Q: What is First Time Through (FTT) or First Time Right (FTR)?
Daniel Högfeldt • Quality rate could also be called first time through. It is important to get a correct FTT number in the OEE calculation.
First Time Through
The only information that is needed to be collected is some combination of; total parts, good parts and scrap parts. The ratio of good parts to total parts will give the FTT rate. On casting machines this is not really an issue. It is somewhat straightforward to count the amount of scrap and total parts the machine made during the shift. Where it could be a problem is when it comes to secondary operations. If scrap parts are not noticed in the inspection after the casting operation some parts could go on to the machining operation. The question here is how to calculate FTT on the machining operations when the scrap is from the casting operation?
How to calculate FTT
One approach could be to send all casting scrap found prior to machining back to the casting operation so that it would hurt their FTT and not the machining FTT. Then it could be sent back and be counted in the casting FTT. If the part is machined and the casting scrap is found after that operation then the part is counted as machining scrap. In this case it is important to have some scrap codes at the machining operation for the casting scrap. That is important because of if the secondary machine turn out to have a poor FTT it is good to be able to see if the defects are machining defects or casting defects.
What if scrap that was found after machining were to be sent back and not noticed in the machining FTT? That would not be such a good idea. Even if it would sound unfair for the machining group to get a lower FTT because of casting defects they might not could notice, the equipment still have machined the part and therefore lost time manufacturing a scrapped part. This has to be noticed in the quality part of the OEE. If the scrap were just sent back to the origin place were it was made outside of specification that time would not be noticed. On the other hand as long as it has been noticed in the machining equipment’s FTT, then it could go back to the casting equipment as well to get an accurate FTT on that machine.
The FTT in OEE should not include parts that is on hold or may be condemned. If the part is transferred and later found to be scrap, the waste percentage should be indicative to the loss.