From one to another!
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From the idea to the product, or: Precision parts manufacturing and a high level of internal manufacturing as the central elements in a company's success in optical systems and instruments for optometrists and occupational medicine
"Precision is under control when you are making practically everything yourself, have the necessary equipment and also qualified, dedicated skilled employees," says Uwe Wambach, Operations Manager at Oculus Optikgeräte GmbH in Wetzlar Germany, by way of describing the ophthalmological instrument manufacturer's philosophy of manufacturing and quality. But let us start from the beginning. Oculus Optikgeräte GmbH was founded as a medium-sized family business in 1895. Originally operating in Berlin, the company later moved to "Optics Valley" near Wetzlar. Here Oculus grew to become a company with worldwide operations with its instruments and complete solutions for ophthalmologists, optometrists and ophthalmic opticians sold in over 80 countries. In the company's three plants in Wetzlar and nearby Münchholzhausen, 265 employees with scientific support develop the complex devices and systems and manufacture them according to top quality standards. In addition to traditional precision mechanics and precision optics, electronics and software also play important roles. The philosophy mentioned above contributes significantly to being able to meet the sometimes extreme requirements of a demanding customer base comprehensively. The fact that this trend continues consistently while medical technology is booming requires appropriate investment in equipment and personnel. So it is no surprise that the rate of apprentices is comparatively high at 9%, nor that the company focusses strongly on mechanical manufacturing, which is divided into the areas of testing and tool making, parts manufacturing, injection moulding and optical manufacturing.
Machining precise parts efficiently and ready for assembly
The mechanical parts manufacturing department has 10 CNC turning and milling machines and three 5-axis CNC machining centres. About 15 skilled employees are responsible for programming and operation in two-shift configuration. Uwe Wambach, a skilled precision engineer, explained: "We produce a very wide range of workpieces, with 5000 or 6000 frequently recurring items as well as new parts. Unit numbers range chaotically between 1 and 4000, given that we manufacture series parts as needed with capacity in batch sizes from 25 to 250. The machines must therefore be very flexible to use and we also have very high requirements for accuracy in terms of shape, angle and reference levels (position of the optical axes). We also want to be able to assemble the precision parts quickly and easily, which is why we are very concerned about machining quality and less about reducing manufacturing time if problems in assembly can be avoided with longer times, for example. There is absolutely no reason why high machining accuracy and high efficiency should be at odds, as can easily be seen from the Hermle C 22 U 5-axis high performance machining centre, which has taken on a sort of benchmark function for us because we are able to machine workpieces with any level of complexity on it, ready for assembly with the exception of surface treatment." The comment about benchmark function should be taken quite literally. Now it is a known fact that fewer highly qualified specialists also want to take on shift work. The only practical way to counter this tendency is with a high level of flexibility in applications and usage and a pragmatic, high degree of automation. 5-axis/5-sided complete machining in one or as few as possible clampings is one of the keys to boosting efficiency and productivity, without having to make any additional investment in personnel capacity.
Towards the goal with 5 axes, partially automated at first
Accordingly Oculus began a consistent investment program, procuring the C 22 U 5-axis CNC high performance machining centre. They also see this as their entry into further manufacturing automation with additional Hermle machining centres that will replace existing machines. Uwe Wambach explains: "We looked at different machine concepts during the evaluation and made some reference visits. The 5-axis concept and the layout of the machine impressed us very much, as did the milling trials, the chip concept and the options for individual equipment. No other machine achieved the precision we wanted in terms of 5-sided complete machining with reproducibly exact axial alignments for optics as effortlessly as the Hermle machining centre. We can't allow ourselves any mistakes at all due to the assembly-ready machining of individual and series parts we strive for, so we went on the safe side with the Hermle C 22 U machining centre." The spacious working area with dimensions of about 400 x 300 mm allows for problem-free complete machining of the largest workpieces (base plates/device carriers) as well as machining of small parts with multiple clampings from all sides. The machine is therefore equipped, among other features, with an NC swivelling rotary table 320 mm in diameter, a tool magazine with 55 pockets (SK40 holder), a motor spindle running at 15000 rpm, the Heidenhain control unit iTNC 530, a touch probe and of course tool breakage monitoring. With the investment in the C 22 U 5-axis CNC high performance machining centre from Maschinenfabrik Berthold Hermle AG, 78559 Gosheim, Germany, Oculus Optikgeräte GmbH had taken the next step in the direction of production automation. Now that the process chain for mechanical manufacturing with integrated quality assurance already has these three important components, CAD/CAM design, NC programming and (CNC) measuring technology, the next logical step is 5-axis/5-sided complete/simultaneous machining with the Hermle C 22 U machining centre. That step will be followed by others in the near future according to Uwe Wambach, as more Hermle machining centres are added and workpiece handling is automated.