Going to the limits –
five centimetres short of them.
It may be a listed historical monument, but it can still perform – and it still gives its all: the mother of all machines, our 105-year-old reverse mill, known as the Wide Reverse Mill. This order really did push us to the limits: to roll a six tonne cast block measuring 320 mm high, 1280 mm long and 1650 mm wide – a considerable chunk of metal – into a gigantic flat sheet. Our customer required these final dimensions: 32 mm thick, 5500 mm long and 3900 mm wide. The whole thing was made of CuAg 0.1 P allow, which means copper alloyed with 0.1% silver; it was destined to be used for cooling purposes in a vacuum crucible.
We proceeded in two rolling processes. In the first rolling pass the block was rolled to a length of 3950 mm; its thickness still measured around 10 cm (95 mm). We then sawed the rolled edges down to the required width of 3,90 metres (3900 mm), leaving just the length to deal with. This was done in the second rolling pass. After just 12 minutes we had produced 5.50 metres at a height of exactly 3.2 cm and a width of 3.9 metres – the final dimensions.
Incidentally, the final width of the Wide Reverse Mill is 4.0 metres, leaving 0.5 cm to spare at either side – barely enough to catch your breath in, let alone for material expansion. Inserted incorrectly just once and the sheet would have been ruined and good for scrap. But it worked. If it fits, it fits.