Making the Right Choice
Selecting a wire EDM CAD/CAM System
Now that you have made
your decision to purchase a specific wire EDM machine there is one more decision
to make. What software package will you use for programming? This last decision
may seem minor when compared to the months of study that went into the machine
purchase decision. However, this decision can greatly affect the productivity of
your machine so it should not be taken lightly.
How can you make an intelligent decision when you donít have the pertinent
information? Everyone claims that their software will program a wire EDM machine
and will do everything you need. How can you know if this is true when you
yourself are not even sure of everything that you may want to do?
Get as much information as possible. Speak
to people involved in the industry. Continue reading this document and use it as
one your resources when evaluating potential CAD/CAM systems. This article was
written by an individual who has been programming NC/CNC equipment since 1976
and has been involved in the CAD/CAM industry since 1986. In the past 17 years
he has personally trained hundreds of customers on the use and implementation of
CAD/CAM software specifically for wire EDM applications. The following insights
will give you a good starting place in your evaluations.
Each companies requirements can be
best defined if we consider these 3 questions:
- Will you import
geometry from an external CAD system or will you create the geometry in your
- How do you intend to
utilize your machine?
- Which machine tool will
you be programming?
Each of these questions is
of critical importance in the decision making process. Letís look at them one at
- If you intend to import geometry from an external source
which formats will you be required to accept?
- DXF (data exchange format). This is an output format
available from AutoCAD and many other systems. It is best suited for 2D
- DWG (AutoCAD native drawing). This is the AutoCAD
native file format. If a DWG file is read directly this will eliminate one
of the translations required for other formats.
- IGES (initial graphics exchange specification). This
is a format that was originally developed to allow dissimilar CAD systems to
share geometrical data. Today it is probably the most popular method of
exchanging 3D CAD data. IGES supports NURBS curves & surfaces.
- X_T and X_B (native Parasolid). These are solids based
formats that are available from all solid modelers that utilize the
Parasolid kernel. The most popular of these would be Solid Works and Solid
- SAT This is a solids based format that is available
from all solid modelers that utilized the ACIS kernel. The most popular of
these would be AutoCAD Inventor and CADKEY.
- SLDPRT (native Solid Works). This is the Solid Works
native file format. This format eliminates the need for a translator as the
model will be read directly in the Solid Works format.
- PSM and PAR (native Solid Edge). These are the Solid
Edge native file formats. No translation is required if the model is read
directly from this native file format.
- VDA (European automotive standard). VDA-FS (Verband
Der Automobilindustrie Flachen Schnittstelle) is a standard file format to
exchange surface data. It is popular in Europe due to the endorsement of
several major European car manufacturers.
- STP and STEP (Standard for the Exchange of Product
model data). The STEP format is most commonly used in AP203 and AP214. AP203
was the original standard adopted in 1995 and AP214 is the latest standard.
This format is most commonly used in the North American automotive industry.
- CATPART (Catia V5 native part). This is the Catia
native part file format. No translation is required if this native file
format is read. Earlier versions of Catia used different file formats
(.model, .exp, .dlv, .dlv3).
- ProE native files (.prt, .asm). These formats are both
ProE native file formats. If either of these formats are read directly it
will eliminate the need for an additional translation
- UG native part files (.prt). This is the native
Unigraphics file format and allows files to be read directly without
- If you intend to create your own geometry what will be
- Will you need to draw simple 2-dimensional geometry?
If so most systems will be able to provide the necessary drawing tools. The
more important question is how easily and quickly will you be able to create
the geometry. In this application geometry creation will most likely be the
most time consuming aspect of preparing a program, so ease-of-use will be an
- Will you have the need to create complex 3-dimensional
geometry? If so you need to insure that the software has the ability to
create and draw in multiple work planes. Geometry creation should support X,
Y and Z data. Many systems require 2-D date (XY) to be created and then
moved to a different Z height or work plane. If your parts are complex this
can lead to additional drawing time and the chance for errors.
- Will you need the ability to create solid models? If
so your system should have some solid modeling capabilities. In most cases
you are going to be drawing simple things like fixtures and material blanks.
If serious design is your intention then it is probably best to consider a
separate design package since most systems that will function well for
programming your wire EDM will not provide an extensive set of design tools.
- Will your parts commonly contain multiple shapes which
need to be machined? If so does the software provide a method for
automatically creating these shapes from either a wire-frame or solid CAD
The CAD capabilities of your software package should be an
important part of the overall evaluation. If you intend to import CAD file
provide to you by outside (customers) sources then it would be best to be able
to import a large number of different formats. Ideally you would not have to pay
extra for these translators but in most cases you can expect to pay for Catia,
ProE, Unigraphics and STEP as software companies must pay a licensing fee to
utilize these formats. If your company will only deal with internal CAD files
then it will only be necessary to verify that the specific translator you
require is fully functional with the latest generation of CAD software. It is
also a plus if the software is certified by the different CAD vendors. This
typically means that the software supports the latest version of the file
formats and that the CAD vendor has checked the translation for accuracy.
