Ref. NDM 890/06.
Ensuring the highest quality tools and dies, with ICEM Surf at Karmann.
The tool systems department of automotive vehicle manufacturing and
engineering services company, Karmann, is using the ICEM Surf software suite
as a key part of its tool and die design process in order to improve the quality of
production tooling and final vehicle body-in-white components.
For over 100 years, Karmann has been providing world-class vehicle engineering
and manufacturing services to the world‟s automotive industry. Founded in 1901
by Wilhelm Karmann when he acquired the factory in Osnabrück, Germany, of
the coach-builder Christian Klages, the company today has some 7,500
employees around the world who work to satisfy customers‟ demands and to
contribute to the future of the automobile.
Famous around the world for its work on convertibles – as well as the legendary
Karmann Ghia – the company has built more than 3.3 million vehicles for its
customers since 1949. Among these have been the Volkswagen Beetle
convertible, all Volkswagen Golf convertibles, BMW coupes, the Porsche 914
and the Volkswagen Scirocco.
Today, its vehicles line-up includes the Audi A4 convertible, the Mercedes-Benz
CLK convertible, the Chrysler Crossfire Coupe and the Chrysler Crossfire
Roadster. In addition to these complete vehicles, the company also produces
roof systems for the Renault Mégane ll CC convertible, the Nissan Micra C+C
and the Volkswagen New Beetle convertible, as well as body-in-white (BIW)
modules for the Mercedes-Benz SLK.
Playing a crucial role in the work that Karmann carries out on vehicles like these
for its OEM customers is the ICEM Surf surface modelling, surface model
validation and design visualisation software suite. For example, in the technical
development and design department, ICEM Surf is used to create all Class A
surface models for the body skins of vehicles under development, with either 3D
scan data from the styling clay model being used as the starting point or with the
designers and surface engineers working directly from the 2D styling sketches
Meanwhile, in Karmann‟s tool systems department, ICEM Surf is used for tool
and die face design during development of the production tooling required for
stamping out the sheet metal components of the vehicle body-in-white. Most of
the time, the work performed by this department forms an integral part of the
comprehensive design, development and manufacturing projects that Karmann
undertakes for its automotive OEM customers, like DaimlerChrysler, Volkswagen
and Porsche. However, the department also offers its tooling development
expertise and services to other manufacturers on an individual contract basis.
Jens Schneider, engineering services manager, Wilhelm Karmann GmbH, says,
“Using ICEM Surf in the tooling development process has made a major
contribution to increased quality of dies and as a result, to the final body shells
that we produce for our clients. Furthermore, it has helped us to cut tooling costs
by eliminating, or at least greatly reducing the need for re-finishing operations.”
With ICEM Surf being used in the technical development and design department,
the data provided to the tool systems department is usually ICEM Surf Class A
surface model data. However, the department also receives surface data in other
formats, such as CATIA V4 and V5, both from external customers and depending
on the project, occasionally from within Karmann.
Irrespective of the source and format of the incoming surface data, the first step
in the tool development process is to analyse the digital surface model for
surface quality and surface properties by reading the data into the ICEM Surf
environment and then using the software‟s surface diagnosis and analysis
facilities. These include zebra-stripe highlights for visually checking surface
continuity, as well as mathematical analysis of surfaces for curvature and
flatness, with the results being displayed as a colour-coded image. Surface
clusters can also be analysed for levelling, with any deviations displayed as a
vector mesh or colour „map‟ along with the minimum and maximum deviation in
numeric values. It is also possible to quickly and easily globally blend surfaces
together in order to fill any gaps between surface units, maintaining tangency and
curvature, as required.
Once this process of analysing the surface model has been completed, the tool
face design process begins in earnest.
The design of the individual body-in-white components and their fixings will have
been defined previously by Karmann‟s technical development and design
department, or the external customer, as appropriate, and signed off. So the part
data relating to surface curvature values cannot be changed by the tool systems
department. However, if a slight curvature was detected on a surface during the
analysis stage, then over-crowning will be required in the tool face design to
allow for the spring-back behaviour of sheet metal after the pressing process.
This over-crowning is performed in ICEM Surf. The engineer defines positions on
the surface model where form changes should be performed, along with a strike
direction for each position. The surface units are then automatically changed to
the new positions, with the surrounding geometry being adjusted accordingly
while maintaining the original design intent, as per the released data. A
„morphing‟ process enables the engineer to then compare the over-crowned
model with the original to ensure the finished pressing will be as designed.
A similar process is performed on other areas of the component model, for
example flanges and complex poly-surfaces, during the initial production process
as well as during the further correction loops in the overall tool and die production
process. This again is to compensate for any spring-back that may occur in the
final die-stamped production sheet metal parts.
Where deep drawn parts are involved, the .stl facet data produced by deep
drawing simulation programs, such as the Autoform DieDesigner used by
Karmann, is read into the ICEM Surf environment where it can be re-processed
to create surface model data that can then be used directly in the die face
development and subsequent NC tool-path generation processes.
Apart from these engineering-oriented capabilities of ICEM Surf, an important
aspect of its use for tool face design at Karmann is that the software has been
developed specifically for the generation of Class A surface data, i.e. the very
high quality of surface model demanded by today‟s automotive vehicle designers
and manufacturers. As a result, the final surface data describing the tool face that
is generated in ICEM Surf is of a very high quality. Consequently, once it has
been transferred, usually via CATIA, to the Tebis or WorkNC CNC 3D milling
tool-path programming software used by Karmann, the resultant milled face of
the die is of a similarly high quality and needs very little, if any hand or other
As mentioned earlier, the modified surface model data required for tooling is
compared with the original released design data before tool production
commences in order to ensure that, as far as is possible at that stage, the final
tooling will produce the parts to the required standard. Nevertheless, final quality
assurance is performed by physically checking the first production parts against
the design data supplied by the technical development and design department.
As Karmann‟s Jens Schneider readily testifies, this use of ICEM Surf in the
production tooling design and development process has provided the automotive
vehicle manufacturer – and its customers - with a number of very real benefits.
For example, the surface model analysis and advanced surface manipulation
capabilities of ICEM Surf enable manufacturing issues to be fully taken into
account in the tool face development process, while the ability of the software to
generate the highest quality of surface model – the Class A surface – means that
the face of the final production tooling is of the highest possible quality, straight
off the milling machine.
This has cut both the time needed for and the costs associated with developing
and manufacturing press tools at Karmann, meaning that the company is able to
stay ahead of its competitors.
Perhaps more importantly though, the increased quality of tooling has enabled
Karmann to considerably increase the quality of the final body shell pressings
that it produces for its customers. And that benefits everyone concerned.
1250 words approx (excluding headline and lead-in).