At Hailsham-based Metaltech Precision Engineers Ltd, using Horn 314 special inserts to machine the bore face and under-cut in a range of stainless-steel pump rotor cases has significantly enhanced the process through reduced cycle times, greatly extended tool life and improved surface quality.
Metaltech, a successful supplier of components to leading manufacturers of stainless-steel pumps, works with both billets and precision castings. The products are high-value-added precision items that are often required at short notice and in a variety of sizes. A common feature of the rotor bodies is the need for an under-cut that ‘separates’ the wall from the flat base.
Richard Page, Metaltech’s production engineering manager, says: “We had been producing this feature for some years with custom-built tooling that used a non-standard insert, but increases in customer demand to around 250 parts per month highlighted shortcomings in that method. Tool life was poor — about one under-cut per cutting edge — and we were losing time on tip indexing and re-setting. In addition, there were issues with insert supply. Essentially, we were coping, but we needed a solution that would provide a reliable response to changes in demand.”
Ringwood-based Horn Cutting Tools Ltd (
www.phorn.co.uk) has an established history of providing tooling solutions for Metaltech, and it was Horn that the company turned to
in this instance.
The solution put forward by Horn uses a mix of standard and special Type 380 holders, allowing through-coolant supply directly to the cutting edge. Type 314 milling inserts, which have Horn’s latest AS45 coating, finish all the faces on the component and produce the required industry-standard under-cut.
Moreover, trials conducted at Metaltech showed that the Horn tool could be run faster than the previous tool package; it is also capable of machining up to eight rotor bodies per edge consistently, whereas the original tooling had to be indexed or exchanged after one or two components. In addition, the Horn tool gives a burr-free under-cut, so the part is finished when it comes off the machine.
Chris Smith, Horn applications engineer, said: “The tool not only produces an under-cut but also finishes the top face and the bore face, both of which require a surface finish of better than 0.8µm Ra. During the trials, we were able to make significant improvements to the insert geometry to further enhance the level of the surface finish, while continually reducing the cycle time. We can now consistently achieve 0.3-0.4µm Ra.”
In conclusion, Mr Page said: “The exercise had nothing to do with reducing costs, but in the end the cost of the Horn insert is about a third that of the previous tooling. However, the big gains for us are the reliability of the process and the increase in the number of cases that can be machined per cutting edge, which saves us a lot of time.
"The task is ‘bread and butter’ work, in that every rotor case we produce has that feature, so ideally we need to have complete confidence in the process — which we now do.
"Ultimately, the project has brought us more benefits than we expected and demonstrates how much the performance of modern tooling technology has progressed compared with what was available only a few years ago.”