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Thiemann P.,FWBI Friedrich Wilhelm Bessel Institute | Strobel G.,Bimaq Bremer Institute For Messtechnik | Goch G.,Bimaq Bremer Institute For Messtechnik
Technisches Messen | Year: 2013

Thermo-mechanical damages, known as grinding burn, may lead to a significantly reduced product lifetime of ground components. Presently grinding burn can be traced only by destructive methods like metallography, X-ray analyses or nital etching. The following pages show results of examinations concerning the qualitative and quantitative detectability of grinding burn using nondestructive methods. © Oldenbourg Wissenschaftsverlag.

Weimer D.,BIBA Bremen Institute for Production and Logistics | Huferath-von Luepke S.,BIAS Bremen Institute of Applied Beam Technology | Tausendfreund A.,Bimaq Bremer Institute For Messtechnik | Bergmann R.B.,BIAS Bremen Institute of Applied Beam Technology | And 3 more authors.
Advanced Materials Research | Year: 2014

A rising trend to miniaturization and function integration requires new materials, tools, manufacturing setups and quality inspection strategies for mass production of micro mechanical systems (MMS). In most scenarios, quality inspection is carried out manually. An expert takes samples out of the manufacturing process and investigates them by means of tactile or optical measurement systems. This time consuming quality inspection process leads to low inspection rates, especially in bulk manufacturing processes, where manufacturing frequencies of 400 parts per minute are common. This contribution introduces an automated optical quality inspection method based on a digital holographic system, which acquires 2D texture and 3D shape information in one single measurement step. Based on 3D data, an automated point separation algorithm splits the measured object shape into elementary geometries and calculates form and position deviations compared to an object model. In the final step, a 2D surface inspection procedure based on multiscale texture analysis detects surface defects with respect to the separated elementary geometries and fuses the result from the 3D shape and the 2D texture analysis to a final rejection decision. The capability of the proposed quality inspection method is demonstrated in a micro cold forming scenario, where a micro cup smaller than 1 mm in all geometric dimensions is the object under investigation. © (2014) Trans Tech Publications, Switzerland.

Mehrafsun S.,BIAS Bremen Institute of Applied Beam Technology | Zhang P.,Bimaq Bremer Institute For Messtechnik | Vollertsen F.,BIAS Bremen Institute of Applied Beam Technology | Goch G.,Bimaq Bremer Institute For Messtechnik
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Micro forming tools require high surface quality as well as contour accuracy, i.e. close tolerances at small dimensions. However, their structuring with necessary accuracy is limited to a small number of applicable technologies due to the mechanical properties of the tool material on micro scale. This contribution reports on an approach for machining techniques for precise tool finishing, developed at Bremer Institut für angewandte Strahltechnik GmbH (BIAS) called Laser-Jet-Process (LJP). This approach is based on a laser-chemical etching method where a focused laser beam is guided coaxially to an etchant jet-stream onto the material surface. The material removal is a result of laser-induced chemical reactions between etchant and surface at low laser powers. The evaluation of data shows a strong correlation of material removal and several process variables. In particular, high laser powers combined with high feed rates of the work piece and low flow rates of the etchant result in a break-off in material removal. In order to overcome this issue, the process boundaries have been experimentally determined and implemented in a quality control system. The quality control system consists of an automated path planning model and an inverse process model. The automated path planning model computes position and Gaussian intensity profile for a sequence of overlapping laser removal paths to achieve the desired tool shape. The inverse process model renders specific process variables for every single removal path from a pre-assembled data pool within experimentally defined boundary conditions. © 2012 SPIE.

Cuypers P.,Bimaq Bremer Institute For Messtechnik | Stephen A.,BIAS Bremen Institute of Applied Beam Technology | von Freyberg A.,Bimaq Bremer Institute For Messtechnik | Goch G.,Bimaq Bremer Institute For Messtechnik | Vollertsen F.,BIAS Bremen Institute of Applied Beam Technology
Technisches Messen | Year: 2010

A laser-chemical process shall be used for the production of micro cold forming dies. This laser-based etching process is able to machine hard materials. To assure a flexible application for the production of high-quality products a process discrete control has been developed, which is based on a model of material removal dependent on the process parameters. This article presents the results of the automated parameter and path planning for a convex curvation on the edge of a drawing die. © Oldenbourg Wissenschaftsverlag.

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