Sheet Metal

Sheet Metal Materials:

‘What is sheet metal?’

The most basic question is ‘What is sheet metal?’  Sheet metal is metal that has been formed into a sheet that is thinner than bar stock, but thicker than foil.
[ However, the most common thicknesses are less than ¼” (6.35mm) thick.]

'What is Plate?'

when a sheet of metal reaches a critical thickness and cannot be used on a turret punch, but rather a CNC machine, it is called a plate.  
[Usually this includes sheets of metal that are 3/16” (4.76) or thicker.]

Types By Material:

• Sheet metal can vary in thickness and types of metals. 
• Plates are categorized by their thickness and labeled by it as well.  Quarter inch steel hot rolled plate is just called, ¼” HRS (Hot Rolled Steel).  
• Sheets of metal thinner than 3/16” are categorized by thickness as well, but the actual thickness is converted into simpler numbers referred to as “gauges” for steel.   

Below are the conversions of gauges into inches for steel:

                10 gauge steel = .135”
                11 gauge steel = .120”
                12 gauge steel = .104”
                13 gauge steel = .090”
                14 gauge steel = .075”
                16 gauge steel = .060”
                18 gauge steel = .048”
                20 gauge steel = .036”
                22 gauge steel = .030”
                24 gauge steel = .024”
                26 gauge steel = .018”

• As the thickness decreases, the unit in gauges increases. 
• There is a completely different system of metric measurements that are less commonly used in the United States. 
• Aluminum is a whole branch of sheet metal by itself.  There are so many different types of Aluminum; certainly too many to list here. 
• Aluminum sheet metal thickness uses inches instead of gauges like steel.

Sheet Metal Types

There are as many types of sheet metal as there are types of metal. If an alloy can be stretched out into a sheet, that is all it takes to be sheet metal. Sheet metal is categorized by their thickness as mentioned above, but then further categorized by its hardness, method of manufacturing, tensile strength, alloy composition, and quality.  With all these different variables, the types are endless.

VIP works with a wide variety of sheet metal types, but here are the most common:

CRS (Cold Rolled Steel) –

CRS is pressed into a sheet in a cold state at the steel foundry.  It has a more homogeneous composition than Hot rolled steel (HRS), which allows better heat conductivity and is easier to machine.  Most of our steel sheets are CRS as well as our bar stock that the machine shop uses. 

HRS (Hot Rolled Steel) –

HRS is formed into a sheet in a molten state and rolled flat while still hot.  HRS is usually of less quality than CRS, is more difficult to machine due to variable composition in the metal.  Most often, VIP uses HRS for thick plate.  Olea uses 3/16” HRS plate for their base plates on most of their kiosks.  Also, the base for mailboxes is 3/16” HRS.  Thin HRS is very rare.

Aluminum – 

This metal comes in many forms, but the most common type is 5052-H32, which is an Aluminum alloy.  Aluminum alloys are mixtures of aluminum with other metals, often with copper, zinc, manganese, silicon, or magnesium. There are too many alloys of aluminum to list.  VIP uses, 5052-H32, 6061-T6, 6061-T4, 2024-T0 for most of our parts.  The number after the 4 digit code is the tensile strength or temper of the alloy that ranges from T0 to T6.  T0 is soft, and T6 is full hard. 

The International Alloy Designation System is the most widely accepted naming scheme for wrought alloys.  Each alloy is given a four-digit number, where the first digit indicates the major alloying elements.  Below gives a description of the different series of aluminum based on the first digit for the major alloying elements:

1000 series are essentially pure aluminum with a minimum 99% aluminum content by weight and can be work hardened.

2000 series are alloyed with copper, and can be precipitation hardened to strengths comparable to steel.  Formerly referred to as duralumin, these were once the most common aerospace alloys, but were susceptible to stress, corrosion, cracking, and are increasingly replaced by 7000 series in new designs.

3000 series are alloyed with manganese, and can be work-hardened.

4000 series are alloyed with silicon.  They are also known as silumin.

5000 series are alloyed with magnesium, and derive most of their strength from work-hardening. It is suitable for cryogenic applications and low temperature work.  However, this type of alloy is susceptible to corrosion above 60°C.

6000 series are alloyed with magnesium and silicon, are easy to machine, and can be precipitation-hardened, but not to the high strengths that 2000, and 7000 can reach.

7000 series are alloyed with zinc, and can be precipitation hardened to the highest strengths of any aluminum alloy.

8000 series is a category mainly used for lithium alloys.

Stainless Steel (CRES) – 

Stainless Steel is an alloy based on chromium and steel and is categorized by its resistance to corrosion.  The gauge thickness is the same as regular steel. Stainless is much harder than regular steel and is not easy to work with in some respects.  Our lasers love it and have no problem cutting it.  However, it is difficult to punch, and can be difficult to weld.