BETTERSACRIMONIOUSACRONYMS

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Sir - I am flattered to see in your 'Buzz Words'editorial, in Computerised Manufacturing lor June'89, that my 1980 paper 'What is wrong with MRP' isstill remembered. I was less happy to note that yousee Period Batch Control as an obsolete method, soold that it was used in Spitfire manufacture, whichhas been replaced with modern MRP, and now byeven more modern MRP II methods.

May I respectfully suggest that this view isuntenable. PBC was the first of the just in time (JIT)systems. Like Kanban and OPT it bases productionon a series of short term production programmes.When the Americans talk about 'MRP and JIT', and'short cycle MRP', they describe systems which arebeginning to look more and more like PBC.

The main problem in comparing MRP and PBC isterminological. In English we describe productioncontrol methods, which base ordering on explosionfrom a production programme, as flow controlsystems. We see the first step in all flow controlsystems as requirement scheduling, which calcu-lates the numbers of parts needed to complete eachperiod programme. Flow control systems are dividedinto different types (MRP, PBC etc) according to theprogramme term (planning horizon, USA) used forexplosion, the method of batching, the choice of leadtime etc.

In the USA, all production control systems whichcalculate the numbers of parts needed to complete aprogramme (master production schedule), are calledMRP systems. In other words requirement sched-uling equals MRP. The Americans see PBC and OPTas variants of MRP. In American terms PBC is anMRP, lot for lot, single standard bucket (period),

'i I single standard lead time, short cycle system. They

don't have many examples, but they are movingrapidly towards lot-for-lot and short cycle systems.

I have read the six papers published inComputerised Manufacturing under the bannerheading MRP II, and am surprised at the low level ofenthusiasm they express for MRP. For example, PhilCheetham's paper says: "MRP and MRP II systemsdo not seem to serve MTO manufacture well at all";Tony Kelby says "the keys to success lie not so muchin the technological tools themselves (MRP), but inestablishing the correct underlying philosophy"; andGreig Sneddon says: "As little as 20% of theimprovement comes from the MRP computersystems". I find myself much in sympathy with yourpanel of authors.

MRP, in its traditional form with ordering basedon explosion from long term programmes of eightmonths or more, and different queues and/or leadtimes for each part, is obsolete. It is obsolete becauseit cannot achieve the high rates of stock turnoverneeded to compete with Japan. MRP II systemswhich use the same ordering methods are alsoobsolete for the same reason.

The Japanese success has been largely based ona strategy of simple material flow (Line Flow or GroupTechnology) and JIT Production Control, (in theircase mainly Kanban), together giving very high ratesof stock turnover.

If we wish to survive in manufacturing there is noalternative: we must adopt the same strategy.

Prof J L BurbidgeWild Goose Leys

Abbots RiptonHuntingdon

CambsPE17 2LB

DOANYTHINGYOU WANNADO

S i r - 1 understand Mr Hindle's view (July/Aug), but,oh dear, what defeatist, negative thinking!

It seems that I am about ten years older than he is,so obviously wiser(?). My two pennyworth of adviceto 'intelligent youngsters' would be:1) If you like to make things, design them, put themtogether, get them to work, then productionengineering is for you.2) Don't be put off by seniors who are obsessed withprofessional status and recognition. These will comewhen we deserve and fight for them; in the meantimeyou will not be hampered by the lack of them.3) Get a good employer, do a first class job andaccept promotion even if it comes outside the strictconfines of your training.

I know of many successful people who started asenthusiastic production engineers. Why shouldn'ttoday's young people not follow their example?

Brian P Smith (Past President)4 Cliff RoadEastbourne

East Sussex BN207RU

NOCHANGESir - I foresee, as a consequence of changing thename of our journal, a great deal of confusion andinsecurity for our established institution. Unfor-tunately, I failed to respond to the advanced publicity,though I have been aware of subtle approaches tochange emanating from about the time the slogan'Manufacturing Matters' was published.

Recently I attended a meeting of newly appointedLink Engineers for south Warwickshire and was givena huge wad of literature and leaflets from manybodies all interested in attracting students in theengineering profession. Not one referred toproduction engineering as manufacturing engi-neering, and following the debacle of the proposedmerger with the Mechanical Engineers, I amsurprised that our Institution should contemplatechange ever again.

The name of our Institution was chosen wiselymany years ago and relatively we are still newlyestablished, though I believe about to mature to theprofessional status we have all striven for. A changenow will destroy this foundation and an executive ofthe Publications Policy Board should perhaps haveconcentrated on influencing the education authoritiesto change the name of the degree and HND courses.

Unhappily, the tail wags the dog, though if theInstitution belongs to the members then surely amore sensible course would have been a vote by allon the proposed change in the title of the journal.

Norman DixonNutford House

Pratts LaneMappleborough GreenStudley, Warwickshire

GOSH,THANKS!Sir - I was most interested and gratified to receivethe Lucas Manufacturing Systems EngineeringHandbook - a very innovative way to commemoratethe Jubilee anniversary. Thank you very much.

I look forward to news of the planned programmefor the year.

W M Treasure2 Navenby Avenue

Old Traf fordManchester M16 9WG

MANUFACTURING ENGINEER SEPTEMBER 1989