Apple has been having issues meeting consumer demand for the new Apple Watch, and now we know why — many units are defective, with faulty taptic engines.

The taptic engine is essentially the part of the watch that vibrates against the user's wrist in the event of a notification or warning.

Only two suppliers are producing the taptic engine for the device, and one of those suppliers, called AAC Technologies Holdings, has been rolling out the defective part. Reports suggest that this led Apple to ditch a number of Apple Watches that had otherwise completed the production phase.

"Our team is working to fill orders as quickly as possible based on available supply and the order in which they were received," said Apple in a statement. "We know many customers are still facing long lead times and we appreciate their patience."

After discovering the flaw from AAC, Apple moved all production to the second supplier of the taptic engines, a Japanese company called Nidec Corp. Of course, because of the fact that it was originally only supposed to handle half of the production, Nidec Corp. is a little behind the production rate Apple might have liked. It is not clear how long it will take Nidec Corp. to catch up on production of the device, however, Apple has said that it will launch the device in other countries in June. Reportedly, Nidec Corp. has done well at catching up with orders, and Apple has been able to ship some units earlier than expected. It is not expected that the device will be sold from Apple Stores until May.

It is possible that a number of units with faulty taptic engines made it out into the world. In fact, a few reviewers even received faulty units.

Apple seems to be experiencing more issues with the release of new products in recent times. In 2010, Apple released the iPhone 4, which then reportedly had a number of issues with the antenna of the device. In 2012, Apple launched Apple Maps, which was a huge flop and led to Apple CEO Tim Cook even referring users to competitors from the likes of Google and Nokia.

The word "taptic" is a play on the word "haptic" and was coined by Apple for the Apple Watch. It is one of the key technologies created by Apple for the watch, and basically uses a motor to rotate a small rod back and forth, creating the vibrating effect.