Statistical parameters in planning aero-engine production

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CoA R E P O R T 158

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THE COLLEGE OF A E R O N A U T I C S

C R A N F I E L D

STATISTICAL PARAMETERS IN PLANNING

AERO-ENGINE PRODUCTION

by

Statistical P a r a m e t e r s in Planning Aero-Engine Production

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-A. H Atkinson and J. T. H a r r i s

ERRATA

Ref. 41 should read: D e J o n g . J . R . The effect of increasing skill on cycle time and its consequences for batch production time standards.

Raadgevand Bureau Berenschot, Amsterdam/ Hengelo.

Ref. 42 should read: Manson.N. Practice curves. Memoires Societe des Ingenieurs Civils de France, Jan. - F e b . , 1955.

(e) Last column for "Ex. last 1" read Ex. 1st 1 (h) " - b " column for "0.437" read 0.427

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R E P O R T NO. 158 F e b r u a r y , 1 9 6 3 .

T H E C O L L E G E OF A E R O N A U T I C S

C R A N F I E L D

S t a t i s t i c a l P a r a m e t e r s in P l a n n i n g A e r o - E n g i n e P r o d u c t i o n b y -A. H. A t k i n s o n , D . C . A e . , and J . T , H a r r i s , B . S c , D i p . S t a t s . , F . S . S . , F . R . E c o n . S . SUMMARY T h i s r e p o r t c o n s i d e r s the e s t i m a t i o n of s t a t i s t i c a l p a r a m e t e r s and t h e i r a p p l i c a t i o n to p r o d u c t i o n planning in the a e r o - e n g i n e i n d u s t r y . A s i m i l a r p a t t e r n of b e h a v i o u r to that a l r e a d y r e c o g n i s e d a s e x i s t i n g in the a i r f r a m e i n d u s t r y i s found t o o p e r a t e , though t h e r e a r e i n d i c a t i o n s of quantitative d i f f e r e n c e s .

T h e b u i l d - u p t i m e to the planned peak r a t e of p r o d u c t i o n in a p a r t i c u l a r s i t u a t i o n i s found to be about e i g h t e e n m o n t h s but with v a r i a t i o n between f i r m s . T h e r e d u c t i o n in o p e r a t o r p e r f o r m a n c e t i m e , which o c c u r s with r e p e t i t i o n d u r i n g the b u i l d - u p p e r i o d and a f t e r w a r d s , i s d i s c o v e r e d to be p r e s e n t in m a c h i n i n g a s w e l l a s a s s e m b l y , but to a l e s s e r e x t e n t . The l o g a r i t h m i c function g e n e r a l l y d e s c r i p t i v e of such a t e n d e n c y i s found to fit the a c t u a l m a n - h o u r content v a l u e s r a t h e r than the cum.ulative a v e r a g e o n e s . The r e l a t i o n s h i p between the l o g i s t i c of output and the l o g a r i t h m i c function i s e s t a b l i s h e d and m a d e use of to e s t i m a t e l a b o u r r e q u i r e m e n t s from the c o m m e n c e m e n t of production o n w a r d s .

In addition to the above c o n s i d e r a t i o n of production v a r i a b l e s , e x a m p l e s a r e given of the u s e of engine p e r f o r m a n c e r a t i n g s to e s t i m a t e c o s t s . F i n a l l y , b e c a u s e of the i m p o r t a n c e of planning to p r o d u c t i v i t y , a t y p i c a l production p r o g r a m m e h a s been included.

S u m m a r y Introduction

P r o d u c t i o n build-up r a t e s in the B r i t i s h a e r o - e n g i n e (a) S t a t i s t i c a l information

(b) The logistic

(c) The meaning of the constants (d) The fitted values of the constants (e) F a c t o r s affecting the r e s u l t s (f) Use of the logistic for planning

(g) Fitting the logistic curve - the method of t h r e e selected points

(h) The growth index B (Ref. 7)

T i m e reduction in a e r o - e n g i n e naanufacture A. B r i t i s h production

(a) S t a t i s t i c a l information (b) The t i m e reduction curve (c) The meaning of the constants (d) The fitted values of the constants (e) D i s c u s s i o n of r e s u l t s

B. G e r m a n production

(a) S t a t i s t i c a l information (b) D i s c u s s i o n of r e s u l t s C. G e n e r a l

(a) The employment of the coefficient of t i m e reduction in planning

(b) The least s q u a r e s method of fitting The t i m e cycle of production and labour build-up (a) S t a t i s t i c a l information (b) T i m e cycle reduction (c) T i m e cycle chart (d) Man power r e q u i r e m e n t s c h a r t P e r f o r m a n c e and c o s t s A. A m e r i c a n studies

(a) S o u r c e , p u r p o s e , p r o c e d u r e and definitions (b) The r e l a t i o n s h i p s

Contents (Continued)

P a g e

B. G e r m a n s t u d i e s 12 (a) S o u r c e , purpose and definitions 12

(b) The r e l a t i o n s h i p s 12 (c) D i s c u s s i o n of r e s u l t s 12

C. B r i t i s h s t u d i e s 13 6. P r o d u c t i o n planning and optimunn d e c i s i o n s 13

(a) Production planning 13 (b) T i m e and s c a l e 18

7. R e f e r e n c e s 14 Table 1. Values of the constants of the fitted l o g i s t i c s and

the t i m e to achieve peak output r a t e s 17 Table 2. The values of the constants for time reduction

c u r v e s fitted to B r i t i s h data 18

1. INTRODUCTION

The establishment of empirical relationships, the quantitiative estimation of p a r a m e t e r s and the useful application of the results have an established history in air-frame manufacture. Little, however, of a similar nature has been

attempted in respect of the production of the power unit of an aircraft. This seems to be due to the fact that airframe production is a younger technology.

However, recent developments in the aircraft industry suggest that empirical planning p a r a m e t e r s could be beneficially employed in aero-engine production. Aircraft are now much more costly than fornaerly with the power plant claiming a greater proportion of that cost and assembly itself playing a more important part in power plant manufacture. F u r t h e r m o r e , the emergence of more competitive conditions makes it essential to pay more attention to estimating and planning

methods.

It was with the intention of establishing planning p a r a m e t e r s that the r e s e a r c h forming the basis of this report was undertaken. Unfortunately, the statistical information obtained was not sufficient to treat the subject as rigorously as was desired; it prevented the consideration of many factors that could influence the situations examined and it made the use of more powerful statistical techniques impossible. Nevertheless, the results are considered valuable. Behaviour in the industry is revealed to be similar to that in the airframe industry, though there are indications of quantitative differences.

Originality in the report is confined mainly to Sections 2 - 4 . Section 5 was included to indicate other types of relationships that could be employed, the form of their behaviour and the data required to estimate the p a r a m e t e r s in them. Significant differences were found in the results from different firms and, since sound production planning inakes a difference to a firm's performance. Section 6 was added, mainly to give an example of a typical production programme.

