There are a lot of humans standing on assembly lines building products, including Apple devices, but some companies have had their sights set on automating that routine for years.

And in some categories, including automobile manufacturing, it has worked out. But that is apparently not the case for Apple, as a new report from The Information details. The story explains how Apple, almost a decade ago, started an endeavor to get robots to manufacture products like the iPad, but, since then, that transition has not gone as expected.

Where it started

In a secret lab in Sunnyvale, California. The company brought in a range of individuals specializing in robotics and automation. The goal? To find a way to reduce the number of humans at its assembly lines, finding the specific areas where a robot could be a better fit for the manufacturing process than a human. But issues arose almost immediately, according to the report:

Building a robot that can fasten screws is among the hardest challenges in the industry. A robot must pick up the screw at a specific angle and align it with a hole using multiple industrial cameras. Apple uses screws so tiny that robots had no way to measure the force used to drill them in. By contrast, human workers can feel the resistance from their hand and can tell when something is off.

As for putting glue onto display panels, Apple’s specifications are so tight that glue must often be placed within a millimeter of its desired spot inside a product. One former team member said well-trained Chinese workers were more adept at applying glue than their robot counterparts.

Lingering headaches

And the issues kept cropping up, too. Fast forward to 2014 and Apple tried to automate at least part of the manufacturing process for the 12-inch MacBook. But that did not go over well, either:

In early trials, the conveyor systems moved erratically, slowing down the movement of parts. A robot that installed the keyboard using 88 small screws kept malfunctioning, requiring humans to come in afterward and rework most of the process. Containers used for moving parts kept piling up on conveyors, creating traffic jams.

A silver lining

But it’s not all bad news for the automation sector. Apple has discovered areas where automating the process can actually be beneficial: testing. According to the report, replacing humans with robots for the more simpler tasks, like testing the Apple TV, the iPad, or the Apple Watch has worked out for the company so far. But, based on this report, it doesn’t sound like automating the full, or even large sections, of the manufacturing process has gone according to plan for Apple, and suggests we won’t be seeing a major overhaul of this nature any time soon.

In the end…

…Apple’s goals for automation have simply changed. The company has Daisy, a robot that helps with the recycling process of iPhones.

Go check out the full report, it’s absolutely worth a read.