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Machine tools and general engineering

Macros reduce time required to create
CNC programs for making press components

Prensas Schuler, São Paulo, Brazil, supplies advanced mechanical and hydraulic press systems for customers in the automotive industry, their suppliers and the household appliance industry. These presses require a wide variety of machined components, including beds, slides, gears, moving bolsters, uprights and many others in a range of sizes and styles. Writing computer numerical control (CNC) programs to produce each of these parts using traditional methods was time-consuming and expensive. The company has reduced the time required for CNC programming by taking advantage of the open architecture of ESPRIT computer-aided-manufacturing software from DP Technology to write Visual Basic for Applications (VBA) macros. The macros prompt the programmer to enter dimensions and other basic information for each type of part and then automatically generate the programs. "ESPRIT provides several important advantages, including the strong support and programming assistance provided locally by Frame Tecnologia and its use of the industry-standard Visual Basic for Applications programming language," said Fabio Avila, Chief of Machining Shop, at Prensas Schuler.

Prensas Schuler manufactures fully-automated press lines, servo presses, transfer presses, progressive die presses, blanking presses, hydraulic presses, try-out presses, forging presses and press automation solutions. Prensas Schuler also distributes the full product lines of its parent company -- the Schuler Group, based in Göppingen, Germany -- including presses for packaging and minting coins, systems for manufacturing electrical motor laminations, and solutions for processing high-strength steels and hydroforming. Prensas Schuler is the largest supplier of metalforming presses in Latin America and the second largest subsidiary of the Schuler Group. The Schuler Group itself is the largest supplier of metalforming presses in the world. The magazine GEO once described one of Schuler's large presses as follows: "Eight-square-meter blanks are fed in at one end and come out as complete car body panels at the other end." Schuler's technologies are helping automotive manufacturers to reduce vehicle weight and conserve natural resources.

Image 1: Prensas Schuler has reduced the time required for CNC programming by using ESPRIT computer-aided-manufacturing software from DP Technology. Per Fabio Avila, Chief of Machining Shop, at Prensas Schuler: "The picture shows a plate that we machine in Floor Type Milling Machine (horizontal milling). Due the quantity of holes, we select all the holes with the same geometry and the software automatically generates the NC program using a sub routine available on the machine. This kind of resource available from ESPRIT software is very helpful for us due to the kind of product that we produce. Basically we produce presses that require customization for the customer. This means that each press is a different project."

The ability to select the holes with the same geometry saves the programmer time, as he doesn´t need to manually look for all the holes with the same geometry. It saves time and reduces the risk of a programmer mistake."


CNC programming challenges
Prensas Schuler produces components for stamping presses in a large machine shop that includes many gantry milling machines and horizontal milling machines. Dozens of new CNC programs must be created each month in order to produce machines to meet special customer requirements. In the past, this was a complicated and challenging task because of the geometrical complexity of these components, as well as special programming touches required to avoid damaging them. Because tolerances are tight, trial cuts and touch-offs are built into the programs to provide operators with the opportunity to verify dimensions to avoid the risk of destroying the workpiece. The programs also need to include detailed annotations that serve as tool setup and machining instructions for the machine operator.

A number of years back, Prensas Schuler purchased new CNC programming software that uses macros to reduce the amount of time required to create new programs. The company wrote macros for each of the main types of parts used in its presses. Each macro prompted the CNC programmer to define whether or not the part should include various special features and automatically excluded conflicting choices. The macro presented a drawing of the part on the screen and asked the operator to enter the dimensions in fields on a table that corresponded to dimensions on the drawing. Finally, it asked the operator to select the machine tool and cutting tools to be used to produce the part. These macros substantially reduced the amount of time required to program new parts and also reduced the number of programming errors.

However, Prensas Schuler found that support was available only by e-mail and the technicians were often unable to provide solutions to the company's problems. Another issue was that the software used its own proprietary macro language, which meant that it was impossible to find programmers who knew the language, so they had to be trained from scratch.

Industry standard macro language and local support
"We looked for a program that would be locally supported and would use a standard programming language so that we could easily find internal and external programming support," Avila said. "We selected ESPRIT because ESPRIT uses the industry standard Visual Basic for Applications (VBA) macro programming language. There are many programmers that already know this language and ESPRIT provides an application programming interface that opens the door for communications with many Windows programs. Another important advantage of ESPRIT is that Frame Technology provides excellent technical support and contract programming assistance in our local area."

A major advantage of VBA is that it is by far the most commonly used macro language.  There are many programmers who already know VBA and a benefit of learning VBA is that, once you master the language, you can more readily write macros for other applications. ESPRIT enables programmers to use VBA to access virtually all of its capabilities. For example, a programmer can create a new dialog box that asks for parameters to define a hole (diameter, depth, XYZ location, hole type). Then the VBA macro automatically creates circles representing the holes, selects the cutting tools, automatically creates the drilling operations, and produces the G-code program all in one step. All of ESPRIT's menus and toolbars are also accessible from within a macro or add-in program via the ESPRIT application programming interface, or API.  This allows the macros and programs to adapt the ESPRIT interface to suit the individual needs of a particular application or business.

Prensas Schuler has several VBA programmers who write ESPRIT macros. Frame Tecnologia provides telephone support to these programmers who can, if they wish, send their code to Frame for comments and corrections. Prensas Schuler also outsources the development of some VBA macros to Frame Tecnologia. Prensas Schuler uses CATIA V5 computer-aided-design (CAD) software to design forming presses. The VBA programmer imports a CATIA V5 parametric model into ESPRIT to serve as the basis for the macro program used to create programs for a family of parts. The VBA macro is then used by CNC programmers to create G-code to produce individual parts within the family.

