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"There's no magic to developing good automation equipment"

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Kurt Meier, a mechanical engineer is aware that selection of appropriate components is necessary for system integrators to build efficient and well-functioning automation equipment. 

Kurt Meier works as a system and machinery designer in the automation department of a well-known manufacturer of small electronic devices, where he designs, plans and refines the equipment right up to the point that the first workpieces start to emerge from the finished plant. 

He is visiting the 32nd Motek show in Stuttgart, the well-known trade fair for production and assembly automation since he needs the components to design a screwdriving unit for an ECU (electronic control unit). His primary objective at the trade fair is to establish which components he would use for the assembly system, obtain information from as many suppliers as possible, and perhaps make a decision about the supplier.

Having already specified each one of the individual processes that make up his assembly task including feeding, handling, screwdriving, assembly, inspection, testing, evaluating, analysis and documentation, he needs to make sure the components he has selected should not exceed his existing budget, yet must still comply with the strict requirements for processing reliability in the assembly of an ECU. He also has to ensure compatibility between the components. 

Kurt Meier decides to visit the stand of DEPRAG SCHULZ GMBH u. CO where the well-respected screwdriving specialist is demonstrating an assembly system for an ECU, similar to the one that might be used to control the engine in a car. He immediately sees parallels with his own application.

For many years Meier has known of the famous MINIMAT screwdrivers from the range offered by machine engineering company DEPRAG in south-west Germany. He likes the technical sophistication and reliability of the EC servo screwdriver and the pneumatic screwdriver, which has proved itself thousands of times throughout the world.

Studying the machinery on DEPRAG’s stand, he observes that the DEPRAG specialists have built a linear transfer system, in square formation with return stroke, on which the most important assembly steps and the system components required are demonstrated. 

In this assembly system, specially designed for the exhibition, the upper and lower halves of the component arrive at a manual workstation on a work piece carrier. The operator manually fastens four screws onto the pre-mounted PCB. Where a high level of processing reliability is required, as is the case in the automotive industry, a MINIMAT-EC manual screwdriver is recommended, guided by a position control stand. A fully automated screw feeder accurately feeds the screws. 

DEPRAG’s technical consultant Martin Wagner explains that all the relevant components for this manual workstation have come from their own in-house design and manufacturing facilities, making DEPRAG competent partners for the automation tasks undertaken by system integrators. All the components have not only been tested thousands of times for reliability and efficiency, but also fit with one another and are harmonised to be compatible.

A position control stand assists the operator at the manual workstation in DEPRAG’s exhibition set-up. Screws for placement on a work piece often have to be fed through in a specific order. This intelligent stand controls the sequence so that no mistake is made. A standard screw feeder from the DEPRAG range automatically dispatches the four fasteners for the screwdriving task to the operator at the manual workstation. 

Kurt Meier also needs an automated feeder for his particular screwdriving task. The fact that his control units need to be assembled inside a technical clean room makes his job even harder. Kurt Meier fears unavoidable contamination caused by abrasion from a vibratory feeder. Martin Wagner offers a feeder system, specially developed to meet the demands of technical cleanliness and enable the screws to be supplied to the separation process via a lifted segment. 

To ensure the removal of other foreign bodies that may get into the feeder supply along with the bulked screws, he offers the DEPRAG particle killer, which uses a vacuum connection to suck out contaminating particles from the air used to shoot the screw into the screwdriver spindle. More vacuum connections are provided wherever abrasion might still occur.

A DEPRAG process unit, the DPU100 controls the manual workstation guiding the operator through the screwdriving process. If the DPU100 gives the OK to the sample part, the operator sends the workpiece holder containing the part to the next workstation. The fully-automated bush press-fit operation is carried out in a compact assembly cell - the DCAM (DEPRAG compact assembly module). 

In the DCAM assembly cell on the exhibition stand four bushings are now press-fitted onto the top half of electronic control unit. For this task the vacuum spindle on the press-fit tool travels towards the bushing feeder, which uses a pick-and-place process to ready the bushing. The spindle fetches the bushing and passes through a visual inspection station where the geometry of the bushing is measured. The result of this test is displayed on the touch screen. If the measurement is correct, it is press-fitted. Processing reliability for this step of the process is assured by means of a force-stroke monitoring system. The linear robot now places the upper half of the ECU onto the lower half four times in succession, and the workpiece carrier moves it on to the next station, another DCAM assembly cell.

Here, the top part is screwed onto the bottom section, a fully automated work step with maximum processing reliability. Process planner Meier knows the benefits of DEPRAG screwdrivers. The screwdriving function modules with EC stationary screwdrivers, recommended for high-spec screwdriving processes, are known throughout the world and are designed to ensure optimum processing reliability. Torques, arcs, speeds, waiting times and direction of rotation can all be programmed as required within the performance spectrum of the screwdriver spindle concerned and adapted to the particular screwdriving task in hand. This is exactly the right screwdriving tool for Kurt Meier’s planned assembly unit. Brushless EC motors guarantee low-maintenance operation. A DEPRAG AST10 automatic sequence controller with integral web server is used in combination with the MINIMAT-EC screwdriver. This means that any screw-driving program can be set up and configured using the Linux operating system.

After the screwdriving operation, a second workstep at this second assembly platform checks the function of the printed circuit board, which was assembled at the manual workstation. For this task, the workpiece carrier is raised and fixed in position, so that a test adaptor can touch the printed circuit board. If this functional test is positive, the DPU200, which is controlling the processes on both the DCAMs, indicates on the screen that the fitted component is ‘OK’. Like all DEPRAG process unit modules, it is also equipped with DCOS software, available in various standard packages. It includes all modern data recording functions as well as statistical quality and process analysis functions. All the principles of an optimum Human Machine Interface (HMI) have been assimilated into the specially developed software. For example, the uncluttered colour touch-screen can be operated by touch with a finger or stylus, and can be easily seen, even from a distance.

Kurt Meier is able to see on the DEPRAG stand how a second manual workstation on the square formation dismantles the assembled component so that the demonstration process could start over again for trade show visitors. In his application such a workstation could be used as a repairs workstation. The fitted component is either removed, or the necessary corrective work carried out as indicated by the control unit. Only once the assembled component has been classified as OK is it released for further processing or packing.

Following the demonstration, Kurt Meier is astonished to realise that he has already found all the components he has been seeking for his assembly unit here on the DEPRAG stand. DEPRAG is able to provide solutions in each of the four areas: screwdriver technology, feeder technology, control and measurement technology while balancing the financial aspect too. The comprehensive advice he receives also convinces him of DEPRAG’s dedication to customers and the skill and experience of DEPRAG’s technical staff. 

But even more decisive for him as a systems integrator is the fact that all the components in the system are from a single source – DEPRAG, immediately eliminating the need for time-consuming arrangements and interface specifications, which would automatically be necessary had he chosen components from different manufacturers. 

Kurt Meier will soon be sending DEPRAG the drawings and sample parts, so that the automation experts can draw up a design. He concludes that with the right partner, harmonising the components for feeding and handling systems, the screwdrivers, the assembly units, the inspection and testing systems, and the evaluation, analysis and documentation systems is no magic process.

This is also the message given out by plant engineers DEPRAG SCHULZ GMBH u. CO. from Amberg, Germany at the 32nd Motek, the international trade fair for production and assembly automation solutions between 7th and 10th October 2013 in Stuttgart. DEPRAG not only minimises work, cost and risk, but also helps plant engineers gain a reliable partner who is prepared to take on responsibility for component function.


 

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