Tube drawing is a process to size a tube by shrinking a large diameter tube into a smaller one, by

drawing Drawing is a form of visual art in which an artist uses instruments to mark paper or other two-dimensional surface. Drawing instruments include graphite pencils, pen and ink, various kinds of paints, inked brushes, colored pencils, crayo ...

the tube through a

die Die, as a verb, refers to death, the cessation of life. Die may also refer to: Games * Die, singular of dice, small throwable objects used for producing random numbers Manufacturing * Die (integrated circuit), a rectangular piece of a semicondu ...

. This process produces high-quality tubing with precise dimensions, good surface finish, and the added strength of

cold working In metallurgy, cold forming or cold working is any metalworking process in which metal is shaped below its recrystallization temperature, usually at the ambient temperature. Such processes are contrasted with hot working techniques like hot r ...

.Degarmo, p. 433. For this reason this process is established for many materials, mainly

metalworking Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale ...

but also

glass Glass is a non- crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenchin ...

. Because it is so versatile, tube drawing is suitable for both large- and small-scale production. The large-scale production of glass typically uses a one step process where glass is directly drawn into a tube from a melting tank. There are five types of tube drawing: tube sinking, mandrel drawing, stationary mandrel, moving mandrel, and floating mandrel. A

mandrel A mandrel, mandril, or arbor is a gently tapered cylinder against which material can be forged or shaped (e.g., a ring mandrel - also called a triblet - used by jewelers to increase the diameter of a wedding ring), or a flanged or tapered or ...

is used in many of the types to prevent buckling or wrinkling in the workpiece.

Processes

Tube sinking

Tube sinking, also known as ''free tube drawing'', reduces the diameter of the tube without a

inside the tube. The inner diameter is determined by the inner and outer diameter of the stock tube, the outer diameter of the final product, the length of the die landing, the amount of back tension, and the friction between the tube and the die.. This type of drawing operation is the most economical, especially on thick-walled tubes and tubes smaller than in diameter, but does not give the best surface finish. As the tube thickness increases the surface finish quality decreases. This process is often used for the tubing on low-cost lawn furniture..

Rod drawing

Rod drawing is the process that draws the tube with a mandrel inside the tube; the mandrel is drawn with the tube. The advantage to this process is that the mandrel defines the inner diameter and the surface finish and has a quick setup time for short runs. The disadvantages are that lengths are limited by the length of the mandrel, usually no more than , and that a second operation is required to remove the mandrel, called ''reeling''. This type of process is usually used on heavy walled or small (inner diameter) tubes. Common applications include super-high pressure tubing and hydraulic tubing (with the addition of a finishing tube sinking operation). This process is also used for precision manufacturing of

trombone The trombone (german: Posaune, Italian, French: ''trombone'') is a musical instrument in the brass family. As with all brass instruments, sound is produced when the player's vibrating lips cause the air column inside the instrument to vibrate ...

handslides.See, for example, this video of the process of making Getzen trombones:

Fixed plug drawing

Fixed plug drawing, also known as stationary mandrel drawing, uses a mandrel at the end of the die to shape the inner diameter of the tube. This process is slow and the area reductions are limited, but it gives the best inner surface finish of any of the processes. This is the oldest tube drawing method.

Floating plug drawing

Floating plug drawing, also known as floating mandrel drawing, uses a mandrel that is not anchored whatsoever to shape the inner diameter of the tube. The mandrel is held in by the friction forces between the mandrel and the tube. This axial force is given by friction and pressure. The greatest advantage of this is that it can be used on extremely long lengths, sometimes up to . The disadvantage is it requires a precise design otherwise it will give inadequate results. This process is often used for oil-well tubing.

Tethered plug drawing

Tethered plug drawing, also known as semi-floating mandrel drawing, is a mix between floating plug drawing and fixed plug drawing. The mandrel is allowed to float, but is still anchored via a tether. This process gives similar results to the floating plug process, except that it is designed for straight tubes. It gives a better inner surface finish than rod drawing.

References

Notes

Bibliography

*. {{DEFAULTSORT:Tube Drawing Metal forming Tubing (material)