- Does your machine have a wire threader?
- If your machine has a wire threader you system will
need to output the necessary M codes to cut and thread the wire. This can be
done automatically or some systems may require you to manually call a
command to cut or thread the wire. If the system does not perform this
function automatically then this will be one additional area for possible
errors in programming.
- If your machine has a submerged work tank the system
may also be required to drain and fill the work tank during wire threading.
- Does your machine require a non-standard programming
- If the control system on your machine requires a
non-standard programming format then you need to confirm that the
programming software is capable of generating the necessary codes and files.
Machine controls that require special program formats may offer additional
functions that are not available on more standardized controls so this is
not necessarily undesirable it simply means that the programming software
will be more critical.
- Will you be programming multiple opening parts?
- If your programs will have multiple shapes to be cut
it will be necessary to program wire cut, positioning and wire thread
commands. The automatic creation of these positioning moves will reduce the
number of steps required to program this type of part as well as the chance
- If your parts have multiple shapes to be cut does the
programming software provide a method of machining multiple shapes without
having to individually pick each shape? If you commonly machine a large
number of shapes this can eliminate the time consuming task of selecting
- If multiple shapes are to be machined does the
software offer a method of sorting the order of the machining to create the
- Do you need to program 4-axis parts?
- If you have the requirement to create 4-axis program
how easy is it to create the synchronization points? Synch points are
necessary when the 2 different shapes have different numbers of segments and
thus require points of synchronization to be selected along the individual
shapes. These point should be able to be selected anywhere along the shapes
not only at the end of segments. Many times it may be necessary to add synch
points after the initial program has been created. If these points can only
exist at the end of a segment then it may be necessary to go back and modify
the geometry to add additional segments.
- Will your 4-axis programs require shapes with
non-planar shapes? Many systems only support planar shapes. If your geometry
is non-planar then this will require an additional step to create a surface
and then slice the surface to create these planar shapes.
- Will you run your machine in unattended machining mode?
- If your machine is equipped with a wire threader and
you intend to run the machine while it is unattended then your programming
software should support the automation of this type of programming. The most
common type of unattended machining is when all of the openings in a part
are roughed without dropping a slug. After the roughing the machine will
wait for the operator and then each of the slugs is dropped and then the
trim cuts can happen fully unattended. If your programming software supports
this type of machining it will save the many steps required to generate this
type of program manually.
- If you intend to run your machine unattended at times
then you should also inquire about how easy it is to change from one
machining technique to another (standard glue-stop to unattended). Will the
software automatically sequence the multiple cuts to create the shortest
possible tool path? Both of these functions are crucial if you intend to
program using this feature since scheduling may change and force a program
to be run while an operator is present. Secondly you do not want the machine
making longer movements than necessary since each of these positioning moves
will be made at least 3 times since the program will contain a rough, cutoff
and trim for each opening.
Machine Type (manufacturer)
Each wire EDM manufacturer has different controls and
features which makes it very important that the programming software that you
select will be able to support the special functions of your machine and also
generate the correct NC code to cut the parts. The following list is intended to
give you the basics required by each manufacturer. When investigating CAD/CAM
software you should address these requirements with each prospective company.
This will also give you an easy way to judge how familiar they are with wire
- Agie 100/123 controls. These controls are no longer
produced by Agie and will only be found on machines produced prior to 2001.
This control uses a very unique programming format. The following is a list of
some of the requirements:
- The NC code can only be output in metric.
- The NC code can only be output in incremental.
- The NC code does not accept decimal points.
- The NC code requires both positive (+) and negative
(-) signs to be output.
- The entry move (lead-in) and first contouring move are
actually reversed in order in the NC code
- If the machines offsetting is to be used all moves
must be tangent and entry and exit moves must be perpendicular.
- 4-axis programs do not use U and V values like most
controls but rather Q and R which are angles relative to the directional
vector. This is the only control on the market that uses this technique.
- AgieVision controls. This is the newest Agie control
from Agie and has been available on machines produced after 1996. This control
offers many advanced capabilities. The AgieVision control uses 3 different
- The .ISO file is a standard NC code file which is the
contouring data in a standard G-code format. A separate .ISO file is
required for each shape to be cut. If you are using no-core machining then 2
separate .ISO files are required for each shape, one for the roughing path
and one for the finish profile.
