Page 46 - MetalForming April 2011

Tooling by Design
By Peter Ulintz
Tool Repair by Welding
When tool and die steels wear or become unexpected- ly damaged in service, metalformers may be able to weld-repair the worn or damaged areas. Welding not only can prove to be a structurally sound and economical repair method, but also can allow a metalformer to return dam- aged punch and die components back into service quickly.
To achieve desirable results, let’s review some important principles of tool and die welding. These principles were culled from a technical article titled, Welding of Tool Steels, which appears on the Key to Metals website (www.keytometals.com).
The article describes four basic types of die steels that can
Peter Ulintz has worked in the sheetmetal-forming industry since 1978. His background includes tool and die making, tool and process engineering, engi- neering management and product development. Peter also operates the website www.ToolingbyDesign.com, a source for the transfer of modern metalforming and tool-and-die technology, and which promotes the use of “Performance-Based Die Engineering Strategies.” Peter Ulintz
pete.ulintz@toolingbydesign.com www.toolingbydesign.com
Tooling Technology
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MetalForming/April 2011
www.metalformingmagazine.com
be repaired by welding: water-hardening, oil-hardening, air- hardening and hot-working steels. Successfully welding these materials depends on the use of a properly developed welding procedure and welding sequence, and careful selec- tion of the welding electrode.
Selecting the appropriate electrode or filler metal, the stamper attempts to match the heat treatment of the die steel being repaired, since electrodes may not always be available to match the composition of the tool steel or the specific heat treatment of each tool or die component. Welding-elec- trode manufacturers provide information concerning each of their electrodes by specifying the types of tool or die steels for which they are designed, including the properties of the weldmetal deposited. Further assistance can be obtained by consulting with representatives of the elec- trode manufacturer.
The electrode selected for a particular tool and die repair must result in weld deposits of sufficient hardness in the as- welded condition. If the repaired tools lend themselves to grinding or EDM machining, treatment other than tempering is not required. However, if traditional machining is required,
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