The Background of Production: How to Perform the Strength Test of Chairs

A Japanese classroom with many sets of a desk and chair are aligned

All the Japanese classrooms look exactly the same

If you have watched Japanese anime, you may notice. All the Japanese classrooms look similar at any time and place. My major in college is education, and I had visited many schools and found classrooms looked surprisingly uniform. As some of you may say “Likewise in my country,” but I think the uniformity of Japanese classrooms is by far more than yours. The main cause would be the classroom desks and chairs, I guess. You can see the same sets in no matter which school you visit in Japan. There’s almost no difference other than the fact that there’s always graffiti on the desk.

Classroom desks and chairs are exposed to tough conditions

Funnily enough, what students do with the chairs is also the same: tilting their chairs back. I bet you’ve done this before. Tilting your chair back and sometimes falling when getting beyond the point of no return. Students of inquiring mind try to figure out the point of no return and sometimes succeed in keeping balance and standing still only with the rear legs of a chair; other students seated behind jerk the backrest.

In addition to the above cases, the time of trial for chairs continues even after school. As students are supposed to clean their classrooms, desks and chairs are stacked up and dragged around every day. It may be natural for classroom desks and chairs to be designed the same for structural reasons to meet the specifications required for the tough conditions of use like this.

In fact, the movement of tilting back chairs just like students do in a classroom is most severe structurally for chairs, and it is highly likely to give heavy damage to chairs. This is the reason why the same movement is adopted in the standard strength test of chairs as shown in the following movie. Chairs are jerked in the backrest with the weight of 60 kg on the seat.

I remembered the days of my teacher training the moment I saw the test. In the Japanese standard (unwritten rule), it is generally said chairs should have a strength to withstand more than 4,000 trials of the test, while our standard is 12,000. Our chairs look slender but are strong and tough enough for long time use. Having said that, I don’t endorse rough treatment of our chairs, of course.

A corporate logo, the letters of C and H are combined to look like a tree in a circle

Shungo Ijima

He is travelling around the world. His passion is to explain Japan to the world, from the unique viewpoint accumulated through his career: overseas posting, MBA holder, former official of the Ministry of Finance.