T 0436/92 (Cutting tools/ACMC) 20-03-1995

1. The appeal is admissible.

2. Admissibility of Documents

Except for the documents mentioned under point IV above, the Board regards each item of the new evidence filed by the parties at the appeal stage either as a logically consistent response to the Opposition Division's decision or being relevant when deciding on the particular question of evident abuse in the present case. The same applies with respect to the relevance of the documents filed after expiry of the nine month opposition time limit (Article 99(1) EPC).

In the statement of grounds of appeal the Appellant objected that the Opposition Division, after deciding to admit document (1) after expiry of the nine month period i.e. only one week prior to the oral proceedings, was wrong to reject the request to file further written arguments at a later stage of the proceedings. In view of the relevance of this document and the fact that it contained only very simple and easy to comprehend technical matter the Board sees no substantial procedural violation.

3. Amendments of the claims

3.1. The following features not contained in the set of claims as granted form part of the present product claims and in adapted form as part of the present method claims according to the main request and/or the first and/or second auxiliary request:

(i) "A whisker-reinforced ceramic cutting tool, not for cutting steel" (first and second auxiliary request) ["for cutting metal except steel" (main request)]

(ii) "...having a tool life as indicated in Metres of work travel of metal cut for a specified set of cutting conditions, in particular cutting speed and feed rate..." (first and second auxiliary request)

(iii) "...silicon carbide whiskers in an amount in the range of 12 to 40 volume percent..." (second auxiliary request)

(iv) "...silicon carbide whiskers ...not being significantly degraded." (first and second auxiliary request).

3.2. In accordance with the decision T 313/86 of 12 January 1988, in particular point 3.5 of the reasons for the decision, said feature (i) above is allowable in that it excludes a part of the subject-matter of Claim 1, namely a partial lack of function of the cutting tool for a defined workpiece, in the form of a disclaimer in regard to the technical problem to be solved (cf. point 7 below).

3.3. Feature (ii) above comprises nothing else than the normal requirements for a product to be suitable as a cutting tool.

3.4. The new range of compositions according to feature (iii) above corresponds to the upper limit of the preferred range to be found in Claim 5 and on page 4, line 12 of the description of the specification (Claim 3 and page 9, line 26 originally filed), and to the upper limit of the more general range to be found in Claim 1 and on page 4, line 4 of the description of the specification (Claim 1 and page 9, line 13 originally filed); such a new combination of values of different ranges is clearly allowable in accordance with decision T 201/83 OJ EPO 1984, 481.

3.5. Feature (iv) is to be found on page 4, lines 42 to 44 (page 11, lines 5 to 9 as originally filed).

3.6. The claims are of narrower scope than the granted claims. The requirements of Articles 123(2) and 123(3) EPC are accordingly satisfied.

3.7. The dependent claims correspond to the dependent claims as granted but renumbered.

4. Clarity and Support of the Claims (Article 84 EPC)

4.1. Bearing in mind the conclusions reached above under paragraphs 3.2 and 3.3 in respect of Article 123 EPC, the Board sees no reason to follow the Respondent's objection regarding the claims with respect to features (i) and (ii) as indefinite.

4.2. According to the explanations given in the description of the specification and as originally filed (cf. point 3.5 above) exclusively referring in context with the silicon carbide whiskers of the invention to a possible mechanical degradation and not even referring implicitly to a chemical degradation process, there is clearly no basis when reading the claims in combination with the description for assuming ambiguity of the term degradation.

4.3. The Board is therefore satisfied that the claims according to the main request as well as the first and secondary auxiliary request are clear and have adequate support in the description.

5. Non-prejudicial disclosure

5.1. In the course of the proceedings there was considerable discussion as to whether or not Article 55 EPC applies to events before the priority date (the so-called "cumulation" issue). The Board would like to remark that "cumulation" is a misleading term, since the defence of evident abuse does not put back the priority date (cumulating another six months to it). The only legal effect is that the particular prior use is disregarded. All other documentation prior to the priority date as claimed remains state of the art. Although the applicability of Article 55 EPC rightly should be the first to be decided by the Board, in view of the conclusion below that the publication of D1 did not constitute an evident abuse, the Board forgoes a discussion on this point, presuming that the Article in question does apply.

