Page 38 - MetalForming Magazine April 2023

especially via directed-energy and pow- der-fed AM.
“This has great interest to us,” he says. “In general, for cold and hot stamping we build a tool from the same material over the entire tool surface, perhaps with inserts here or there, or some blocks of different material. But, especially in forming and cutting tools, there’s a need for different localized properties in the material. We can heat treat to surface-harden somewhat selectively and locally. With laser heat treatment or possibly in combination with powder-fed AM, we see the ability to change the surface of a die—attach- ing powdered metal to the die surface of a different metal alloy.”
Specific to hot stamping, Austin identifies two areas of a tool that often undergo significant abrasion and galling, and coating pickup: male radii and sidewalls.
“Those areas are candidates for changing surface material via AM,” he says. “If we can additively place powder selectively into areas of a new die susceptible to abrasion and galling, the AM material may not last very long, but we’ll have the ability to add it on again and again. Most hot stamping tools experience a rel- atively short life before recutting, and recutting doesn’t work very well for sidewalls due to the lack of contact pressure due to sidewall geometry. We see opportunity in the repair busi- ness where, instead of performing one or two recuts and then replacing some or all of the steel as is common for longer-term or higher-volume part programs, we can use AM for tailored surfacing—placing hardness or tough- ness where needed.”
AM also may find use, Austin notes, in repairing gaps in hot stamping tool- ing, which can cause material or coat- ing buildup that detracts from heat transfer and leads to longer quench times during hot stamping, and dis- tortion that affects part quality.
One other thought from Austin on future use of AM in die repair:
“I can see the creation of standard- ized cells that scan a die, then selec-
tively rebuild via AM. Another scan then provides the new surface for CNC- machine recutting. This hybrid cell would allow us to use AM to add mate- rial to repair a die or build new, then scan again before some final subtrac- tive work. In almost all cases, we’ll never be able to print net shape—it will be near shape and we’ll need machining to finish.”
With AM, Austin concludes, “every- one originally had stars in their eyes, saying that ‘we’re going to print a whole tool and do it lights out, and we’ll have a cost reduction.’ That is not on the horizon.”
But, as Austin has detailed, AM def- initely has a future in tool build and repair, especially in the hot stamping arena. MF
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MetalForming/April 2023 35
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