PRODUCT DESIGN OF CHAIR

Chair – Product – Brief

History of the chair

The chair is of extreme antiquity. Although for many centuries and indeed for thousands of years it was an article of state and dignity rather than an article of ordinary use. the United Kingdom and Canada, and in many other settings. Committees, boards of directors, and academic departments all have a ‘chairperson’. Endowed professorships are referred to as chairs. It was not, in fact, until the 16th century that it became common anywhere. The chest, the bench and the stool were until then the ordinary seats of everyday life, and the number of chairs which have survived from an earlier date is exceedingly limited; most of such examples are of ecclesiastical or seigneurial origin. Our knowledge of the chairs of remote antiquity is derived almost entirely from monuments, sculpture and paintings. A few actual examples exist in the British Museum, in the Egyptian Museum at Cairo, and elsewhere.

In ancient Egypt chairs appear to have been of great richness and splendor Fashioned of ebony and ivory, or of carved and gilded wood, they were covered with costly materials, magnificent patterns and supported upon representations of the legs of beasts or the figures of captives. The earliest known form of Greek chair, going back to five or six centuries BCE, had a back but stood straight up, front and back.

The 20th century saw an increasing use of technology in chair construction with such things as all-metal folding chairs, metal-legged chairs, the Slumber Chair, moulded plastic chairs and ergonomic chairs. The recliner became a popular form, at least in part due to radio and television, and later a two-part. The modern movement of the 1960s produced new forms of chairs: the butterfly chair, bean bags, and the egg-shaped pod chair. Technological advances led to molded plywood and wood laminate chairs, as well as chairs made of leather or polymers. Mechanical technology incorporated into the chair enabled adjustable chairs, especially for office use. Motors embedded in the chair resulted in massage chairs.

CHAIR DEFINITION

A chair is a kind of furniture for sitting, consisting of a back, and sometimes arm rests, commonly for use by one person. Chairs also often have four legs to support the seat raised above the floor. Without back and arm rests it is called a stool. A chair for more than one person is a couch, sofa, settee, loveseat, recliner or bench. A separate footrest for a chair is known as an ottoman, hassock or pouffe. A chair mounted in a vehicle or in a theater is simply called a seat. Chairs as furniture typically can be moved.

The back often does not extend all the way to the seat to allow for ventilation. Likewise, the back and sometimes the seat are made of porous materials or have holes drilled in them for decoration and ventilation.

The back may extend above the height of the head. There may be separate headrests. Headrests for seats in vehicles are important for preventing whiplash injuries to the neck when the vehicle is involved in a rear-end collision.

Design and ergonomics

This rocking chair in the Adirondack style is made of rough wood to give it a rustic look.Chair design considers intended usage, ergonomics (how comfortable it is for the occupant), as well as non-ergonomic functional requirements such as size, stack ability, fold ability, weight, durability, stain resistance and artistic design. Intended usage determines the desired seating position. “Task chairs”, or any chair intended for people to work at a desk or table, including dining chairs, can only recline very slightly; otherwise the occupant is too far away from the desk or table. Dental chairs are necessarily reclined. Easy chairs for watching television or movies are somewhere in between depending on the height of the screen.

Ergonomic design distributes the weight of the occupant to various parts of the body. A seat that is higher results in dangling feet and increased pressure on the underside of the knees (”popliteal fold”). It may also result in no weight on the feet which means more weight elsewhere. A lower seat may shift too much weight to the “seat bones” (”ischial tuberosities”).

A reclining seat and back will shift weight to the occupant’s back. This may be more comfortable for some in reducing weight on the seat area, but may be problematic for others who have bad backs. In general, if the occupant is suppose to sit for a long time, weight needs to be taken off the seat area and thus “easy” chairs intended for long periods of sitting are generally at least slightly reclined. However, reclining may not be suitable for chairs intended for work or eating at table.