- The .SBL file is the script file and is used by the
AgieVision control to setup all of the necessary parameters for each .ISO
file. These parameters include:
Wire Start Hole
Exit Point (lead-out)
Part thickness and Land height
Separation Cut amount
Part Material and Stock Size
Wire Type and Diameter
Quality Target (tolerance, surface finish, corner accuracy)
- The .SBR file is a list file containing the names of
all the .ISO files used for the specified program
For a programming system to be
effective for this control you need to be able to create all 3 file types. If a
system only generates the .ISO files then it will be necessary to perform the
remaining functions covered by the script file at the machine controller.
Another item to consider is how often the post processor is updated for this
machine, since one of the advantages of the AgieVision control is that it can be
updated in the field. This allows users of machines with older controllers to
be updated to the latest functionality. As Agie adds new capabilities to this
control the programming software must be updated to reflect these improvements.
- Charmilles Robofil controls. This control is still
offered on some Charmilles machines and was the most common control on most
Charmilles machines produced prior to 2002. This control also uses 3 different
file types. These file types are as follows:
- The .ISO file is the main NC code file. The program
can be written using a single .ISO file with all cuts written in a single
file or separate .ISO files can be written for each shape.
- The .CMD (command) file contains the setup
information. This file will vary in complexity depending on whether single
or multiple .ISO files are being used. This file contains parameters for the
Part Thickness and Land height.
Wire Offset Amount and Direction.
Taper and Stop use.
Technology File information.
- The .TEC (technology) file contains the cutting and
offset information. This file is created at the machine using the CT-Expert
software and can also be created offline if the programming software is
integrated with the CT-Expert software.
This control can be programmed
offline with a system that only outputs the .ISO file but it will then be
necessary to generate the .CMD (command) file at the control. The Charmilles
control has a number of special functions which should be supported by the
programming software. These functions include: Wire Protection Strategy, Corner
Control and Twist Mode. For production machining jobs the automated pickup
functions can be programmed in the .CMD file.
- Charmilles Millennium controls. This is the control
supplied on most Charmilles machines produced since 2002. This control uses a
more traditional main and sub program method and it also utilizes a .TEC file.
It also has the CT-Expert software for creating technology files which can be
integrated with offline programming software. This control also supports the
Wire Protection Strategy, Corner Control and automated pickup functions.
- Mitsubishi controls. Mitsubishi has produced a large
number of machine models over a considerable period of time. As the machines
have progressed the capabilities have increased. It is important to clarify if
a post processor for a specific machine is available and if that post
processor has a cutting condition database containing the E-paks, feed rates
and offsets provided by Mitsubishi. Mitsubishi machines typically require that
a lower power setting be used during the entry move with the full power
setting being activated once the cut has been started. The programming system
should be capable of outputting 2 sets of E-paks for the initial roughing cut.
It would also be helpful if a specified distance for the insertion of the
second E-pak could break the contour automatically. Another requirement for
certain Mitsubishi machines is the output of a dwell (G04) command after the
lead out move when cutting outside shapes. This is necessary due to the wire
lag created during a roughing cut under certain conditions. A wire break can
occur if this dwell is not programmed. Machines equipped for submerged
machining need tank drain and fill commands output when automatic wire
threading is to be used. All of these commands could be manually inserted if
necessary but it would be best if the software could output them automatically
- Sodick controls. Sodick has also produced a wide variety
of machines with different controls. It should be verified that a post
processor is available for a specific control. On older Sodick controls it is
necessary for the wire offset to be applied and canceled in two stages. This
avoids the offset being applied to the entry and exit moves, which will leave
a small scallop on the part. Different Sodick controls have different
techniques for programming the actual values for the ďHĒ offset registers, so
it is necessary to have different post processors capable of outputting this
information in either format.
The wire EDM industry is different than the chip-making industry in the fact
that each manufacturer uses a unique control. This means that there needs to be
machine specific functionality included in a programming system to effectively
take advantage of the features offered by the individual machine manufacturers.
This level of specialization will only be possible from software companies who
are willing to make a serious commitment to their wire EDM modules. With wire
EDM representing a very small percentage of the overall CAM marketplace most
software companies will not devote much R & D to a product with such a small
potential market. Search out a company who is committed to the wire EDM market
and has the years of experience required to provide you with a comprehensive
solution to your programming system needs. Another important factor that can
only come with years of experience is customer support. You want someone
knowledgeable in wire EDM programming to be there to provide support when you
have a question.
The CAD/CAM software you purchase will definitely affect
the productivity of your wire EDM equipment. This purchase should be given the
consideration it deserves. Use the information provided here, talk with people
at the wire EDM manufacturer and speak with other people in the business. Do
whatever it takes to make sure that you have the necessary information to make
an informed decision.