Principles of Software Flow

Woollard and the origins of Flow Production

Professor John Seddon has published an excellent article challenging the conventional wisdom around the need to achieve economies of scale.  I whole heartedly agree with the point being made, and the conclusion that is reached: “Economy of scale is a myth. Economy comes from flow.”

I would, however, like to challenge one assertion that is made: that the benefits of flow were first identified by Taiichi Ohno at Toyota.

Ohno minimised stock throughout the process, his ideal batch size being one. Whereas most manufacturers still focus on unit costs (and employ accountants for whom it is central to their doctrine: for example, inventory counts as ‘value’ on the balance sheet), Ohno focused on the flow of the work, confident that better flow would lead to lower overall costs. And so it did. His system would tolerate higher unit costs; it was not dependent on low costs per unit. What was critical was the availability of the part, not the cost – an affront to convention. Ohno was the first to demonstrate that greater economy comes from flow rather than scale.

His second and more profound challenge to convention was to put variety into the line, making different models in the same production line.

Why do we believe in economies of scale?

These principles were identified by Frank G. Woollard, who introduced flow at Morris and Austin.  In his 1954 book “The Principles of Mass and Flow Production” he set these principles out in detail.  On the subject of minimising stock and work in progress he writes on page 69:

One of the many advantages of flow production is that it reduces the inventory, that is the stock in stores and the work in progress…  The ideal objective… is an inventory kept to the lowest figure consistent with the maintenance of the flow of supplies to the production lines.  The reduction of working capital or the improvement of the liquid position due to a smaller inventory is not the only advantage; the lesser bin capacity absorbed, the smaller stores area required and the saving of double handling and of multiple paper-work are all very real economies.  Incidentally with flow production methods the reduction of inventory may be a as much as 75 per cent and even more.

Page  69 of Principles of Mass and Flow Production

In his article Professor Seddon presents a clear progression from Smith through Ford to Ohno, with manufacturing laboring under Smith’s flawed theory until Ohno developed the Toyota Production System.  Woollard’s writing suggests a more tragic story, where these principles were well understood in the factories of Britain’s industrial heartland, only to be lost in the decades that followed.  It seems likely that the principles were preserved or possibly rediscovered by Toyota.

In his comments on page 84 regarding the production of multiple products on a single production line Woollard shows that this knowledge was well dispersed and not limited to Birmingham, England.

At one period, for instance, the Ford Motor Co. handled, in sequence, all current types of cars and trucks – without pause or intermission – on one assembly line.  To-day, in their assembly plant, the Austin Motor Co.handle three body types and right- and left- hand steering on the same assembly track.  One American concern assembles 500 different sizes and types of air cleaners on one conveyor line.  They do not, in this instance, come in sequence but by a changeover limited to a 24 hour run for any one model.  These mutations can be matched on the machine lines provided sufficient care and attention is given to jig and fixture design, and the method of changing tools is carefully studied.

Page  84 of Principles of Mass and Flow Production

Seddon observes that the true cost in the public-sector factories is about the human factors and not just the economic figures.

One cost that is apparent is sickness, absenteeism and staff turnover. Being treated as a ‘resource’ to be ‘optimised’ is not motivating. Nor is the realisation that it is impossible to help people solve their problems because of the need to work to the internal arbitrary measures. In some respects life in modern public-sector factories is little different to the conditions that created Ford’s ‘five-day man’[4]. Both HMRC and NHS Direct currently report low levels of staff morale.

Why do we believe in economies of scale?

The fact that human engagement is more important than machine utilisation was also observed by Woollard and his contemporaries.  He relates this on page 45.

The Scani-Vabis Company of Sweden… claim that on group production there is a reduction of the cycle time fo some 40 percent; that the morale of these lines has been improved; that the workmanship is of higher quality; that the training time has been reduced, and that a greater degree of expertness is acquired.  They say that this latter is largely due to the greater interest engendered by several jobs flowing through the line.  It is true that certain machines are working at 10 per cent to 15 per cent less efficiency than would be achieved on the batch method : but, that be all, it is a small price to pay for the general improvement due to the group production system which they are hoping to extend.

Page  45 of Principles of Mass and Flow Production

Woollard saw the potential for Flow production as another “complete turn in the industrial revolution” (page 15) but he was also aware of the dangers and limitations.  Regarding human matters the warning given by Woollard in his closing comments is poignant  considering the tragedy of the decades that were to follow.

On the human side it must also be watched, for – like all tools of management – it can be misused.  Flow production, with its obvious sequences and accurate timing, could be the instrument of a slave-driving tyranny, whereas properly employed it will promote discipline in an equitable and gentle, if irresistible, manner, making the daily task lighter for all.

Flow production is, in fact, a logical development that has tremendous advantages and when properly applied is of benefit to the whole community.  These methods may not promote any individual art but they can provide a common basis for a comfortable existence , and, when they relieve mankind of the more arduous labours – as ultimately they will – those who labour can, if they desire, follow their bent as individual craftsman in their extended leisure hours

Page  187 of Principles of Mass and Flow Production

Growing up as a child in the 70s Birmingham was dominated by the motor industry and strikes and conflict.  Now very little of that motor industry remains.

The 1970’s and its associated strikes and management problems decimated the industry. Japanese imports made matters worse and the car and motor cycle industry went through many mergers and closures. The great names such as BSA and Triumph lost ground against the Suzuki’s and Yamaha’s from Japan and the Datsun and Honda’s looked set to finish off what remained of the British Motor Industry.

In Britain it was the mindset of slave-driving tyranny tyranny that triumphed.  Since Woollard’s time we have traveled further and further away from the goal of equity.


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