Question

You have the choice to purchase one of two machines, which can produce exactly the same product. Machine A has a MTBF of 100 hours and MTTR of 10 hours, Machine B has a MTBF of 10 hours and a MTTR of 1 hour.

What is the availability of each machine?

In terms of process stability and inventory which machine would you prefer to purchase & why?

Answer 1

Answer:

We would prefer to buy / purchase Machine A because of the following reasons as

· The Machine A and B can produce the same product with similar processing timeline. Hence from the timeline point of view, we can purchase any of Machines i.e. A or B,

· Machine A has a MTBF of 100 hours and MTTR of 10 hours. Thus this machine can run continuously for 100 hours before any failure or downtime. Thus we can achieve smooth production for long duration and it will not make any disturbance/ obstacle due to failure or breakdown. Though the MTTR of 10 hours is high, but it is one time and it is matching exactly with adding the downtime of Machine B. Thus Machine A is better in terms of MTBF ( mean time between failures) and MTTR ( mean time to repair).

· For production point of view, we need a machine which can run longer without failure, thus a machine with larger MTBF is better choice than smaller MTBF. Hence we selected Machine A.

· MTTR should be low, but if we compare for longer range , the MTTR for both machines A & B will going to be same, hence Machine A do not have poor MTTR as compared to Machine B. Thus our choice is Machine A.

· Machine B has a MTBF of 10 hours and a MTTR of 1 hour. This machine will show repeat issue/failure after every 10 hours, create obstacle in production on daily basis. This will reduce the motivation for employee and difficult to manage the production. Hence we will not select machine B.

The actual availability of both the machine is same i.e. machine A get failed after 100 hours for 10 hours. Machine B get failed for 1 hour in every 10 hour, means for 100 hours of time, it will also down for 10 hours. Thus the availability is same for both machines. Both will be down for 10 hours in 100 operating hours.

In terms of process stability and inventory, machine A will be preferred because it will create better production as it can run for long time of 100 hours without any failure and will not create any inline inventory due to no repeat failure in machines in short intervals.