WNT UK Ltd.
BDL Tool & Die Engineering’s is transforming itself from a specialist manufacturer of specialist fastener dies into a full service sub-contract engineering company. This change has brought with it certain challenges that are being met with the help of suppliers such as WNT (UK).
With extensive experience in the tool and die sector BDL Tool & Die Engineering is using it to good use developing its customer base, adding precision general engineering to its portfolio. With its knowledge of machining hard materials such as high speed steel and even tungsten carbide it has focussed much of its attention on industries with similarly challenging materials. One in particular, the sub-sea hydraulics industry has proved to be responsive to BDL’s skills set, leading to a growth in turnover of over 50 per cent in the past 12 months and significant investment in its machining capacity.
“Like many companies we had to cut back during the crash and this made us take stock of the direction we wanted to head in, once things started to improve. The decision to expand on our traditional business and open up our manufacturing to more general engineering has proved to be a good decision. We now work for a diverse range of industry sectors, including aerospace, automotive, and motorsport, where we are an A1 approved supplier for one of the leading engine manufacturers. However it has bene the hydraulics industry that has given us our biggest area of growth, particularly sub-sea, which given the present situation with oil price is more pleasing,” says Phil Morris, BDL Tool & Die Engineering’s Managing Director.
As a result, the business has increased the number of employees to 60 and has taken on apprentices to bolster future skills levels. In addition, the last two years has seen the arrival of ten additional CNC machines, including five-axis machining centres. With these new customers also came new challenges and when a new contract from a hydraulics customer was won it became apparent that new machining methods would be needed to make it financially viable. “We had taken on this components as part of an ongoing contract and the material an S-series stainless steel was something we had limited knowledge of, so we programmed it using the experience we had and produced the first batch successfully in terms of quality, but the cycle time was excessive and we recognised that we had to do something to improve on this,” says Phil Morris.
BDL turned to WNT and its Technical Sales Engineer Warren Howard who reviewed the existing process and arrived at a new machining strategy and tooling package that significantly reduced the cycle time and reduced tooling costs. Originally BDL’s CNC milling supervisor Dan Green had put the job onto a five-axis machining centre and was using indexable insert tooling to rough and finish mill the deep pockets and cut outs in the component. The resulting cycle time was four hours per part. “With Warren working alongside us we looked at the process and he came to the conclusion that the way forward was to switch to solid carbide tools, move the part from the five-axis machine to a four-axis machine and change the whole strategy. Warren spent time with us in front of the machine, which gave us the confidence to try various speeds and feeds. The support that we received from Warren and WNT was superb and has certainly given us the confidence to develop alternative strategies on other jobs,” says Dan Green.
The main change was to use a trochoidal milling technique, taking lots of smaller cuts, but at much higher feedrates using a 16 mm WNT HPC cutter with a 2mm corner radius with additional cuts being taken with a WNT 12 mm ball nose cutter. The cutting data for the main milling operation was 3500 revs/min (175 m/min) and a feedrate of 2500 mm/min (0.15 mm/tooth). Depth of cut was 28 mm and the step over was 2.4 mm or 15 per cent of the cutter diameter. Switching to a trochoidal approach produced a much softer cutting action that resulted in not only reduced cycle times, but also extended tool life. With the indexable inserts the tips had to be indexed after every component, with the switch to solid carbide and the trochoidal milling each cutter lasted for five components before it needed regrinding. Cycle time fell from the original four hours down to 1.5 hours and the quality of the parts also improved as the new milling strategy eliminated the step-over marks left by the previous indexable insert cutters.
“As we continue to diversify and bring in new business, maybe being asked to machine materials that we are not familiar with, we have the confidence to bid for that work in the knowledge that we can call on the expertise available from WNT to provide the ideal machining solution that will enable us to be competitive and profitable,” says Phil Morris.