5.2. Although the confidentiality agreement was not signed on behalf of Greenleaf Corporation, the Board has found that the fact that Greenleaf immediately took part in the development work and other relevant circumstances at least indicate a common understanding that Greenleaf was bound by the agreement, albeit tacitly. Greenleaf therefore was not at liberty to disclose any information about the cooperation without permission from ACMC.

The Appellant has the burden of proof that the publication constituted evident abuse. This term indicates that mere negligence or breach of confidentiality does not suffice. Deliberate intention to harm the other party would constitute evident abuse, as probably also knowledge of the possibility of harm resulting from a planned breach of this confidentiality. The state of mind of the "abuser" is of central importance (cf. T 585/92 of 9 February 1995 to be published in the OJ EPO, point 6 of the reasons).

In the present case, the affidavits by Mr Greenleaf differ somewhat. In his first declaration he stated that the publication of the advertisements took place inadvertently (point 5 in P/6). In the third one, Mr Greenleaf stated that he was aware of the confidentiality agreement, but did not seek the approval of ARCO (the predecessor of ACMC). He assumed that ACMC would not object to the promotion of the new product. He did not advise any one at ARCO or ACMC that he was planning any advertisement. All decisions were taken by Greenleaf Corporation alone.

The above suggests that Respondent 03 may well be right in supposing that both companies were working together and that the absence of any objections from ACMC could be assumed to indicate that - even if not having expressly given their permission to the advertisements - ACMC at least, after the fact, condoned the Greenleaf initiative. The claim by ACMC that there was no response to the 19 February 1985 letter because it never reached them has not been supported by any independent evidence. If the confidentiality agreement had still been enforced by ACMC, there would at least have been a reaction after the magazines in question had been published, if for no other reason than to be in a position to prove that ACMC considered the advertisement to be in breach of the agreement and therefore constituted abuse under the law.

The Board therefore finds that the Appellant has not proven, on the balance of probability, that the publications occurred in violation of the tacitly agreed confidentiality. In other words, the publication was not an evident abuse within the meaning of Article 55(1) EPC.

6. Public prior use of the product WG-300

Although prior use relates to a lack of novelty in terms of Article 54(2) EPC, it is more convenient to consider it at this stage of the decision since the conclusion has an influence on the nearest prior art when considering the problem underlying the patent in suit.

The Board agrees with the Appellant's submissions that none of the presented "Exhibits" clearly and unambiguously showed under what circumstances the alleged use of WG-300 occurred, e.g. place of alleged use and possible secrecy agreements.

Moreover, at the oral proceedings before the Board, Respondent 03 made no reply to the Appellant's submissions that the competitor Kennametal (Respondent 03) had obtained the WG-300 sample in "an unclean way".

Therefore, a public prior use of WG-300 is not proven.

7. Problem and Solution

7.1. The Board accepts the Appellant's submissions that document (11) be regarded as the closest prior art; this was no longer disputed by the Respondents at the oral proceedings.

7.2. Document (11) dating from 1969 is a final technical report giving results of a continued effort designed to develop new and improved ceramic cutting tool inserts for the more efficient and economical machining of the refractory hard metals required in the fabrication of aerospace devices. The report is subdivided into two groups of tool materials, on the one hand carbide boride and nitride tools and on the other hand alumina based tools. In respect of the latter group the report describes "Alumina + Metal Nitride Systems", "Alumina + Metal Boride Systems", "Alumina + Metal Carbide Systems", "Aluminum Oxide - Magnesia - Silicon Carbide Systems" and "Aluminum Oxide - Magnesia - Tungsten Carbide Systems". Under the heading "Cutting Tool Evaluation Tests", the subparagraph "Al2O3 - Additive Systems" on page 186 last paragraph including a reference to Table 80 on page 188, cutting test results with a workpiece of steel inter alia on tools from the system 95 wt% modified alumina and 5 wt% silicon carbide whiskers are represented. The modified alumina comprises 98.75 wt% Al2O3 and 1.25 wt% MgO. According to Table 80 a modified alumina without an additive shows a more then ten times better tool life than said whisker modified composition.