An interesting feature of the r e s e a r c h is the light it throws on the importance placed on statistical information by different countries. American industry has long since been recognised to be more statistically conscious than British industry. However, it is revealing to observe that the Germans had reduced the collection of detailed statistical information, its analysis and application to a routine procedure using standardised documents, for the purpose of furthering the war effort.

The report is based on a thesis submitted by A. H. Atkinson in partial fulfilment of the requirements for a Diploma of the College of Aeronautics. We should like to convey our thanks for help received, particularly from the Ministry of Aviation, where Mr. S. Bentall has always been of very valuable assistance. Security reasons have prevented a more detailed description of the data employed but the statistical methods used enabled the data to be presented in a modified form.

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-2. PRODUCTION BUILD-UP RATES IN THE BRITISH AERO-ENGINE INDUSTRY T h i s section c o n s i d e r s the behaviour of the monthly r a t e of output of an a e r o -engine in relation to the t i m e from the output of the first of a s e r i e s .

(a) S t a t i s t i c a l information

Data w e r e obtained in r e s p e c t of nine t u r b o - j e t engines built in B r i t a i n for m i l i t a r y p u r p o s e s , at seven different f a c t o r i e s , in the e a r l y 1 9 5 0 ' s . As indicated in Table 1, five of the engines w e r e of the s a m e type.

In view of the l a r g e amount of v a r i a t i o n in the original d a t a , each s e r i e s was smoothed by a 5-month moving a v e r a g e . In addition, the output r a t e s w e r e adjusted to yield an attained peak production r a t e of 100 in each c a s e . The d a t a , so modified, a r e plotted in F i g s . 1, (a) - (j). (b) The logistic The s y m m e t r i c a l logistic Y » k 1(1 + 10^'^^^) (1) o r , in another f o r m ,

log^^ ( H ^ J

- a + bX (2)

w h e r e Y i s the output r a t e of month X(X « 1 being the e a r l i e s t month of any output) and a, b and k a r e constants to be d e t e r m i n e d , was found to be d e s c r i p t i v e of the g e n e r a l trend of each s e r i e s , though in t h r e e of them it was confined to a section of the original data only.

The decision to fit the logistic to p a r t only of the original data in c e r t a i n of the s e r i e s was justified by the behaviour of that s e r i e s itself. It r e f l e c t s a change of p r o g r a m m e which i s liable to o c c u r in the i n d u s t r y . The fitted l o g i s t i c s a r e i n s e r t e d in each of the f i g u r e s .

(c) The meaning of the constants

(i) The constant k is an asymptote of the logistic and, since b i s negative in t h e s e s t u d i e s , it b e c o m e s the upper a s y m p t o t e . It i s the value that Y a p p r o a c h e s a s X tends to •<> . In a s i m i l a r way, the value Y = 0 i s the lower a s y m p t o t e , which i s approached as X tends to -«> .

(ii) The constant a locates the logistic on the time scale and it will accordingly be positive and finite. It d e t e r m i n e s the value of the logistic at X •• 0. As such, it will not reflect r e a l i t y a s no output o c c u r s in month 0. T h i s i s , however, of s m a l l consequence.

(iii) The constant b d e s c r i b e s the r a t e of approach to peak production and the s m a l l e r it i s in absolute value, the longer the build-up p e r i o d . In view of t h i s i n v e r s e r e l a t i o n s h i p and its negative sign, Stanley^'' proposed the use of B w h e r e

the build-up period is then directly related to B and the steeper the logistic

in its central part, the smaller the value of B.

(d) The fitted values of the constants

The values of the constants obtained by fitting the logistic to the several s e r i e s are shown in Table 1. In addition, tliose of B and M - the time to achieve the peak output rate - are included.

(i) The values of M vary generally between 15 and 21 with a well defined mode at 18 months.

(ii) The values of k vary generally between 101 and 107 with a mean of 104. (iii) The values of the constant a vary between 1.24 and 2.01 but without a

defined average.

(iv) The values of -b vary between 0.091 and 0,212, again without a well defined average.

(e) Factors affecting the results

The sample cannot be considered sufficient in size to investigate the many factors that could be expected to influence the results. Certain tentative conclusions can be drawn, based on the results and on additional information made available with the original data. These are that

:-(i) Neither the scale of output nor the size of the unit manufactured affected the results significantly.

(ii) The variation in results between factories was greater than that within factories.

Section 4 will reveal that the logistic can be influenced by other factors, namely the reduction coefficient,

the rate of labour build-up, the cycle time of production and the average working week.

These will not only in general affect b but also the constant a, since the

amount of work-in-progress will itself be influenced by them.

Finally, there will be, in addition to the usual unexplained variance, the effects of subjective e r r o r s of fitting.

(f) Use of the logistic for planning

(i) The values k = 104, a = 1.40, -b = 1.55 yield a value of Y = 100 at X = 18 and can be considered as representing average behaviour. (ii) In view of (e) (ii) of this Section, quantitative values for the parameters

4

-d e r i v e -d f r o m a f a c t o r y ' s own h i s t o r i c a l -d a t a woul-d be subject to s m a l l e r s t a n d a r d e r r o r s than t h o s e obtained from the a v e r a g e b e h a v i o u r of a n u m b e r of f i r m s and t h e y would be a c c o r d i n g l y m o r e s a t i s f a c t o r y for i t s own p l a n n i n g .

(iii) The e a r l i e r an e s t i m a t e i s m a d e , g e n e r a l l y the l e s s r e l i a b l e will be the value obtained. H o w e v e r , once d e l i v e r i e s have begun, an i n c r e a s i n g amount of d a t a will b e c o m e a v a i l a b l e for c o m p a r i s o n with the e s t i m a t e d s t a n d a r d and for p u r p o s e s of e x t r a p o l a t i o n . To t h i s end, a s e t of c u r v e s with a r a n g e of v a l u e s for the p a r a m e t e r s could be d r a w n on t r a n s p a r e n t m a t e r i a l , placed o v e r o b s e r v e d d a t a and the placing adjusted to r e f l e c t the t r e n d in that d a t a .

(g) F i t t i n g the l o g i s t i c c u r v e - the method of t h r e e s e l e c t e d points T h e equation for the l o g i s t i c c u r v e i s u s u a l l y quoted a s

Y = k / ( 1 + e^ ^ ^ ^ ) (4) but s i n c e , in p r a c t i c a l c o m p u t a t i o n , it i s m u c h m o r e convenient to take l o g a r i t h m s

to the b a s e 10, a s t a b l e s of t h e s e a r e u s u a l l y r e a d i l y a v a i l a b l e , the c u r v e fitted to the d a t a will be

Y = k / ( I + 1 0 ^ ' ^ ' ^ ^ ) (5) Select t h r e e p o i n t s , not n e c e s s a r i l y included in the d a t a , through which the c u r v e

i s to p a s s . Denote t h e s e by (X,, Y,), (X^, Y^) and (X^, Y^) w h e r e X3> X^ > X , . A r e s t r i c t i o n placed on t h e s e points i s that t h e y m u s t be equally spaced on the X c o - o r d i n a t e , i. :-. (X^ - X^) = (X^ - X,) = n.

