What started off in 1983 as a 800 gram Motorola device, sneeringly called "jingling bone", has embarked on an unbelievable triumphal procession around the entire globe: the mobile telephone. Experts meanwhile estimate there to be 4 billion mobile phone users worldwide. The market is flooded with a multitude of mobile phone models, which can do a lot more than just phone. The Finnish giant in this sector, Nokia, is the largest producer of mobile telephones, followed by Samsung. Today's handy weigh less than 80 gram, they take photos, record and play back videos, surf the Internet or are navigators for drivers and pedestrians who are unfamiliar with the surroundings.
Mobile phones are produced in an industrial mass production environment. Three-shift production operation places high demands on people and material. The often quoted maxim "time is money" demands robust, low maintenance machines, which operate smoothly, even at high cycle rates. If during screw assembly in a factory in the mobile telephone sector delays are caused by screw presenters, for instance as a result of jamming of the hardware in the feeding device, this jeopardizes production targets and the profit margin is not achieved. Particularly when the demands of industrial series production are very high, an extremely robust design is required. Devices with marginal guide plates and tooling are unable to support the duty cycle of the operator over extended manufacturing periods.
Recently a "distress call" from a customer in India reached DEPRAG SCHULZ GMBH & CO. KG: please build us a functional and robust screw-presenter! For a project of this type, DEPRAG, being an automation expert with Head Office in Amberg/Upper Palatinate, who are renowned for quality and competency in auto feed systems, proved to be the suitable partner. DEPRAG engineers went to work. Within a short period of time they developed a robust, extremely low maintenance screw presenter designed for mass production.
What is a screw presenter? When a worker uses screws to assemble mobile phones at his workstation in the prescribed cycle time, not only the individual parts of the phone are supplied to him automatically via a conveyor belt. He also receives the screws from the screw presenter, isolated and synchronized with the production, from where he takes them with the tip of the screw driver. In trade jargon: He picks the presented screw with a magnetic bit or by means of vacuum finder. Then he tightens the screw using an industrial screwdriver, picks it and tightens it, picks it and tightens it; always according to the manufacturing rhythm.
The screw presenter, designed by DEPRAG for mass production that presents small screws, looks like a small bowl. For many years DEPRAG has been a specialist for vibration drives for transporting screws, threaded rods, bolts, rivets, washers, O-rings and other small parts. This is how the Deprag screw presenter functions: A vibratory electro-magnet beneath the feed bowl generates micro-wave movements in connection with alternating current, a set of springs and an integrated regulator. This micro-wave moves the screws in the bowl and finally transports the screws individually to the "pick-up point" via a feed rail. A special guide plate guides the drive bit with the screwdriver accurately and securely to the pick-up point of the screw (the screw drive). That way, a secure and comfortable picking-up of the screw at a high mass production rate is achieved reliably and repeatedly. This screw presenter is also the first choice for miniature screws for Mobile phone manufacturing and for screws with lengths/diameters that don't allow other feeding techniques. The cycle speed can be changed with an easy to operate dial, when a new employee starts his job after a shift change.
The screw presenter operates fault-free, even under the most demanding production conditions. During development, the DEPRAG engineers focused on robustness and durability of the device and have deliberately selected a low maintenance design. If despite this, maintenance work must be performed every now and then, it can be done easily and in a user-friendly manner. Due to their compact design, multiple DEPRAG screw-presenters can be arranged efficiently in limited work spaces.
If the required screw sizes change during production, the screw presenter is designed for a quick change-over. Easy to exchange components, like guide rails and separator slides, allow a flexible adaptation to changing screw types, whether they are smaller, larger or with a different head. “Because of that, the new screw presenter becomes a long-term companion in production” states DEPRAG Sales Manager Jürgen Hierold. The extremely robust screw presenter, re-designed for mass production, is used wherever a fully automated screwfeeding machine cannot be employed cost-effectively. Jürgen Hierold: "If required we also develop feeders tailored to the requirements of the customers specific application”.
At this year's AUTOMATICA, DEPRAG presented their new generation of screwfeeding machines, the Series 6, for full automatic screwfeeding in demanding, automated manufacturing plants. Differences in vibration speed have always been a thorn in the side of the screw feeding process. Specifically the constantly changing level of parts in the feeder bowl with a subsequent change in mass, lead to speed and cycle fluctuations. This is an annoyance, which is frequently bypassed by implementing complicated technology. In the new Series 6 screw feed system, DEPRAG solves the problem in a surprisingly simple way: A sensor captures the oscillation amplitude in the feeder bowl and the Series 6 screwfeeding machine automatically adjusts the vibration according to the mass of parts in the bowl - independently of bowl level and temperature!
Sales Manager Jürgen Hierold emphasizes: "With the Series 6 screwfeeding machine the screw always arrives at the separation point using the same transporting speed. This is a good example of our constant strive for innovation. The new generation of screwfeeding machines convinces with high functionality and thereby contributes towards an improvement of process reliability".
Miniaturization also places new demands on traditional screwfeeding machines. If the material to be transported is very small, the feeder bowl contains more individual parts, which impose a higher weight/mass ratio on the bowl. In order to achieve functionality, a relatively high oscillation amplitude must be generated. The individual screw on the other hand is very small and therefore very light. Under heavy oscillation it becomes too active in the bowl and this impedes the ability of the feed system to bring the screw to the point of separation in sequence with the assembly cycle. In this case too, automatic control of the oscillation amplitude is the ideal solution.
The Series 6 screwfeeding machine operates user-specific, i.e. it can be adapted to the individual speed of the worker. Up to ten employees can log into the device control system with a user RFID chip and the screw feed system functions at the rhythm that is saved per the individual worker. These system parameters can also be manually adjusted on the control system via the membrane keypad and LCD display.
Incorporation into an existing facility is quick and without major effort, because a number of important functions are already contained in the integrated sequence control system: It can control and monitor multiple peripheral devices like valves, level control of the feeder bowl, separator in-feed or blow feed control of the screws. This means a substantial reduction of programming costs for the customer in terms of PLC control. In addition the standard controls include a “duty cycle simulation mode” so that the customers series production can be simulated in long-term testing i.e. the customer-specific application cycle is emulated during system setup in the DEPRAG facility before the screwfeeding machine is delivered. This way a high degree of reliability is guaranteed from the moment the first screw is "automatically delivered".
Besides the high quality Series 6 screwfeeding machine and this robust durable screw presenter, DEPRAG also offers a wide range of feeder solutions for manual and automatic assembly. Whether it is a vibration drive, oscillating rail (sword)- or centerboard design for sensitive components or a linear conveyor system, the feeder specialists will find an appropriate solution for all applications regarding automated parts feeding. "All reliable feed systems have one thing in common - they are robust and designed for mass production” Jürgen Hierold emphasizes.
The automation specialist, DEPRAG SCHULZ GMBH & CO. KG is presented in more than 50 countries with 600 employees. Further core products include screwdriving technology, automation, air motors and industrial power tools. With innovative assembly systems and assembly plants, the company offers flexible manufacturing solutions for manual assembly of small production series up to highly automated mass production. The Head Office of DEPRAG, who have been involved in innovative solutions for plant design for decades, is in the city of Amberg in Bavaria/Germany.
DEPRAG SCHULZ GMBH u. CO. KG
Tel: 09621 371-343
Fax: 09621 371-199