demolition bar

By Rslik Date 09-30-2010 16:40

I'm trying to help a friend, who is designing a new tool for the building construction industry.
The best description I can give is, the tool works similar to a long handle (Crowe) pry bar. The business end of the bar is shaped like an enlarged fork, with an attached hollow round-tube handle, which is curved for ease of use.
He would like to have the fork end of the tool made as a casting, that would have a spurr end which would allow the casting to be welded to the curved handle.
At this point he is ready to contact a companies to quote a pricing for the casted part of the tool. Can anyone suggest a specific type of material, that this part should be casted from ?

By DaveBoyer (*****)

Date 10-01-2010 01:53

He needs to discuss the intended use and heat treatment with the foundry, as there are several possible casting alloys that might work, and if He wants smaller quantities, His parts will be cast in a run with other parts.

By Rslik Date 10-01-2010 13:51

Dave, thanks for your feed back. If you don't mind, make a suggestion if only as a starting point. For example, what material is it that's used for making tools such as pry bars ?

By DaveBoyer (*****)

Date 10-02-2010 01:42

Most of the pry bars are forged, and forging works on many alloys that are not so great as castings, and may not be weldable..

You mentioned that the cast part will be welded to the handle, this requires that the casting alloy is weldable without a whole lot of grief.

This website should be of help:

http://www.metalcastingdesign.com/content/view/104/193/

This paragraph from the website above pretty well sums it up.

"There are three keys to selecting the right steel casting alloy for optimized performance and cost. One, utilize the geometry of the steel casting to uniformly carry the loading. Secondly, start with carbon steel for most applications, modify the heat treatment and then add alloying elements to improve properties. Finally, engineers should know the design limit for an application and work with a metalcasting facility to design the part and select a material. "

He needs to determine what the minimum yield strength of the material is, and this is based on the geometry of the part. Then He can choose the cheapest material that is strong enough, and weldable. Heat treatment of the cast part complicates the manufacturing greatly, due to the welded joint.

Making the stub that the tube handle attaches to long enough to reduce the load at the junction lessens the problems.

What I am getting to is that the overall design is at least as important as the alloy selection.

Hope this helps.

By Rslik Date 10-03-2010 15:30

Once again, thank you for your guidance Dave and thanks for attaching the website. I'll pass this information along.
Rick