In view of the test results, it is then concluded that due to the high chemical reactivity of silicon carbide with the work metal, no improvement of wear resistance could be attained. As an overall result it is stated on page 197 fifth paragraph, that cutting tests performed with tools fabricated from the system modified Al2O3 - SiC whiskers showed that these tools had a lower life than modified alumina tools without additives and that such an additive does not improve the tool life of alumina base cutting tool materials.

7.3. In the light of the said prior art, the technical problem underlying the patent in suit can be seen in providing an alumina based cutting tool having an improved tool life over alumina tools without additives.

The problem is solved by the whisker-reinforced cutting tool according to present Claim 5 (see paragraph VII above).

According to the experimental evidence in the patent specification, in particular page 7, line 35 up to page 8, line 24, a cutting tool as presently claimed with a content of 25 volume percent silicon carbide whiskers show at least a 1.5 times better tool life than a conventional alumina insert (E). Although these experimental data are based on different cutting conditions than those described in document (11), in view of the extreme test conditions demonstrated in the patent specification with respect to load and thermal cycling of the tool tip, the Board is convinced that there is at least a relative improvement of the cutting tool according to the invention in comparison with those tested in document (11) and is thus satisfied that the problem has been solved in a plausible manner.

8. Novelty

8.1. At the oral proceedings the Appellant did not dispute that the mere wording of the product claims of the present main request and first auxiliary request referring to a range of 2 to 40 volume percent of silicon carbide whiskers embraced the cutting tool according to document (11) with 5 weight percent of silicon carbide whiskers. It was, however, argued that in the light of the decision G 2/88 the term whiskers according to the invention should be regarded as carrying a new functional feature which provides a surprising effect and thus this effect must be read into the claim as a distinguishing characteristic. The Board cannot accept this argument since the relevant passages of the decision G 2/88 relate only to a question referred to the enlarged Board of Appeal with respect to use claims. Accordingly, the said decision is not applicable to product claims. Moreover, the present sets of independent product claims do not comprise any concrete physical or chemical parameters characterising the whiskers used which might have served to distinguish them from the whiskers known from document (11).

Novelty of the subject matter of Claims 6 of the main request and of the first auxiliary request can accordingly not be recognised under Article 54 EPC.

8.2. After examination of the cited prior art, the Board concludes that the subject-matter according to the second auxiliary request is novel. Since novelty of the independent method Claim 1 and independent product Claim 5 of this request referring to 12 to 40 volume percent of whiskers has not been disputed by the Respondents, it is no longer necessary to consider this matter in detail.

9. Inventive step

9.1. Although document (11) explains the difficulty of using silicon carbide in a cutting tool due to the high chemical reactivity of this material with steel as a work metal, its teaching would not inhibit the skilled person from using it in cutting tools for workpieces other than steel. However, the overall test results in (11) are such that, as already indicated above under point 7.2, there would be no incentive to continue to develop new cutting tools on the basis of alumina reinforced with silicon carbide whiskers. Moreover, since (11) proposes a broad spectrum of materials other than silicon carbide whiskers suitable as additives to alumina not showing so serious negative effects, the skilled person's attention is clearly shifted in the direction of other additives, such as metal carbide, nitride and boride systems referred to therein.

9.2. More than 20 years elapsed after document (11) was made available to the public before the next reference to silicon carbide whiskers in ceramic cutting tool materials occurred in the form of document (1), an advertisement headed "Greenleaf Introduces the Most Significant Advance in Cutting Tool Materials since Coated Carbides". According to said advertisement the so-called "Ceramic Composites" are proven ceramic cutting tool materials reinforced with a lattice of small single crystal silicon carbide whiskers. This material, offered under the trade name WG-300, is described as having excellent cutting properties with e.g. ground-in chipforms on interrupted cuts at low and high speeds.

As regards the unspecified ceramic material mentioned in the said advertisement the Respondents made inter alia reference to documents (4), (7), (8) and (9). The Board agrees that these documents show that alumina dates back to the early 1900's as the only ceramic cutting tool material used in industry and remained an important material for this purpose up to the priority date of the patent in suit.

Prima facie it might have appeared, in the light of this historical review, that alumina would be the obvious choice for the unspecified ceramic body referred to in (1).

