Press Release

Screwdriving Technology

(Press Release, September 2011)

Using the right technology to fasten miniature screws to the frame

Sunglasses provide a clear view

DEPRAG places the focus firmly on innovative technology for micro-assembly operations

Anyone looking for an overview of innovative technology for micro-assembly operations should venture a look at the DEPRAG stand at MOTEK 2011 this October, where the focus is on modern micro-assembly operations - and ground breaking new products are on display. Trendy sunglasses will be assembled live before visitors' eyes. At a single glance visitors to the exhibition will obtain a well-founded overview of how fasteners - barely visible to the naked eye - are assembled using a process-reliable method. Screwdriver, process controller, screw feeder, position control stand, electronic measurement and the DCOS control unit concept - everything on this semi-automatic assembly station is designed towards miniaturisation in the production process. Whether the task is to assemble a hearing aid, a heart pacemaker, a satellite navigation unit, a mobile phone or fashionable sunglasses - micro-assembly can be truly process-reliable only by applying the utmost attention. Tiny fasteners can create gigantic problems; so sharp-sighted planners take a longer look when it comes to designing equipment to handle micro-components.

DEPRAG Sales Manager Jürgen Hierold promises: “After just one look at the sunglasses being assembled on our stand, visitors will be able to see more clearly. They will have an overview of every aspect of micro-assembly. And, to boot, they will walk away with a free pair of newly-assembled sunglasses for improved vision.“ DEPRAG SCHULZ GMBH u. CO. KG from Amberg in Oberpfalz, Bavaria is well known as a one-stop-shop for sophisticated designs for the automation industry. Industrial miniaturisation is a huge challenge for all plant engineers. DEPRAG continues to make a name for itself with innovative products and by enhancing their existing product offering. At MOTEK 2011, which takes place from 10th to 13th October at the new exhibition centre in Stuttgart, attracting a wide range of trade and industry visitors, it will be demonstrating its expertise in the industrial assembly of micro-components. By demonstrating a semi-automated screwdriving system for sunglasses on its exhibition stand it is sharpening the industry's vision with regard to process reliability and quality management.

First, we focus on the screwdriving task in hand. The arms of the glasses are fastened onto the frame with tiny screws. A MICROMAT® EC screwdriver from the DEPRAG range screwdrivers - proven a thousand times over - does the job. Screw tightening torques for this extremely compact, flexible screwdriver, the size of a ballpoint pen and designed to meet maximum industrial demands, are freely programmable. Torque, rotation angle, speed, holding time and direction of rotation can be programmed, within its performance range, individually to each screwdriving task. The stationary DEPRAG EC screwdrivers are distinctive for their high torque accuracy and they also possess comprehensive monitoring/control functions for optimum process reliability. The MICROMAT® EC screwdriver is equipped with a brushless, extremely low-maintenance EC motor, to guarantee a long service life. The highly accurate torque analysis using the motor current draw, along with exact angle of rotation measurement, enables accurate control of the screw tightening process and recording of all pertinent parameters.

The EC screwdriver is controlled by the new DEPRAG AST5 screwdriver controller, which will be introduced to a wide audience of industry professionals at the exhibition. It is the ideal process controller for carrying out manual screw assembly operations with the DEPRAG EC screwdriver from the NANOMAT® EC (new) and the MICROMAT® EC low torque screwdrivers covering a torque range of 0.08 to 80 Ncm.

Even at first glance the observer is struck by the small and handy design of the new AST5, devised for micro-assembly work. It will fit on any manual workstation, even where space is a premium. Produced according to the typical, clearly-arranged DEPRAG design, it is operated via a user-friendly touch screen. The process controller contains standard screwdriving programs to assemble components to torque and to loosen them by rotation angle. Their parameters can be adjusted to the job on hand directly via the touch screen. User-specific screwdriving programs can be compiled quickly and easily using the embedded program commands as a platform. The AST5 can hold up to 100 user programs, which can be called very easily via the colour TFT display unit. Users select individual user profiles either by typing in a program number or by calling the name of the program which can be set by the user. The programs can be configured and the control functions called via a standard web browser as well as directly on touch panel display. Separate PC software is not required.

The new AST5 contoller records the results of the screwdriving assembly cycles from the previous seven production days, and stores them for retrieval via the Ethernet connection. Additional points in favour are the detailed graphical display of screwdriving curves, the integral SPC functions as well as comprehensive options for analysis. This ensures successful traceability of production work, along with optimal quality management processes.

Furthermore, the AST5 provides the option to combine with an automatic screw feeding device, as will be comprehensively demonstrated at the MOTEK exhibition stand. It is one thing to assemble such small screws, as small as a grain of rice, with process reliability, but automatically separating and feeding them repeat ably to the screwdriver in a precise rhythm is quite another. DEPRAG will introduce a further innovation to this years MOTEK visitors: the screw feeder for micro-assembly operations, with a vibratory bowl volume of just 0.05 litres!.

