How roller skates are made

A skate wheel is molded twice: a hard nylon core first, then a polyurethane tire shot around it.

stations: 8
things upstream: 49
raw sources: 15
steps from the ground: 8

The short version

A roller skate is a boot fixed to a frame or plate that carries the wheels. Inline boots are injection-molded shells with a soft liner, while quad skates usually use a high-top boot or a flat-soled one. Each wheel is a molded core wrapped in polyurethane, with two ball bearings in its hub. Bolts or rivets join boot and frame.

Mold the boot shell

Urethane plastic with dye for color is injected into a mold, cools, and is ejected as a finished shell. Quad boots come in two styles: a high-top with a raised heel, or a flat-soled boot cut at or below the ankle.

Goes in
Polyurethane
Fit the liner and straps

A liner of soft cloth or plastic foam is cut to the boot's size and fitted inside. Bought-in parts such as the cuff, straps and metal buckles are attached.

Goes in
Plastic
Mold the wheel core

Nylon or Rilsan granules, often mixed with carbon for strength, are melted and injected into a steel mold. The core does the job of a rim.

Goes in
Nylon
Shoot polyurethane around it

The core moves to a second mold, and molten polyurethane is injected around it to form the tire. Some makers pour the urethane instead. The wheel then cools and comes out.

Goes in
Polyurethane
Seat the bearings

Two ball bearings go into each wheel hub so it spins freely on the axle. Skates have carried ball bearings since the 1880s.

Goes in
Ball bearing
Mount the wheels

Wheels are secured on axles in the plate, or in a row in an inline frame. On a quad skate the axles pivot, so leaning to one side steers the skate.

Goes in
Bolt
Join boot and frame

An inline frame is riveted to the shell or fixed by a coupling system. A quad plate is bolted on through holes drilled in the sole, with low-profile bolt heads inside the boot and nuts facing the floor.

Goes in
Bolt
Add the brake

Inline skates typically get a rubber brake attached to the frame, at the back of one skate.

Goes in
Vulcanized rubber

End of the lineRoller skates

Worth repeating

The first reported use of wheeled skates was on a London stage in 1743.
Early polyurethane wheels were too grippy and slow for wooden rink floors, so skaters at first preferred wheels of clay or rubber mixed with fibers.
Two years can pass between a new skate wheel's first design and mass production, and the mold alone takes almost six months.