A method and a system of forming a workpiece assembly including an intermediate element between first and second workpieces. A ring element is included in or on the intermediate element. The ring element is for rotating the intermediate element about the intermediate elements axis. With heating elements positioned between the intermediate element and the first and second ends of the first and second workpieces, portions of the intermediate element and the first and second workpieces are heated to a predetermined hot working temperature, in an inert (non-oxidizing) atmosphere. While the heated portions are at the predetermined hot working temperature, and while the intermediate element is rotated about its axis, one or both of the first and second workpieces are moved axially, to engage the first and second ends with the intermediate element.

A method for making a face guard for use in a ball game includes: providing a specific material; annealing the material by first maintaining a temperature between 410 and 430 C. for 3 hours and then lowering the temperature by about 30 C./hour; cutting the annealed material into a main-body member and plural supporting members; butt-joining the two ends of the main-body member by applying a specific pressure to the two ends; welding the supporting members to the main-body member to form a face guard body; performing a T4 heat treatment on the face guard body by first maintaining a temperature between 450 and 550 C. for 1.5 hours and then quenching for 7 seconds; performing a T6 heat treatment on the face guard body by first maintaining a temperature between 100 and 120 C. for 24 hours and then cooling by air; and performing an anodizing surface treatment on the face guard body.

The cold pressure welding apparatus includes a first holding part capable of sandwiching a first flat conductor, a second holding part disposed opposite to the first holding part and capable of sandwiching a second flat conductor, and a drive part for moving the first holding part and the second holding part. The drive part can move the first holding part and the second holding part between a first direction separated position and a close position along a first direction. The drive part can move the first holding part and the second holding part between a second direction separated position and a sandwiching position along a second direction.