Grinding

Grinding machines

HERZOG offers a wide range of grinding machines - all with the objective of optimum surface preparation

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HB 3000: Automatic grinding machine

Material: Steel, pig iron
Sample shape: Round, oval, square, double-thickness
Method: cup wheel and belt grinding
Fully automatic sample preparation by coarse and fine grinding

HB 4000: Automatic grinding machine

Material: Steel, pig iron
Sample shape:
Round, oval, square, double-thickness
Method: Belt grinding ( course and fine grinding)
Fully automatic sample preparation by coarse and fine grinding

HBF 4000: Automatic grinding and milling machine

Material: Steel, pig iron
Sample shape: Round, oval, square, double-thickness
Method: belt grinding and/ or milling
Fully automatic sample preparation by coarse grinding and milling

HTS 2000: Semi-automatic grinding machine

Material: Steel, pig iron
Sample shape: Various types according to clamping method
Method: cup wheel grinding
Manual sample input and output, automatic grinding

HT 350: Manual grinding machine

Material: Steel, pig iron, foundry
Sample shape: Various types
Method: disc grinding (2 discs, fine and course grinding)
Manual sample preparation

HS 200: Manual grinding machine

Material: Steel, pig iron
Sample shape: Round, oval, square
Method: Pendulum grinding, cup wheel grinding
Manual sample preparation

HT 3000: Automatic grinding machine

Material: Steel, pig iron
Sample shape: Round, oval, square, double-thickness
Method: cup wheel grinding
Fully automatic sample preparation by coarse grinding

HERZOG expertise in grinding

HERZOG provides the appropriate grinding solution for our customers’ needs – from full automation to manual stand-alone machines. There are various options available, including belt or cup wheel grinding, coarse and fine grinding, sample water cooling, as well as an optional milling cutter for, e.g., calibration samples.

Core characteristics of our grinding machines are compact construction, easy operation and highest safety standards – all with the objective of optimum surface preparation.

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Grinding

Normally, the first work step on the sample is surface grinding. This ensures that a flat surface is created on which all components of the surface are, if possible, on one level. For this step it is preferable to use fixed grinding particles with a large grain in order to achieve a high, consistent removal rate, short working times and maximum flatness. In some cases it may be necessary to follow the surface grinding with another work step to fine-grind the material. Grinding media made from other composites are used for this, which further minimise any remaining deformations on the sample surface. Herzog would be pleased to advise you in selecting the optimum grinding process and grinding material.

Spectroscopic process

Optical emissions spectroscopy (OES) in particular but also X-ray fluorescence analysis (XRF) are frequently-used methods for analysing metals and solid bodies. These analyses are applied both in the metals industry such as in steelworks and also in foundries and production. On the basis of its short analysis times and the highly-accurate measurement results, OES is the preferred method for monitoring the alloys used. It is used in the production, material testing and quality control of raw materials and both semi-finished and finished products. In XRF analysis, an X-ray beam stimulates the emission of a fluorescence that corresponds to the chemical composition. This can be analysed and compared with the results of standard samples.

The importance of sample preparation

Thanks to software and hardware improvements, the processes named above are achieving increasingly detailed analysis results and are constantly lowering the evidence threshold for individual elements. As a result, sample preparation of the metals and materials being analysed is becoming increasingly important. Even minor contamination or slightly defective surfaces on the samples used can lead to incorrect analysis results and misinterpretations. For metal analysis in particular, the sample surface must be perfectly prepared because any spectroscopic analysis can only be as good as the quality of the samples.

Inhomogeneity of the production sample

It is also of crucial importance for the the sample surface being analysed to be representative and homogeneous. This applies particularly to production control samples in steelworks, but also to other production locations. For various reasons, the top layer of a sample is not normally representative of the steel melts being examined. Firstly, due to the brief direct air contact with the warm sample surface, a layer of scale approximately 10µm thick forms following separation from the mould of the sampler. Secondly, the larger part of the non-representative sample layer consists of inhomogeneities known as segregations. These segregations arise as a result of separations of the solutes occurring on the solidification front as the liquid steel taken from the steel melt solidifies. The cause lies in the different solubility of the alloy elements in the solid and liquid phases. For the most part, these separations also remain following complete solidification and represent lasting inhomogeneities of the chemical composition.
 

In addition, as a consequence of the melt solidifying from the outside inwards, the centre of the casting that solidifies last is in most cases oversaturated with typical by-elements such as carbon, phosphorus, sulphur, boron etc. This means that depending on the alloy composition, about 0.3 - 0.6 mm of the sample surface must be removed to allow the representative undisturbed sample layers to be analysed. Currently, this involves mainly using the milling and grinding machining processes. The sample preparation form selected depends on the material and analysis processes, but not least also on experience and tradition in the company and laboratory.

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