Degradation insert with overhang

1. A hammer mill, comprising:

a hammer body comprising at least one insert disposed partially within at least one cavity in a distal end of the hammer body;

the insert comprising an impact head with a stem protruding from a base end of the head;

the stem comprises a smaller cross sectional thickness than the head;

the stem comprises a collar at a second end of the stem adapted to be press-fitted within a cavity formed in the hammer body;

the head comprises a head with a recess formed in its base end and is adapted to interlock with the stem; and

a tensioning mechanism applies a rearward force putting the stem in tension.

2. The mill of claim 1 , wherein the stem and head are made from the same material.

3. The mill of claim 1 , wherein the stem and head are made of two dissimilar materials.

4. The mill of claim 3 , wherein the material of the stem has a coefficient of thermal expansion greater than a coefficient of thermal expansion of the material of the head.

5. The mill of claim 1 , wherein the base end of the head is adapted to protect a region of the hammer body proximate the stem.

6. The mill of claim 1 , wherein the stem is press fit into a cavity formed in the hammer body.

7. The mill of claim 6 , wherein a material of the stem has a coefficient of thermal expansion equal to or greater than a coefficient of thermal expansion of a material of the cavity.

8. The mill of claim 1 , wherein a plurality of inserts are packed in proximity to each other on the hammer body.

9. The mill of claim 1 , wherein the insert comprises at least one flat to accommodate packing.

10. The mill of claim 1 , wherein an overhang formed by the base end of the insert contacts the hammer body.

11. The mill of claim 1 , wherein the insert is threaded into a cavity formed in the hammer body.

12. The mill of claim 1 , wherein the impact head comprises a plurality of layered materials.

13. The mill of claim 1 , wherein the stem and head are interlocked.

14. The mill of claim 1 , wherein the stem comprises a locking mechanism adapted to interlock a first end of the stem within the recess.

15. mill of claim 14 , wherein the locking mechanism comprises a radially extending catch formed in the first end of the stem.

16. The mill of claim 1 , wherein a locking fixture is disposed within a cavity formed in the hammer body and locks the stem to a wall of the cavity.

17. The mill of claim 1 , wherein the base end of the head comprises an upward extending taper.

18. The mill of claim 17 , wherein a cavity formed in the hammer body comprises a seat complimentary to the base end of the head.