* Improper product from upstream processes (wrong dimensions, doesn't assemble, wrong physical properties, etc).
* Unplanned downtime.
* Being behind on production goals (meaning they won't stop the machine for you to install and test your new widget that might fix everything).
* Management turning down many very useful OEM upgrades on a cost basis.
* Imbalanced production rates. The bottleneck of the factory should be the primary focus for improvements.
And for a fun fact: lubricant used in food production equipment must be safe for humans. For this reason, vegetable oil and similar products are often used.