Product Market Need
Research has proved that most computer chairs manufactures have not considered various Human Ergonomic principles to produce, safe, health conscious chairs (Fredericks & Butt, 2005, p 38). Currently these manufactures mainly design computer chairs for support and comfort, but, this product “Ergonomic Computer Chair” will be keenly designed taking into consideration ways of reducing to pressure that is mainly imposed by normal computer chairs, on the human musculoskeletal system, that is mainly created by sitting for long period of time. This product design will also consider various aesthetic issues to produce the most appealing Ergonomic Computer Chair, to tap on the current market of trendy office computer chairs.
The actual suitable markets will be: Eastern Europe, Southeast Asia, Africa, South America, Mid East Oceania, Eastern Asia, Western Europe and North America.
Product Design Specification
The norms that were used to determine various specifications of the computer chair were calculated using the Compliance Matrix BIFMA G1-2002, which is represented in Appendix 1.
Specifications for the Ergonomic Computer Chair:
All Chair Padding: backrest, seat pan, and armrests.
The Chair Armrests: will be adjustable down and up (with a movement range between 7” to 11’ minimum) and at the same time out and in (the chair hand arm rest adjustable range is between 18”to 22”).
The Actual Chair Base: is a minimum 5 casters.
The Chair Materials:
1. unlike the regular computer Seats mainly made of not mesh, this will be made by genuine leather.
2. It will have a non-steel bottom; all the tough fixed parts will be by hard plastic.
3. The Chair frame shape will be guided by a reconstructed mold, making this chair to be without any attachment on the outside. Applying for patent will be necessary to protect this mold.
The assumptions in this design are: that this chair is for an average person going by the standards of Healthy Computing (2007, p 125). This is because it wanted to meet a proper fit that mainly enables comfort, and at the same time it is ergonomic appropriate. The design procedure have taken into account the Ergonomic Seating Standards, hence, this Ergonomic Computer Chair, serves most of the worlds population with out of normal body sizes and shapes. These standards are highlighted by the American National Standards Institute and the Human Factors and Ergonomics Society (National Safety Council, 2007, p 67-87).
The Complete Working System Evaluation
Summary of Critical Features of the Chair
The main exceptional and desirable features of this chair are: the chair’s completely adjustable arm rests, the forward tilt, adjustable lumbar support, and the seat depth adjustment that is 3”.
The Chair’s Adjustability Features of Armrests
The human boy arms signify about 10.2% of its overall body weight that results to significant application of the weigh to the shoulders upper back, and the neck. Fixed or Static cause muscle fatigue, but supporting the arm reduces this (Healthy Computing, 2007, p 256). To meet the chair design applies various adjustments to factor in the flexible movement ranges and size range of its operators. Figure 1, represents a nearly perfect computer chair without an armrest, while Figure 2 is one with the armrest.
Figure 1: A nearly Perfect Computer Chair without an Armrest
Figure 2: A Computer Chair with an Armrest
The Armrest Height; the 18”to 22” range is a considerable variation that allows for a seated resting elbow of a normal sized person.
The Adjustability of Front-to-Back; this is achieved through a 360° rotating arm caps, that does not knock into the computer desk’s edge, allowing more reaches, and promote resting posture.
The Pivot and Width; the width of 10” is at the mid of the allowed 7” to 11” standard, and the centrally located pivot allows the extreme rotation.
The Armrest Height; is adjustable between 7” to 11’ achieves the same. Figure 3 represents the 3600 armrest movement.
Figure 3: The 3600 Armrest Movement.
The Chair Seat Depth Adjustment
The 3” adjustability height will ensure that everyone secures adequate support on the chair through this adjustment.
The Chair Forward Tilt
The forward tilt of the computer chair will allow a healthy spinal cord posture, leaning the chair and forward and back makes it offer alternative sitting posture, and this can releases lower back burden.
The Chair Seat Loll
After lolling our chair merely 20° (from an angle of 90° to 110°) decreases the pressure on the user’s spinal discs by about 40% (Andersson & Martin, 1999, pp 366-370).
Pure Leather Rather than Artificial Leather on the Chair
Despite the fact that artificial leather is similar to pure leather, they are not the same. Pure leather was chosen to meet support the various movements of the chair. The artificial leather would gather static friction force and wear out fast, hence jeopardizing the desired movement of the chair. Pure leather is very thick and will maintain the desired pressure on the movement of the joint allowing for a relatively smooth adjustability, rather than, swift risky movements that would be witnessed once the artificial leather wears out. Over retention of heat might also jeopardize the mobility of the chair.
Pure leather is aesthetically visible, it maintains the executive look throughout its life span, and easily clean by waxing that can last up to six months. The artificial leather on the other hand will look dull making the chair loose its aesthetic value.
Lastly, the large thickness of pure leather encourages comfort, through a firm but comfortable feel, and this enable the desired comfort standards to be met. The artificial one is hard or at times unnecessarily soft; this will bring back the undesired sitting postures that go against the econometrics standards (Susannah, 1999, p 45).
Suitable Manufacturing Processes for the Mold
The process cycle for injection molding is very short, typically between 2 seconds and 2 minutes, and consists of the following four stages: Plastic moldings will has the main advantage, of precision, to archive a perfect design all the measurements must be accurately achieved; and molding presents an accurate precession at a lower cost, the molding machine is represented in the figure ()((() below.
The process is as folows:
Clamping: before inserting the material into the molding machine, the 2 halves of the mold are fixed together using the clamping unit. Then all first half is connected to the injection molding machine and the other one is allowed to slide. The hydraulically drove clamping unit presses the two mold while exenterating enough force to retain the molds firmly closed as the hard plastic material being is injected.
Injection: the raw hard plastic material, typically in the procedure of bits, is suckled into the actual injection molding engine and progress to the mold by the injection component. Throughout this procedure, the hard plastic material is molten by pressure and heat. The melted hard plastic is then injected into the already constructed mold very fast and the accumulation of pressure holds and packs the material.
Cooling: the already melted hard plastic confined in the mold starts to cool as rapidly as it creates interaction with the inner mold surfaces. This process allows the plastic to solidify into the already desired shape of the design. But, the shrinking aspect that will occur during cooling is already factored in through accurate calculations. The molding machine can not be opened till the mandatory cooling time has passed.
Ejection: later when the cooling time has elapsed, the cooled part of the chair is removed from the molding machine through the ejection system, that is connected to the tail half of the molding machine. Once the molding machine is untied, a mechanism is applied to eject the chair part out of the machine. So as to ease the ejection of the chair part, a mold discharge fluid id drenched onto the planes of the mold hole before the injection of the hard plastic material. Thus, the molding process is complete.
Chaffin, D.; Andersson, G.; & Martin, B.J. (1999). Occupational Biomechanics, New York:
John Wiley & Sons, 366-370.
Fredericks, T.K. & Butt, S.E. (2005). Objectively Determining Comfortable Lumbar Support in
Task Seating. (Available from Haworth, Inc., One Haworth Center, Holland, MI 49423).
Handley, Susannah (1999). Nylon: The story of a fashion revolution: A celebration of design
from art silk to nylon and thinking fibres.. Baltimore, Md: Johns Hopkins University
Healthy Computing, (March 8, 2007). Office Ergonomics – Chair Setup and Usage. Accessed
on 19th March, 2012, from:
National Safety Council, (2007). Injury Facts, Itasca, IL: National Safety Council, 47-83.
Figure 4: Appendix 1: Compliance Matrix BIFMA G1-2002