Then the p a r a m e t e r s of the c u r v e a r e calculated from the following e x p r e s s i o n s . 2Y Y Y - Y N Y ,

+Y,)

k = (6) 1 n l°g,o Y, Y 3 -Y,(k Y^(k

-V

- Y , ) (7) - ^ ' / k - Y s

Sufficient points can be calculated using the e x p r e s s i o n

l ° g i o ^ • ^ ) = ^ + ^ ^ <ö> t o enable the c u r v e to be fitted

(10) Substituting the values

b(X^ -X^) = log(^L_Isj . i o g ( ^ i L _ I j (11)

1 Y, (k - Y^)

<^. - ^ i ) = b ^°S Y^ (k - Y, ) <^2) Hence, if Y, and Yj are fixed quantities, (Xj - X,) is inversely proportional to

- b; i . e . the time taken to increase from Y^ to Y^ is proportional to - 1/b = B

3. TIME REDUCTION IN AERO-ENGINE MANUFACTURE

This section considers the behaviour of the naanufacturing man-hour content of an engine in relation to the cumulative number produced.

A. BRITISH PRODUCTION (a) Statistical infornaation

Data were obtained in respect of two different turbo-jet engines manufactured under differing circumstances. Information was provided in respect of the details of manufacture as indicated in Table 2.

Actual man-hours are not recorded but only an index of them. The value to which each s e r i e s tended, after a considerable number of components had been produced, was chosen as a base and given a value of unity in each case. Certain of the s e r i e s are proportional to the actual man-hour content of the given item (unit) whilst others are proportional to the average man-hour content for production, up to and including the given item (cum.ulative average). The data, as such, are plotted in Figs. 2 (a) - (q).

(b) The time reduction curve

The mathematical function generally descriptive of this is given by

Y = a x ' ^ (13) where Y is the man-hours for the Xth unit and a and b are constants to be

determined. Where Y is the unit value, it is denoted by Y and where it is the •^ u

cumulative average, it is denoted by Y . The function can be put into the form (h) The growth index B (Ref. 7)

Equation (4) can be expressed in the form log ( ^ ^ ) = a + bX

Let (X^, Y,) and (X^, Y^) be two points on the logistic. in (10) and subtracting, we have

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log Y = l o g a + b l o g X (14) so that by plotting the observed values of Y against those of X on a log-log

scale, it can be readily determined to what extent the function will prove a

satisfactory fit. The fitted functions, excluding certain values in some cases, are inserted in each of the Figs. 2 (a)-(q).

(c) The meaning of the constants

(i) The constant a is the value of Y at X = 1, reflecting in this study the man-hour content of the first of a series as a multiple of that of a high cumulative value.

(ii) The constant b describes the slope of the line on log-log scale. It will be negative and the greater its absolute value, the greater the rate of time reduction. Directly from it we have the coefficient of time reduction, given by

L = (100/2""^)% (15) It represents the value of Y for a given X as a percentage of that of X / 2 .

If the function fits either form of the s e r i e s satisfactorily, then it will fit the value obtained by transforming that s e r i e s into the other form, provided certain initial values are excluded. The value of L will remain significantly unaffected by this procedure.

(d) The fitted values of the constants

(i) The values of the constant a vary widely where the cumulative average is ennployed and between 2.3 and 3.2, without a well defined mode, where unit values are considered.

(ii) The average value of -b, for machining, is approxiniately 0.185 and, for assembly, approximately 0.250. The corresponding coefficients of time reduction are approximately 88% and 84% respectively.

(e) Discussion of results

The sample itself is too small for other than tentative conclusions.

(i) Time reduction is experienced in machining, as well as assembly, but to a l e s s e r extent.

(ii) Differences between firms are likely to be significant. Engine B, in particular, was produced under war-time circumstances.

(iii) The logarithmic function describes more satisfactorily the trend of unit data values than that of cumulative average data. The greater scatter of unit data around the fitted trend is due to the smoothing effect of averaging. (iv) A discussion of the values of the constant a serves little purpose in view

of the subjective element in the choice of the index base. However, it indicates that a reduction to about one-third of the man-hour content of the first of a s e r i e s is at least possible.

B . GERMAN PRODUCTION (a) S t a t i s t i c a l i n f o r m a t i o n

A n u m b e r of w a r - t i m e s t a n d a r d s t a t i s t i c a l d o c u m e n t s w a s o b t a i n e d , showing d e t a i l e d b r e a k d o w n in t e r m s of c o s t , weight, t i m e and m a n - h o u r s for raw m a t e r i a l , c o m p o n e n t s , p r o c e s s e s and p e r f o r m a n c e , a s t h e y a p p l i e d . One of t h e s e d o c u m e n t s , r e p r e s e n t i n g an o v e r a l l s u m m a r y for a n u m b e r of t y p e s a s i n d i c a t e d , i s shown in F i g . 3 , A s e m i - l o g a r i t h m i c s c a l e h a s b e e n employed and 85% t i m e r e d u c t i o n c u r v e s s u p e r i m p o s e d .

(b) D i s c u s s i o n of r e s u l t s

(i) C l o s e a c c o r d with an 85% law i s o b s e r v e d g e n e r a l l y . The a g r e e m e n t between t h i s and engine B of the B r i t i s h d a t a i n d i c a t e s that t h i s law a p p l i e s , v e r y g e n e r a l l y , u n d e r w a r - t i m e c i r c u m s t a n c e s .

(ii) T h e G e r m a n s r e c o g n i s e d the i m p o r t a n c e of d e t a i l e d s t a t i s t i c a l i n f o r m a t i o n for h i s t o r i c a l and planning p u r p o s e s . The m o r e d a t a that a r e a v a i l a b l e , the m o r e r e l i a b l e the p a r a n a e t e r s e s s e n t i a l for e s t i m a t i n g future r e q u i r e m e n t s . C. GENERAL

(a) The e m p l o y m e n t of the coefficient of t i m e r e d u c t i o n in planning

(i) T h e unit function, r a t h e r than the c u m u l a t i v e function, should be e m p l o y e d , (ii) Different coefficients of t i m e r e d u c t i o n apply to m a c h i n i n g , a s a g a i n s t

a s s e m b l y and for differing c i r c u m s t a n c e s .

(iii) P r e - p l a n n i n g r e q u i r e s that an e s t i m a t e of the constant a, in m a n - h o u r s , be obtained by c o n s i d e r a t i o n outside the scope of t h i s s e c t i o n . When the first of the s e r i e s i s known, a rough e s t i m a t e of the constant a i s obtained. When f u r t h e r d a t a b e c o m e a v a i l a b l e , c u r v e fitting can be employed and compai-ison with an e s t i m a t e d s t a n d a r d and e x t r a p o l a t i o n u n d e r t a k e n . F o r t h i s p u r p o s e , v a r i o u s coefficients can be plotted on t r a n s p a r e n t m a t e r i a l . On l o g - l o g s c a l e , c u r v e s having the s a m e coefficient of t i m e r e d u c t i o n will be p a r a l l e l .