However, when deciding on the question whether or not the skilled person would, in the light of the disclosure of the advertisement according to (1), have had an incentive to arrive at the solution of the technical problem underlying the patent in suit, the developments in the field of cutting tools which had taken place in the period since publication of the studies on which document (11) is based would inevitably have been taken into consideration. In other words, for practical purposes, the skilled person would not have ignored the whole trend in the field of ceramics in general and in particular of cutting tools at the priority date.

9.3. In this respect the Board sees no reason to doubt that the documents filed by the Respondents could represent a trend concerning the use of whiskers and the matrix materials in industry.

Document (12), the so-called Tateho-Report, relates to properties and the use of silicon nitride whiskers and silicon carbide whiskers. On page 22 of this document "machining tool" as a use of silicon carbide material is mentioned beside other uses such as furnace material, pump parts etc. Table 8 on page 24 shows examples of matrices with silicon carbide whiskers to demonstrate shock strength of the reinforced ceramics. The examples comprise four silicon nitride and three silicon carbide matrices. The report also describes the excellent thermal shock resistance of reinforced sialons. Alumina is only mentioned as an aid at low concentrations of ca. 3 weight percent.

Document (6) is headed "High-tech ceramics" and mentions in general terms on page 26 that because of their hardness and wear resistance these ceramics find many uses, including cutting tools and bearings. On page 35 it is then stated in connection with the manufacture of whiskers that silicon carbide whiskers have been used to boost the fracture toughness of aluminum oxide, zirconium oxide and other ceramics. There is no hint that a whisker reinforced alumina might be used as a cutting tool.

Document (10) describes, in an abstract, sialon based ceramics reinforced with silicon nitride whiskers useful for cutting tools and abrasion resistant tools.

The somewhat older document (13) describes with respect to the problem of tool wear and the chemistry of metal cutting the interaction of silicon carbide with steel, which was already known from (11). At the end of the chapter on page 203, right column, it is stated that "even the traditional application of white alumina cutting tools for the machining of brake drums is now being replaced by silicon nitride tools where rough and semi-finish turning is being performed at speeds ranging from 4200 to 5000 sfpm". The rest of this publication, which exclusively relates to cutting tool materials, refers inter alia to sialon ceramic tools, alumina tools with zirconica or titanium carbide as additives and boron carbide composites. It is concluded that "not only will existing materials be further improved with respect to mechanical properties, wear resistance, tool life etc., but entirely new families of ceramic tool materials will be introduced into the field".

Although documents (3) and (5), both published a short time before the priority date of the patent in suit, relate to silicon carbide whisker reinforced alumina bodies within the claimed percentage range (cf. (5) chapter experimental procedures and (3) Table 1), it is to be noted that these documents describe materials for use as structural components in heat engines and high temperature energy conversion systems.

In the Board's judgement the skilled person would have taken into account the proven trend to new matrix materials. It is in no way realistic to ignore the teaching of each of the prior art documents unambiguously relating to a large number of ceramic materials other than alumina suitable as cutting tool matrices and to regard alumina as the only suitable matrix material. There would therefore have been no reason to combine the disclosure of (3) and (5) with the publicity campaign according to (1).

Accordingly, there would not have been the slightest incentive when taking into account the aforementioned prior art relating to the development in the field of cutting tools and even ceramics in general, to overturn the poor reputation of the silicon carbide whiskers reinforced ceramic cutting tools of document (11) and so to use this material, against the trend in the art, in order to improve by a much higher whisker content the tool life of alumina based materials.

9.4. Document (2) relating to a mixture of silicon carbide particles and alumina particles for cutting tools was published about ten years before document (11) and was combined by the Opposition Division with document (1), with respect to its silicon carbide content. It is clearly not relevant when discussing an improvement of tool life of a whisker reinforced alumina matrix.

9.5. The other prior art cited during the procedure is deemed to be of less relevance than the documents discussed above.

9.6. It is accordingly the Board's view that the subject- matter of the independent product claim of the second auxiliary request would not have been obvious from either citation taken singly or in combination. Thus, the required inventive step is not lacking and Claim 5 as well as method Claim 1 including the new and inventive cutting tool together with dependent Claims 2, 4. and 6, satisfy the requirements of Article 56 EPC.