This document summarizes research on sheet metal microforming, specifically single point incremental forming (SPIF). It discusses the advantages of SPIF in providing flexible, customized production at low cost. Some drawbacks regarding accuracy are also highlighted. The document reviews numerous studies investigating factors that influence forming accuracy and strategies for minimizing errors. These factors include process parameters, tooling variations, and techniques like laser assistance. Future research opportunities are identified in developing forming limit criteria, improving formability, computational simulations, and applications in industries requiring high precision parts like aerospace and automotive.

1. AMAE Int. J. on Production and Industrial Engineering, Vol. 01, No. 01, Dec 2010
© 2010 AMAE
DOI: 01.IJPIE.01.01.35
31
Sheet Metal Micro Forming: Future Research
Potentials
Manish Oraon1
; Vinay Sharma2
Asst. professor; university polytechnic; B.I.T. mesra, ranchi, india
Manish_oraon@yahoo.com
Department of production engg.; B.I.T. mesra, ranchi, india
vinay1970@gmail.com
Abstract - The paper is aimed to discuss some relevant issues
concerning an innovative sheet metal forming technology,
namely Single Point Incremental Forming. The advantages of
this technology are addressed, including its capability to provide
effective answers to some impellent industrial requirements:
process flexibility, strong customer orientation, production of
highly differentiated goods at low industrial costs. As well some
relevant drawbacks are highlighted, mainly as concerns the
level of accuracy permitted by the process. A wide recognition
of the research efforts in this field is presented, taking into
account some general considerations on the difference sources
of shape and dimensional errors, as well as the influence of the
most relevant parameters. Finally, some strategies for error
minimisation are presented and discussed
Keywords: Microforming; Incremental forming; Laser; Micro
machining.
I. INTRODUCTION
A substantial mutation is occurring in sheet metal forming
companies basically oriented to the development of more
efficient strategies in terms of flexibilityand cost reduction.
Sheet forming companies attempt to satisfy market demands
by producing highly differentiated products, with small lot
sizes. Customers, in fact, ask for exclusive products and they
are driven to invest more if this aspect is taken into account.
Furthermore, due to the market competition, a lowproduction
cost is strictly required with the aim to improve the margin
of profit even if the sale price reduces. In the incremental
forming of sheet metal, a simple-shaped tool imposes
deformation locallyon the sheet in a consecutive manner. In
this process, the ball tool moves on the sheet according to a
programmed tool path on a CNC milling machine. The sheet
is located with the periphery fixed by bolts on a die, which
is hollow and square in cross section. The basic idea of single
point incremental forming (SPIF) processes is that the final
shape of the component is obtained by the relative movement
of a simple and small punch with respect to the blank, rather
than by the shape of the dies. Such process is carried out on
CNC machines, where it is possible to assign and control
the punch movement according to fixed paths. The
production process of sheet metal microforming is slower
than in conventional production methods but the surface of
finished part will smoother than previous one. The forming
paths are generated directlyfrom the 3D CAD file, and often
no tooling is needed. If a support tool is required, the same
3D CAD file can be used for making the support tool. In
many cases the support tool is not needed and the process is
shorter. The comparison between them can be easily
understood by the block diagram.
II. FORMING METHODOLOGY
The methodology uses in micro forming is shown as in
fig.2. Firstlythe help of CAD/CAM determines the tool path
which gives an idea about the movement of the tool. With
generated tool path from CAD, the CNC milling
Fig 1. production process of deep drawing
machine makes the product in precise form. Here the tool
geometry is different from the milling cutter, the tool is a
cylindrical rod with hemispherical head in few millimeter
diameter.Among the different possibilities, incremental sheet
forming (ISF) has proved to be a very reliable solution as
shown in many different works carried out by Kim and Park
[1,2] investigate the formability of an aluminum sheet un-
der various forming conditions was assessed and difficult-
to-form shapes were produced with the ISF technique. The
machine setup for the experimental work as shown in fig.3.
He also investigated the forming limit curve for the forma-
tion of the desired shape. Ambrogio et al.[3] and Kopac and
Campus [5] investiated Different process configurations,
both by numerical and experimental approaches, taking into
account. They considered twodifferent shapes, namelytrun-
cated cones and pyramids. The simulated figures of the cones
were as shown in figure3. F. Micari et. al. [6] investigated
on some general considerations related to the difference

