Most of the materials needed to manufacture are purchased in bulk from sources other than the manufacturer. Some materials come from custom manufacturers and are made specifically to meet certain standards. Thread used to sew seams and embroider logos is purchased from one source. Nylon fabrics are purchased in bulk and are typically 60 inches (152 cm) wide and 20 or 30 feet (6 or 9 m) long. The width of the fabric generally corresponds to the standard width of the cutter. The same width specifications apply to closed-cell foam purchased in thick sheets. Non-corrosive plastic zippers and snaps are purchased from another outside source, such as materials like strapping and reflective tape.
The manufacturing steps for life jackets are similar to those of any automated garment manufacturing process, but differ in specific features such as raw materials and, more importantly, safety specifications. The operation required to complete the garment from scratch is known in the industry as "cutting and trimming". Up to 100 in an automated manufacturing process such as the one described here.
1. Marker creation
The pattern design is digitally entered from a computer into a machine called a plotter, which draws a template for the pattern design on a long sheet of white paper. The drawing is called a marker.
2. Preparing the nylon
A machine called a spreader unfolds bolts of nylon fabric along a table, usually 66-72 inches (168-183 cm) wide and up to 100 feet (31 m) long. Thin fabrics such as nylon can be layered in 25 layers for cutting. Wrinkles are smoothed by the spreader or by hand, and markers are placed on top of the nylon.
3. Cutting patterns
✱ Some manufacturers use automatic cutters to cut pattern pieces from nylon. Other manufacturers may use hand-cut pieces .
✱ Portable electric straight cutters, similar to a jigsaw. In automatic cutting, a digital pattern is fed into the cutter. A sheet of cellophane wider than the fabric is drawn over the top of the marker and fabric layers. A vacuum pulls the cellophane tight against the table to hold the marker and nylon layer in place. A knife cuts the pattern from the cellophane, marker, and fabric layers simultaneously. The cut patterns are then bundled and transferred to the assembly area. The pattern pieces can be identified by the markers read by the cellophane.
4. Cutting foam
✱ A band saw called a separator is used to cut the closed-cell foam to the desired thickness. The band saw has a long, thin blade welded into a continuous ring that moves up on a driven wheel and up on one or more idler wheels, then down through the material being cut. The foam then undergoes the pattern cutting process in the same manner as nylon.
✱ Small cutters called die cutters are used to cut reflective tape and small attachable pieces (such as strips) from the rolls.
5. Assemble the pattern pieces
✱ Multiple sewing professionals, each stationed in front of an industrial sewing machine, match and sew the pieces together. The pieces are sewn together from the inside out and then turned over.
✱ The cut foam pieces are inserted through open seams and then sewn together.
✱ The tape, reflective tape and tabs are sewn at the end. Snap fasteners are attached through eyelets or riveting machines, similar to those used by shoemakers for lace holes. Computer-aided embroidery machines - much like those used by department stores to customize towels - are used to embroider brand names and logos.
✱ Individual finished undershirts are placed in plastic bags for protection. These bags are loaded into corrugated cardboard boxes and delivered to the distribution center.