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QUALITY IMPROVEMENT OF WATER JET CUTTING

Objective


Quality criteria as well as measuring procedures were chosen to characterise the quality of the cutting result. All samples were measured in one lab to guarantee comparability of results.

Extensive know-how about the influence of process parameters on the cutting quality was delivered. Extensive cutting tests at several facilities (industrial and research) were conducted. Quality criteria were measured and evaluated.

On the basis of extensive quality data a first technological model for the prediction of the roughness of the shoulder of the cut was developed. The model showed encouraging agreement with experimental data.

Aluminium and glass samples have been cut using a range of suspension type, abrasive water jet cutting machines. Analysis of major process parameters have shown clear trends which seem generally apply to both the cutting of aluminium and glass. Ideally, it should be possible to determine surface roughness by either increasing abrasive concentration or reducing traverse speed.

Different abrasive cutting heads were tested in order to understand the influence of the mixing chamber design on the cut quality. Six different abrasive cutting heads were tested. After analysing the 6 abrasive cutting head designs and discussion of results, a new abrasive cutting head was developed. Innovative aspects of the cutting head are:

- autocentering of water nozzle and focusing nozzle
- reduced angle of the entrance of the focusing tube and increased length
- mixing tube and focusing tube are monobloc.

First tests with the so called "Euro cutting head" showed improved cutting quality.

The influence of process parameters on the accuracy of the cut contour, by analysing the squareness at the top and the bottom of the workpiece as well as dimensions of overshots at incontinuities, like angles, was investigated. Such criteria are of great interest for manufacturers of cutting systems to qualify the accuracy of cutting systems.
Water jet cutting is a very young technology that offers due to its possibilities the opportunity to cut nearly every material. Especially difficult-to-machine materials like composites (metal matrix), austenitic steel, titanium and aluminium as well as xome ceramics can be cut. Water jets are a non-thermal cutting tool, so that no heat-affected zone occurs and also heat sensitive materials can be cut.

Aim of the project is to improve the quality of cut to minimise or avoid further machining operations. Criteria will be chosen to characterise the quality of the cutting result. Working groups will run parallel R&D activities in relation to the main parameters that influence the quality of the cutting results. These results will lead to an improved knowledge of all partners to produce more efficient quality cuts.

Funding Scheme

CON - Coordination of research actions

Coordinator

UNIVERSITAET HANNOVER
Address
Appelstrasse 11A
30167 Hannover
Germany