OnePlus has in the past invited various publications and journalists to tour their production facility so as to show the world how it puts phones together. Normally when journalists are invited for factory visits by most brands, the companies are particular about not allowing any photography or filming inside. This time, however, OnePlus invites Linus Sebastian of Linus Tech Tips to tour their production facility that was producing the recently launched OnePlus 6. Linus brought along with him his 8K Red Weapon camera and recorded his visit in intricate detail. Linus says that when he shot the video, OnePlus was in the PVT or Production Validation Test phase of production. Here’s all the steps OnePlus apparently takes to ensure a certain quality in the final product.
Inspected by Hand
During the construction of the OnePlus 6, the device is inspected by humans at various stages. They check for any physical blemishes on the outer housing, the display and the buttons in general. They also inspect the construction for any glue leakage. If any imperfections are found the part is either scrapped, or, like in the case of a glue leak, the whole phone is apparently taken apart and reassembled.
Machine Precision to achieve Perfection
OnePlus says that the alignment of various components must be exact in order to ensure structural and functional integrity. The company, for example, uses a machine to dispense the glue that is used to seal the display assembly with the housing. Machines are capable of repeated and precise behavior such as this one, so relying on them is a better idea. The company also uses machines to align and place the back panel, along with applying pressure on it to seal the back in place. With a human, it would be difficult to ensure the exact pressure being applied at the exact spots for a precise amount of time, a thousand times over.
Post Construction Quality Assessment
Once the phone has been assembled (going through checks and inspections at each stage), it goes through a final visual inspection and wipe down. Software is loaded onto it and then, each finished unit goes through what is called a thorough quality assessment process. There are 16 steps in the QA testing which involve testing the flash, proper functioning of OIS, an autofocus test which involves moving the camera away from and closer to the test target and even a human inspection of all camera functions in case the QA software may have missed something. The headphone jack is also tested to ensure it behaves the right way when plugging and unplugging headphones. Other tests ensure that the antenna, WI-Fi and GPS chips dash charging and other aspects of the device are working as per specification. At some point during this stage, a machine is also seen applying a screen protector to the OnePlus 6, a practice that has become standard since the OnePlus X to prevent damage during shipment. Finally, the process wraps up with another visual inspection and wipe down, after which the devices are placed in protective sleeves and shipped off to packaging.
The above steps are what OnePlus would have followed when it started mass producing the phones, but Linus says that when he visited the factory, OnePlus was in the PVT (Production Validation Test) phase. What this means is that the phones coming off the QA testing line are then subject to an additional battery of tests, also shown in the video. PVT is a stage just before mass production where the company would produce a few thousand units of what it would consider “ready-to-ship” devices, and then subject them to a few real-world scenarios that help test the robustness of the device. Here are the tests the OnePlus 6 had to go through.
Part of the testing involves putting the OnePlus into a chamber that is capable of rapidly changing the inside temperature from 75 degrees Celsius to -40 degrees Celsius. The phone stays in this chamber for up to a week and a half. From here, the phone then goes into a second chamber that maintains very high temperatures at 95 percent humidity. From the humidity chamber, the phone is put through a raindrop test where the phone is subject to simulated rain for a 100 hour. OnePlus expects that after a few days of drying, the phone should be fully functional. Interestingly, during the tour of the assembly line, Linus does mention that the lower half of the OnePlus 6 has the same kind of water seals found on higher end smartphones with IP ratings, but OnePlus does not offer any kind of claims or warranty against water damage. At closer inspection, the rain chamber does seem to look like the one that would be used for IPx3 and IPx4 testing, but since the given that there are no details about the rate of flow or angle of spray, there’s no way to know if OnePlus is indeed testing against an IPxx standard. If the phone survives all three of these tests, then it moves onto the next phase.
Drop and Tumble Tests
The next step in the PVT phase for the OnePlus 6 is going through a series of drop tests. OnePlus apparently dropped the OnePlus 6 onto a smooth slab of marble from multiple heights. For each height, the phone is dropped twice on its front face and twice on its back. The acceptance rate for this test is a maximum of 10 percent screen damage, but the rest of the phone must function as intended. After the drop test, the phone goes into a tumbler. Think of the tumbler to be essentially like the dryer in machine, but instead of spinning horizontally, this one spins vertically and a lot slower. The idea is to simulate real-world fall scenarios. After 150 drops, the phone must not have more than 10 percent screen damage, but there is no clarity on whether OnePlus expects the phone to function normally here as well.
The endurance lab is the last step in the process. Here, OnePlus has machines that test the robustness of the charging port and the headphone jack by plugging and unplugging cables and applying pressure on them. There is also a machine that simulates the pressure your phone undergoes when you decide to sit with the phone in your back pocket. This device applies 25 kilos of force on the screen a total of a thousand times. The last step is putting the phones through a staggering number of minor drop tests. The OnePlus 6 is dropped from a height of 10cm 10,000 times on its back, 10,000 times on its front and 2,000 times on each edge for a total of 28,000 drops. OnePlus expects the phone to easily survive the minor drop test.
To be clear, it is not the same unit that is going through each of the three test phases above. Of the phones that roll off the assembly line, a batch would perhaps first go through one of the test labs. Only once they have found the right combination of materials, construction and assembly practices, using that “recipe”, phones are made for the other two tests. The PVT phase allows a manufacturer to fine-tune and refine the “recipe” for the smartphone before it goes into mass production. For example, if the OnePlus 6 was constantly failing the bend-test in the endurance lab, the company would have to rethink the material choice or the structural design. If during the 1m drop test onto a marble slab the phone’s functionality was impacted, the company would have to re-examine how it was putting the inside components together. Once all these imperfections have been ironed out and a phone design that can pass all these tests has been achieved, then the phone goes into mass production.
While getting a look behind the closed doors of OnePlus’s quality control lab is great, we still don’t have clarity on a few things. For starters, we don’t know the order in which OnePlus tested the OnePlus 6. Was it subject to the Endurance lab before the environmental tests or did the drop tests come first? We also don’t know the number of failures before OnePlus would consider sending the phone back to the drawing board. The entire production process is an evolving process, with each step being refined and tested as the company moves closer to mass production. The assembly line and its failures are as critical as the Environmental, Drop and Endurance tests, with learnings from each possibly having an impact on the others. You can see Linus’s factory visit in its entirety below.