Miniaturisation of fasteners poses a difficult task for auto feeding technology. When the subject screws are very small, the vibratory bowl contains a mass of components, which afflicts the process with a large amount of load stress. A proportionally wide vibration amplitude is necessary to set the parts motion. On the other hand, each screw as an individual is very small and light, and if the vibration amplitude required to move the mass of parts is quite large, the individual screw will react with excessive motion making it difficult to control and separate. The new DEPRAG feeder for micro-components overcomes this problem with piezo technology. A high-frequency piezo drive excites the 0.05 litre vibratory bowl with very fine vibrations. These regulated vibratory movements help to convey and align miniscule items as small as the head of a needle, ready for separation. A frequency of between 60 and 400 Hz can be precisely regulated. Sales Manager Jürgen Hierold explains: “now It is possible to automate the screw assembly process in miniature products”.

Nutrunner and automation experts DEPRAG always have an eye on the process reliability aspect of their systems. The screwdriving process demonstrated on the sunglasses at the MOTEK exhibition stand will also address this point: The operator workstation is equipped with a position control stand (PKS). This tool support stand ensures that the screwdriver is always guided in the perpendicular plane - essential for miniature screws. The stand also absorbs the screwdriver's torque reaction, making the process more comfortable for the operator. But, the position control stand does more. If the work involves several screw positions, it is possible to use the PKS and the relevant controller to specify and control the sequence in which the individual screws are driven. The controller contains a host of functions to govern the entire manual assembly process, such as clamping and locking the parts, feeding the fasteners, or triggering measurement functions. Measurement results can be stored or transmitted to a database via a TCPIP module.

Industrial precision screwdrivers such as the DEPRAG MICROMAT® achieve extremely high torque accuracy. They achieve a CmK value greater than or equal to 1.67 with a tolerance requirement of plus/minus 10% in relation to the 6 Sigma method according to ISO 5393. In other words, a CmK value of 1.67 signifies an error rate of just 0.6 per million screwdriving operations. This makes the MICROMAT® suitable for applications where safety-relevant screw joints are in process, such as medical technology. It is in such fields that the regular verification of the screwdriving process is a burning issue. What simply results in scrap material or rework in the assembly of sunglasses, could prove to be fatal in the performance of medical equipment , i.e. loose, incorrectly assembled screws. This is why industrial screwdrivers are checked and recalibrated at regular, specified intervals. Calibration checks can be performed directly in the process, using manual measuring instruments, without the need to dismantle the tool from the workstation.

Visitors to the show will also find their attention drawn to DEPRAG's offering in terms of measurement technology, forming part of the one-stop-shop philosophy: “The new ME6000 electronic measurement system is one of the finest to be found currently on the market,” assured Sales Manager Jürgen Hierold. With the ME6000 the DEPRAG portfolio of torque measuring instruments has been expanded by adding this high quality precision measuring instrument, which achieves double the measurement accuracy of the tried and tested ME5400. It is recommended for use anywhere where a measurement accuracy of 0.5% is desired. This is an absolute necessity for torques of less than 0.5 Nm. “It is in the miniature assembly field with extremely low torque values that the screwdriver results can be displayed and verified to the best possible effect in the curve characteristics. We can thus achieve further improvement of process reliability in this delicate area,” explains Jürgen Hierold.

The parent controller for the sunglasses assembly station is based on the DCOS (DEPRAG CONTROL SYSTEM), the innovative equipment and process control system at the utmost industrial level. It brings with it a host of benefits with regard to traceability, documentation and archiving the production process (SPC). Current product liability legislation acts against manufacturers in the event that faulty products should reach the retail shelves. So who is liable if the end product was manufactured from several components? To answer this question, it must be possible to provide traceability.

The DPU100 operating unit can be connected via an EtherCat port to the company's network/Intranet/Internet system. Integral network capability, problem-free connection to SCADA and MES systems, optimum data management and storage, and above all, access to the usual PC applications such as browsers, data backup and remote access allow almost limitless possibilities for application.

DEPRAG promises visitors to its stand that they will gain an informative overview of technical innovations for complicated micro-assembly operations. And they will leave not just in possession of a pair of sunglasses. Anyone casting an eye over the complexities of assembling a pair of glasses will receive a well-founded insight into how one-stop-shop DEPRAG solves the most delicate screwdriving operations in today's miniaturized technology with a high level of process reliability and necessary traceability. Sales Manager Jürgen Hierold sums up: “We make sure that we are giving the right view. Even miniature screws can be reliably fastened using a carefully planned system.”

Press Contact:

Dagmar Dübbelde
Carl-Schulz-Platz 1
D-92224 Amberg
Tel: 09621 371-343
Fax: 09621 371-199

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