The latest development from WNT (UK) sees the combination of a tungsten carbide base layer being sandwiched by CBN. While the method used to combine these two materials, brazing, has been around for longer than most care to remember, the use of this technology to create this sandwich effect for a CBN insert has not been possible up until now.
The problem before was that while it was possible to braze a small segment of CBN on to a carbide base, when you attempted to braze a second piece the original braze would melt and the CBN would move or be dislodged. The new, patented, manufacturing process used on the WNT inserts overcomes this problem, allowing multiple CBN ‘edges’ on a single insert.
Of primary importance to the user is the price advantage that this system brings to CBN insert manufacture. For example, CNGA or DNGA style inserts now have four CBN cutting edges as opposed to the single cutting edge normally found on these shapes of insert. Similarly, WNGA style inserts now have six CBN cutting edges as opposed to one.
The traditional method of manufacturing CBN inserts has been highly labour intensive, something that has been reflected in the price of these cutting tools. However, the new process used by WNT dramatically reduces the labour content to such an extent that insert prices are typically 40 – 50 per cent of those currently on the market. As a result the cost per part is reduced by a considerable margin.
For example*, if a traditional, single-edge insert can machine 100 parts at a cost of £35 per insert, the cost per part is £0.35. With the new WNT insert you could produce 400 parts but at a cost of just £17.50, or £0.043 per part. Cost per component savings of this magnitude will have a significant impact on the profitability of many jobs that were previously being called into question. And, in the case of automotive production, where volumes are conventionally high the effect on the bottom line of a manufacturing company can be considerable.
“The financial argument of these new Sandwich CBN inserts is one that should be obvious, and welcome, by any company undertaking hard turning operations,” says Adrian Fitts, Business Development Manager, WNT (UK). “We are also confident that with the added benefits of newly developed coatings, which improves tool life, reduces adhesion of swarf to the insert, and reduces tribo-oxidation (or surface wear) that we will also see an increase in the number of parts per edge when compared to conventional CBN inserts.”
The new inserts are available in the most common CNGA, DNGA and WNGA insert styles, with a choice of eight different edge preparations for each style of insert. In addition, three grades of CBN are available, PBC15-S for grey cast iron, spheroidal-graphite cast-iron, superalloys, and sintered steels; PBC25-S for steels up to 65 HRc (uninterrupted cut); and PBC40-S for steels up to 65 HRc (interrupted cut).
Because of the specific application of these inserts and to ensure the highest levels of productivity WNT (UK) would be happy to oversee initial cutting trials.