Images 2, 3 and 4: These pictures show a Skoda milling machine milling a plate to be used in Prensas Schuler presses.

Image 2 shows the plates fixture on the machine. We can see the same plate in the picture "simulação esprit," which shows the NC program's simulation in ESPRIT.The main idea was to compare the NC simulation in ESPRIT and the real aplication on the shop floor.

Image 3 shows the same plate in a different view, but also shows the rotary table available in the same machine with a Eccentric Gear already prepared for the machine. Image 4 shows the same plate in a different view.

VBA macros save time
The VBA macros work essentially the same as the macros produced with the previous software. The macro asks the CNC programmers questions about the part and the tooling that will be used to produce it, and builds the program based on their answers. The macro produces not only the finished G-code program but also a tool list and a tool setup diagram that shows the zero point for the tooling on the part. With the aid of a macro, a CNC programmer can create a CNC program for a new part in a matter of minutes compared to the hours required using traditional methods.

The next step is simulating the program in ESPRIT to verify the geometry of the finished part and the integrity of the machining operation. ESPRIT generates the toolpaths and G-code needed to machine the part. ESPRIT then simulates the machining operation while the programmer views each cutting tool being loaded and taking its assigned cuts along with the entire machining environment in dynamic 3D solids. In some cases, the programmer may see that the final geometry does not exactly match the design intent, so he goes back to the initial part geometry, makes a small change and pushes another button to update the program. In other cases, he might see an opportunity to reduce machining time by moving a feature to a different tool or changing the order of operations.

"ESPRIT macros improved the process of creating CNC programs for machining forming press components," Avila concluded. "ESPRIT's use of the VBA programming language makes it much easier to find and train programmers to create macros. The macro programming support provided by Frame Tecnologia helps us quickly overcome any obstacles that we discover in our path. Our goal is to further improve our macro programming capabilities in order to further reduce programming time and eliminate machine setup errors."

Image 5: Screen capture from ESPRIT, which shows programming to machine a gear.

Image 6: ESPRIT utilization.JPG: Programmer using ESPRIT.

Image 7: Schuler´s Team programmers.JPG: Prensas Schuler's team of programmers.

Image 8: Workout with Frame technician.JPG: A Mr.Fernando from Frame (ESPRIT's representatives in Brazil) during a session for programmers.


About ESPRIT
ESPRIT is a high-performance computer-aided manufacturing (CAM) system for a full range of machine tool applications. ESPRIT delivers powerful full-spectrum programming for 2-5 axis milling, 2-22 axis turning, 2-5 axis wire EDM, multitasking mill-turn machining and B-axis machine tools, and high-speed 3- and 5-axis machining.

DP Technology in profile
DP TECHNOLOGY is a leading developer and supplier of computer-aided manufacturing (CAM) software for a full range of machine tool applications. ESPRIT, DP Technology's flagship product, is a powerful, high-performance, full-spectrum programming system for milling, turning, wire EDM, and multi-tasking machine tools. ESPRIT and the personnel who support it embody DP Technology's passion for excellence and vision of  technologies potential.

DP Technology reinforces its commitment to technical excellence by dedicating nearly 20 percent of its annual revenue to ongoing research and product development. This long-term focus has produced powerful technological innovations that have placed ESPRIT in an industry-leading position since its market launch in 1985.

DP Technology maintains its worldwide headquarters in Camarillo, California, U.S.A. and product development teams in California and Florence, Italy. Sales and support operations are located in Europe, Asia, and North and South America.

At DP Technology, we love what we do and our success is mirrored by the thousands of customers who've expanded their manufacturing capabilities with ESPRIT.

For further information about ESPRIT, contact:
(in the United Kingdom) CAM Supplies & Services Ltd., C5 Business Centre, North Road, Bridgend Industrial Estate, Mid Glamorgan CF31 3TP, UNITED KINGDOM. Telephone: 0871 218 3001, E-mail: sales@camsupplies.co.uk

(in the United Kingdom) Scotcam Limited, 25 Larchfield Crescent, Wishaw, Lanarkshire, ML2 8TY Scotland, UNITED KINGDOM. Telephone: 0777 611 7629, E-mail: info@scotcam.com

(in Europe) Hélène Horent, DP Technology Europe, MIBI, 672 rue du Mas de Verchant-CS37777, 34967 Montpellier Cedex 2, France. Tel: +33 (0)4 67 64 99 40, E-mail: esprit.europe@dptechnology.com Website: http://www.espritcam.fr/

(in North America) DP Technology Corp., 1150 Avenida Acaso, Camarillo, California 93012, USA. Telephone: +1-(800) 627-8479, Fax: +1-805-388-3085. E-mail: esprit@dptechnology.com Website: http://www.espritcam.com/

(in Germany and Austria) DP Technology GmbH, Kirschäckerstr 23 - Eingang 2, D-96052 Bamberg. Telefon: +49 (951) 299 526-0, Fax: +49 (951) 299 526-29. E-Mail: esprit@dptechnology.de Website: http://www.espritcam.de

(in Spain) ESPRIT CAMCENTER, Avda. Muntanyola 150, 08529 Muntanyola. Tel: +34 618 14 79 87, E-mail: info@camcenter.es Website: camcenter.es
S.C.A. INTEGRAL, Plaza Josep Pallach 2, 08035 Barcelona. Centralita: +34 902 361 721, E-mail: info@integralplm.com Website: http://integralplm.com/es/home/   
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