Cycle time is the time it takes to add value at a single station of your production process. It is the inverse of the production rate. The station with the longest cycle time determines the production rate of your entire process. Bring it down!
Running out of glue, tape or other basic consumables can shut down your entire line. Put a paper card next to your consumables that says “Order more X” and have your workers pass the card to the front desk. Once the consumables arrive, place the card back with them.
Your product and its parameters such as lead-time, quality, and cost are valuable to your customer. Think about your manufacturing process as a stream in which many hands add up to this value. Now you can ask whether an activity is creating value or should be considered waste.
Lean is a mindset to get done more with less by identifying and reducing activities and stuff that does not directly add value in a five-step iterative process. You will be surprised at how much there is to optimize!
A compass is a great indicator of where to go as long as you are far from the pole. The closer you get, the more it gets off, eventually even letting you turn in circles. Manufacturers compare optimality with the true north - best practices might do the opposite as you come closer to true north.
The production rate, i.e. the number of products per time that your process can produce, is determining how long it takes to fulfill an order of a certain volume as well as the lead-time of a made-to-order product. It is determined by the production rate of your slowest station, where improvement should start.
There is no benefit of running faster than the slowest station in your process. Identify cost-effective ways to slow a fast station down (energy, tool tear-and-wear, decreased maintenance, etc.), and use them.
Overprocessing is difficult to pinpoint and might make up the unique quality of your product, but reviewing every step of your production process for cheaper alternatives that maintain customer value might save a lot of time and money in the short run.
As an order proceeds along your line, value is added only in a fraction of the total manufacturing lead time. Some time is spent on processes that could be sped up or altogether removed, such as transportation. A lot of time is lost waiting. Graph out the different times along your value stream and color them green, orange, and red to see how you can improve lead-time!
Think about your production line as a busy highway. Ever wondered how traffic jams come seemingly out of nowhere? One way to reduce traffic jams is to throttle traffic, think metering lights. You can do the same in your line using a “pull” system.
Make sure you continuously reassess what maximizes value for your customer. Today it might be reducing lead time, tomorrow it might be to maximize quality or reduce cost. There is always something left to optimize!
Lead time is the product of the number of products you can make per day (production rate) and the number of products currently in the making (work-in-process). Increase the production rate of your “slowest” station or limit the number of products in your line by introducing a “pull” system.
The ultimate goal of “lean” is customer value. This can be anything that the customer is willing to pay for such as higher quality, lower lead time, lower price, more customizability, less carbon footprint - you get the idea. These goals might be mutually exclusive, but simply optimizing for cost, time or else is not necessarily what the customer wants.
Inventory is everything you keep in stock to make things as well as half-done products on your shop floor. If your inventory is too small, your manufacturing line starves. If it is too high, you are wasting money and space.
Are your manufacturing cells still grouped by process instead by product? Use Optio's "Ratsnest" feature to visualize common product categories, switch to cellular manufacturing and increase your flow!
The Takt time is a time interval at which things need to move in your line. It needs to be equal or larger than the longest cycle time in your process to keep things flowing. It also keeps your WIP constant and thereby makes lead-time predictable.
You are only getting optimal throughput if all of your stations producing work at the same rate. First try to get all of your stations into the same ballpark by splitting and merging tasks, then optimize those that are slow.
OEE is defined by the fraction of what has been done and what could have been done in a given time. Measure OEE across all of your stations to get a quick glance at process health and where problems are brewing.
Digitization can provide you with real-time information, but you will need to know what you are looking for! Define what the goal is and map your value stream to understand what data you need and how to use them.
Anything that limits the amount of work-in-process in your line is known as a “pull-system”. Only release a new work order whenever a finished good leaves your line or release orders at a preset interval (“Takt”). Both times, your WIP stays constant and your lead-time remains predictably low.