The Theory of Constraints is a methodology for identifying the most important limiting factor (i.e. constraint) that stands in the way of achieving a goal and then systematically improving that constraint until it is no longer the limiting factor. In manufacturing, the constraint is often referred to as a bottleneck.
The core concept of the Theory of Constraints is that every process has a single constraint and that total process throughput can only be improved when the constraint is improved. A very important corollary to this is that spending time optimizing non-constraints will not provide significant benefits; only improvements to the constraint will further the goal (achieving more profit).
Five step process
Problem situation: Samsung Note 7 Battery Explosions, Turns Crisis into Opportunity
The core of the situation is that Samsung faced a serious issue with Galaxy Note 7 phones that have a high propensity of batteries failing and in many cases catching on fire, leading to personal and property damage. In a report, the company detailed flaws in battery design and manufacturing that it believescaused the crisis. It affects the utilization of the phones. All the inventory and operating expenses turn into loss for the company.
To regain trust, Samsung had to identify the root cause of the issues with the Galaxy Note 7 and apply these learning to future product designs.
Galaxy Note 7 phones have a problem of batteries failing or catching on fire, leading to personal and property damage. Samsung builds a test lab to findthe root cause of the Note 7’s issues. They tested around 200,000 devices and 30,000 batteries in an attempt to replicate the cause of fires in the phones. Batteries from two different manufacturers had flaws. The principal root cause of the first manufacturer’s battery problem (Battery A) was negative electrode deflections. The second manufacturer’s product (Battery B), suffered from abnormal ultrasonic welding burrs.While the principal cause was different in each type of the battery, the result was the same. A small subset of batteries could overheat and potentially catch fire. It’s clear that the smart phone industry’s desire for ever thinner phones with longer battery life have strained battery manufacturing processes.
After that old Note 7s being replaced by hundreds of thousands of new “safe” models. The safe models or updated models of Note 7’s were updated to ONLY charge to 60% of its capacity. This in turn, keeps the devices from “supposedly” overheating.
The test lab tested the whole device, including areas such as the role of wired and wireless charging as well as fast and normal charging. It also tested the water resistance, with and without the back cover.
Samsung tested other device features such as the USB-C charger and Iris scanner.It evaluated the software and algorithms tied to wireless charging. It even evaluated how third party applications were impacting the phone. Additionally, it worked with three independent third party test labs – UL, Exponent, and TUVRheinland – to assess issues across software, hardware, manufacturing, logistics and handling. The finding from Samsung tests and the independent labs revealed the same results.
As the updated models of Note 7’s were updated to ONLY charge to 60% of its capacity and this prevents the battery from overheating. But the problem is still not fully eradicated. Hence Samsung creates battery advisory group and designs an 8-point battery safety system to avoid further damages.
It has implemented a multi-layer safety measures protocol at the product planning and a new 8-point battery safety system. This system includes:
Durability Test -Conducting additional durability tests, including battery nailing, stress testing with extreme temperatures and overcharging tests.
Visual Inspection- Visually checking the battery to compare it with samples confirmed to be in accordance with standardized criteria.
X-Ray Test- Running X-ray tests to inspect any possible battery issue such as a deflection of the electrode, which we found to be one of causes of the Note7 issue.
Disassembling Test- Disassembling the battery cell to perform a detailed check of the overall quality, including the battery tab welding and insulation tape conditions, which we found to be an issue with Note7.
TVOC Test- Performing a sensing test to detect leakage at the battery component and complete device levels.
OCV Test- Inspecting the battery condition by checking voltage change in a normal temperature.
Charge and Discharge Test- Applying new large-scale charge and discharge tests to all devices, which we initiated with our investigation into the Note7 issues.
Accelerated Usage Test- Engagingin 2 weeksof real-life consumer usability scenarios, which we were able to shorten to a five-day test period.
Then,identify a new constraint -because there always is one.These five steps are a continuous improvement cycle. Therefore, once this constraint is resolved the next constraint should immediately be addressed to increase the throughput. This step is a reminder to never become complacent, aggressively improve the current constraint and then immediately move on to the next constraint.