2. AMAE Int. J. on Production and Industrial Engineering, Vol. 01, No. 01, Dec 2010
© 2010 AMAE
DOI: 01.IJPIE.01.01.35
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difference sources of shape and dimensional errors as in fig-
ure 4, as well as the influence of the most relevant param-
eters. Finally, some strategies for error minimization are pre-
sented and discussed. E. Maidagan et. al. [7] proposed a
new method; the Sculptor process (fig. 5) which aims at de-
veloping a new concept of sheet metal forming in small and
medium Sculptor process proposed an additional substitut-
ing upper and lower dies with two
production process of micro forming
generic forming tools placed in on both sides of the blank,
giving rise to a flexible die system. This way a truly dieless
forming process is obtained. G. Ambrogio et al.[8] focused
on the investigation ofthe influence of the process parameters
on accuracy through a reliable statistical analysis. The
obtained models permit to implement some effective actions
to improve the accuracy taking into account a simple case
study.
Fig. 2: steps for single point sheet metal microforming
A. Petek et. al [9] investigateAn interesting alternative is to
substitute the rigid tool with a high velocity water jet (WJ).
The comparison between using a rigid tool and a water Jet
forming shown in fig 6.The aim to identify the most influ-
ential parameters affecting the forming process through ex-
perimental comparison of the two observed methods. V.
Franzen et al.[10] researched on the PVC sheets where the
experimentation is based on the
Fig.3:[Ref 3 ]Incremental forming of an aluminum incremental sheet on
CNC milling machine.
Comparison of FLCs in both and
conventional forming methods
utilization of an ordinaryCNC milling machine and a single
point forming tool to shape commercial PVC sheets and the
overall investigation is centered on the characterization and
evaluation (fig.7) of the formability limits of the process as
a function of the major operating parameters. J.R Duflou et.
al. [11] carried the analysis of forming a series of cones.
The experiments were conducted to determine the influence
of dynamic, local heating respectivelyon the process forces,
the process accuracy, the formabilityand the residual stresses
in formed workpieces. Guoqiang Fan et. al.[12] proposed a
new method for hot incremental forming. The method is
based on simple tooling and is easy to employ.
Fig. 4. [ Ref. 5] Geometrical errors during the SPIF process.
It makes use of electric current for heating hard-to-form sheet
metals at the tool–sheet interface in order to fully utilize the
formability of these materials. The potential effect of
processing parameters, namely current, tool size, feed rate,
Fig.5[Ref. 6] Incremental Sheet Forming
processes
SCULPTOR processes

3. AMAE Int. J. on Production and Industrial Engineering, Vol. 01, No. 01, Dec 2010
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and step size, on the formability are investigated. They
conclude that electric hot micro forming technique is feasible
and easy to control. Probably the process could be used for
other hard-to-form materials and asymmetric parts (such as
pyramids) show more distortion than axisymmetric parts
(cones).
Fig. 6: [ref.8] The main tool in RTSPIF and WJSPIF.
Working principles and relevant process parameters of RTSPIF and
WJSPIF.
J.R. Duflou et al.[13] proposed an experimentally explored
multi-step toolpath strategyis reported and the resulting part
geometries compared tosimulation output. Sheet thicknesses
and strains achieved with these multi-step toolpaths were
verified and contribute to better understanding of the material
relocation mechanism underlying the enlarged proess
window.
Fig. 7 [Ref. 9] Formability limits and defects in SPIF of PVC sheets. (a)
Schematic illustration of the typical modes of failure. (b) Picture showing
a crack (mode 1) and a surface defect. (c) Picture showing wrinkling along
the wall thickness (mode 2) followed by a crack (mode 1).
G. Hussain et al. [14] targeted the investigation on the effect
of wall angle (èmax
) in single point incremental forming of
sheet metals. Two tests were carried out in order to evaluate
the formabilityofan aluminum sheet. In the first test, conical
frustums and square pyramids (fig. 9), a set of each, were
produced by systematically varying the wall angle in order
to investigate èmax
. The result obtained from the experiment
as shown in table 2
Fig.8 [ref. 11] The structure of the machine laser-assisted
TABLE 1: FORMABILITY TEST RESULTS OF VARIOUS
INCREMENTAL FORMING PROCESSING
Fig. 9 [ref. 13]. Some parts formed in the Test-1: (a) representative
conical frustums and (b) representative square pyramid
J.P. Wulfsberg et. Ai. [15] makes an approach to solve the
problems (size effects related tosmall dimensions). He found
that, the laser assistance of the micro forming process to
benefit from e.g. the growing influence of thermodynamic
aspects.