Designed to reduce the risk of falls for wheelchair-bound residents who propel themselves with their feet, the Dyn-Ergo Scoot Chair facilitates safe and comfortable independent mobility. An array of adjustments including seat height, seat depth, armrest height, and back angle fit the chair to the resident for proper positioning and full contact of feet with the floor without having to slide or lean forward. An adjustable tilt creates a wedge to reduce slumping, sliding, and falls. The tilt adjusts forward to lift and aid exiting the chair. Swing-away footrests store out of the way at the sides. Adjustable lateral supports also are available.

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An adjustable office

chair

The back of the chair will support some of the weight of the occupant, reducing the weight on other parts of the body. In general, backrests come in three heights: Lower back backrests support only the lumbar region. Shoulder height backrests support the entire back and shoulders.

Some chairs have foot rests. A stool or other simple chair may have a simple straight or curved bar near the bottom for the sitter to place his/her feet on.

A kneeling chair adds an additional body part, the knees, to support the weight of the body. A sit-stand chair distributes most of the weight of the occupant to the feet. Many chairs are padded or have cushions. Padding can be on the seat of the chair only, on the seat and back, or also on any arm rests and/or foot rest the chair may have. Padding will not shift the weight to different parts of the body (unless the chair is so soft that the shape is altered). However, padding does distribute the weight by increasing the area of contact between the chair and the body. A hard wood chair feels hard because the contact point between the occupant and the chair is small. The same body weight over a smaller area means greater pressure on that area. Spreading the area reduces the pressure at any given point. In lieu of padding, flexible materials, such as wicker, may be used instead with similar effects of distributing the weight. Since most of the body weight is supported in the back of the seat, padding there should be firmer than the front of the seat which only has the weight of the legs to support. Chairs that have padding that is the same density front and back will feel soft in the back area and hard to the underside of the knees.

Designed to reduce the risk of falls for wheelchair-bound residents who propel themselves with their feet, the Dyn-Ergo Scoot Chair facilitates safe and comfortable independent mobility. An array of the way at the sides. Adjustable lateral supports also are available.adjustments including seat height, seat depth, armrest height, and back angle fit the chair to the resident for proper positioning and full contact of feet with the floor without having to slide or lean forward. An adjustable tilt creates a wedge to reduce slumping, sliding, and falls. The tilt adjusts forward to lift and aid exiting the chair.

Armrests

A Large Armchair

A chair may or may not have armrests; chairs with armrests are termed armchairs. In French, a distinction is made between fauteuil and chaise, the terms for chairs with and without armrests, respectively. If present, armrests will support part of the body weight through the arms if the arms are resting on the armrests. Armrests further have the function of making entry and exit from the chair easier (but from the side it becomes more difficult). Armrests should support the forearm and not the sensitive elbow area. Hence in some chair designs, the armrest is not continuous to the chair back, but is missing in the elbow area.

A couch, bench, or other arrangement of seats next to each other may have arm rest at the sides and/or arm rests in between. The latter may be provided for comfort, but also for privacy e.g. in public transport and other public places, and to prevent lying on the bench. Arm rests reduce both desired and undesired proximity. A loveseat in particular, has no arm rest in between.

Chair seats

A bench is long enough for several people to sit on

Chair seats vary widely in construction and may or may not match construction of the chair’s back (backrest).

Some systems include:

• Solid center seats where a solid material forms the chair seat.
  • Solid wood, may or may not be shaped to human contours.
  • Wood slats, often seen on outdoor chairs
  • Padded leather, generally a flat wood base covered in padding and contained in soft leather
  • Stuffed fabric, similar to padded leather
  • Metal seats of solid or open design
  • Molded plastic
  • Stone, often marble
• Open center seats where a soft material is attached to the tops of chair legs or between stretchers to form the seat.
  • Wicker, woven to provide a surface with give to it
  • Leather, may be tooled with a design
  • Fabric, simple covering without support
  • Tape, wide fabric tape woven into seat, seen in lawn chairs and some old chairs
  • Caning, woven from rush, reed, rawhide, heavy paper, strong grasses, cattails to form the seat, often in elaborate patterns
  • Splint, ash, oak or hickory strips are woven
  • Metal, Metal mesh or wire woven to form seat

Standards and specifications

Design considerations for chairs have been codified into standards. ISO 9241, “Ergonomic requirements for office work with visual display terminals (VDTs) — Part 5: Workstation layout and postural requirements” is the most common one for modern chair design.

