190 Bayer, Enparantza, Maier, Obermair, and Schmiedinger
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As identified by the questionnaires, the required information is rarely delivered com-
pletely by the customer and therefore further time-consuming inquiries are the conse-
quence.
When an order is placed, the design starts from an in-depth study of the use of the
final product and consists of optional mold-filling simulations, construction and creation
of technical documents (e.g., in AutoCAD, CATIA, Solid Edge), specification of CNC
(computerized numerical control) programs, as well as the design of inserts, sliders, and
cooling system. Examples for the variety of information required during this phase are
production-related preconditions, customer machine data, as well as internal machine
tool data, and information about standard parts and their specifics.
Based on the product’s specifications, the production planner uses information
about production-related preconditions such as the company’s capacities and capabili-
ties to plan further steps. To implement CNC programs, select cutting strategies or plan
work orders, detailed information, and experiences are necessary.
In production, dies and molds are produced using CNC machines or other produc-
tion facilities. Examples of information required in this process step are standard part
information, cutting data and cutting strategies, machine data, as well as production
plans. Particularly, the choice of an adequate cutting strategy including selection and
sequence of cutting tools is strongly based on experience. To define cutting strategies,
the mold material, the tool used (diameter, length, notation, supplier, number of cutting
edges, coating), and the cutting parameters (revolutions per minute, cutting speed, feed
rate, radial cutting depth, axial cutting depth) have to be taken into account. Knowledge
about cutting data and cutting strategies is mostly tacit and therefore not documented.
Quality criteria for a cutting strategy are, for example, the wasted material or the lifetime
of a cutting tool that is additionally influenced by characteristics of the machine tool
used.
The following step test is dominated by extensive testing of dies and molds in
compliance with the customer’s requirements. Tested parameters are especially surface
structure, dimensions of the mold/die, or stability of critical parts. Possibly, improve-
ments concerning design are necessary, if the injection mold or die cast part does not
meet the expectations of the customer or the requirements catalog. Insufficient test
results can lead to changes of mold design. These changes are expensive, because the
process has to restart from the mold design. Every point mentioned as failure in the test
phase has to be corrected in the production phase. The number of redesign cycles ranges
from 4 to 20 cycles per mold or die and has in Europe an average of seven cycles.
Regarding costs, the reduction of the number of redesign cycles promises large improve-
ments in time and costs.
Redesign can be handled by reducing some areas of the die or mold (e.g., milling,
grinding, etc.) or adding some material (through welding), if necessary. Adding material
to forms reduces the quality extremely and most companies do not give a high lifetime
guarantee for such dies or molds. Thus, new design, production, and test cycles can be
necessary. When all requirements are fulfilled, then the form is delivered to the customer.
Technical Environment
The degree of process automation and of the use of IT varies much from company
to company depending on its size, the region, the type of product, and the customers.