TUBE 2217855 - Caterpillar

A cone grinder or rotary de-burring tool, shown in Illustration 17 can be used to produce a smooth concave profile as shown in Illustration 18. Toe grinding, besides removing minor imperfections, will improve fatigue strength of the weldment by 30%. Care should be taken not to overheat the ground surface until the surface becomes discolored. Avoid leaving deep grinding marks that can act as stress concentrators. Verify with dye check that the ground surface is free of imperfections. If the imperfection was a crack, ensure that the crack has been removed completely and does not go any deeper.
Illustration 19 g03365649
TIG toe welding
(G) Weld metal
(H) Molten weld pool
(J) Base metal
(K) Arc
(L) Gas Shielding
Illustration 20 g03365650
TIG welding repairs
(M) TIG weld with filler wire
(N) Remelted toe with TIG process Another method to reduce local stress concentration at the toe of the weld is by TIG dressing. TIG dressing is a method of remelting the toe area and producing a more generous weld toe radius. Refer to Illustration 19 and item (N) in Illustration 20.With TIG welding, poor overlapping weld starts can also be improved by remelting the welds and filling with additional wire. This technique is shown by item (M) in Illustration 20. The areas must be preheated before any TIG welding. As most base edge failures usually begin at the front of the base edge, toe grinding or TIG dressing need only be applied to the following area:
Only the first few inches of weld start, and up to the base edge bevel transition to the flat surface
Illustration 21 g03365651
TIG welded toe
Refer to Illustration 21. Rounded adapter straps that are welded at the rear should also be considered for toe grinding or TIG welding.Sidebar/Corner Adapter Welds
Illustration 22 g03366556
Rough sidebar weld
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Example of a sidebar weld that has been ground with a disc grinder
Another area of potential crack initiation and corner adapter failure is at the sidebar. Since the top of the adapters are solidly attached to the sidebars, the straps cannot flex with the base edge like the center adapters do. Therefore, stresses are higher at the corner adapter location. Irregular or poorly blended welds at the sidebar, shown in Illustration 22, cause bucket corner loading forces to concentrate at this corner joint. The concentration of loading forces at this corner joint can become great enough to initiate a crack and ultimately lead to adapter failure or sidebar weld failure. These stresses can be reduced by blending the welds between the front of the sidebar and top of the strap as shown in Illustration 23.J-Series Adapter Strap Tail Welds
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Example of cracks starting at the rear of tail welds propagating in either of two directions
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Example of a J-Series completed tail weld
The J-Series adapter strap tail welds are another area susceptible to cracking when the bucket is subject to high loads. Feathering tail welds extending out past the back of the adapter strap may have poor penetration into the adapter. This poor penetration into the adapter may result in a discontinuity that acts like a