4. AMAE Int. J. on Production and Industrial Engineering, Vol. 01, No. 01, Dec 2010
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TABLE 2: SYSTEMATIC INVESTIGATION OF ÈMAX
Experimental investigations (fig.10) were carried out to
determine the workpiece temperature byvarying laser power
at constant heating time.
Fig. 10 [ref. 14]. Laser-assisted micro forming
III. PROCESS ADVANTAGES AND LIMITATIONS
The advantages and disadvantages of SPIF are as follows
[4].
Advantages:
 Useable parts can be formed directly from CAD
data with a minimum of specialized tooling. These
can be either Rapid Prototypes or small volume
production runs.
 The process does not require either positive or
negative dies hence it is dieless. However it does
need a backing plate to create a clear change of
angle at the sheet surface.
 Changes in part design sizes can be easily and
quickly accommodated, giving a high degree of
flexibility
Making metal Rapid Prototypes is normallydifficult,
but easy with this process.
 The small plastic zone and incremental nature of
the process contributes to increased formability,
making it easier to deform low formability sheet.
 A conventional CNC milling machine or lathe can
be used for this process.
 The size of the part is limited only by the size of
the machine. Forces do not increase because the
contact zone and incremental step size remain small.
 The surface finish of the part can be improved.
 The operation is quiet and relatively noise free.
Disadvantages:
 The major disadvantage is the forming time is much
longer than competitive processes such as deep
drawing.
 As a result the process is limited tosmall size batch
production.
 / The forming of right angles cannot be done in one
step, but requires a multi-step process.
 springback occurs, however algorithms are being
developed to deal with this problem.
There are lots of research is going on to minimize the problem
associated with the microforming / ISMF. L. Kwiatkowski
et.al [16] developed a concepts to decreasing the main
process time by applying several forming zones on the part
through multiple tools working in parallel which gives the
improved the surface finish as well as the formability of the
sheet metal. J.P. Wulfsberg et al.[15] introduce the laser to
enhancing the stretching capabilityand formability of sheet.
IV. FUTURE RESEARCH SCOPE
In industrial implementations ofmicroforming, it is very
important to know the limiting factors of the process. The
limiting factors may be due to special features of the micro
forming. There are lots of research is going on related to the
improvement of micro forming process such as
 Construction of forming limit criteria in incremental
forming process
I. Forming Limit Diagram,
II. Ductile fracture criteria
 Improvement of formability using Preform design
 Warm incremental sheet metal forming technology
I. Lightweight materials (Al, Mg) using
halogen heating device
II. Electric heating based micro
forming
III. Laser assisted micro forming
 Development of computational techniques using
Finite Element Method
 Fast calculation of plastic deformation, Process
optimization
To simulate the actual manufacture of parts using numerical
modelling techniques

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V. APPLICATION OF MICROFORMING
There are a number of areas where high precision of the
product is required for the accuracyof the performance. Some
of the following area where these types of product can
manufacture by microforming .
 Aerospace: Instrument panel, Body panel,
Passenger seat cover etc.
 Automobile: Door inner/outer panel, Hood panel,
Engine cover etc.
 High customized products: Denture plate, Ankle
support, Metal helmet etc.
VI. CONCLUSION
As can be seen from the large amount of research
activities in the field of microforming, some aspects are
already identified and described, but several problems are
still unsolved. Thus, onlya few applications in this relatively
wide field are already industrially applicable (especially in
the field of microelectronics), other applications are close to
a breakthrough. In most research areas great effort has been
made to identify the size effects, now these effects must be
described and solutions must be proposed to solve the
problems that occur. This can be done purely academically,
but considering the great advantage of the forming process
for serial manufacturing, it will also be reasonable to start
future research activities together with industry, not only to
enhance process knowledge but alsoits usabilityand stability.
REFERENCES
[1] Y. H. Kim & J. J. Park., Effect of process parameters on
formability in incremental forming of sheet metal. Journal of
Materials Processing Technology130-131, (2002) pp 42-46.
[2] Y. H. Kim & J. J. Park. Fundamental studies on the incremental
sheet metal forming technique. Journal of Materials Processing
Technology 140, (2003) pp 447-453.
[3] G. Ambrogio, L. Filice, L. Fratini, F. Micari, Some
relevant correlations between process parameters and process
performance in incremental forming of metal sheets, Proc. of 6th
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[4] Jadhav S., Goebel R., Homberg W., kleiner M; process
optimization and control for incremental sheet metal forming,
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© 2010 AMAE
DOI: 01.IJPIE.01.01.35