29. The ‘World class OEE’ trap in machine productivity monitoring

An OEE pitfall to avoid in machine monitoring
A big mistake a lot of organizations make is to be obsessed with OEE as an absolute value, and set a ‘Pass or Fail’ number, like in a school exam. They set an arbitrary number (like 60 %) and strive desperately to achieve this number. Once they achieve it, they think their job is done, and sit back and relax.

One such arbitrary number is World Class OEE. This is generally accepted to be 85 %. The roots of this number are in mass production, in the automotive industry. To achieve this, you would need these numbers for A, P and Q:
A = 90 % (10 % downtime between cycles)
P = 95 % (5 % downtime within cycles)
Q = 99 % (1 % part rejection)
If yours is not a mass production industry, it is going to be very difficult (or even impossible) to achieve this number. In mass production the process is set, tooling is fine tuned to a single part, there is no downtime for setup change, and various other downtimes can be minimzed by daily analysis and fine tuning of the process and equipment. In small batch production your production batch sizes are small, frequent setup changes add hugely to the downtime, and the process, tooling and machines are not fine tuned to any of the parts that you are making. In small batch production, OEEs between 50 % and 60 % are common.
Within a single organization itself, multiple plants or cells could be doing different types of parts, some mass production and some small batch production. How then will you set a single OEE target for these widely different types of production ?
Don’t be obsessed with the absolute value of your OEE. Instead, use it as a measure of productivity that needs to be improved, month on month. It could be just 40 % now, but the point is to increase it steadily, by say 1 % every month. Set a target for periodic improvement, not an absolute value.
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Etc
Biryani and Pulao – what’s the difference ?
The word Biryani is derived from the Persian word ‘Birian’. In Persian, Birian means ‘Fried before Cooking’. Meat (or vegetables) is fried in ghee and half-cooked. Separately, rice is fried in Ghee and half-cooked. The rice and meat are layered in a vessel called a Handi. You can see the layers in the vessel, and the different layers are visible and have a different taste when served.

Biryani – in the Handi and on the plate
Pulao is from the Persian word Pilaf. Rice is browned in oil, and separately, meat (or veg) is fried in Ghee and cooked with aromatic spices in water. The rice and this broth are mixed together and cooked. The pulao is a homogenous mixture when cooking, and looks and tastes homogeous when served.

Pulao – vegetarian and meat-based
The difference between biryani and pulao is in the LAYERS. Biryani has layers, while pulao does not. So Biryani is multi-dimensional and more interesting as you eat it.
I first learnt this about this difference about 10 years ago, in a restaurant in Bangalore called Biryani Merchant (no longer in existence, sadly). They served 3 different types of biryani on any given day (out of the 10-odd types in India). There was a leaflet on each table educating you about biryani. The menu was fixed, and you paid a fixed amount, ate as much as you could. Way back then, as a young lad of 45 I could put away vast quantities of food. Owners of ‘eat-all-you-can’ establishments used to shiver as I walked in, thinking of the damage I was about to do to their balance sheet.
India has a large variety of Biryanis: Lucknow, Hyderabadi, Kashmiri, Ambur, Kolkata, Bohri, Calicut, Tahiri (this is a vegetarian biryani).
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