Just been told that my supplier can't do CDS for my trailing arms. He can do CFS. I've never heard of this before.

I've got a couple of hours before i need to go and buy the stuff.

So trailing arms - wanted to use 2mm but will accept 1.5mm (although i appreciate this means I'm pushing it doing anti squat).

what's the difference in strength between CFS and ERW and therefore which should I go for? As all the loads (if not using anti squat) should be push or pull will 1.5mm ERW be strong enough for a road car?

those cfs ones are fibreglass and I'd steer well clear

linky



EDIT
I'll get my coat

[Edited on 5/2/09 by liam.mccaffrey]

As far as I can see CFS is CDS. The CFS comes from the old BS for Cold Drawn Seamless. This was BS6323 PtIV CFS3 and I believe know to be EN10305.

Ask the supplier for the full description. Also you could do with knowing the condition ie annealed/normalised/as drawn which could have more of an impact on it's suitability than the actual spec.

quote:

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So trailing arms - wanted to use 2mm but will accept 1.5mm (although i appreciate this means I'm pushing it doing anti squat).

---

Anti squat puts a bending stress on the arms.

CFS - the supplier said its not as strong as CDS, hence the asking.

CFS - Cold Formed seamless
CDS - Cold Drawn seamless

[Edited on 5/2/09 by MikeR]

Mike, The only references I can find to Cold Formed Steel Tube are all for the construction industry. It does not sound suitable to me.

thanks Mike - looks like i'm going to be going for ERW then unless peeps say "NO" and deciding if its 1.5mm or 2mm

(issue with 2mm is i need to get a bit of metal to fit inside it turned down which is an inconvenience)

i thought cds was cold drawn seamless?

I would be happy with 1.5mm tubing if the car were mine. I cant see how antisquat would lead to a bending action though?

[Edited on 5/2/09 by JoelP]

sorry, CDS is seamless .... i was rushing over lunch, correcting the original post now,.

This May Help

Thier descriptions:

Electric Resistance Welded (ERW)
Cold formed, electric resistance welded tubing can be produced in round, square or rectangle shapes. ERW tube is produced by processing a flat rolled steel into strips which are cold-formed, welded and seam annealed or normalized (depending on the manufacturer). You can usually identify ERW tube by the blue strip down one side of the tube (which is the welded area). The ERW process can guarantee the weld to be as strong or stronger than the rest of the tube body. The origin from a flat strip results in a more concentric product than Cold Drawn Seamless (CDS). ERW can also be known as CREW (Cold Rolled Electric Welded).
Typical Applications:
Structural columns, beams, supports, heavy equipment frames with 58,000 PSI tensile.

Cold Drawn Welded (CDW)
Produced from a steel strip by cold forming, electric resistance welding (ERW) and cold drawing to finished dimensions, CDW is the most versatile and widely sold mechanical tubing grade. A variety of thermal treatments can be applied to alter the mechanical properties and machinability. CDW is used for a tremendous variety of machine parts where close tolerances and higher mechanical properties are needed.
Typical Applications:
Automotive components, shock absorbers, hydraulic cylinders, sleeves, bushings, axles and shafting.

Drawn Over Mandrel (DOM)
DOM is formed from strip and Electric Resistance Welded (ERW) then cold drawn through a die and over a mandrel resulting in improved inner surfaces and dimensional quality. This process, called cold drawing, may be repeated more than once to reach the planned OD, ID, or wall dimension. Multiple draws can also be used to increase the strength or improve the surface finish of the tubes. During the drawing operation, the tubes may be process annealed to increase the ductility of the material. Lower cost alternative to CDS with equal or superior physical properties.
Typical Applications:
Machined parts, rollers, shafts, sleeves, steering columns, axle tubes, drive shafts, bushings and is most readily adaptable in cylinder applications with a 80,000 PSI tensile.

Cold Drawn Seamless (CDS)
General purpose seamless tubing, which is a solid bar of carbon steel drawn over a mandrel to form the tube section. CDS allows selection of chemistry and rough tube size. Cold drawing produces higher physical properties without heat treating. Offers widest range of sizes and chemistries in mechanical tubing. Better tolerances and reduced machining allowances over Hot Finished Seamless (HFS).
Typical Applications:
Machined parts, bushings, spacers, bearings, rollers, shafts, sleeves and cylinders with a 75,000 PSI tensile.

Cold Rolled Electric Welded (CREW)
Cold rolled steels are steels that are shaped by high pressure rollers at normal temperature in the steel mill. Cold rolling work hardens the material substantially. The steel is then welded by the electric weld process. A cold rolled steel can be either a mild steel or a high carbon steel. Can also be termed as ERW (Electric Resistance Welded). See » ERW

Hot Rolled Electric Welded (HREW)
Hot rolled steel is steel that is rolled to size in the mill while red hot. Hot rolling steel does not work harden it as much as cold rolling. For this reason, hot rolled steel is more easily machined than cold rolled.

What's the difference between Tube and Pipe?
The general term for pipe was that it was primarily used for carrying gas or liquid. It was not intended for structural use because the dimensions used in describing pipe was not dimensionally accurate. Measurement was referred to its inside diameter and wall thickness. The inside diameter was a true dimension, but over the years had become "nominal" (in name only) so that when pipe size was referred to, it was an approximate inside diameter measurement with the thickness described by the term "schedule".

[Edited on 5/2/09 by ashg]

Well the bloke in metal supermarket definately said cold formed seamless as i had to ask him what CFS stood for.

Bought 1" OD 14g (2mm) wall now. Hopefully it will be ok & if the roads clear enough to get up the motorway it will give my dad something to do this weekend