carbon steel selection: AISI, ASTM, SAE?? 6

[keyen]

Most of the stuff I design needs to use ASME BPVC Section II materials. This makes is somewhat easy to choose materials.

How would I go about selecting a material specification for a tool such as an arbor (example shown at the end of this post)?

When I research the materials available I seem to bounce between ASTM, AISI, and SAE standards. Many of the standards are concerned with chemistry, manufacturing methods, tolerances, etc... However, tensile/yield information seems to be less available (unlike ASME Section II).

My questions:
1. Is AISI obsolete for steel selection/designation (yet still used in common, less formal, settings)?
2. When tooling (such as the aforementioned arbor) is designed, is ASTM or SAE more commonly used (in North America)?
3. Is there a need to understand both ASTM and SAE for this kind of tooling, or can one suffice?
4. Which reference can I look too to help guide me along?
5. For the arbor I've mentioned, what material would you choose (assume an average cost, strength, corrosion resistance) as a starting point? Where would you find the mechanical properties? The full specification would be helpful to me.

Many thanks.

 

[mrfailure]

Lots of questions, I'll answer just a few:

First, you would need to select the right tool steel for this arbor, one that stays tough and is dimensionally stable if this sees heat. Without knowing more, a recommendation really should not be made. But you should look up tool steel types in reference books and from suppliers.

AISI is nothing more than chemical composition limits. These are now UNS standards and are published by ASTM and AISI jointly. Note that the UNS designations are alphanumeric now, but a copy of the published UNS book will give you the cross-referenced common designations. More important, it will also give specifications under ASTM and SAE (among others_, which you will want to consider in applying to tool steels.

ASTM and SAE are material specifications and they will specify properties beyond chemistry; those are the specs you should go towards in your engineering drawing.

Lots of references. A starting point would be ASM Handbook Volume 1 so you can bone up on tool steels and their properties.

Finally, you might want to consider using a material engineer to help you with your specific material selection.

 

[CoryPad]

1. Yes
2. ASTM
3. Not necessary to understand both
4. You need to ask a more specific question
5. Grade 8620 according to ASTM A29. Perhaps ASTM A108 and/or A304 could be used also. This is for the initial bar stock composition and quality. Then you need to specify heat treatment, e.g. carburize, quench and temper. Surface hardness of 58 HRC to 62 HRC, effective case depth (to 50 HRC or equivalent) of 1.0 mm to 1.3 mm. Core hardness of 35 HRC to 40 HRC. Conversion of hardness to strength is in ASTM A370. There is no easy place to find all of this information, although the entire ASM Handbook series is excellent.

 

[Maui]

We manufacture arbors for a variety of applications, and the most common material choice is case carburized and heat treated 8620 that satisfies the hardness criteria listed by Cory. Other grades can be used as well. Common alternative choices include 3310 and 9310.

Maui

 

[tbuelna]

ASTM material standards are a good choice for commercial applications like your machine tool component. They provide control of many characteristics, such as alloy composition, material form, material quality, and manufacturing processing. However, you must also specify the appropriate process standards for heat treat, NDI, etc, used to produce the part.

There are ANSI standards that define the dimensions/tolerances of machine tool components like your tapered holder.