METAL THERMAL EXPANSION CHART

[MEXICOWANDERER]

Please allow this to run-it's-course. Then I can say I tried my best. ALUMINUM / COPPER / STEEL (set screw). This is what I have been yelling about...

Metal Temperature Range
(oF) Thermal Expansion
(microinch/(in oF))
Admiralty Brass 68 - 572 11.2
Aluminum 68 - 212 13.1
Aluminum Bronze 68 - 572 9.0
Aluminum Alloy - 2011 12.8
Aluminum Alloy - 2017 13.1
Aluminum Alloy - 2024 12.9
Aluminum Alloy - 3003 12.9
Aluminum Alloy - 5052 13.2
Aluminum Alloy - 5086 13.2
Aluminum Alloy - 6061 13.0
Aluminum Alloy - 7075 13.1
Antimony 5
Beryllium 6.7
Beryllium Copper 68 - 212 9.3
Bismuth 7.2
Cast Iron, grey 32 - 212 5.8
Cast Steel, 3% C

7.0
Chromium 3.3
Cobalt 6.7
Copper 68 - 572 9.8
Copper-Base Alloy - Manganese Bronze 11.8
Copper-Base Alloy - C1100 (Electrolytic tough pitch) 9.8
Copper-Base Alloy - C14500 (Free Machining Cu) 9.9
Copper-Base Alloy - C17200, C17300 (Beryllium Cu) 9.9
Copper-Base Alloy - C18200 (Chromium Cu) 9.8
Copper-Base Alloy - C18700 (Leaded Cu) 9.8
Copper-Base Alloy - C22000 (Commercial bronze, 90%) 10.2
Copper-Base Alloy - C23000 (Red brass, 85%) 10.4
Copper-Base Alloy - C26000 (Cartridge brass, 70%) 11.1
Copper-Base Alloy - C27000 (Yellow brass) 11.3
Copper-Base Alloy - C28000 (Muntz metal, 60%) 11.6
Copper-Base Alloy - C33000 (Low-leaded brass tube) 11.2
Copper-Base Alloy - C35300 (High-leaded brass) 11.3
Copper-Base Alloy - C35600 (Extra high-leaded brass) 11.4
Copper-Base Alloy - C36000 (Free machining brass) 11.4
Copper-Base Alloy - C36500 (Leaded Muntz metal) 11.6
Copper-Base Alloy - C46400 (Naval brass) 11.8
Copper-Base Alloy - C51000 (Phosphor bronze, 5% A) 9.9
Copper-Base Alloy - C54400 (Free cutting phos. bronze) 9.6
Copper-Base Alloy - C62300 (Aluminum bronze, 9%) 9.0
Copper-Base Alloy - C62400 (Aluminum bronze, 11%) 9.2
Copper-Base Alloy - C63000 (Ni-Al bronze) 9.0
Copper-Base Alloy - Nickel-Silver 9.0
Cupronickel 68 - 572 9.0
Ductile Iron, A536 (120-90-02) 5.9 - 6.2
Gold 7.9
Hastelloy C 70 - 200 5.3
Inconel 68 - 212 6.4
Incoloy 32 - 212 8.0
Iridium 3.3
Iron, nodular pearlitic 68 - 212 6.5
Iron, pure 68 - 212 6.8
Magnesium 14
Malleable Iron, A220 (50005, 60004, 80002) 7.5
Manganese 12
Manganese Bronze 68 - 572 11.8
Molybdenum 3.0
Monel 32 - 212 7.8
Nickel-Base Alloy - Nickel 200, 201, 205 8.5
Nickel-Base Alloy - Hastelloy C-22 6.9
Nickel-Base Alloy - Hastelloy C-276 6.2
Nickel-Base Alloy - Inconel 718 7.2
Nickel-Base Alloy - Monel 8.7
Nickel-Base Alloy - Monel 400 7.7
Nickel-Base Alloy - K500 7.6
Nickel-Base Alloy - R405 7.6
Nickel Wrought 77 - 212 7.4
Niobium (Columbium) 3.9
Red Brass 68 - 572 10.4
Osmium 2.8
Platinum 5
Plutonium 19.84
Potassium 46
Rhodium 4.4
Selenium 21
Silicon 2.8
Silver 11
Sodium 39
Stainless Steel - S30100 9.4
Stainless Steel - S30200, S30300, S30323 9.6
Stainless Steel - S30215 9.0
Stainless Steel - S30400, S30500 9.6
Stainless Steel - S30430 9.6
Stainless Steel - S30800 9.6
Stainless Steel - S30900, S30908 8.3
Stainless Steel - S31000, S31008 8.8
Stainless Steel - S31600, S31700 8.8
Stainless Steel - S31703 9.2
Stainless Steel - S32100 9.2
Stainless Steel - S34700 9.2
Stainless Steel - S34800 9.3
Stainless Steel - S38400 9.6
Stainless Steel - S40300, S41000, S41600, 41623 5.5
Stainless Steel - S40500 6.0
Stainless Steel - S41400 5.8
Stainless Steel - S42000, S42020 5.7
Stainless Steel - S42200 6.2
Stainless Steel - S42900 5.7
Stainless Steel - S43000, S43020, S43023 5.8
Stainless Steel - S43600 5.2
Stainless Steel - S44002, S44004 5.7
Stainless Steel - S44003 5.6
Stainless Steel - S44600 5.8
Stainless Steel - S50100, S50200 6.2
Tantalum 3.6
Thorium 6.7
Tin 32 - 212 12.8
Titanium 68 - 200 4.8
Titanium Alloy - Ti-5Al-2.5Sn 5.3
Ti-8Mn 6.0
Tungsten 2.5
Uranium 7.4
Vanadium 4.4
Wrought Carbon Steel 70 - 800 7.8
Yellow Brass 68 - 572 11.3
Zinc

[Gjac]

MEX said, "Still does not stop the aluminum buss bar from growing larger with heat " Wouldn't the Al set screw expand at the same rate having the same CTE as the Al buss bar?

