N
ovember
2014
99
Fontijne Formitt
Article
Improving the quality of tube
formed products using spinforming
By Jeff Mansveld MSc, global marketing manager, Fontijne Formitt, Netherlands
Spinning process
Currently spinforming technology has progressed to
modern CNC controlled machines. The primary objective of
spinforming is to create a symmetrical shape or form from
flat blanks or tube without creating a major reduction in the
thickness of the parent material. Fontijne Formitt is focused
on tube spinning which is a more difficult process compared
to spinforming blanks, as an inner mandrel is not present to
create the final spun form. From the tube shapes round and
oval, it is possible to achieve a cylindrical reduced diameter
of the shell. Additionally, spun shapes can be combined
with cast, drawn, forged or machined parts to reduce costs
and increase productivity. Spinning the tube ends can be
performed concentric, eccentric and oblique.
Concentric spinning
Concentric spinforming machines form a reduced end profile
that is concentrically aligned with the tube’s central axis.
Fontijne Formitt’s concentric spinner can automatically control
the part length without trimming in most cases. Dynamic length
control provides accurate part length compensation for varying
material parameters. A concentric spinner can be placed in a
horizontal or vertical design, in which the vertical spinner uses
less floor space.
EST-OST spinning
The Eccentric Spinning Technology (EST) and Oblique Spin-
ning Technology (OST) spinning process forms a reduced end
profile that is eccentric to or at an oblique angle to the tube’s
central axis without rotating the part. Using advanced mechan-
ical design and machine control techniques, the possibility of
spinforming complex transition angles such as eccentric and
oblique can be realised.
With an increasing demand for quality tube shaped
products, space saving solutions and cost savings
in production processes, it is important to select the
production process that fits your business model.
This article will explain how a spinforming machine
is successful in improving the quality of tube formed
products and lowering the production costs.
Using different types of angles is, especially in the automo-
tive industry, a frequently occurring request, because of space
saving solutions. The various complex shapes can be more
easily connected with other components. For example cata-
lytic converters can be formed by EST/OST to save space re-
strictions in the engine compartment.
First, the shell is loaded in the work holding clamp of the EST/
OST spinning machine where the datum positions the part on
the correct depth. The shell is static and the two forming rollers
rotate around the part to form the end in multiple steps. Form-
ing different angles requires a movement in several ways, with
in total a 4-axis machine.
The shell is moved by work holder in a horizontal direction and
multiple times fed in and out to form the end (
Z-axis
). Together
with the movement of the two rollers (
X-axis
) the shell can be
spinformed. The shell is moved off centre by work holder to
form an eccentric (
Y-axis
), and the shell is angular rotated by
work holder to form an oblique shape
(A-axis
). The EST-OST
spinning machine can be equipped with automatic trimming of
the shell ends.
Benefits
In general, spinning is more efficient than other metalforming
processes.
No welding
Spinforming technology eliminates the need for welded tube
end-pieces, for example two circumferential welds for one
piece cone ends and six (2x longitudinal and 4x axial) welds
for two-piece cone ends. This enhances overall component
quality and reliability, as possible leaks from weld processes
are nearly eliminated. Indoor pollution created by welding is
eliminated as there are no weld gases.
Scrape rate
One-piece end cones which are commonly made by dies
in combination with a press for concentric end cones or a
hydrostatic process for eccentric and oblique end cones
End product
Oblique
Eccentric
