Hacker News Reader

Comment by _nalply | Hacker News Reader

Speculating but I think a production line has a rigid synchronized speed. If a step suddenly takes more time everything else must wait.

Imagine a queue of people at a buffet where overtaking is not allowed. If someone dawdles around at the juicer, people behind them need to wait while the salad bar is emptying and suddenly the cashier has nothing to do.

View on HN

Many years of Japanese factory management techniques have demonstrated quality and efficiency in the auto industry. They work closely with the line by making sure consistency is maintained to a high degree in the queue and by stopping the line when it needs to fix the problem to keep problems from compounding downstream.

Adding a capacity for parallel fix up product looks good temporarily but ends up decreasing quality and productivity with a lot of extra waste - one thing that Boeing has recently shown again.

If a station has a longer cycle time than others on a line, you just duplicate the station so that the throughput remains the same. If you have say 10 painting stations, you can on average pass a car through in 1/10th the time it takes to paint a car.

This makes sense when everything is running normally, but if one of your 10 painting stations goes down for a day, every upstream assembly step is forced to run at 90%, since the painting step is now a bottleneck. Given the huge cost of idle capital, it makes sense to minimize the upstream impact of any given issue.

And if any one of your single stations goes down the line is forced to run at 0% speed. You add sufficient redundancy and perform preventative maintenance so the line doesn't go down. 11 car painting stations is still way easier, cheaper, and safer than building 1 station which is 10 times faster that can never go down.

That adressing throughput not costs. If you keep costs contant, lower prices but acchive higher throughput, the only thing you acchieve is to lose money faster than you would have done otherwise by just lowering costs straight away.

Reply on news.ycombinator.com