Investigation of ergonomic parameters of easy chairs in Moratuwa furniture manufacturing establishments

Abstract

Sitting on a comfortable seat helps to relax the body and reduce energy consumption. but on the otherhand prolonged sitting slackens abdominal muscles and may cause back ache. Application of medicaland ergonomic principles in the design of a seat can maximize advantages and minimize disadvantagesin sitting.

In Sri Lanka the demand for a furniture depends on the customer perception to comfort and beauty ofthe product. The present study aimed to find out whether the easy chairs manufactured in the MoratuwaFurniture Manufacturing Establishments were ergonomically designed for the Sri Lankan users.

The investigation was initiated with the identification of easy chair designs in the Moratuwa FurnitureManufacturing Establishments. A representative sample of two popular easy chair designs, the KuluPutuwa and the Meda! Putuwa, was then selected.

The different design parameters of these twochairs were measured. It was observed that there were differences in the dimensions of the majordesign parameters of the chairs between companies.

Sri Lanka has no specific standards for designing offurniture. Hence design standards were developedfor easy chairs in the present study based on available anthropometric data for Sri Lankan users andother published anthropo:netric data on seat designs.The different design parameters of Kulu Putuwa and Medal Putuwa were then compared with thosedeveloped ergonomic standard values. It was observed that only the back rest height of the easychairs was ergonomically acceptable in all the companies surveyed. Seat height, seat depth. seatwidth and ann rest height were lower than the accepted standard values. Such improper dimensionsshould result in discomfort and body pain. The angle of rake and angle of tilt, which indicate theinclination of the back rest, were significantly lower in the sampled chairs. The inclination of the backrest was iower than the req u ired 115°- 120°, wh ich should resu It in low back stress and static musculartension, which may lead to development of back injuries.

In order to improve the ergonomic parameters of the Medal Putuwa, a prototype chair was designed.Seat height, seat depth, seat width, arm rest height, of the prototype char was lower and it had higherangIe of ti It and angle of rake. The designed prototype chair was evaluated against a normal controlchair, and the users rated the ergonomically designed chair was much better compared with thecentro I in terms of comfort.

The present study reveals the need for Sri Lanka to have specific standards based on the body sizesof users, for des ign of furn iture. This wi IIenable the production of ergonomically correct and aestheticallyacceptable quality furniture in Sri Lanka.