Casters Industry Information
Casters are wheel assemblies which are attached to the
bottoms of furniture legs to provide furniture mobility and shock absorption. Furniture
casters, colloquially known as furniture wheels, are used on beds, chairs and
tables in homes, offices, schools, hospitals, banquet halls, restaurants,
retail stores, truck garages and industrial manufacturing plants and
warehouses. Chair casters are one of the most common types of furniture casters. Furniture glides, unlike casters, are wheel-less furniture leg
attachments which allow furniture to sit or be moved across the floor with
minimal friction and scratching. Swivel casters allow caster wheels to pivot,
giving furniture on swivel casters greater ease of movement than furniture
attached to rigid casters. Being able to roll tables, chairs and equipment
platforms around smoothly is important in manufacturing warehouses, where
equipment, workstations and chairs are frequently moved around the facility. It
is also very important in hospitals, where computer stations, beds, IV racks
and other equipment are constantly in transit. Industrial casters, which are for more high strength applications, are used in these settings.
Caster wheels, axles, wheel centers and housings are fabricated
from different types of polymers, stamped metals and rubber materials. Wheels
are most often made from a grey, non-marking thermoplastic rubber, although
rubber, polyamide and tread polyurethane are used for heavy-duty casters. Rubber-wheeled
casters with pneumatic wheels in both medical and industrial applications provide quiet,
shock-absorbing movement when moving heavy tables, workstations or beds. Caster
brackets are the hardware which attach to the furniture, while caster housings
are the hardware which connect the caster wheel axle to the bracket. Brackets
and housings for casters are made from stamped steel, while
lighter-duty office and household casters are usually thermoformed
polypropylene. Hospital bed casters, equipment table casters and similar equipment use locking casters
to safely secure furniture in place; locking casters have an additional
piece of locking hardware attached to the wheel housing.
Industrial caster applications require heavy duty casters, often made of steel, which
can withstand heavy loads, uneven floor surfaces and being jarred against
ledges. For this reason, industrial furniture casters are fabricated from
stamped steel housings and brackets, aluminum or cast iron wheel centers and
axle nuts and thermoplastic rubber or tread polyurethane caster wheels. Some
caster assemblies are two-wheeled, providing a broader, more stable support for
heavy equipment. Medical and hospital furniture casters are medium-duty with
soft rubber of polyamide wheels and polypro injection molded housings for
smooth, quiet operation. Office and household chairs are made from lower-duty
thermoplastic materials, although bed casters typically have strong metal
housings.
In the past, all swivel casters used kingpins both to attach
the caster housing to the caster bracket and to provide pivot motion. Kingpins
absorb a significant amount of stress, particularly in high-impact industrial
applications, and they are consequently the number one cause of swivel caster
failure. "Kingpinless" casters have become quite common among medical casters,
office casters and even industrial casters. In kingpinless casters, a raceway
of ball bearings connects the upper bracket to the caster housing in place of a
kingpin. These are not only far more wear-resistant, but provide smoother
swivel motion as well. Office tables and household furniture which remain
stationary and do not need casters usually use furniture glides as
alternatives. Furniture glides are smooth-bottomed leg attachments which allow
furniture to be moved, when needed, with minimal damage done to the floor and
to furniture legs.