(b) T h e l e a s t s q u a r e s method of fitting b = ^ (16) E V w h e r e : a = W - bV (17) E wv = EWV - W EV (18) Lv^ = E V* - V EV (19) -__ EW ^ ^ EV (20) n n W = log Y , V = log X (21) n = n u m b e r of p a i r s of r e a d i n g s

E X A M P L E - F i g u r e 2(b) 8 -X 1 2 5 1 0 0 1 1 5 Y 3.64 3.42 3.05 1.33 1.15 TO TALS W 0.5611 0.5345 0.4842 0.1239 0.0607 3.9835 V 0.0000 0.3010 0.6990 2.0000 2.0607 17.8594 W V 0.0000 0.1609 0.3385 0.2478 0.1251 3.8015 2 V 0.0000 0.0906 0.4886 4.0000 4.2465 27.9630

w

V E WV EV^ b log a 3.9835 14 17.8594 14 0.2845 1,2757 3.8015 - (0.2845)(17.8594) - 1.2795 27.9630 - (1.2757)(17.8594) 5.3744 1.2795 5.3744 0.2845 0.5882 3.875 - 0.2381 (- 0,2381)(1.2757)

4. THE TIME CYCLE OF PRODUCTION AND LABOUR BUILD-UP

This section considers the relationship between the logistic of output, the time reduction coefficient, the cycle time and the rate of build-up of man-power. (a) Statistical information

Data were obtained of cycle times in respect of one turbo-jet engine. These are not sufficient to establish empirical p a r a m e t e r s but they will serve to illustrate the use that can be made of such material. The data are recorded in Fig. 4, where it will be observed that detail; for processes have also been made available.

(b) Time cycle reduction

A reduction in the time cycle of manufacture can be expected, following the reduction in man-hour content. However, it cannot be expected to be so strong and our example i s , in fact, one with a reduction coefficient of approximately 90.2%. There i s , too, variation between p r o c e s s e s .

(c) Time cycle chart

This can be obtained by the following procedure.

(i) Derive a delivery schedule by cumulating the values of the relevant logistic. (ii) Derive the time cycle for the first of the s e r i e s by the use of p a r a m e t e r s

or by production control methods.

(iii) Apply the relevant time cycle reduction coefficient to the above to obtain the starting schedule for the p r o c e s s .

The chart will readily yield the nunaber of partly processed units at any one time. Thus Fig. 4 indicates tiiat, eight months after the start of production, 37 engines have commenced and 33 have completed the first engine build-up process, making five engines in the partly processed stage at that tinae.

(d) Man power requirements chart

The cycle time reduction chart can be used in conjunction with the time reduction coefficient and an estimate of the man-hour content of the first of a s e r i e s to establish the manpower requirements at any one time during production.

(i) Obtain the average unit man-hour content of those in process at any one time by means of the reduction coefficient and an estimate of the man-hour content of the first of the s e r i e s .

(ii) Obtain the average cycle time for the stage considered. Proceeding with the example above we have

No. of engines at first engine build = 5 Average cycle time in hours = 72 Average man hours per engine * 430 Therefore, number of operators required j. .„„ at this stage = — ^ = 30

10

By this nneans, manpower requirements can be obtained for the total period of production as shown in Fig. 5.

5. PERFORMANCE AND COSTS

This section considers the improvement in performance with time and its relationship with costs, both monetary and physical.

A. AMERICAN STUDIES

(a) Source, purpose, procedure and definitions

The empirical relationships set out below are taken directly from Ref. 33. They are based on the experience of turbo-jet manufacture before 1950. The purpose of the studies was to relate costs to military effectiveness. The

procedure adopted involved, firstly, obtaining the time trend of performance factors and then relating costs to deviations from the trend. Certain common terminology, generally employed in the studies, is

N = the number of observations r = correlation coefficient

S.E. = the standard e r r o r of forecast Other t e r m s employed are defined with the relationships. (b) The relationships

(i) Trend of engine thrust with time T = 9584 (1.127)* T = thrust in lbs. military rating

t = time in units of six months, to design initiation Range of T = 1560 to 16400

Range of t = 1943 to 1950 N = 8, r = 0.945

(ii) Trend cf specific fuel consumption with time S . F . C . = 0.9531 (0.9897)'*

S . F . C . = Specific fuel consumption in I b s / h r / l b . thrust Range of S . F . C . = 1.14 to 0.85

Range of t = 1 9 4 3 to 1950 N = 13, r = 0.684 (iii) Development costs and performiance

C^ = 3301.0 (AT)°-220 ( , s . p . C . ) « - « ^ ^ «

C_ = development costs ($ 000's) at 1948 p r i c e s . The costs are those incurred from the initiation of design, after the award of an experimental contract, to the first bench test of an experimental engine.

A T = the percentage increase over the thrust trend

A S . F . C . = the percentage decrease from the S . F . C , trend Range of AT = O to 92

Range of A S . F . C . = O to 11.1

N = 8, S.E. = 1.43

(iv) Improvement development costs and performance = 394.1 (AT )°-^«^ ( A S . F . C . , / - ^ ^ ^

m M

= development costs for improvement of basic engine ($ OOO's) at 1948 p r i c e s .

= the percentage increase in thrust over previous model of s e r i e s . Where A T , , <; 1, T , , = 1 is employed.

M M ^ '

= the percentage decrease in the S . F . C . from previous model Where S . F . C . «;1, S. F . C. = 1 is employed.

Range of AT^^ = 7.7 to 27.2 Range of A S . F . C . = 0 to 9.3

N = 8, S.E. = 1,40

(v) Development time and performance

Tj^ . 10.6 ( A T ) ° - ^ ^ ^

T_^ = peace-time months between design initiation and first bench test. Range of AT = 0 to 92 N » 8, S.E. = 1,16

S M

*^DM m AS.F. C-M (vi) P r o d u c t i o n c o s t and p e r f o r m a n c e ,0.233 , _ „ ^ . 0 . 0 3 5 7 (M \ ' " ' ^ ^ ^ \ 5 0 0 / C = 8.069 T ( A S . F . C . ) P

C = c u m u l a t i v e a v e r a g e cost p e r engine for M e n g i n e s ($ OOO's) at 1948 p r i c e s . M = c u m u l a t i v e n u m b e r of e n g i n e s produced

Range of T = 1560 to 16400 Range of A S . F . C . = 0 to 11.1

12

-(vii) Production time and performance No significant relationship found to exist.

Production time (P) = elapsed time from the date of the first test to peak production.

Range of P > 5 to 35 Mean of P =17.6

N = 11 (c) Discussion of results

The relationship between costs and performance, as defined, are revealed to be logarithmic, i . e . a given proportionate increase in a given determining variable is associated with a given percentage change in the level of costs. The effect of the thrust, in this respect, is greater than that of the specific fuel consumption. However, the range of the latter is much smaller than that of the fornaer.

