PC-based manufacturing control for electrical part

Rohde and Schwarz is producing HF cages under the fully-automatic control of a Softing 4Control PC-based automation system which incorporates a visualization system known as 4C Console

Rohde and Schwarz produces, among other things, radio frequency instrumentation and test and measurement instruments for HF engineering and communications technology.

For these highly-specialised applications, Rohde and Schwarz has developed a unique HF front panel 'cage' based on an aluminium top plate for mechanical strength, a 0.1 mm plate spring and a thin (also 0.1mm) copper-alloy film of similar thickness for HF shielding.

Over ten thousand HF cage variants are possible, posing considerable manufacturing challenges.

The HF cages are actually manufactured in Teisnach, Southern Germany, where the three components are machined and assembled under the fully-automatic control of a Softing 4Control PC-based automation system which incorporates a visualization system known as 4C Console as well as the 4C Control module.

4Control handles the manufacturing sequencing, the assembly robots, and the packaging of the HF cages using programs generated automatically from data created at two other sites - Rohde and Schwarz's design department in Munich and the production planning department in Memmingen where the business data processing system (SAP R/3) integrates directly with the 4Control system in Teisnach.

All three sites communicate electronically, eliminating the need to print out design data, transfer it to Teisnach and enter it once again for the control programs.

4Control transparently calculates and converts the CAD data and the geometrical data for the NC machines, integrating this with the order data and coordinating the order of manufacture and the tracking of parts.

Several orders can be processed in parallel without delays.

The robot parts handling system is designed for high flexibility and very short setup times.

Eight individual NC machines are served by the robot and the production sequence is developed by 4Control based on individual order data.

4Control automatically calculates all production steps and generates the control codes for the NC machines, saving several worksteps and eliminating errors.

4Control calculates the start and target positions, depending on the individual cage geometry, and controls the robot online.

This allows fast traversing between the high number of different production positions and enables the manufacturing sequence to be dynamically optimized.

While a cage is being assembled at one station, other parallel stations process another six cages.

Optimizing the individual order data as well as the run itself has been especially decisive in cutting time and costs.

There is no need to store large amounts of data since it takes 4Control only seconds to calculate the programs and optimize each order, so production processes can be executed dynamically in real time.

At the end of the production run, the components are packed in the pallet stack ready for dispatch.

Depending on the size and type of the cage and its screws, 4Control chooses one of 24 packaging types.

A label printer downloads the required barcode label as directed by the PC-based control system.

In addition, the components can be individually labeled with text or with circuits by laser.

Even quality assurance is in the hands of 4Control which maintains the associated statistics.

The 4C Console module is Web-browser based, so monitoring the production processes is simple.

Using ISDN links, Rohde and Schwarz staff in Munich and Memmingen can track orders and monitor their status continuously.

The Internet could also be used.

Says Reinhard Seif, Managing Engineer of the Automation Projects Department at Softing who led the integration project: "The different manufacturing steps, order handling and process synchronization are now completely organized by 4Control.

The direct connection with the design department in Memmingen and the planning and commercial departments in Munich eliminates any need to print out the order and CAD data.

Furthermore, manually re-typing this data for the control system is unnecessary so production throughput times are greatly reduced." Sief continued: "This consistency and integration at all corporate levels is very laborious to implement with a conventional PLC.

In contrast, a PC-based control system is highly flexible and easily capable of meeting Rohde and Schwarz's vertical integration requirement from the very top of the enterprise right down to the production line." 4Control can also do complex arithmetical processing - for example, create the optimization algorithms from the geometrical data and the functionality of a PC-based system becomes even more advantageous because its internal data management is much simpler than with classical PLC systems.

With 4Control, complete automation systems, including connections to production management databases such as SAP R/3 and CAD, are more cost-effectively implemented across different locations and easily changed or extended at any time.

4Control synchronizes the individual NC machines and the robot in such a way that orders cannot overtake one another.

This would certainly have been very difficult to implement with a PLC.

4Control calculates the optimal traverse paths and without having to execute the rigid function blocks of a PLC, the installation can run at optimum capacity.

Furthermore, since the installation comprises one PC-based solution instead of several separate PLC systems, the need to link different hardware systems is avoided.

Field connections are implemented with PROFIBUS-DP, using a Softing PROFIBUS board and commercially-available PROFIBUS I/O components.

The advantages of the PC-based 4Control solution can be summed up as increased flexibility, shorter throughput times due to automatic production optimization, higher transparency and easier production monitoring, distribution of the production to different locations through enterprise-wide IT integration, and virtually paperless production.

Thanks to these advantages, Rohde and Schwarz have achieved shorter production times, fewer worksteps and highly integrated workflows.

Anton Fruchtl, Head of Production at Rohde and Schwarz, commented: "Thanks to our PC-based control platform 4Control it was easy to integrate and synchronize the order processing system, the CAD system and the production line, with the result that we reduced production times from 15 days down to 3 days for Rohde and Schwarz.".

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