While batching production steps might seem like the only efficient way to complete a task, it can actually inhibit your opportunity to keep the process flowing.
Modern Machine Shop,
From the monthly column: Competing Ideas
I deliver this message time and time again: “Stop batching!” For anyone unfamiliar with the term, batching means doing a little bit of work on a lot of different “things.” When one step is finished, you go back and work on the same “things” until all the work is done and the entire production process is complete.
The quantity of “things” going through the entire process is the batch size. When we batch things, whether they are parts, assemblies, services or information, we introduce waste into the process. The predominant form of waste is waiting, as most of the things in the batch sit while someone works on one of their “batchmates.” Many people understand that batching is wasteful and have taken steps to eliminate or minimize it. Unfortunately, others see nothing wrong with batching. Some even believe it is the only efficient way of getting things done.
Batching drives me crazy, especially when I see examples such as these:
• For parts that need to be drilled and tapped, operators set up a single-spindle drill press to drill all the parts and then set up the same drill press to tap all the parts. Even if the drilling and tapping processes are quick, it can take a long time for the first part to be finished.
• Operators finish 50 parts on a CNC machining center and then take all 50 parts to a pedestal grinder to remove burrs and sharp edges.
• An operator on a single-piece-flow assembly line works on three or four parts at once, and then puts them all back on the line at the same time. The operator at the downstream station must go from doing nothing to scrambling to handle this sudden, unnecessary surge of parts.
• An employee releases an order for 20 products to production without having all of the components available. When the job starts, it can be assembled only to a certain point. After that, the process must stop until the rest of the components arrive. Only then can it restart.
• A warehouse attendant picks parts to fulfill 10 orders at once. The attendant then brings the parts for those 10 orders to a computer for processing and finally packs those 10 orders in preparation for shipment.
• An employee enters 10 new customer orders into the management information system. However, the employee prints the orders at the end of the day, and they are delivered to the manufacturing floor the following day.
• An employee handles a customer-service issue on the telephone and takes notes during the conversation. Afterwards, the employee enters the notes into a corrective-action file so someone can follow up on the issue.
As strange as some of these examples may sound, they represent the type of batching activities that occur regularly. Some of you may have seen similar examples. This batching mentality can be tough to break because it has existed for decades and is “the way things have always been done” in some companies. Batching is defended with comments such as: “It enables operators to get into a rhythm;” “It provides us with a cushion in case equipment breaks down;” “Our people have limited skills and work best when they can do one thing over and over;” and “The type of equipment we have forces us to batch.”
With regard to equipment causing the need to batch, traditionally there have been certain types of equipment that we believe must produce a large quantity of parts all at once. For example, heat treating has been viewed as a “batch-oriented process” in which we put all the parts into an oven, wait a certain amount of time and then pull the parts out of the oven. However, there are alternative types of heat treating. Many heat-treat furnaces include conveyors that keep parts moving. Each part receives the required heating time in the furnace, but when finished, parts exit the furnace at different times. Conveyors eliminate the need for batching and accommodate a “continuous-flow” approach instead.
Similarly, if we think of the latest innovations in machining, many have addressed the batching problem. Any CNC machine that has tool changers, rotary tables or multiple spindles is geared to do more in one setup, thereby reducing the need to batch parts through consecutive operations. Some companies have developed their own creative means of eliminating batching and benefitting from faster product throughput times.
I will continue to urge companies to stop batching whenever possible. After all, when we B-A-T-C-H, we run the risk of Bringing All Timely Completions to a Halt.
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