B. GERMAN STUDIES

(a) Source, purpose and definitions

The empirical relationships in graphical form are shown in Figs. 6 and 7 and have been taken directly from the original German documents. They were used by the Germans for production planning purposes,

(b) The relationships

(i) Direct production manhours and engine dry weight

The reduction factor of direct production manhours per engine, in relation to engine dry weight, was 87%.

(ii) Direct production manhours and engine horse power

The reduction factor of direct production manhours per engine, in relation to engine nominal H . P . rating, was 85%.

(c) Discussion of results

The relationships established are revealed to hold over more than 20,000 engines. However, the reduction factor, including engine dry weight, is higher than that including H. P. rating, the latter being the same as the manhour reduction factor. The reason for the difference a r i s e s from the tendency of an engine to increase in weight during a production programme because of modifications or the use of heavier materials to overcome shortages.

It is observed that the value of direct manhours per kilogramme (pound) at 20,000 engines was in the range 2.2 - 3.2 (48-70) and that the value of direct manhours per H . P . at the same stage was between 1.7 and 2.1 for radial engines and between 1.25 and 1,9 for in-line engines.

C. BRITISH STUDIES

Lack of data enabled only a superficial examination of British production costs. Six samples of 1954 data showed values between 1.6 and 2.8 of direct manhours per lb. of engine dry weight for piston engines and between 2.7 and 4.2 direct

manhours per B . H . P . for the three radial engines of the samples. Compared with the German values, the former are very much reduced and the latter higher. The reduction is due to improved technology and the increase due to greater complexity.

6. PRODUCTION PLANNING AND OPTIMUM DECISIONS

This section gives a typical production programme and considers the implications of timing and scale of operation.

(a) Production planning

Sound production planning enables a realistic delivery date to be established and early corrective action and adjustments made. A typical example, treating the first production model of a turbo-jet engine, is shown in Figs. 8 - 1 1 .

Fig. 8. Items susceptible to delays, those requiring special equipment and those with long cycle times, are given attention before the release of the design to

production. The specification of materials and sub-contracting policy needs to be established at an early stage.

Fig. 9. When the design has been released to production, more information will be available to enable parts to be treated in detail.

Fig. 10. Each long dated item, or a group of similar items, is given separate treatment. Details of special equipment are included and its history recorded by filling in the relevant triangles.

Fig. 11. This records the time span for sub-assemblies and subsequent stages and the dates at which the relevant rigs and the fixtures are required.

(b) Time and scale

An aero-engine passes through many distinct phases in its journey from the initial idea to quantity production. Two important problems arise in this time span, It is necessary to decide, firstly, the extent to which the phases should overlap and,

secondly, the intensity or scale at which each phase is to operate.

The more a phase overlaps a subsequent one, the less complete or finalised the information available for decisions in respect of that subsequent stage and thus the greater the probability of wastage through incorrect decisions. The economies of a reduced overall time span have thus to be set against the wastage.

There are also economies and diseconomies of scale. A greater rate of output at a lower unit cost can generally be achieved by more capitalistic methods of production. The decision as to which method of production to adopt will depend on expectations in respect of the market. However, a larger output may mean a greater

14

l o s s , so that a careful appraisal of the market is necessary to decide the optimum scale of production.

Evaluation is not a straightforward procedure. Many of the values made use of will be based on expectations. Intangibles will need to be considered. Finally, firms operate in differing circumstances and what is best suited to one need not necessarily be the optimum solution for another.

7. REFERENCES

Production Planning (Airframe)

1 . 4. 5. 6. 7. 8. 10. 11, 12, Mensforth.E. Fielding, C . E . Mensforth,E. P e t t e r , W . E . W . Edwards, G.R. Lickley,R.L. Robinson,D- C. Stanley, P . J . Thornton, F . O. Povey,H. Bunnett.L.E. Banks, F . R . Airframe production. J . I n s t . M e c h . E n g r s . , Vol.156, 1947, pp 24-38.

A review of production problems in relation to aircraft design.

J . R o y . A e r o . S o c . , Vol.51, 1947, pp 511-533. Aspects of the design and production of airframes with particular reference to their co-ordination and the reduction of the development period.

J . R o y . A e r o . S o c , Vol.48, 1944, pp 210-263. Problems in the development of a new aeroplane. J . R o y . A e r o . S o c , Vol.53, 1949, pp 197-252. Evaluation of the design of an aeroplane. J . R o y . A e r o . S o c , Vol.52, 1948, pp 357-382. Some developments in aircraft production. J . R o y . A e r o . S o c , Vol.53, 1949, pp 39-66. The time to reach peak output, with special reference to aircraft production.

C. o. A. Report No. 30, 1949. Planning and aircraft development.

J . R o y . A e r o . S o c , Vol.55, 1951, pp 303-322. Planning and production methods used on the construction of the Comet.

J . R o y . A e r o . S o c , Vol.55, 1951, pp 459-517. Production research on aircraft.

J . R o y , A e r o . S o c , Vol.56, 1952, pp 179-188, Workforce and plant size examination.

Aviation Studies (International), London, June 1956. The importance of time in aircraft manufacture. J . R o y . A e r o . S o c , Vol.61, 1957, pp 5-36.

Wright,T. P . Robbins.S.M. , Murphy, T. E. Raymond, A. E. C r o u s e , P . B. Kienzle.O. Wright,T. P . Middleton.K.A.

Factors affecting the cost of aeroplanes. J . A e r o . Sci. , Vol.3, 1935-1936, pp 122-128.

Economics of scheduling for industrial mobilisation. J . Political Economy, Feb. 1939.

Some factors affecting the cost of manufacture and operation of large aeroplanes.

S . A . E . . June, 1939.

Projecting labour loads in aircraft production. Aero.Digest, Vol.43, 1943, pp 216-243.

Leistung Steigerung in der Fertigung. V . D . I . , Vol.86, No.43/44, Oct. 1942.

A study of elapsed time between engineering and production of military aircraft.

Aircraft Production Board, Resources Control Office, U . S . A . , March, 1944.

Wartime productivity changes in the airframe industry.

Bureau of Labor Statistics, Washington,U.S. A. Serial No. 1776, 1945.

Lilley.T. , and others.

Problems of accelerating aircraft production in World War U.

Harvard School of Business Admin. , Boston, Mass. 1946. Rucker.A. W. Shenstone, B. S. Dunkin,T.G. Bergman, H. Stanford Res. Institute. Stanford Res. Institute. United States Munitions Board.

Measuring labour's productivity.

Industrial Conference Boards, Inc. , New York, 1946. Preliminary estimation of aircraft p r o g r a m m e s . A.V.Roe Canada Ltd. , June, 1947.

A mathematical method of estimating labour requirements.

Ind.Div. H.Q. , Air Material Command, U.S.A. November, 1949.

Development of production acceleration curves for airframes. California, Dec. 1949.

