Machine design material selection
Machine design material selection
(OP)
I am in the process of designing a machine. I wish to drill and tap the frame to receive screws. I plan on using SAE grade 5 fasteners and need to select a suitable steel for the base material. In reviewing the ASTM specs I spotted A284 as a possible good material (steel, weldable, for machine design) spec. Having a significantly lower yield strength than the grade 5 fasteners, it adheres to the rule of thumb for nuts vs bolts (soft and ductile vs strong and tough). Without having to go through strength of male and female thread calcs is it reasonable to use this material?
cntrlnr
cntrlnr





RE: Machine design material selection
ERT
http://www.akeng.com
RE: Machine design material selection
ASTM A284 listed some high tensile and
yield properties for this material?
A36 only has 36000 psi yield strength.
RE: Machine design material selection
So, the selection of one or more suitable steels needs to be based on design use of the machine versus your statement regarding fasteners.
RE: Machine design material selection
RE: Machine design material selection
2. Dampening is minimal within a welded steel frame. If this is the key objective, consider using a cast iron frame if you have the product volume to justify it. It is advisable to increase fastener engagement depths when tapping cast iron.
3. Regarding ASTM A284, or the A283 standard which has replaced it - can anyone confirm diamondjim's comment regarding it being higher strength than A36?
ERT
RE: Machine design material selection
RE: Machine design material selection
cntrlnr
RE: Machine design material selection
You might want to look at this company for all the machine base, parts of, or the material for. I've found this to be one of the least expensive approaches to fabricating machines.
http://www.americangrinding.com/
RE: Machine design material selection
Grade D gives a Min UTS of 60-72ksi and a min Yeild of 33 ksi and 20% elongation
A36 has a min UTS of 58-80 and Min Yeild of 36 and elongation of 20%
Diamondjim, in my world, all of this is junk iron. you can't hardly GET steel weaker than this.
If you need strength, weldability, and availability, look at ASTM A572 GR 50 (50 KSI Yeild) or GR 70 (70 Ksi yeild)
Gr50 can be welded using the same weld procedures as A36, Gr 70 is a bit more demanding but only slightly.
RE: Machine design material selection
If you don't need much stability or accuracy, perhaps because your design allows adjustment or it is just not needed, great. If you need to stress relieve, then your choice of material should be integrated with that decision.
BK
RE: Machine design material selection
I am designing an o-ring-plate-capped, thick-wall extrusion that will hold 10-20 PSI Nitrogen over 10 years. I know aluminum is a lot like "Swiss-cheese", can you recommend a place to find physical characteristics of various types of aluminum alloys? Possibly recommend a surface treatment to seal aluminum? The right thing to do is use stainless steel for this product, but I have machined a lot of stainless and I just would rather work with aluminum if possible.
Warren Powers
RE: Machine design material selection
BK
RE: Machine design material selection
Sorry.
Warren Powers