Coatings for cutting implements

DETAILED DESCRIPTION We claim: 1.
A method of treating an edged cutting implement which comprises depositing a coating of a refractory material on the implement by means of sputter ion plating, said sputter ion plating being carried out using a sufficiently high bias current to prevent deposition of the coating at and near an edge of the edged cutting implement.
2.
A method as claimed in claim 1 wherein the refractory material is titanium nitride.
3.
A method as claimed in claim 1 wherein the implement is in the form of a knife blade.
4.
A method as claimed in claim 1 wherein the implement is in the form of a drill.




Description:
The invention relates to an edged cutting implement carrying a refractory material coating and a method of providing such a coating; the coating, which is provided by techniques such as sputter ion plating, terminates adjacent a cutting edge of the implement thereby to improve the cutting performance thereof.
There is much interest in improving the cutting performance of edged cutting implements both in terms of ability to cut and retention of ability to cut after extensive use.
It is known to coat edged cutting implements such as cutting blades to improve their cutting performance; see, for example, U.
K.
Pat.
No.
1,380,583.
Such coatings, however, cover not only surfaces defining a cutting edge but also the cutting edge it self.
The invention is concerned with coatings that do not cover the cutting edge itself, i.
e.
with coatings that terminate adjacent the cutting edge.
The invention includes an edged cutting implement carrying a refractory material coating terminating adjacent a cutting edge of the blade thereby to improve the cutting performance thereof.
The invention also includes a method of treating an edged cutting implement which comprises depositing a coating of a refractory material on the implement by means of ion plating under conditions such that the coating terminates adjacent a cutting edge of the implement thereby to improve the cutting performance thereof