Method for making a tread assembly

A method of making a tread assembly, comprising:

• placing a matrix lining onto a molding base;
• positioning a first rubber block in a first central cavity in a central mold;
• positioning a second rubber block in a second central cavity in a central mold;
• wherein the first rubber block has a first characteristic and the second rubber block has a second characteristic different from the first characteristic;
• positioning the central mold adjacent the molding base such that a first lug cavity rim presses into the matrix lining in a first location to permanently form a first outer periphery indentation having an inside perimeter and an outside perimeter, and such that a second lug cavity rim presses into the matrix lining in a second location spaced from the first location to permanently form a second outer periphery indentation having an inside perimeter and an outside perimeter, each pressing having adequate pressure to prevent escape of excess material;
• liquefying each rubber block by compressing and heating;
• pressing each rubber block through a respective injection cavity into a respective lug cavity to form tread elements, wherein a first tread element is disposed within the inside perimeter of the first outer periphery indentation and a second tread element is disposed within the inside perimeter of the second outer periphery indentation;
• gathering escaped excess material from each rubber block in a respective molding recess;
• cooling and resolidifying the tread elements;
• and
• separating the central mold from the molding base to release the tread assembly.

A method of making a tread assembly, comprising:

• placing a matrix lining onto a molding base;
• positioning a first plurality of rubber blocks in a first plurality of central cavities in a first central mold;
• positioning the first central mold adjacent the molding base such that each first lug cavity rim defining a first lug cavity presses into the matrix lining in a first location to permanently form in the matrix lining an outer periphery indentation having an inside perimeter and an outside perimeter, the pressing having adequate pressure to prevent escape of excess material;
• liquifying the plurality of first rubber blocks by compressing and heating;
• pressing the plurality of first rubber blocks through a corresponding plurality of first injection cavities into a corresponding first lug cavity having a first height to form a plurality of tread elements;
• gathering escaped excess material from the first rubber blocks in a plurality of first molding recesses;
• cooling and resolidifying the tread elements;
• separating the first central mold from the molding base, the molded tread elements each having a tread element base that has a shape and size defined by the shape and size of the corresponding first lug cavity rim and that is disposed within the inside perimeter of the outer periphery indentation;
• positioning a plurality of second rubber blocks into a second plurality of central cavities in a second central mold;
• positioning the second central mold adjacent the molding base such that each second lug cavity rim defining a second lug cavity presses into the matrix lining in a corresponding first location, the second lug cavity rim fitting inside the outer periphery indentation, and the pressing having adequate pressure to prevent escape of excess material;
• liquifying the plurality of second rubber blocks by compressing and heating;
• pressing the plurality of second rubber blocks through a plurality of second injection cavities into corresponding second lug cavities having a second height to form a second layer on each of the plurality of tread elements;
• gathering escaped excess material from the second rubber blocks in corresponding second molding recesses;
• cooling and resolidifying the tread elements;
• separating the second central mold from the molding base to create a tread assembly of spaced tread elements;
• and
• wherein each corresponding second lug cavity rim and first lug cavity rim are substantially the same shape and size and where the second height is larger than the first height.