may be incorporated into a single die.
A solid die may have one or more orifices or apertures through which the softened alloy is
forced (extruded). Multiple apertures in a single die produce multiple extrusions with each stroke
of the press.
Solid dies may, on occasion, be used to produce hollow profiles by means of a fixed or floating
mandrel. The use of a mandrel for extruding a hollow shape through a flat die usually involves the
use of hollow billets, cylindrical source stock that may have been cast or bored. Piercing mandrels,
however, do not require the use of cored billet.
. 4 A solid die, as shown here, produces shapes without any enclosed voids and/or
semi-hollow conditions.
注释：
Orifices [′ɒ:rəfɒs, ′ɒr-] 模孔
Apertures [′æpətjuə] 模孔
Mandrel[′mændril] 心轴、模芯
Piercing mandrel 穿孔针
A semi-hollow die extrudes a shape that is nearly hollow, partially enclosing a void, the area of
which (the area of the die tongue) is large in comparison with the gap where the tongue is
connected to the main body of the die.
While a solid or semi-hollow die is a single piece, it requires support from additional tools
called backers and bolsters. Depending on the complexity of the extruded shape, the total cost of
the extrusion tooling may include charges for these supplemental tools.
. 5 A semi-hollow die also produces shapes without enclosed voids; however, unlike a
solid die, it produces shapes with a tongue ratio of 3:1 or greater.
Hollow dies take a variety of forms. Bridge, porthole, and spider dies, for example, include a
fixed stub mandrel as an integral part of the die. Each type of hollow extrusion die serves certain
functions and carries its own advantages and disadvantages. The manufacturing methods and costs
vary widely. The choice of design, and even manufacturing methods, will depend on the profile,
press and container size, and production requirements.
. 6 A hollow die produces shapes with one or more enclosed voids. The die shown here,
when used together with a mandrel and other support tooling, produces a profile with six voids.
The most common types of hollow dies are the porthole and pancake. They typically are the
most cost effective and easiest to manufacture, allowing the designer to be much more creative in
the placement and shaping of the ports and feed. They are also the easiest for CNC Machining
(Computer Numeric Control), which allows for the die maker and die corrector to quantify any
alterations for production improvements on future dies.
A critically important characteristic of extrusion dies is that the effective bearing length controls
the metal flow through the die. The objective is to have all parts of the profile emerge from the die
at the same speed. The longer the bearing length, the greater the resistance to the flow of
aluminum and the shorter the bearing length, the less resistance to flow. Through effective design,
the thick parts of a profile can be slowed through the use of longer bearings to match the speed of
the thinner parts with short bearings.
注释：
Porthole [′pɒ:tɒhəɒl, ′pəɒrt-] 分流孔
Pancake 饼状
Bearing [ɒbɒəriŋ] 工作带
Resistance [ri ɒzistəns] 抵抗, 反抗, 抵抗能力
Profile [ ɒprəufail] 型材
Direct Extrusion Operation
Fig. This diagram shows the basic steps involved in extruding an aluminum profile.
Once the shape of the final product has been identified, the proper alloy selected, and the die
prepared, to make ready for the actual extrusion process, the billet and extrusion tools are
preheated. During extrusion, the billet is still solid, but has been softened in a heating furnace. The
melting point of aluminum varies with the purity of the metal, but is approximately 1,220°
Fahrenheit (660° Centigrade). Extrusion operations typically take place with billet heated to
temperatures in excess of 700°F (375°C), and--depending upon the alloy being extruded--as high
as 930°F (500°C).
The actual extrusion process begins when the ram starts applying pressure to the billet within
the container. Various hydraulic press designs are capable of exerting anywhere from 100 tons to
15,000 tons of pressure. This pressure capacity of a press determines how large an extrusion it can
produce. The extrusion size is measured by its longest cross-sectional dimension, sometimes
referred to as its fit within a circumscribing circle diameter (CCD).
As pressure is first applied, the billet is crushed against the die, becoming shorter and wider
until its expansion is restricted by full contact with the container walls. Then, as the pressure
increases, the soft (but still solid) metal has no place else to go and begins to squeeze out through
the shaped orifice of the die to emerge on the other side as a fully formed profile.
About 10 percent of the billet, including its outer skin, is left behind in the container. The
completed extrusion is cut off at the die and the remainder of the metal is removed to be recycled.
After it leaves the die, the still-hot extrusion may be quenched, mechanically treated, and aged.
Lubricated saws are equipped with delivery systems that feed the lubricant through the teeth of
the saw for optimal efficiency and cut surface.
Automatic devices clamp profiles in place for sawing. Saw chips are collected for later
recycling.
注释：
Billet 坯料
Heating furnace 加热炉
Extrusion press with die 带模具挤压机
Saw 锯割
Stretcher [ɒstretɒə] 拉伸机
Aging oven 时效箱
Fahrenheit [′færənɒhaɒt] 华氏温度
Quenched [kwentɒd] 淬火的
Aged 时效
Clamp 夹具
Profile 型材
Circumscribing circle diameter 外接圆直径
Aging
Some extrusion alloys reach their optimal strength through the process of aging, sometimes
known as age hardening. Natural aging occurs at room temperature. Artificial aging takes place
through controlled heating in an aging oven and is sometimes referred to as precipitation
heat-treating.
When the profile emerges from the press it is in a semi-solid state, but rapidly solidifies as it
cools or is quenched (whether by air or water). Non-heat-treatable aluminum alloys (such as those
utilizing manganese or magnesium) derive their strength through natural aging and cold working.
Heat-treatable alloys (such as those utilizing copper, zinc, and magnesium with silicon) are further
strengthened or hardened through controlled thermal treatments that affect the metallurgical
structure of the alloys.
Either way, the aging process ensures the uniform precipitation of fine particles through the
metal, yielding maximum strength, hardness, and elasticity for the specific extrusion alloy.
注释：
Age hardening 时效强化
Natural aging 自然时效
Artificial aging 人工时效
Precipitation [priɒsipiɒteiɒən] heat-treating 沉淀热处理
Non-heat-treatable aluminum alloys 不可热处理铝合金
Metallurgical 冶金的
Packaging
After sufficient aging, whether in an aging oven or at room temperature, the profiles are moved
to other areas of the plant for finishing or fabricating, or to be packed and prepared for shipment to
the customer.
Most extrusion plants are equipped to accommodate any likely packaging requirement. Profiles
are palletized in such a way as to be protected from surface damage, twisting, or other hazards.
Customers may specify their own packaging requirements, or the type of extruded product may
suggest a particular method of packaging for ease of storage or delivery.
注释：
Packing 包装
Fabricating 加工
Palletized [′pæliɒtaizd] 托盘化的
