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CORRESPONDENCE

THE DELFT REPORT

From : Mr. W. G. Ainslie, M.I.Prod.E.

Referring to my comments on the Delft Conference,published in the March Journal, I wish to make itclear that these were not intended as a criticism ofthe Birmingham University Courses, which are at aPost-Graduate level. It was unfortunate that, un-known to me, my present position was stated in theintroductory paragraph, since it has created theimpression of inconsistency.

I fully support the Birmingham policy on Engin-eering Production; indeed, that is the reason why Isought to join the staff of the one British Universitywhich has so actively recognised this study for thepast nine years, and which now has a flourishingPost-Graduate course.

The comments published were written in November,1956. to the Education Committee of the Institution,prior to my joining the University staff, and as suchcannot express University opinion.

THE SOUTHAMPTON CONFERENCE

From : Mr. C. A. Burton, Sciaky Electric WeldingMachines Ltd., Slough.

I would like to take this opportunity of con-gratulating the Institution of Production Engineersfor all the excellent work carried out in making theFifth Annual Aircraft Production Conference such anoutstanding success. This is the first time I have hadan opportunity of attending this function and I amquite sure that this Conference will go from strengthto strength in the years to come.

I should like to make one or two suggestions whichI trust will be regarded as constructive criticism.Firstly, I would agree with a remark made by Mr.H. G. Gregory, that apart from a very short introduc-tory preamble by each of the lecturers, the timeavailable should be devoted entirely to discussion.I had a feeling that there were many present who hadno opportunity of asking questions and, therefore,if more time were made available as suggested, itwould be particularly helpful.

In my own particular field I was most interestedto hear Mr. N. K. Gardner's Paper. This was. with-out doubt, a most praiseworthy effort which did notwarrant Mr. Gardner's anti-climax statement whenhe intimated that many people may have listened tohis lecture being critical of spot-welding, and wouldbe going away still critical of spot-welding.

I am quite sure that the Handley Page Companyhave investigated every possible angle of this processand they have proved conclusively that spot and roll-

spot welding, with the use of modern welding equip-ment and the introduction of adequate quality controlprocedures, can now be regarded as completelyreliable.

Mr. S. G. Nash raised a query during the discussionwhen he asked what problems may be expected whenwelding stainless steel aircraft of the future. Hequeried the effect of the high pressures necessary forspot-welding stainless steel, and also asked if it mightbe possible to carry out assembly work with the useof portable machines. My own opinions of thisfuture trend are that owing to the very low. inter-facial resistance of light alloy materials, and the Sactthat high welding currents, in some cases of theorder of 150,000 amperes, have to be applied to theworkpieces in conjunction with a variable electrodepressure cycle, it is most unlikely that portable spot-welding plant, with tne aid of compressed air orhydraulically operated welding guns, will bedeveloped.

It is quite a different matter, however, wherestainless steel is concerned. This material requiresvery much lower welding currents than light alloysand a variable electrode pressure cycle is not re-quired. The comparatively high constant pressuresto be used can be very easily obtained by means ofhydraulically-operated portable guns deriving theirpressure from air-hydraulic intensifier units fitted tothe machines. This obviates the necessity of fittinglarge air cylinders to the welding gun units andobviously reduces the bulk size and weight accordingly.

It is interesting to note that complete railwaycoaches are being manufactured by the SorfameCompany in Amadora, Portugal, the material being17/7 stainless steel. Extensive use of portable gunwelding plant is made, and providing that militaryaircraft of the future are designed with a view toemploying resistance welding processes, then I cansee no reason why similar schemes to those at presentemployed on commercial projects cannot be adopted.

From : Mr. N. T. Burgess, Metallurgist, AluminiumDevelopment Association.

I was present at the Fifth Annual Conference onAircraft Production, which I found most absorbing.As time for discussion was limited, I should like tocontribute herewith, with the hope that the authorconcerned can offer some reply.

I refer to the Paper on " Contour Etching " by Mr.A. W. Sheppard. This Paper and the film were muchappreciated and I should like to ask if the removalof quantities of metal by such a comparatively slowprocess results in less distortion, finally, than isevidenced in many cases when such components ashe illustrates are machined by conventional pro-cedures. Many members of the aircraft industry willbe aware of the great difficulties in machining suchitems where, unless the aluminium alloy sheet is

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