Comparison of technical characteristics of various aluminum extrusion methods
專欄:Industry information
發布日期:2015-06-01
閱讀量:475
作者:佚名
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Technical comparison of various aluminum extrusion methods:Extrusion typeHot extrusionCold extrusionUnlubricated positive extrusionLubricated positive extrusionBack extrusionPositive extrusi..........
Technical comparison of various aluminum extrusion methods:

Extrusion type

Hot extrusion

Cold extrusion

Unlubricated positive extrusion

Lubricated positive extrusion

Back extrusion

Positive extrusion

Hydrostatic extrusion

Tool form

Plane die, can be split using split split die

Conical or curved mold, can not use the split combination die to squeeze hollow parts

Plane die, can not be used to split the split die

Plane die, can not be used to split the split die

Plane die, can not be used to split the split die

Squeeze pressure

When the billet is long, the pressing pressure is significantly increased, and the pressing force can be increased by 30% to 40% due to friction with the extrusion barrel.

When the billet is long, the extrusion pressure is increased, and it is difficult to avoid the pressure peak in the initial stage of extrusion.

The pressing force is low and constant, which is 30%-40% lower than that of positive extrusion.

As the length of the material increases, the pressing force increases. As the front end of the material is shaped properly, the pressure peak at the initial stage of extrusion can be eliminated.

The pressing force is low and constant, and since the lubrication and the front end of the raw material are formed into an appropriate shape, the pressure peak at the initial stage of extrusion can be eliminated.

Tool life

Short life

Shorter

Short life

Available thousands of times or more

Long mold life and difficult sealing of the extrusion tube

Blank material

Suitable for extruded aluminum alloys, especially for extruded pure aluminum and low strength aluminum alloys

Suitable for extruding hard aluminum alloys and brittle aluminum-copper alloys, composites

Can be extruded aluminum alloy, the inner surface of the hollow product can be lined with other metals

Various aluminum alloy

Can extrude various aluminum alloys and composite materials

Blank size, shape

The length of the blank can be up to 3-4 times the diameter. When using a piercing needle, the concentricity of the hollow blank is required to be high.

Length up to 5 times the diameter, high concentricity of hollow billets

The length can be more than 5 times the diameter, and the diameter can also be selected to be larger than the blank without the lubrication.

The length is 3 to 5 times the diameter, and the long hollow billet concentricity is guaranteed.

The length can be up to 10 times the diameter, the shape of the section can be optional, or it can be spiral, and the front end of the blank is conical.

Blank surface finishing

Generally no surface finishing

Surface finishing is important

Surface finish

Surface finish

Surface finish

Material deformation uniformity

Longitudinal and lateral unevenness

More uniform

More uniform

More uniform

Longitudinal and horizontal

Product size, shape

The circumscribed circle of the product can be close to the diameter of the extrusion tube, and can be extruded into porous, complex and hollow products. The extrusion ratio is optional (8-100).

The circumscribed circle of the product can be close to the diameter of the extrusion tube, and the porous product cannot be extruded, and the composite material can be extruded, and the shape can not be complicated.

The circumscribed circle of the product is 70% of the positive extrusion, and the porous extrusion makes it difficult to adjust the concentricity of the hollow product. Products with less complicated shapes, extrusion ratio is 20-80

The shape is relatively simple, the extrusion ratio of pure aluminum is 100-300, the extrusion ratio of 6063 alloy is 50-100, and the extrusion ratio of 6351 alloy is 25-50.

The circumscribed circle of the product is smaller than the positive extrusion, the shape is simpler than the hot extrusion, and it is possible to twist

Product accuracy, surface

No oxide film on the surface, beautiful, high precision

No oxide film on the surface, beautiful, high precision

The size is relatively uniform, the precision is higher than the positive extrusion, but the surface quality is not as good as the positive extrusion

Good surface quality, high precision, up to ±0.025mm, surface roughness below 1μm

The surface roughness is below 1μm, and the eccentricity of the tube is 0.01-0.03mm.

Product strength

Longitudinal unevenness, some alloys have squeezing effect

Uniform longitudinal

Uniform longitudinal

Due to the large extrusion ratio, softening can be achieved by solid solution, quenching, extrusion, and quenching.

Softening due to large extrusion ratio

Surface defects

Extrusion cracks occur when the extrusion speed or extrusion temperature is high due to different material types

The billet has surface defects and is prone to oxide film.

The billet has surface defects and is prone to oxide film.

Exposing the surface defects of the blank

Exposing the surface defects of the blank

Internal defect

From the cross section of the billet, the surface defects tend to extend to the inside, and the high-speed extrusion causes the grains to become thicker, which is prone to coarse ring and tail.

Using a flat mold will produce subcutaneous defects in the product, and if a conical mold is used, it is in good condition.

Not easy to produce internal defects

Not easy to produce internal defects

Not easy to produce internal defects

Extrusion residue

Large thickness (thick to 20% of the length of the blank or radius)

Moderate thickness

Is half the thickness of the non-lubricated positive extrusion, and the ratio of the length of the blank is lower.

The surface of the pressing plate is roughened, and the thickness of the extruded residue can be reduced.

In order to prevent the conical part from flying out, the volume of the crushed material is larger.

Extrusion speed

Limited by grain coarsening and surface cracking, 2-25mm/s for 6-series aluminum alloy, increasing extrusion speed with unequal heating

For aluminum alloys, it can reach 2-5 times of unlubricated positive extrusion

For aluminum alloys, the extrusion speed can reach 3 times that of unlubricated positive extrusion.

Can reach dozens of times of hot extrusion of aluminum alloy

Can reach dozens of times of hot extrusion of aluminum alloy

Process other than extrusion

Short process, easy to correct distortion

Process for removing lubricant after lubrication and extrusion

The blank is loaded, and the process of taking out the extruded residue is more than the positive extrusion

Less process

There are many processes, but if thick film lubrication is used, the process can be reduced.

Processing device

Product cooling devices can be installed near the mold, such as online quenching, etc.

Product cooling devices can be installed near the mold, such as online quenching, etc.

To retrofit positive extruders, design new procedures and special structural tools and molds

Compared with hot extrusion, a large-capacity extruder is required, and a heating device that does not need to extrude a billet is required.

Special equipment is required, but if you use thick film extrusion, ordinary extruders are also available.


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