Not sure if I'm on the right tangent, but what comes to my mind is "disposable" tooling - hacksaw blades, drill bits even screwdriver bits. Even screws (let alone nails) are rarely re-used these days. Each part may be very small (grams) but as there as so many people using so many of them in daily life (both professionally and DIYers), I would have thought the totals would added up fairly quickly. Likewise some parts are 'over supplied' - e.g. the last lock I bought came with two faceplates and two latch plates (one each brass and chrome) - so half were intended to be thrown away unused.

   - Andy.

I would have thought that the bits that wear out and get replaced frequently (blades, cutting teeth, etc) would be relatively small compared with the overall machine.  Does anyone have any idea how much metal that adds up to Worldwide over a year?

What do you mean by scrap? Many metals can be reused with a much lower environmental cost than smelting the metal from ores.

Casting rather than machining can aparenty reduce scrap, but what is the overal balance

Hi Simon, UK Gov and Eurostat have some great data: Approx. 8mT a year of commercial metal waste every year from foundational manufacturing industries in the UK alone. In the EU this is worse, around 600mT. 
I am hoping to use this platform to reach out to a network of professionals which can provide some more detailed examples in the context of these manufacturing processes and industries, such as mining, recycling, waste, metal manufacturing, paper, plastics, transport etc.

Hi Roger, in this case I am talking about large metal components such as dies, roll mill rollers or mining / tunnelling equipment, crushers etc. These components are often multi-tonne parts that are replaced when worn out as opposed to being reclaimed.
I am hoping to use this platform to reach out to a network of professionals which can provide some more detailed examples in the context of these manufacturing processes and industries, such as mining, recycling, waste, metal manufacturing, paper, plastics, transport etc.

Anything come to mind?

Cheers,

Alex

Hi Andy, an interesting thought. I am sure so much waste comes from the examples you have given. Unfortunately, the only data available classes all this as "domestic waste" and we do not have any information in the public domain that is more detailed.
It would certainly be interesting to run a survey and try to establish how much "over-supplied" or "multi-option" parts contribute to this issue, thanks for the thought provoking comment.

In my experience many of these large components will be replaced when worn out to minimize downtime. They may then be sent for repair or rebuild if possible. Sometimes building up a worn surface by metal spraying/welding and then regrinding is possible, in other cases it may be difficult to reach the required specification so melting down as scrap is the sensible option. For example:

www.precisionrolls.com/

I have no connection with them, it was just the first one that came up when I searched.

The metal industries are in general very good at recycling scrap and have done so for decades. Consumer electronics and white goods are a bigger problem, as are Lithium based batteries and composite wind turbine blades.