Intro: Welcome to the E6S-Methods podcast with Jacob and Aaron, your source for expert advice on Lean, Six Sigma, and performance improvement methods. In this episode number 45, we finish off our discussion on unbalanced flow, part 2 of our “Value Stream Essentials” series. ***Unbalanced Work Flow Makes Work Overflow*** Here we go.
Objection 1: Our processes are too complicated to look at flow
Counter 1: No process is too complicated. It may take some digging and hard work, but the more complicated the process is, the more likely you need to balance the workflow.
Objection 2: We don't deal with customers. This doesn't apply.
Counter 2: Everyone has a customer. There is always someone waiting for the work package to come through.
Objection 3: Our process demand are too variable. All we can do is react.
Counter 3: Variable processes are more complicated, custom orders, etc. There are other techniques to regulate ubalanced demand.
I Symptoms of unbalanced process flow
a. Missing promised delivery dates.
b. Work piling up in certain areas, no matter how hard they work. Complete stress. Significant overtime work.
c. One department overwhelmed, while another has it easy.
d. Think of a Dam, or a toilet
e. Explain overflowing toilet, overpromise under delivery, compounding lead times out of control. Little's Law
II Causes of unbalance process flow
a. Processes do not observe Mass Balance.
i. Mass Balance equation. Accumulation = In – Out + Generation (Pkgs/time)
ii. For Accumulation to equal zero, the mass going out must equal mass coming in. Otherwise you get an overflow in the form of Work in Progress (WIP)
1. Examples of WIP
a. Partially processed product stacking up between process steps
b. Emergency Room Waiting Area
c. Call Center Queue
d. All lines and traffic jams
e. All Floods, Overflowing Toilets, Gutters, Bathtubs, Dams, are like WIP
iii. In Business, Takt Time must equal Throughput Time (Time/Pkgs: Math inverse of Mass Balance, but same idea)
1. Takt Time = demand rate. The rhythm a single product (order) comes in.
a. Calculated based average order volume and normal work hours (discounted for breaks)
2. Throughput Time = the actual rhythm of a process. The rate the product or orders get spit out.
a. Lead-time : The time the customer waits between order placement and order fulfillment
i. The more unbalanced the workflow, the more lead-time will climb
1. Assuming FIFO (first-in-first-out, i.e: “first-come-first-served”) Little’s Law Applies
a. Little’s Law
i. Lead Time = (Throughput Time)*(WIP)
ii. As WIP increases, lead time multiplies (slope of the line), continues to climb (customers wait longer)
b. Theory of Constraints – Eliyahu Goldratt (Late author of The Goal, Critical Chain & more)
i. A process can move no faster than it’s slowest step. (Chain only as strong as weakest link)
ii. The slowest step is the “Capacity Constraint” (The “clog” in the drain.)
1. Easily visible in the Gemba by how much WIP piles up before it
2. Value stream map and process load chart are key tools to analyze, then visualize, brainstorm, and simulate improvements.
Outro: Thanks for listening to episode 45 of the E6S-Methods Podcast. Stay tuned for episode number 46 where Jacob and I take a pause to reflect and debate on the direction of the podcast. Subscribe to past and future episodes on iTunes or stream us live on-demand with Stitcher Radio. Have an idea for an episode? Contact us! Follow us on twitter @e6sindustries. Join a discussion on LinkedIn. Find outlines and graphics for all shows and more at www.E6S-Methods.com. “Journey Through Success”