[TheForge] foil, sheet and plate

[Dave Smucker]

In my experience, the dividing line between plate and sheet is about 11 gage (gauge) or about 1/8 inch.  In ferrous metal there is very little foil produced since it becomes so hard to roll at very light gauges.  There are some special products for which it is produced in foil gauges but very expensive.  The technical reason for this is that as the metal gets very thin the rolls flatten rather that the metal being rolled.  Special mills with very small rolls can deal with this but they are costly to run and maintain.  I would call the break point between sheet and foil at around .001 being foil.  Some would define the break point between sheet and plate as the point where it becomes difficult to coil the metal but today very heavy gauges are coiled.

In the aluminum industry the break points are quite clear.  (Gauge numbers are not use in aluminum only inch thickness or mm thickness).  The break point for sheet to plate is 0.125 being sheet and thicker being plate.  The break point for sheet to foil is normally at 0.001 being foil and above being sheet.  When I was the division engineer for foil at Alcoa's Davenport Works we rolled lots of foil down to 0.00025 for packaging products.  We had even rolled, with great difficulty some 0.0001 foil for the Echo Satellite in the 1960's.  (before my time)  Light gauge foil is all pack rolled - rolled by placing two thickness together through the mill with a light film of oil between them to keep them from welding together.  This is why when you look at your household foil it has one shinny side (next to the roll) and one matt side next to the other aluminum.  The reason that you can roll aluminum to foil much easier that steel is that pure aluminum it not near as strong as steel.  Almost all aluminum foil is 1100 or nearly pure aluminum.  Again roll flattening is an issue and all foil is run with the rolls "below face" in other words with no metal between the rolls the mill is still loaded.  The edges do pinch and the metal must be trimmed at each pass.

The Davenport foil mill has been closed for many years now and foil is no longer produced at this site.

Dave Smucker
Brasstown, NC

-----Original Message-----
From: theforge-bounces at mailman.qth.net [mailto:theforge-bounces at mailman.qth.net] On Behalf Of terry l. ridder
Sent: Sunday, July 2, 2017 6:31 AM
To: theforge e-mail list <theforge at mailman.qth.net>
Subject: [TheForge] foil, sheet and plate

hello

considering ferrous metals only.

what defines the dividing line between foil and sheet?
what defines the dividing line between sheet and plate?

aluminium, copper, brass, etc will all have different criteria.

--
terry l. ridder ><>
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