innovations CASTING
Farm Equipment Supplier Yetter Increases Part Life With CADI
Y
etter Manufacturing, Colchester, Ill., needed a solution to a prematurely wearing fertilizer knife fabrication for its Coul-
ter assembly, an agriculture product designed for high-speed, high-volume fertilizer applications. “When we had the fabrication
part, it worked better than anything we had like it,” said Lonnie Lucas, engineer for Yetter. “But the knives were one of the first parts to wear on the assembly.” T e company also was dissatisfi ed with the knife’s fabrication time and dimensional instability. Several com- ponents welded to the knife also wore prematurely and required increased inventory for replacement. When worn, the complete knife assembly required signifi cant cost and down- time to replace. “The part requires so many small
pieces, and each had a tolerance,” Lucas said. “The knife is made to run at an angle, and that tolerance is sensitive.” Over the years, Yetter had sourced
many cast components from Leth- bridge Iron Works, Lethbridge, Al- berta, Canada, so it knew converting to a casting could help reduce the number of parts on the assembly, decrease cost and improve dimensional stability. But the agriculture equipment manufacturer wasn’t sure which iron alloy would provide the necessary hardness in the application. T e fertilizer knife is attached to the Coulter disc to keep the blade free of residue and protect the fertilizer delivery tubes from wear. It creates a 4-in. trench in the soil for fertilizer or ammonia placement. In operation, the knife shatters the trench cavity’s hard side walls to help close it quickly so the liquid nitrogen delivered to the soil via tubes is not exposed to the air to become gas. T e knife’s application re- quires high wear resistance due to the severe conditions of the application. To achieve optimal performance out
The original knife fabrication worked well but was one of the fi rst parts on the Coulter assembly to need replacement.
of the cast conversion, Yetter worked with Lethbridge to produce prototypes in three materials: 27% high chrome iron, austempered ductile iron (ADI)
and carbidic austempered ductile iron (CADI). CADI is a relatively new family of ductile iron that few North American
Lethbridge Iron Works produced the cast conversion of the fertilizer knife in carbidic austempered ductile iron, which exhibits excellent wear resistance.
Jul/Aug 2012 | METAL CASTING DESIGN & PURCHASING | 49
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