Relationships for determining the optimum expansibility of the elements of a peace-time aircraft procurement programme.

California, December, 1949.

Production planning for emergency procurement. March, 1950, U . S . G . P . O .

16 2 7 . 28. 29. 3 0 . Heineman.E. H. Monnier,M. Neale,R. A. Hotz,R.

Production Planning (Engines) 31. Banks, F . R . 32. 3 3 . 3 4 . 35. 36. 37. 38. 39. 4 0 . 4 1 . 4 2 . 4 3 . Banks, F . R . Stanford Res. Institute. F o u c h . G . E . Brownridge, E. W. Berghell,A.B. Hughes, R . C . , Golem, H.G. Raborg, W.A. Dennington, C. T, Andress, F . J . DeJong,J. R. Manson,N. McCampbell,E.W. McQueen, C.W.

Problems in aircraft production. (Lecture to the Industrial College of the Armed F o r c e s , Washington, D . C . , Feb. 1953).

La conception des prototypes en vu de leur fabrication en s e r i e .

A . F . I . T. A. Congress, P a r i s , 1953. Basic prerequisites for production.

Anglo-American Conference, London, 1953. Air Force develops new production plan. Aviation Week, Vol.60, 12/4/1954, pp 13-14,

The art of the aviation engine.

J . R o y . A e r o . S o c , Vol.52, 1948, pp 527-550. The birth of an engine.

Aero.Engng. Rev. , Vol.12, June 1953, pp 31-43. Cost performance relationships for airframes and turbo-jet engines, California, Oct, 1949. How to co-ordinate sub-contracting to meet production schedules. American Machinist. Special Report No. 354, 1954.

The economical production of jet-engines in Canada. Orenda Engines, Ltd. , Canada, 1955, Production engineering in the aircraft industry. McGraw-Hill Book Co. 1944.

Production efficiency curves. 1944.

Mechanics of the learning curve.

Aero.Digest, Vol.65, Nov.1952, pp 17-21. Practical learning curves improve shop performance. Iron Age, Nov. 1953. The learning curve as a production tool.

Harvard Business Rev. , Vol.32, 1954, pp 87-97. The effect of increasing skill on cycle time and

its consequences for batch production time standards. Raadgevend Bureay Berenschot, Amsterdam/Hengelo. Practice curves. Memoires Societe des Ingenieurs Civil de France. Jan. -Feb. , 1955.

Cost estimating from the learning curve. Aero. Digest, Vol.72-73, 1956, pp 36-39.

F i g u r e 1. ( a ) (b) ( c ) (d) ( e ) (f) ( g ) (h) / j ) Engine 2 3 4 5 F a c t o r y A B C D E F D G A k 104 113 107 105 101 107 1 0 3 101 101 a 1.66 1.51 1.97 1.44 1.51 1.37 1.24 2,01 1.72 - b 0,167 0.120 0.207 0.148 0.163 0.142 0.106 0.091 0.212 B 5,99 8.31 4.83 6.76 6.12 7.05 9,42 10.95 4.71 M (months) 16 21 15 18 2 0 18 18 33 1 8

TABLE 1. VALUES O F THE CONSTANTS O F THE F I T T E D LOGISTICS AND THE TIME TO ACHIEVE PEAK

18 -F i g . 2 (a) (b) (c) (d) (e) (f) (g) (h)

(J)

(k) (1) (m) (n) (P) (q) O p e r a t i o n T o t a l d i r e c t T o t a l m a c h i n i n g M o t o r component m a c h i n i n g T o t a l fitting T o t a l a s s e m b l y A s s e m b l y & s u b -a s s e m b l y F i n a l e r e c t i o n T o t a l t e s t i n g C o m p r e s s o r c a s i n g m a c h i n i n g R o t o r s u b - a s s e m b l y m a c h i n i n g R o t o r s u b - a s s e m b l y m a c h i n i n g T u r b i n e s u b -a s s e m b l y m -a c h i n i n g T u r b i n e b l a d e s m a c h i n i n g G e a r b o x m a c h i n i n g G e a r b o x m a c h i n i n g engine B B A B B A B B B B A B A A B Sample s i z e 14 14 12 14 13 7 13 13 14 14 12 7 10 13 13 M a n - h o u r content C u m . a v . Unit Unit Unit C u m . a v . Unit C u m . a v . C u m . a v . Unit Unit Unit C u m . a v . Unit Unit C u m . a v . a 3.57 3.87 3.08 2.27 4.11 4.04 5.69 16.72 2.85 2.35 2.60 5.30 3.15 3.52 8.87 -b 0.196 0.238 0.155 0.162 0.227 0.264 0.241 0.437 0.199 0.172 0.133 0.278 0.138 0.190 0.400 L 87,3 84.7 89.8 89.4 85.4 83.3 84.6 74.4 87.1 88.7 90,3 82.5 90.9 87.6 75.7 E x . 1st 2 E x . l a s t 1 E x . l a s t 3 E x . 1st 2 E x . 1st 2 E x . 1st 7 E x . 1st 2

T A B L E 2. THE VALUES O F THE CONSTANTS FOR TIME REDUCTION CURVES F I T T E D TO BRITISH DATA

\

vv

\ V

^ \ \ ^ ^ ^ ^ n z O z m — 11 o 5 CS ^ . ^ * ^ ^ ' ' ' ^ s ^ ^ ' * ^ ^ ^ V , O :_ /-^ ^ ^ > ^ ^ ^ ^ — - ^ > < ^ < C V ^ ^ ^ \

i

ENGINES DELIVERED PER MONTH

> z o T m u z H T O •Tl O c: H 0 c -K ^ O z H X > > • D m 3) i-\ m -H > <r> m O -n •0 m > 33 > -\ m ^~> • n

P

TO m > _H O (/I I 77 (D m -t ^ ni 7. r<i z 6) 7 o m r-m 33 m O T)

s

o o

V

^ „ ^

5 Q z m

9

3 o -n

7

ENGINES DELIVERED PER MONTH ENGINES DELIVERED PER MONTH •> »

V

V

^ m z O -n z o -n<r > ^ n -* ^ m O u "~«. < ^-^'^*^' ^ \ ^*^ ^ ^*" 1 \ / S. \ , \ _, \ ^ — V < -_\ , \ V — 0 / > 2 u z o rn ""%> m ,^^ ^ </> ± > CD -D n m 2 ' J s

o 2

O z H I z

2

H T3 C m z m z >! o m o z G r^ -n cp •o O m m > C X < m m

ENGINES DELIVERED PER MONTH

ui O y t • 8

A

\ ^ . ^ ^ V * N s z Z Ö J n 3 :D -n

\ m w -ft o 5 o ^ A 1

1

ENGINES DELIVERED PER MONTH

O >

z

o

H I m ^ O 7 O G

c

H •D C .H ^ G

z

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m i/i o m < m

9

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^ • ~ ' - « . . ^ _ *• i * -+ ""—~—~. • ^ - * . V, h,^^^^ -• ^ -• - -^--.-t ^ 1-• ~ * - v " " • - + — •

