Business & Management The principles of Lean

TIMWOOD – Inventory & Motion

A continuation of “Wasteful thinking..”, an abridged version of the series of articles by Andrew Malson, first published in WHERE To Print magazine.


Surplus inventory impacts working capital, takes up space and takes time to manage. On the other hand, if your business isn’t cash restrained and you have the space and time to manage it, holding “excess” inventory may provide better purchasing terms, reduce lead-times for production and create a more “agile” supply chain. What is absolutely critical is that the business never loses focus or control over inventory.  

When a print business relies on small, frequent customer orders, producing the next one, maybe even two, order cycles can be a profitable approach but I’ve known businesses applying this methodology across a broad range of order lines, with orders that are only required once a year. This gets out of control quickly and expensively; keeping inventory, of anything requires time and effort to manage it. In one example, I took over running a media print business that had CD cover print in stock, where the CD had been out of production for at least 5 years!

A glimpse into a recurring nightmare of a Lean practitioner

Work with suppliers to help manage inventory. Suppliers may provide consignment stock or other favourable terms but also, when managing substrates, determine how many different types, sizes and grammages are really required? Does a check of the paper store result in an annual clear out, or prompting a decision that a previously “inappropriate” size or grammage has now become appropriate? These examples suggest an inefficient and wasteful approach to Inventory.

An effective tool from the Lean “toolbag” is Red Tagging. Red Tagging will give a fair indication of how inventory and location is being managed. One would hope that everything is easily identifiable; that it is current and useful but as someone once said, “hope is not a management technique”.

Red Tags as applied in a print business I ran in Poland

Printers should understand their ink usage as accurately as possible and assess stock levels with usage volume compared to availability of supply. Ink manufacturers produce in multi tonne batches for CMYK and most of the Pantone ® colours, there needn’t be vast inventory, managed stock reduces waste without adding unwarranted cost. If spot colour work is low, plan to mix in-house, if spot colour usage is above 5 kilo, have the ink supplier mix it. Where there is a volume of unspoilt ink and a requirement for a frequent spot colour, the ink supplier can match the spot colour using the old stock; with spectral analysis they will find an accurate match, in almost all cases.


Whilst the health benefit to office staff is laudable, as they complete their 10,000 steps per day walking from admin to production, is this really necessary? If there is one thing that the COVID situation has taught us, from a business perspective, it’s that travel is not always necessary (I’ll not state the obvious regarding planes, trains and automobiles); can your future meetings between be conducted online?

Where’s the production meeting today?

In my last assignment, the daily production meetings were held in a building adjacent to the main production hall, up three flights of stairs and involved at least 14 people from all over the plant. As I wrote that, I realised that there were only 3 attendees that worked in that same building, a huge waste of people movement. We could have “onlined” it just as effectively and set face to face meetings, with specific attendees, in specific locations, at other times of the day.

Another aspect of motion waste is the manner in which we conduct and perform set up, or make ready, on our equipment. In an ideal world, we would move, seamlessly, without stoppage from the end of one job to the next but this is impossible. We must change plates, inks, paper, tooling and other settings; whilst we might strive for elimination, we must settle for minimisation.

The Spaghetti diagram

The simplest and least costly, the Spaghetti diagram, is scalable, meaning it can expand to cover areas outside of one machine (or workstation, this is an excellent tool for the office); it is quick to record and can be done over a relatively short period, a single shift, for example. The idea focusses on the movement an individuals do to perform their tasks over a given time (this can apply also to one individual); for every motion, a line is drawn that represents the distance and direction of movement. Analysis of the resultant diagram will identify repetitive motion and how best to relocate objects, tools or equipment to reduce motion waste.

This spaghetti diagram was used to analyse movement patterns on a rotary flexo/diecutter producing millions of boxes per day

SMED (Single Minute Exchange of Die)

SMED takes this a few steps further and is defined in its use as a method to specifically reduce make ready/change over times. The object of SMED is to externalise all tasks where possible, ensuring that the operator has everything needed to quickly and efficiently begin processing the next job. In simple terms, externalise means to maximise as many operations as possible away from the machine in order to have the components ready and available at the required time (for example, mixing spot colours in preparation for the next day’s production).

The pinnacle of SMED thinking, an F1 pitstop. The evolution here has jumped a few “generations” but one can imagine the teams analysing the videos, post race, to see where the smallest of gains can be made.

I have implemented SMED on numerous occasions and it has always proven beneficial. I can also testify that the operators that went through the SMED process were positively motivated after undertaking the training; they were directly involved in improving their working day.

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