PDA

View Full Version : Why is solid material cheaper than tubing?



KiddZimaHater
10-03-2012, 10:35 PM
I make alot of bushings, tubes, sleeves, etc. for customers, and I'm puzzled by material pricing.
Why is Solid material less expensive than Tubing? (in most cases)
Here are some examples I came across:
2-1/2 OD X 1" ID steel tubing = $96.00 per foot
2-1/2" Solid 1018 steel = $31.00 per foot
:eek:
2" OD X 1" ID Aluminum tubing = $17.00 per foot
2" Solid Aluminum = $15.00 per foot
:p
So my question is:
Why would material with the same OD, but a giant hole in the middle, be more expensive?
Doesn't make sense does it?
:confused:

darryl
10-03-2012, 10:47 PM
DOM costs more in manufacturing. I think rolled and seam welded is a less expensive production process, but still it is another step in the production of the material. You've mentioned two very heavy wall tubings, so I'm not surprised that the cost is not reflected in weight of materials alone. Solid shapes are mostly just rolled to size, so it's minimal in production costs.

Try sourcing accurate to size and shape materials and see what they cost.

JoeLee
10-03-2012, 10:51 PM
I think darryl summed it all up. Manufacturing costs are greater than material costs for most alloys.

JL...................

Boostinjdm
10-03-2012, 11:06 PM
That steel "tubing" you mentioned is actually DOM it is rolled and welded then Drawn Over a Mandrel cold to remove the weld flashing. That is why it is more expensive.
The aluminum is extruded to shape and the hole requires a bit more finicky equipment than the solid so it is only a little more expensive.

becksmachine
10-03-2012, 11:20 PM
Ok, look at it this way.

All of the sizes you listed have wall thicknesses that can't be made by rolling and welding flat strip into a pipe/tube shape.

Consequently the option available to the manufacturer is the same option available to us in our shops, take a solid bar and put a hole in it somehow. Obviously additional labor makes the same bar, with a hole in it, cost more than the bar without a hole.

Depending on the method used, there will be some savings in material, but as we both know, those chips we make all day are not worth nearly as much as the time it took to make them.

Dave

wierdscience
10-04-2012, 12:31 AM
Heavy wall mechanical tubing is made by rotary piercing-

http://en.wikipedia.org/wiki/Rotary_piercing

Like already mentioned it's expensive to do,however so is drilling out the center of a solid.

When I plan a job IF a heavy wall tube can be had where it can be cutoff and skimmed to ID dimensions with a boring bar that is usually the way to go assuming the amount of material to be removed is less than 10% of the OD.More than 10% and boring will take to long at which point drilling from solid close to dimension and then boring is best.Finding the best cost/time curve is the trick.

In Aluminum the numbers are closer since 99% of Aluminum bar stock is extruded.

You might give these folks a call-
http://www.southerntoolsteel.com/index.html

I've gotten better prices from them on HWMT than from Speedy,they also offer toolsteel hollow bar in all grades.

Black_Moons
10-04-2012, 04:49 AM
That steel "tubing" you mentioned is actually DOM it is rolled and welded then Drawn Over a Mandrel cold to remove the weld flashing. That is why it is more expensive.
The aluminum is extruded to shape and the hole requires a bit more finicky equipment than the solid so it is only a little more expensive.

as I understand it, DOM tubing starts its life as a solid and is actualy punctured and drawn over a mandrel, hence why its so much stronger then regular welded tube: No weld to weaken it. Its also expensive as hell compared to welded tube.

ecortech
10-04-2012, 06:34 AM
as I understand it, DOM tubing starts its life as a solid and is actualy punctured and drawn over a mandrel, hence why its so much stronger then regular welded tube: No weld to weaken it. Its also expensive as hell compared to welded tube.

Very common misconception.
Most commonly available DOM is welded seam tube that is drawn over a mandrel sizing both the i.d. and o.d.
The size of DOM is held to a much tighter tolerance than ordinary welded tube, also no weld flash on the i.d. due to the sizing operation.
The drawing process also work hardens the tubing to a degree.

Ed

Forrest Addy
10-04-2012, 06:41 AM
as I understand it, DOM tubing starts its life as a solid and is actualy punctured and drawn over a mandrel, hence why its so much stronger then regular welded tube: No weld to weaken it. Its also expensive as hell compared to welded tube.


Seamless tube and pipe is not so much stronger but as a pierced and rotary forged product the material is homogenous and more reliable as a pressure boundry or a stressed structural element. High pressure steam hydraulic, aircraft and race car parts, and lot of other high confidence applications require seamless tube or pipe. Seamless is not necessarily stronger than DOM or butt welded but you can safely work it closer to maximum properties specs. Thus more bang for the weight.

RLWP
10-04-2012, 06:55 AM
The only exception I can think of would be centrifugally cast pipe

Richard

justanengineer
10-04-2012, 07:26 AM
Its bc so much of that solid stock is actually billet and the manufacturer can skip a few extra steps at the end of the process.... ;)

bosox
10-04-2012, 11:31 AM
Actually, the manufacturing process sums it all. More processes involved, additional cost.

DR
10-04-2012, 01:01 PM
As someone else pointed out, wall thickness is a major factor in price comparison.

Go to online metals site and do some comparisons. 2" solid round cold finished 6061 aluminum is three times the cost of same material in 2" OD tube with a thin wall.

Forrest Addy
10-04-2012, 02:40 PM
Hey! That's right. The starting material for piercing IS rightly called a "billet". It was rolled from an ingo into a bloom, then cropped into segments for further processing into rods, rounds, shapes, and tube.

See? There is a use for the term "billet" besides dyed anodized blister packed "Amaze Your Friends" pseudo speed equipment.

lazlo
10-04-2012, 06:25 PM
Seamless tube and pipe is not so much stronger but as a pierced and rotary forged product the material is homogenous and more reliable as a pressure boundry or a stressed structural element.

I can confirm that first-hand: I've forged DOM tubing, and as soon as you get it hot, you can see the seam, and like normal welded tubing, the seam will split from hammering long before the parent metal.

Peter S
10-04-2012, 09:49 PM
Here are some examples I came across:
2-1/2 OD X 1" ID steel tubing = $96.00 per foot
2-1/2" Solid 1018 steel = $31.00 per foot

Can you guys buy tubing of this size in the USA? That is serious stuff, and I would expect much more expensive than solid.

We sometimes use Hollow Bar, but it is usually/always? higher strength than mild steel, so more expensive material and more expensive to make, yet still ideal for some jobs.

DR
10-04-2012, 09:58 PM
I can confirm that first-hand: I've forged DOM tubing, and as soon as you get it hot, you can see the seam, and like normal welded tubing, the seam will split from hammering long before the parent metal.

DOM or seamless DOM? I've seen the seamless material being pierced, there definitely is not a seam.

I bet a lot of the welded DOM tubing is sold as seamless DOM.