FIG. 2 (a\ ENGINE B JOTAL DIRECT MANHQURS

" ' * ^ - - ~ _ 1 FIG. S f h l F M R I M F R * ^ * - . * -_{* - + ~} -\-/ - 1 1 M T O T A L M A C H I N I N G M A N H O U R S - . . ^ _ FIG. 2 ( c ) MAJOR C FIG. 2 (d ] TOTAL Fl -* • - - , - • • - . 1 1 1 ENGINE A OMPONENT M / 1 1 1 •~~ + -ENGIf T T I N G f •JE E M;

1

• i ^NK + _ + - + CHIN -~-i ! lOl JRS 1 4-I N G M A N H C - - . i . ' "t~*~ )URS 1-+-.1.^ k— ,__ O 10 lOO lOOO CUMULATIVE NUMBER OF ENGINES PRODUCED

FIG. 2. CUMULATIVE AVERAGE OR UNIT MANHOURS IN RELATION TO NUMBERS PRODUCED

^ u * • z 3 ^ 2 u ^ 5

d

^ - - . . . ^ • | - - . . -

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1 *

r ~

s.. -«. ^ • l -4. _{: ^ !} 1 FIG. 2 . 0 ) ENGINE A 1 - - i i J

~^rf

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ASSEMBLY AND SUB-ASSEMBLY MANHOURS ~~ h l O . ^ . [<i) t N O l N t F I N A L F R F r T I D N 1* *• >VL + B MANt ^ n l l (

+ i- 1 1

F i r T L ' " ["'"""^'^s^ TO • ( • i S -^ \* '. 1 1 r^r-;. 2 . ( h ) ENGINES 'E TAL TESTING MANH

1 1 1 1 1 1 ^ " \ '

r^

1 - ^ _+^l rj—~^^^+

irr*

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•jL

- k..^j • • • • h ID IOC CUMULATIVE NUMBER OF ENGINES PRODUCED

lOOO

FIG. 2. CUMULATIVE AVERAGE OR UNIT MANHOURS IN RELATION TO NUMBERS PRODUCED

. + + ^ ^ ~"~- ~ + , • _ ^ . . ^ ^ * , + l - | 0 . . ^ . y j t N O I N t ö 1 1 1 I I 1 I I COMPRESSOR CASING MACHINING MANHOURS i _ 1 1 1 1 1 1 1 1 1 / 1 1 I 1 FIG. ROT< • . i _ ^ FIG. ROT F I G . _ TURE -+ 2.Q(.) ENGINE DR SUB-ASSEN/ 2 . (i) ENGINE DR SUB-ASSE^^ ^ B 8LY h A BLY K + 2.'(m) ENGINE' B )INE SUB-ASS * ~~\''-£MBLY ^ :^: vlACt •+• . dACI-MA ^=»-, - ~ HINI <INIh - ^ CHI ~~ + i + -^G M/l JG MAh

~r

vJING K ^''• * NHOURS • ^ + + IHOURS

-k^

4ANH0UPS ~ ' * - + • ~- +

~~i

C2 * — O 10 lOO lOOO CUMULATIVE NUMBER OF ENGINES PRODUCED

F I G . 2 . CUMULATIVE AVERAGE OR UNIT MANHOURS IN RELATION TO NUMBERS PRODUCED

1-5 z > < 2 D O ^. ^ ^ • .^ • " ^ .

r^

— — ^ -... 1 1 1 1 FIG.2. (n) ENGINE A r TURBIN F i n 0 fry GEARBC E BLA ; ENG )X MA DES INE CHIh MACh

1

A ^-J giNG N 1 ~ FIG.2.(q) ENGINE B + GEARBOX MA '>^ CHI^ ^ ^ giN( • V - , J t ilN -IA IIN i-NI +. ^AN 1 *~ •*. G -iC t >4ANHOURS .!_ )L _; HOI. 1 ^ RS ^ . - ^ JR5 f-• ^"*^-- « — . r--'*^ •••-wt X lO lOO CUMULATIVE NUMBER OF ENGINES PRODUCED

lOOO

FIG. 2. CUMULATIVE AVERAGE OR UNIT MANHOURS IN RELATION TO NUMBERS PRODUCED

ISSUE A OCT. 1944

G E R M A N AIR MINISTRY F E R T G . X T B

PRODUCTION PLANNING DATA

SUMMARY ENGINE llPISTON ENGINES GERMAN HIGH COMMAND DOCUMENT REF ISSUE |A| I I I I

TOTAL PRODUCTION MANHOURS FOR ENGINE AND EQUIPMENT RELATED TO CUMULATIVE ENGINE PRODUCTION

^SUMMARY OF PRODUCTION OF ENGINES TYPES AT ALL FACTORIES"^ TOTAL DIPECT

MANHOURS PER ENGINE 6 4 0 0 6 0 0 0 5 O 0 O 4 0 0 0 3 0 0 0 2 0 0 0 6 0 0 SO 5 0 0 l O O O 2 0 0 0 5 0 0 0 ! 0 , 0 0 0 2 0 , 0 0 0 5 0 , 0 0 0 l) PRODUCED IN CfKIWN FflCrOKIfS ONir. 2) PlCODWCIlOMCHHNCiD LOCflflON COWlliUvf PtODKUOK OF ENCINf

3.«.CI SUHO tS ruNo llO 111 tOHO Tuno ill i>^J ae/iho 31i lis lO IkO 1Ü7 so o LOI '30 D8 i.J3 0(J 4 / 0 iJ7 \IOO«} Dli LIS U^} Ucoj a/rw no

FIG. 3 . GERMAN WAR-TIME STANDARD DOCUMENT T Y P E 2. OVERALL SUMMARY OF THE PRODUCTION

MANHOURS P E R ENGINE FOR AERO-ENGINE MANUFACTURING P R O J E C T S

FIG. 4. TYPICAL TIME CYCLE CHART FOR THE ASSEMBLY AND TESTING OF TURBO-JET ENGINES

TOTAL PRODUCTIVE MANPOWER

16 2 0 24 PERIOD OF PRODUCTION aUILD-UP

36 4 0 4 4 46 S2 CONSTANT PRODUCTION RATE

MONTHS

^EDUCTION OF MANPOWER DUE TO EFFECT OF LEARNING

FIG. 5. TYPICAL MANPOWER FORCAST CHART FOR TURBO-JET ENGINE PRODUCTION

GERMAN HIGH COMMAND DOCUMtNT

REFERENCE ISSUE

FIG. 6. GERMAN WAR-TIME DOCUMENT. SUMMARY OF DIRECT MANHOURS PER UNIT O F ENGINE DRY WEIGHT

FOR PISTON AERO-ENGINE MANUFACTURING PROJECTS

GERMAN AR MINISTRY GU/C FERTG^r B

PRODUCTION PLANNING DATA

iDIRECT MANHOURS/B.H.P ( R A N G E S ) ENGINES TOTALS GERMAN HIGH COMMAND DOCUMENT REFERENCE ISSUE |A| M I 30JOOO I SSUE 'A' FEB ' 4 4

