Ever spend a ton of money on the newest fancy gadget that the sales person promised would double your throughput only to find that six months after it has been installed, your numbers are kinda sorta where they were before? Or, perhaps, you hired a few people to push more out the door, only to discover that although you may have shipped more product, per labor hour you actually got slightly less efficient. There is a reason for both these scenarios and thankfully there is also a fix.
If there were rules to lean manufacturing, Rule 1 should be: Get good at the basics, execute them relentlessly and if you ever find yourself getting lost or confused, revisit them immediately.
For those who know me, you already know I am a true blue lean maniac and a huge fan of Eli Goldratt’s “theory of constraints” (referred to as TOC going forward). So much so, that I got my certificate from the Goldratt Institute in 2014. My approach is this: Use TOC as the focusing mechanism and lean as the execution and improvement tools. Let’s dig in.
The fundamentals we will be covering are the five focusing steps.
Step 1. IDENTIFY THE CONSTRAINT: This tells us where to focus all our lean improvement techniques. We know if we don’t affect the constraint (or bottleneck) we will not see the system improve.
Step 2. EXPLOIT THE CONSTRAINT: This means that we are going to use our heads not our wallets. Do everything possible to improve the constraint before we start spending money.
Step 3. SUBORDINATE ALL NON-CONSTRAINTS: This means it’s the function of all non-constraints to base their decisions on the needs of the constraint, not what’s best for them.
Step 4. ELEVATE THE CONSTRAINT: Only after we do the first three steps do we spend money to increase capacity at the constraint. Adding capacity can be expensive with regard to time and money, so we do this last.
Step 5. RETURN TO STEP 1: The end result of the first four steps, is the constraint will move somewhere else.
The first most important thing to understand is a bottleneck. Every business has one that limits the throughput of the entire factory. The real challenge is identifying it. Finding the one thing that is slowing down all the things takes a trained eye, some experience and bit of luck. If you’re not sure where your bottleneck is, look for the big pile of work, it could be paper on someone’s desk or actual products on the shop floor. Then start with the process right in front of that. If it’s not your real bottleneck, don’t worry, cycle through the five steps a few times, and you will find it. When you do, you will immediately know it.
Following the steps
STEP 1. When identifying the constraint, if you happen to guess wrong and add capacity before the bottleneck, what will happen is you will actually end up sending more work to the constraint. Ever pile work onto someone and get a good result? Me neither. In all likelihood, you will actually see a reduction in overall performance of the system.
If you guess wrong and add capacity after the constraint, the result will be pulling work away from the constraint faster than its producing it, thus having that work station constantly running out of things to do. In the end, your throughput does not change.
STEP 2. To exploit the constraint, this is where you focus all your cool lean tools and techniques to eliminate waste! Watch the movement of the worker. Bring tools and machines closer to reduce transport. Make sure equipment is functioning perfectly. Create shadow boards so operators are not searching for tools. Stage parts correctly and do everything you can think of at the constraint to make the person’s job easier. Everything you do during this phase should be at no cost or low cost to the company.
STEP 3. Subordinate all non-constraints. What the heck does this mean? It's a fancy way to accomplish two very important tasks.
A) Get everyone thinking about the bottleneck operation. When they understand their station has excess capacity, that will actually hinder the process. If fully utilized, they won’t mind slowing down a bit to consider how they can help the constraint operation.
B) Slow down each step of the process to operate at the same speed as the constraint. In lean terminology this would be a form of line balancing.
STEP 4. Elevating the constraint at this point is the next natural progression. Whether it be with some additional tooling, a new piece of equipment or the latest software application. Just be sure you have done a great job of Step 2 and exhausted avenues for improvement. All too often, we listen to smooth talking sales people and fall for fancy new machines when in fact we could yield a tremendous benefit before having to go out back and prune the money tree.
STEP 5. Repeat. After Step 4, your constraint will move. This is sometimes the part we seem to forget. You run through the focusing steps, it works, and you are so busy reaping the benefits that you think it’s over. But, like all continuous improvement efforts, no matter where you are, you have only just begun.
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