There are multiple specific standards for different types of chairs. Dental chairs are specified by ISO 6875. Bean bag chairs are specified by ANSI standard ASTM F1912-98. ISO 7174 specifies stability of rocking and tilting chairs. ASTM F1858-98 specifies plastic lawn chairs. ASTM E1822-02b defines the combustibility of chairs when they are stacked.

The Business and Institutional Furniture Manufacturer’s Association (BIFMA) defines BIFMA X5.1 for testing of commercial-grade chairs. It specifies things like:

• chair back strength of 150 pounds (68 kg)
• chair stability if weight is transferred completely to the front or back legs
• leg strength of 75 pounds (34 kg) applied one inch (25 mm) from the bottom of the leg
• seat strength of 225 pounds (102 kg) dropped from six inches (150 mm) above the seat
• seat cycle strength of 100,000 repetitions of 125 pounds (57 kg) dropped from 2 inches (50 mm) above the seat

The specification further defines heavier “proof” loads that chairs must withstand. Under these higher loads, the chair may be damaged, but it must not fail catastrophically.

Chair pads are cushions for chairs. Some are decorative. In cars, they may be used to increase the height of the driver. Orthopedic backrests provide support for the back. Some manufacturers have patents on their designs and are recognized by medical associations as beneficial. Car seats sometimes have built-in and adjustable lumbar supports.

Chair mats are plastic mats meant to cover carpet. This allows chairs on wheels to roll easily over the carpet and it protects the carpet. They come in various shapes, some specifically sized to fit partially under a desk.

Remote control bags can be draped over the arm of easy chairs or sofas and used to hold remote controls. They are counter-weighted so as to not slide off the arms under the weight of the remote control.

Cantilever chair

Cantilever chair “Cesca” by Marcel Breuer

A cantilever chair has no back legs, relying for support on the properties of the material from which it is made. This famous form was designed by Mart Stam in 1926, and remains an important example of 20th century design.

Another designer of cantilever chairs was Hungarian designer Marcel Breuer who was experimenting with steel tubing.

Folding chair

A folding chair is a light portable chair that can be stored in a stack, row or on a specially designed cart (or dolley). They are usually used for seating large amounts of people in an arena where permanent seating is not possible or practical. This includes mostly large outdoor or indoor cultural events such as funerals, college graduation, religious sermons and sport and athletic games and competitions. In the private sphere, folding chairs are used for any social situation requiring extra seating such as parties, card games, and temporary seating at the dinner table. They typically weigh between 2 to 5 kilos (five to ten pounds) and are produced in a variety of styles, folding mechanisms and materials.

History

Folding chairs were already being used in Ancient Egypt, Greece and Rome. The curule chair of the Roman magistrate was a folding chair, as well as the seat of the emperor. The frame was mostly made of wood, and seldomly made of metal. The wood was inlaid with artistic carvings, gilded, and decorated with ivory. In Northern Europe, folding chairs date back to the bronze age.

The folding chair became especially widespread during the Middle Ages. Here it was treasured as a liturgical furniture piece. Since the 15th and 16th century the folding chair has mostly had arm and head rests. Of course, newer chairs which are often found in functions and events are also called folding chairs. In 1947, Fredric Arnold created the first aluminum folding chair with fabric strapping for the seat and back. By 1957, the Fredric Arnold Company of Brooklyn, New York, was manufacturing more than 14,000 chairs per day. Today, the folding chair is mostly made of hard plastic or metal or wood. Folding chairs can be divided into different categories.

High chair

A high chair is a piece of furniture used for feeding older babies and younger toddlers.

Problem

Design and construct a safe, comfortable and durable chair using only the cardboard from boxes.

Documentation

1. The entire process from start to finish will be documented through photographs.
2. Fliers, business cards, company information/history is required.
3. Four drawings of your final chair from different views (front, side, top, perspective). These drawings should include actual measurements.
4. A vigorous analysis of the forces present in your chair when it is occupied. Numerical values will be required here, showing how the force is distributed.

arm rest in between.