FIG. 7. GERMAN WAR-TIME DOCUMENT. SUMMARY OF DIRECT MANHOURS PER B . H . P . FOR ALL AERO-ENGINE

SPOOL-COMPRESSOR ROTOR

RELEASE TO

PRODUCTION

I Klirt- hPtC" B6«efO 1 peocfc»a£s wfrgefeo

AWINGS AVAILABLE

•

MATERIAL LISTS

LONG DATED MATERIAL ORDERING

^M ADVANCE DRAFTING 1 ADVANCE PLANNIN'

[ADVANCE T o d L DESIGN

/ MATERIALS-DRAFT PLAN-PROGRAMME

ADVANCE TOOL MAN

>ilANUFACT,URI.._ ' .11 i l l I I Pl^ANlilll'lÓ I M i l I I I I TOOL DESIGN. X X ^ I MANUFACTURING SPREAD I MAJOR COMPONENTS

_f

TOOL* MANUFACTURE ,1 i t—S 2 2. DELIVERY OF FIRST PRODUCTION ENGINE

X V X X I t XXXXXXXXX X

x x x x X X x x x X r r x x

. FIRSTS-BATCH COMPONENT -MANUFACTURE. » » i

MAJOR EQUIPMENT TIMING I PROFILE LATHE-UNIV.- (DISCS')

I I Jl

TTT

I I I ,> . 2. PROFILE L J 1 , T H E - ( I N T E R N A L SPOOL) -12 3 SERRATION GRINDER- (BLADES')

4 INTERNAL GROOVE EQUIP - (cOMP CASING)

i i u

5. BROACH EQUIP- ( B L A D E S » DISCs) J 5 6. MILLING E Q U I P - ( B L A D E G R O O V E S - S P O O Q J 6 7. MILLING EQUIP- ( C ' J T - O U T - S P O O L ) J 7

8.BORING EQUIP- (COMR C A S I N G ) _{J 6}

9. CURVIC GRINDER - (pISCs") _{_J9}

MONTHS

FIG. 8. TYPICAL OVERALL TIMING PLAN FOR THE MANUFACTURE O F THE FIRST PRODUCTION MODEL O F A T U R B O - J E T ENGINE P R O J E C T

KEY.

1. M A T E R I A L DEL» S B W I

2. DETAIL P L A N N I N G PtRCOD

3. JIG AND T O a DESIGN 1 4 TQOl IMG nFllfïPAN C

b o 6 4 è o 6 l i , . 1 iiiiniiiniA > —-—-^ K X ir X X X X 1 COMPONENT No. DESCRIPTION SPOOL-COMP ROTOR , 1 ' ( L I S T OTHER COMPONENTS OF T « SAME ENGNE SECTION

OKI THIS S H E E T ) l A T C H T I M E S=C iSSEMBLY A N D T LADE : • • . • . . 1 '-sTy///'////A 7 PROJECT: 1

PRODUCTION PLAN CHART- MATERIAL. PLANNING, TOOUNG. BATCH RELEASE. 1

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FIG. 9. PRODUCTION PLAN CHART FOR THE MANUFACTURE OF COMPONENTS FOR THE MANUFACTURE OF THE FIRST PRODUCTION MODEL OF A

OF COMPONENT

I J

INTERNAL PROFILING EQUIPMENT

MILLING SET-UP FOR BLAOE GBOOVES

MILLING EQUIPMENT FOB CUT-OUTS

SU3TTING EQUIPMENT FOB BlADt SI.OT5

(PLANNED) (ACHIEVED) I M4 MACHINE SHOP CYCLE TIME JOB HISTORY.

DELIVERY REQUIRED FOB INSTALLATION AND FUNCTION TESTMACHINE TO BE rULLY OPERATIONAL PPODUCTION STARTS

-FIG. 10(a) PRODUCTION P L A N CHART FOR THE MANUFACTURE O F LONG-D A T E LONG-D ITEMS FOR THE FIRST PROLONG-DUCTION MOLONG-DEL OF A T U R B O - J E T

ENGINE PROJECT

SKETCH Of

FORGING FURNACES

HEAT TREATMENT EQUIPMENT

BROACHING EQUIPMENT

SIGMA GAUGING EQUIPMENT

l ^ HIsmBV

ROTOR AND STATOR BLADES

PRODUCTION PLAN CHART-LONG DATED ITEMS PROJECT.*

MO>^H J F M A M J W / . S O N D J F M A M J I Y A S O N O

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(PLANNED') CACHIEVEOJ

MORE ROTOR STAGES

T T T

4-,

^ ^ M A C H I N E SHOP CYCLE TIMES ROT(3B BLADE STAGES

MORE STATOR STAGES STATOB

> BLADE

DELIVERY REQUIRED FOR WÏTALLAT10N AND FINCTION T E S T » -MACHINE TO BE FUUY OPERATIONAL - PHOOOCTlOi STARTS

FIG. 10(b) PRODUCTION PLAN CHART FOR THE MANUFACTURE O F A GROUP OF SIMILAR LONG-DATED ITEMS FOR THE FIRST PRODUCTION MODEL O F A

KEY TO SUB-ASSEMBLY STAGES No. 1 2 3 4 5 6 7 B 9 10 I I l 2 13 K '= D E S C R I P T I O N F R O N T B E A R I N G F R A M E C O M P R E S S O R C A S I N G

COMPRESSOR CASING-COMB C H « « E « CoiX'' I N - E T GUIDE .'ArJE5 ACCESSORY B O / No I T U R B I N E B A L A N C E S T A R T E R O I L P U M P FUEL P U M P V A L V E S TACHOMETER B U R N E R S

COWPPESSOa CASING BLADE ASSY REAR B E A R I N G No, 16 17 I S 19 2 0 21 22 2 3 2 4 25 2 6 2 7 2 8 29 3 0 D E S C R I P T I O N S C A V E N G E R P U M P R E D U C T I O N GEAR 6 U I L 0 A C C E i S Q S ' B O / N o 2 E X h A J f T L U C T M O T O R I N G RIG DISC L'JMPRfSiOR O l S C S . i M O l S fl/VD e t d O f S COMPRESSOR C A S I N G . F R A M E . I G.V

MOTORING RIG TEST STRIP

M A I N S H A F T TURBINE DISCS C O M R . E T E R/A B A L A N C E

ND::LES

OVERSPEED TEST - ROTOP CHECK AND F I N A L 6 A L A N C E ,

STRIP, W R S d H N S P f c r

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TEST BEDS, FINAL BUILD AND DESPATCH

—r-2 5 If^yRl. U3CK X cu«pAncM. — I 1 1 — 2 0 15 lO WORKING DAYS

FIG. 1 1 . TYPICAL CYCLE RELATIONSHIPS FOR ASSEMBLING AND TESTING A TURBO-JET ENGINE (FIRST PRODUCTION MODEL)