[MEXICOWANDERER]

Still does not stop the aluminum buss bar from growing larger with heat. The vibration issue down here "encouraged" me to do away with set screws. A machinist friend made up a bunch of phosphor bronze 3/4" bars by machining them in an automated milling machine. 2, 4' square stocks. I SOLDERED 5/8" long silicon bronze dog point #10X32 studs (dog point means the tip of the stud is smaller with no threads to start nuts easier) and silicon bronze external tooth lockwashers and nuts were selected. This was a lot of work. I also made serious battery buss bars, using the same format. 3/4" thick, 3/8"X24 FINE thread silicon bronze studs, soldered, 4" wide. But these had heavy hex nuts 5/8" across the flats and bronze combination inside and outside tooth S/B lockwashers. Mounted on linen Bakelite pads. Cutting the pads made a terrible stink. Commercial fishermen went nuts over these items. The big bars were nickel plated 3-times thicker than normal nickel in Oakland. Silicon bronze withstands salt air fine, plating the buss bars protected the copper. They would cost a veritable fortune these days. Nickel plating or no, some of the buss bars passed 400 starting amperes at 24 volts with no hassles. These bars NEVER had problems with loosening. AC or DC.

[Gjac]

MEXICOWANDERER wrote:
Put Larry Curley and Moe in the same sack and near pandemonium reins.

Replacing steel set screws with phosphor bronze would make sense, but the price wouldn't.

On a hot summer day when thousands of air conditioners are working look at the sag of high voltage transmission lines between towers. Some of those conductors reach near 300F in open air. Expansion at work. Aluminum must be respected because it expands so much. I do not like electrical (or any other type of) RV fires!

So the moral of the story is to use Al set screws in an Al buss bar or retighten the steel set screws periodically because of steel is half of the thermal expansion of Al.

[MEXICOWANDERER]

Put Larry Curley and Moe in the same sack and near pandemonium reins.

Replacing steel set screws with phosphor bronze would make sense, but the price wouldn't.

On a hot summer day when thousands of air conditioners are working look at the sag of high voltage transmission lines between towers. Some of those conductors reach near 300F in open air. Expansion at work. Aluminum must be respected because it expands so much. I do not like electrical (or any other type of) RV fires!

[RCMAN46]

When I was working on large steam turbines with General electric sections of the turbine had bolts that were about 3-5 inches in diameter.

The bolts had a hole in the center. A cal rod heater would be inserted and the bolt heated. Then the nut would be tightened until the bolt was stretched by an amount measured with a dial indicator.

Also remember trying to drill a 1/2 inch hole in a 4 inch thick copper bus bar. You can only drill about 1/8 inch at a time then pull the drill bit out and let the copper cool. If you tried to just drill all the way the copper would cool and grab the drill bit and then almost impossible to get the bit out.

[MEXICOWANDERER]

Ever see a "Polka Step" painted on a dance floor?

That's what my back looked like after the DW made a midwinter midnight trip to the bathroom.

OK, here's what happens...

Ever try and remove steel spark plugs from a warm aluminum cylinder head?

Stuck tighter than a Bull's ... in .....

Warm bussbar freezes steel set screw.

Aluminum expands greatly around copper wire conductor.

Time after time after time. Causing the TIN coating to migrate

Recommendation

Use a brand new RV for the summer
Before storage tighten the loose buss bar set screws and check every other screw in the box.

After the second season tweak as necessary.

RV's that have heaters loading a breaker for many hundreds of hours should be checked annually.

On receptacle or toggle switches I use flat forked #6 terminals to attach wire to the screws. This positively STOPS problems. The fact that the terminals are TIN coated should not be overlooked. I solder the fork (spade) terminals to the wire.

[JaxDad]

There's one other one you missed;

The frozen feet of a DW can retract all the way across a King sized bed to find a warm DH.

[Gjac]

I must have missed some previous threads. Is this to show that dissimilar metals expand at different rates so if you use steel set screws in an Al buss bar they will loosen?

[Golden_HVAC]

On the 100 ton punch press that we had at Weiser Lock, they would heat the 24" long bolts to say 300F, then install them to a certain torque, before they cooled back to room temperature. It put a lot more pull on the bolts and held them very tightly. They where 3" and 4" diameter bolts with about 8 threads into the attachment side.

Now they have a new system. They use cap screws to raise the bolt into place. So basically you hand tighten the bolt into place. Then by tightening about 20 allen head screws to around 100 foot pounds, it will raise the head of the bolt from it's mounting surface, stretching the 3" bolt enough to put the equal amount of pressure on the fittings.

Fred.

[CA_Traveler]

OMG When I was in college we had to memorize the resistivity of a cubic inch of Anaconda red brass - but not the thermal expansion.

[westend]

Good efforts on the education front, Mex!

Yes, tightening load center neutral and ground bar screws should be done periodically. For my 12V distribution buses where a lugged cable is attached to a threaded copper bar, I chose to use two star lock washers and a nut on the fastening bolt. These are in a location where periodic tightening isn't easily accomplished. The ground-> frame junction gets some special treatment, also. Lately, i've used a protective spray formulated for battery terminals on most of these type of fasteners. The spray is an indicator of fastener movement and it also tends to "glue" the pieces as it is somewhat adhesive.